# Re-conversion of a Scooter [pics on pg 2, post 17]



## 3dplane (Feb 27, 2008)

*Re: Re-conversion of a Scooter*

Hey Dj!
I probably missed it somewhere but what is the actual race? Like ten laps around something? or who scoots in first after 30 minutes?
Cool little scooter.
Barna


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## TX_Dj (Jul 25, 2008)

*Re: Re-conversion of a Scooter*

Barna,

The challenge will be two parts. I'm still fuzzy on the exact details, but it's more or less like this:

1) Speed/Acceleration Test: Zip down to a cone, come around it, and zip back to the starting point. Lowest time wins.

2) Range Test: Round and round a pre-defined course. Whoever has the most laps within an hour wins.

The first one is no sweat. The second one may end up being won by whoever is willing to abuse their batteries the most. I don't want to go below 80% on mine, and I expect others will not either, but someone may.


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## TX_Dj (Jul 25, 2008)

*Re: Re-conversion of a Scooter*

Things are coming along nicely.

Found that REI has cheap webbing straps with quick-release buckles for ~$2. Using these to restrain the batteries within the scooter. Should work quite nicely. 1" web straps are very strong, and the large buckles should hold back lots of force if the batts try to come free in a wreck.

Finished tearing out the old rear crossmember, and welded in a replacement roughly in the same position of the old seat post receiver tube, but back a bit- serves two purposes, the cross member, plus it is a hard stop for the battery pack to keep them from sliding back into the contactor and other items I'll be putting behind the batteries.

Removed all the stickers from the frame and did a quick-n-dirty rattle-can flat black paint job on the frame.

Got the new throttle mounted a few nights ago, and got the cable routed thru the steering down-tube. Controller is mounted in its new home where the old one was.

Got the chain and sprocket and rear wheel completely degreased, and mounted back up- reverse of the old orientation (sprocket on the left now instead of the right) because the new motor turns the opposite direction had has a freewheel sprocket installed on the motor shaft. The chain had years of dirt and grease and grit on it, and thanks to the awesome degreaser that I use on the S10 before painting the frame, it is completely free of grease or oily residue. Will use a dry teflon lubricant from here on out.

Working tomorrow on the new motor mount. The new motor is a larger diameter than the original, and furthermore has its bolt holes on tabs outside the diameter... the original mount won't work at all. No worries, though... I'll get it worked out tomorrow.

Hooked up all the electrics on the bench last night and heard the motor run for the first time.

My battery configuration will change from the original plan, but only in the wiring... still using the same batteries and same number of batteries.

I've decided on this project not to get wrapped up trying to take pics as I go along... it's a short enough project that it'll be fine to just have before/after pics. It's going to be a whole different beast when I'm done. 

Unfortunately, I didn't get out soon enough to pick up connectors for my wiring, and the only store I know of that has the connectors I need closed earlier than I expected, and is closed tomorrow. So... pics soon enough, but not tomorrow.


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## ice (Sep 8, 2008)

*Re: Re-conversion of a Scooter*

That looks great.  I'm excited to see how you will modify it...


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## Zemmo (Sep 13, 2007)

*Re: Re-conversion of a Scooter*

Anyone interested in seeing the scooter challenge rules, they are posted on our NTEAA website. That address is www.NTEAA.org. 

After seeing DJ's scooter, I need to get mine going. It has just been sitting there and it needs a few things fixed before it is ready.


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## TX_Dj (Jul 25, 2008)

*Re: Re-conversion of a Scooter*

Hehehe Zemmo! Starting to feel the heat of competition now, are ya? 

Should have some pics soon.

Spent yesterday afternoon and early evening building the new motor mount. The new motor is heavier, torque-ier, and larger diameter than the old one. As such, the new mount puts the motor beyond the reach of the stock chain. I was supposed to drop by the custom scooter store in Plano to pick up some chain this morning, but as morning-commute-autopilot would have it, I was more than 3/4 of the way to the office before I remembered.

Talked more with my EE friend, he's interested in the challenge my battery charging puzzle presents, and he's working feverishly on getting me a schematic to build the new charge system. Previously I was going to simply charge parallel banks of "buddy pairs", but after a lot of discussion and debate, he and I have decided it's a bad idea to put lead acid batteries in parallel with each other without isolation... so that's somewhat changed the charging paradigm. The design is not yet complete, so I don't want to let any cats out of bags ... but suffice to say I'm most likely going to end up with a completely custom charger rig as well. 

Tonight I finish up a few things on the motor mount, and get it affixed to the scooter and get the motor mounted to it. My ammeter/shunt should be on my doorstep as well, if not today then tomorrow. Still not entirely necessary for the scooter to have a voltmeter/ammeter onboard, but if I can find a way to build a "dashboard" to mount them to, I'm gonna do it!

I'm saving pics for when the design is completed and ready to run, then I'm going to take a lot of photos and get a friend to videotape me running it. I'll still be running with "stock comparable" gearing at first, but that's just because I want to see how much more torque and acceleration it has with the same-ish top speed (new motor has a 15T gear, old motor had a 12T gear, but with the difference in max RPM the ground speed works out to just about 1mph faster)...

I'll have a "top speed" wheel sprocket on hand in time for the challenge.


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## TX_Dj (Jul 25, 2008)

*Re: Re-conversion of a Scooter*

Things are really coming together. Still no pictures yet... but soon!

I finally have all the parts I need except my "gofast-sprocket", or at least have them on order. The main problem here is that the BladeZ folks decided to use a non-standard hub size for the wheel, both in sprocket locating bore and in bearing surface to bearing surface width. It's making it a real bear to get a smaller sprocket installed!

Last night I got started on wiring everything up.

Pics real soon now.


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## Zemmo (Sep 13, 2007)

*Re: Re-conversion of a Scooter*

We are getting down to only a few more weeks before the race. I still don't have mine up and running again. I have been watching craigs list for a parts scooter but haven't had any luck. Mabye I should convert the scooter into a contactor controller deal. So starting off at 12 volts and then switch it to 24 volts. 

I am glad to hear yours is coming along a lot better than mine. We want to see pics!


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## TX_Dj (Jul 25, 2008)

*Re: Re-conversion of a Scooter*

I'll have pics up soon enough. I just want to be certain as to which nooks and crannies I'm stuffing the rest of the components, and/or finish the complete build, before I put any pics up... but there WILL BE PICS!!!


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## TX_Dj (Jul 25, 2008)

*Re: Re-conversion of a Scooter*

So, I got everything in its place today. 

Checked and double-checked everything.

Plugged in the main pack.

Threw the switch.

The contactor said *CLACK!* and the controller diagnostic panel (some LEDs) lit up.

Back tire was off the ground, goosed the throttle and *WHIZZZ!*

Hooked my ammeter up to each of the two battery packs, and watched for the volts to change, and they were both changing, and I had voltage present at the output of the isolation diode regardless of if either pack was connected, and more importantly, with both packs connected. 

Pushed it out into the driveway, put my foot on the deck, locked the front brake and yanked on the throttle... she spun up and started to smoke a little... the tire, that is!

Gearing is "almost stock", and works out to just about 1 mph faster than stock, due to the slower RPM but larger drive sprocket on the motor.

My "go-fast" sprocket is on order, and should be here mid next week. 

A little problem though... while it is noticeably more peppy than before, it really doesn't seem to be all that different except on the minor hills around the house here. It will hold 15 mph where the old one would have dropped to 9-10 mph. However, I would expect far less voltage sag than the controller diagnostic LEDs lead me to believe, due to the parallel packs. Either I have an issue somehwere in the system, or I read the battery mfr's spec sheet wrong, or my isolation diode is causing me problems, or my ammeter shunt isn't letting all the watts get thru or SOMETHING. I dunno what yet, but I have all day tomorrow to tinker, and there's no light remaining today.

Oh, tomorrow I'll get pics once I have everything re-(re-)painted and secured permanently.


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## TX_Dj (Jul 25, 2008)

*Re: Re-conversion of a Scooter*

Couldn't resist tinkering with it more tonight.

Found that one of the battery strings was improperly connected. These batteries use .250" quick connect blades, and I'm using fully insulated connectors. One of them had the battery terminal wedged between the plastic and the connector, not quite a good connection for passing current.

Fixed that, took it out for another spin, and had no sign of sag from the onboard LEDs.

Decided to go for a "real" shake-down run.

Put about 7 miles on the scooter, full throttle, never let up unless I was going downhill or needed to slow for a corner or stop. Didn't sag once until I turned around to come home, which was mostly up-hill. Again running mostly full throttle at top speed, with a few spots where I slowed a bit going up hills to see what speed yielded the "green" light on the so-called volt meter that came with the controller, and then I'd slam it to the max again.

It never dropped below "yellow", and would pop back to "green" if I slacked out the throttle.

Got home and opened it up, not letting it rest at all, got voltage readings of 36.9 and 36.8 on the two strings of batteries. By the time I got the charger, the readings were already climbing back up due to resting.

Not too shabby for fresh batteries that still need to get broken in.

The freewheel sprocket is interesting, I must say. If I'm zipping along and release the throttle, it takes about 2 seconds for the motor to spin down... sounds kinda like something George Jetson would drive.  I'll have to see about getting a video or something when I'm doing my pics.


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## TX_Dj (Jul 25, 2008)

*Re: Re-conversion of a Scooter*

And the band plays on... 

Today I picked up the last of the parts to build my "dashboard" which will have the voltmeter, ammeter, and power switch that triggers the main contactor.

After last night's escapade, and the second pack "resting" all night, I had 37.9 V there, or 12.63 V per battery, which is still technically "100% state of charge" depending on who you consult. Not too shabby at all. Can't wait to get the voltmeter installed so I can see for sure what the voltage is at all times, and not trust a "dummy light"


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## TX_Dj (Jul 25, 2008)

*Re: Re-conversion of a Scooter*

Alas, another busy day working on the scooter, and I've run out of daylight.

The "dashboard" is finished, and just received its last coat of paint. 

Looks like it may be next weekend before I get pics up. Drats.


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## TX_Dj (Jul 25, 2008)

*Re: Re-conversion of a Scooter*

Well... it's been a long road... and it hasn't been cheap... 

But this ole scooter is just about done. The electricals and dashboard are all rigged in their final configuration, all instrumentation is in place and functional, all the painting has been done...

The only thing I'm lacking yet is the "go-fast" sprocket, which should be on my doorstep tomorrow, just in time for me to hand it off to my machinist friend, if he has time to work on it for me.

It's too dark right now, and the shop is too messy. I'll try to get up early tomorrow so I can snap some pics of the scooter in the morning light. "Early" for me means sometime before 9am (my shift starts late, and I'm a night owl anyhow). Probably won't be able to post the pics until I get to work... we'll see.

I love it when a plan comes together.


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## Zemmo (Sep 13, 2007)

*Re: Re-conversion of a Scooter*

It sounds like you have made some great progress! Now I know I am going to loose! I wanna see your dash board you made. I know what the LED light thing you talk about. It isn't very usefull, just basic info. I am excited to see your end project.


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## TX_Dj (Jul 25, 2008)

*Re: Re-conversion of a Scooter*

Interesting thing is... after I got the instruments wired up, it became immediately obvious to me that the "yellow light" wasn't due to voltage sag as much as a warning that I was pulling more that "continuous rated" amperage for more than a few seconds.

So, I only posted two pics of what it looked like before... but I'm going to post more pics of what it looks like after. go back to the first page if you need to see what it used to look like. It looks quite a bit different now. Take a look at the "diameter" of the motor from the "original pics" and understand that the motor was actually about half the diameter of the shroud around it... then compare to the size of the new motor. 


























































I had "just enough" blue quick connect female connectors, and one of them messed up when I was crimping it... that's why the top side of the ammeter wire is just wrapped on the fuse box terminal.

If you look carefully at the last pic of the fuse box, on the right side you'll see 3 thick wires coming off the 30A terminals, those are the wires to my dual-diode package. two are fused from the batteries, the one in the middle comes back up and gets fused again before feeding the contactor solenoid.

Why the solenoid? Doesn't the controller have it's own power control?

Yes, sort of. The precharge circuit will draw current all the time even if the switch input for the controller is in "disable" position. In fact, it can only disable by running current thru that switch!

Now if I clack the contactor, there's a brief precharge pause before the controller engages its internal relay. Also, the contactor terminals are rated for far more amperage than the scooter is rated- thus if there's an emergency shutdown need, I can throw the switch on the dashboard without fear of welding the contactor terminals during disconnect.

I rolled around the neighborhood last night, checking volts and amps every time I passed a street light. I can pull 30A very briefly, but it seems to limit to about 25A not too long after that. Flat ground at "top speed" with this sprocket seems to pull about 12-14A.

The freewheel sprocket is a godsend, though... I can cut out power long before when I would have needed with the old setup and still coast pretty darn far.


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## Zemmo (Sep 13, 2007)

All I can say is WOW! I will vote right now on the best looking conversion right now! That is really great looking, nice mounts, painted, arranged and everything.


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## TX_Dj (Jul 25, 2008)

Thanks Jared!  Like I've been saying... better have some trophies with my name on 'em, cuz I plan on taking at least one home with me. 

I do think I had my fuse box upside down when I marked the holes for it, and I think that's why it looks lop-sided in the photos. the holes are offset on the mounting flanges. I'll have to take the motor and tire off when I'm test-fitting and building a chain for the "go-fast" sprocket, I'll see if I can turn the fusebox upside down and make it fit "straight" like it's supposed to, otherwise I'll just have to deal with it. LOL

Edit: I see that the pic of the fuses I chose for posting here doesn't really show the crookedness of the fuse box... below is what I'm talking about:


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## TX_Dj (Jul 25, 2008)

BLAST!!!!!!!!!!!!!!!!!!

I just was staring at this picture and figured out why it's wrong!

The holes will be in the same orientation even if I flip it over. the problem is that I marked and drilled from the wheel well, which is a mirror image of the hole placement for the inside compartment. Argh. No wonder it came out lop-sided!

If I'm to fix that, it will involve drilling a 3rd hole... and if I get sufficiently motivated, I'll end up doing just that.


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## TX_Dj (Jul 25, 2008)

Welp... all the hard work paid off... I managed to pull 3 trophys at the Scooter Challenge. Only took two, conceded one to a little girl who was there on her little Razor vespa look-alike, that one was for "Best Looking" which hers certainly was.

We had competitors in each voltage class, 12, 24, 36 and 48. I had the fastest acceleration and top speed out of all classes. I also pulled the most laps overall with 80 laps, just barely squeezing past the #2 and #3 finishers (both in my class) after having repeated trouble with the scoot.

Twice during the race, one of my battery connections came loose, leaving me running on only one pack. I thought I was at the end of the line the first time this happened, and pulled over to look at the scooter and found the trouble and got back in and made up for lost time.

Here's a crude wiring diagram I made in MS Paint. 










And here's a pic of the scoot & tropies:










I love it when a plan comes together.


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## Zemmo (Sep 13, 2007)

That was a great race! You were definetly flying! I am surprised we were able to ride the scooters for an hour! I figured we would be dead in the water after 30 or maybe crawing at 45, but we were still going through the whole hour!

I had a question about your diode that prevents flow back to each battery. The one that prevents the batteries from discharging each other into the other. How does the charger work if it won't allow the back flow of electricity? Do you charge up each bank indevidually? Just curious how that works out. I think next year I will take on more of a project and not do the frankenscooter. Give you a real run for your money.


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## TX_Dj (Jul 25, 2008)

Zemmo said:


> That was a great race! You were definetly flying!


And that was the slow sprocket! 

The fast sprocket is a major amp sucker. It tops out around 22-23 mph and will pull a solid 30A until almost at that speed. I was going too fast and too close to the cone when I made my speed run. I thought I was gonna hit the curb!

The "slow" sprocket accelerates really well and will hold speed going up most hills. I noticed I was staring at my ammeter a lot on the uphill stretch, and when I was going slow up it, I was trying to pull 10A or less just to keep from killing the battery sooner.



> I am surprised we were able to ride the scooters for an hour! I figured we would be dead in the water after 30 or maybe crawing at 45, but we were still going through the whole hour!


No kidding! I'd bet I could get the thing to go a lot farther than I have if I try to keep the amps under 15 or so. Also, if the A-pack didn't get disconnected, I probably could have made a few more laps. The harder draw on the B-pack while the other was disconnected really changes the discharge profile.



> I had a question about your diode that prevents flow back to each battery. The one that prevents the batteries from discharging each other into the other. How does the charger work if it won't allow the back flow of electricity? Do you charge up each bank indevidually? Just curious how that works out.


Currently the batteries get disconnected to charge, and each bank is charged separately. I only have one charger at the moment. It's the closest match to the battery manufacturer's recommended charge profiles that I could find for under $30. Marvin's been working up a dual charge controller design for me to build. One unit, one connection, both batteries charged independently.



> I think next year I will take on more of a project and not do the frankenscooter. Give you a real run for your money.


I spent most of the early evening wondering if I could build something like the mini-dirt bike that Bill was riding, but maybe in the 72v exhibition class.


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## TexasCotton (Sep 18, 2008)

What was the cause of the bad connection that came loose TX? Where the battery all lead acid?


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## TX_Dj (Jul 25, 2008)

Yes sir... all lead acid. The batteries I chose use a F2 .250" quick disconnect blade. I used 10 AWG wiring for the batteries and such, and the wires are somewhat stiff. The deck makes slight contact with the terminal connections, and the deck slides side-to-side slightly when cornering. It just slowly started to push that one positive connection off the battery.

Some of the suggestions I received included using some sort of rubber isolation damper to "stand off" the deck from the scooter frame to add a little clearance for those wires.

Truth be told, the batteries were about 1/4" taller than I had expected, because I looked at the case dimensions and didn't pay attention to the terminal heights on the drawing.

I think I'm going to get some 1/4" fuel hose and slit a gap in it and push it over the edge of the frame. It may be enough, and fuel hose is cheap and relatively lightweight.


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## WCRiot (Nov 25, 2007)

I am so happy that I found this thread. On Saturday I am picking up this same exact scooter from someone at a garage sale for $5. The batteries don't hold a charge but it is in good condition and comes with everything it should.

My plans were to supe it up so this thread is perfect. Unfortunately I'm not on the same budget as you because I wont be using the scooter too often. But it will still be a fun project.

First thing is first. I need to find some batteries to make this baby carry by 200lb ass!


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## Zemmo (Sep 13, 2007)

It is amazing how much the scooters can haul around. I am 6'1' and 270 lbs, my scooter ran on upgraded batteries for the full hour. Of course being only 24 volts, it did only crawl up hills and did ok on flats. But I was able to complete tons of laps on it.


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## TX_Dj (Jul 25, 2008)

WCRiot said:


> I am so happy that I found this thread.


Glad I posted about it, then! I was hoping it could help someone out!



> On Saturday I am picking up this same exact scooter from someone at a garage sale for $5. The batteries don't hold a charge but it is in good condition and comes with everything it should.


WOW what a deal! I wouldn't pass that up even for twice that price. Scrap value alone should be more than that. The scooter weighs in at about 25 lbs with the motor and batteries and such removed. It has a lot of steel in it.



> My plans were to supe it up so this thread is perfect. Unfortunately I'm not on the same budget as you because I wont be using the scooter too often. But it will still be a fun project.


Well, even though the challenge gave me a budget of no more than $500 to retrofit, I went well beyond what *I* would have liked to spend, while remaining JUST under the challenge budget. Between original purchase years ago (new, from a dealer) and the retrofit, I have something close to $800 invested in this scooter now. 



> First thing is first. I need to find some batteries to make this baby carry by 200lb ass!


Takes a pair of 12v 12Ah batteries, in a standard size. They're pretty easy to find replacement. If it still has the original batteries, take good measurements of each to be sure the replacements will fit before ordering. There's not a lot of spare room in the battery bay.

Also, be advised that the Mfr supplies the battery with screw lug/quick connect hybrid terminals, it looks like they tapped them for the screw threads. You'll likely need to replace the screw terminals in the stock wiring harness with quick connect fasteners, but that's easy enough.

The only way I could get more capacity in mine was to remove the seat post receiver and go with the 6x 6Ah batteries with the dual diode to isolate the parallel connection. During the challenge, I had wished I had the seat still, though I've rarely used the seat during my ownership of the scooter.

I don't run mine as much as I did when I commuted downtown on the train every day. In fact, I've only run it once since the challenge last month.


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## WCRiot (Nov 25, 2007)

TX_Dj said:


> Glad I posted about it, then! I was hoping it could help someone out!
> 
> 
> 
> ...


How do i find a good charger for the future setup? This seems like it is going to be a good learn experience as well.

So i understand that the batteries in series simply add up the voltages to 36V but what about the ah rating? How did you determine what your motor could handle and what you wanted?

I need to have a different power setup than what the Mfg originally designed for. But, I want to try and keep the motor and controller factory as long as they can handle the power input that I want to have.


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## TX_Dj (Jul 25, 2008)

WCRiot said:


> How do i find a good charger for the future setup? This seems like it is going to be a good learn experience as well.
> 
> So i understand that the batteries in series simply add up the voltages to 36V but what about the ah rating? How did you determine what your motor could handle and what you wanted?
> 
> I need to have a different power setup than what the Mfg originally designed for. But, I want to try and keep the motor and controller factory as long as they can handle the power input that I want to have.


The stock setup for the BladeZ XTR 450 SE uses 24v, two 12v batteries in series. The stock charger is a 24v 2A charger that will overcharge the batteries

My reconversion is currently using a 36v 1.8A 3-stage charger whose design is a good match for the battery manufacturer's recommended charge profile on the battery I'm using. I have to charge each pack separately since I have only one charger and the diode will not permit charging both batteries at the same time. (lest they discharge on one another, defeating the point of the diode)

Currently in design is a custom charge control circuit that precisely matches the charge profile from the battery manufacturer. A pair of these driven by a separate power supply will isolate the batteries from each other, and let me charge both packs, at their own separate rate requirements through one connection to the scooter, with the power supply and charge controllers in a single convenient external device.

Would like to put in place some sort of regulation between the batteries in each pack, so I don't overcharge any individual units, but not sure I have room for it.

When wired in series, a voltage source increases the overall voltage output. I.e. if I have 4 each of 1 volt cells, and wire the positive of one to the negative of the next, and so on, I end up with 4 volts. If each of those cells are each 1 Ah, I still have a 1 Ah battery.

When wired in parallel, a voltage source remains at the same voltage output is obtained, but the capacity is increased. Again, if I have 4 cells of 1 volt and 1 Ah each, I will end up with a 1 volt output, but I will have an Amp-hour capacity of 4 Ah.

At first look, this may appear that the parallel configuration yields more storage capacity, but this isn't necessarily true.

Consider this. If I connect a device to the 4 volt series pack which draw 1 Amp at 4 volts, each battery supplies one amp of current. 4 volts * 1 amp = 4 volt-amps, or 4 Watts. If I connect a device to the 1 volt parallel pack that draws 4 amps, again 1 volt * 4 Amps = 4 Watts. However, in the parallel connection, we're splitting that load over 4 batteries rather than increasing the voltage over 4 batteries. Each battery still only supplies 1 Amp of total current, and that increases just like the volts increase in series.

So. If I have 4 batteries that provide 1 volt and 1 Amp each, if I configure them in series, i get 4 volts and 1 Amp-hour = 4 Watt hours. If I configure them in parallel, i get 1 volt and 4 Amp-hours = 4 Watt hours.

Either way, they have the same capacity.

In my scooter, I have 6 batteries, 3 per string, 12v each, 6 Ah each. Each string is series, resulting in 36v per string. Each string has a 6 Ah capacity. Two strings in parallel give me 36v still, but 12 Ah. 36v * 12 Ah = 432 Watt-hours. I could, instead, configure all 6 in series and have 72v at 6 Ah = 432 Watt-hours.

As for motor/controller sizing, it depends on how much work you want to get done, and how efficient it needs to be while doing that work. Torque is generated in two ways, essentially, with an electric. 1) is the number of amps the controller can push out, and the number of amps the motor can sustain, and 2) the length of the "lever" which the amps are pushing against.

The armature outer diameter relative to the shaft it turns on is the "lever" We're pushing on it with electromagnetic forces. The longer a lever is, the more torque it can generate. The more force you put on that lever, the more torque you'll get out of it. The amps put the force in. 

As physics is, the shorter that lever is, the easier you can turn it quickly, but less torque output from the force. The longer that lever is, the more torque you get out, but it becomes difficult to turn it fast. I.E. you can spin a wing nut very fast with your finger, but not a lug wrench for your car tire.

The stock XTR SE 450 motor is only about 3" outer diameter, the armature is smaller diameter than that. It's fed with 14 or 16 gauge wire, but the windings are likely small and can't take a whole lot of amps. So, you have a short lever, and little ability to get force on it. Thus it lacks torque. It has it, just not gobs of it. The controller is limited to 24v, so it's limited with how fast it can spin. Also, the faster it spins, the less amps you can get on it, so it makes less torque when wound out than it does nearly stopped. It's rated for up to 24v and 450W, or 18.75 Amps. It's max RPM at 24v is 3060 RPM.

The replacement motor I used is about 5-6" outside diameter, and takes 12 gauge wire and is designed (rated) for 1000W @ 36v. That's 27.777 amps, just over 9 amps more. So I have a longer lever, and can put more force on that lever. But it's max RPM at 36v is 2600 RPM.

In either case, I have an appropriately sized controller.

In either case I probably could switch the controller and add 12 more volts at the max rated amps, and get more power and more speed. I.E. 36v * 19 = 684W or 48v * 28 = 1344W. 

Here's the caveats, though... first of all, you'll never see the motor taking full volts and full watts at the same time. second, your efficiencies change as RPMs change (and volts at the motor only come up as RPM comes up, they go hand in hand). Third, increasing voltage on a motor that is not rated for that voltage could cause you to overspeed and destroy the motor. 

Whew, that's long winded, eh?


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## WCRiot (Nov 25, 2007)

So i picked the scooter up and here is an update.
It is actually a BladeZ XTR 250 Lite
THe batteries aren't in as bad shape as was stated. They defiantely don't hold much of a charge but I am trying to revive them.

TX_DJ. Any help with how I can make this bad boy haul ass on a budget?
I have two of these batteries sitting in my lab: http://www.apexbattery.com/yacht-cb...cle-batteries-yacht-motorcycle-batteries.html

Now the batteries in my scoot are a 5ah the ones above are a 4ah. So that may actually make the scooter slower. What do you think?

Where should I start? The controller seems really big and heavy.
Also, I need to figure out a better charging method based on what you told me about the charger that is supplied by the mfg. Right now I have two chargers indvidually hooked up to each battery to help them recover some life. But when I am at home I was going to use the charger from the mfg. What are my options for now?


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## Qmavam (Aug 17, 2008)

TX_Dj said:


> Here's the caveats, though... first of all, you'll never see the motor taking full volts and full watts at the same time. second, your efficiencies change as RPMs change (and volts at the motor only come up as RPM comes up, they go hand in hand). Third, increasing voltage on a motor that is not rated for that voltage could cause you to overspeed and destroy the motor.


 Hi TX_DJ,
Thanks for your posting, I picked up one of the BladeZ XTR (I think 450s) at a yard sale a while ago. Your posts have me interested in getting it into running condition.
I have recently got an electric gokart running. I put a 2hp, 28v, 65amp, 2600rpm motor on the kart. I've been running at 36 volts, but this weekend
I upgraded to 4-12 volt batteries for a 48 volt system. Right now I'm using standard car batteries, and dreaming about deepcycle batteries. I'm using an Alltrax 48v 300 amp controller.
I attached a picture,
Anyway , my experience with the kart, makes me question your info quoted below.

Quote,
"first of all, you'll never see the motor taking full volts and full watts at the same time, second, (snip) (and volts at the motor only come up as RPM comes up, they go hand in hand)"

If you apply full throttle (max voltage to motor) the current would be maximum, (the battery voltage might sag slightly but not much with fresh batteries).
From a stopped start, load is maximum so this would be the time of peak amps and peak watts. If you back off on the throttle (reduce the voltage
to the motor) the current to the motor will also reduce. Voltage to the motor is constant (dependent on throttle position)

Quote,
"Third, increasing voltage on a motor that is not rated for that voltage could cause you to overspeed and destroy the motor. "

This is correct to a point, however, many EVers overvolt their motors. Theory being you don't run the motor at full voltage for long periods so the motor doesn't overheat, and the load caused by the vehicle prevents the motor from overspeed.
My gokart with a 65 amp motor will draw 200 amps with the 36volt system
when I hard accelerate from a stop. this current reduces as the kart picks up speed and the load on the motor is reduced. It will full speed cruise at about 40 amps. Now that I'm at 48 volts I expect a maximum current of 270 amps. Now I agree I'm probably abusing the motor, because this is a gokart and we drive it, ah well, like a gokart, as fast as we can!!
Anyway just a little point of kwibble.
Thanks again for the BladeZ posting.
Mike
PS. gotta work on my amp meter, with the 48v system I'm pegging the needle!


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## TX_Dj (Jul 25, 2008)

WCRiot said:


> TX_DJ. Any help with how I can make this bad boy haul ass on a budget?


Well, the best bet is to look for deals on scrap scooters with better capabilities, and go that way. It cost me about $480 to do everything I mentioned in this thread, and that was using new parts. And it doesn't exactly haul ass, but it did win the race.



> I have two of these batteries sitting in my lab: http://www.apexbattery.com/yacht-cb...cle-batteries-yacht-motorcycle-batteries.html
> 
> Now the batteries in my scoot are a 5ah the ones above are a 4ah. So that may actually make the scooter slower. What do you think?


Voltage sets the speed (based on how the motor is wound). Amp hours is a measurement of how much power the battery can provide over time. I.e. if that's the 20-hour rate (most common), then 4 Amp-hours means that you could run just under a 1/4 amp load for 20 hours.

Also, that's a starter battery, not a deep cycle. If you want your batteries to last, you need to get the deep cycles. It's been said before, "Only a rich man can afford cheap batteries", meaning of course that starter batteries are cheaper than true deep cycles. Because they won't last long if you deep cycle them, requiring more frequent replacement.



> Where should I start? The controller seems really big and heavy.
> Also, I need to figure out a better charging method based on what you told me about the charger that is supplied by the mfg. Right now I have two chargers indvidually hooked up to each battery to help them recover some life. But when I am at home I was going to use the charger from the mfg. What are my options for now?


Define "big and heavy"... the 24v/20A controller that came out of my scooter weighed less than a pound and was about 1.5" x 2" x 4". The 36v/30A controller that went in was just over a pound, and about the same dimensions.

Your scooter is different from mine, using all different components. Anything I said about my scooter's stock setup may not be applicable to yours.

You posted your own thread, so I'll follow up there in a second.


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## TX_Dj (Jul 25, 2008)

That's a COOL little kart!  If I ever meet you, I want to ride it! 




Qmavam said:


> I picked up one of the BladeZ XTR (I think 450s) at a yard sale a while ago. Your posts have me interested in getting it into running condition.


Cool! It can be a lot of fun.




> I have recently got an electric gokart running. I put a 2hp, 28v, 65amp, 2600rpm motor on the kart. I've been running at 36 volts, but this weekend
> I upgraded to 4-12 volt batteries for a 48 volt system. Right now I'm using standard car batteries, and dreaming about deepcycle batteries. I'm using an Alltrax 48v 300 amp controller.
> I attached a picture,


I see. Very cool little setup there. Did you build it custom, or was it a conversion of an ICE frame?



> Anyway , my experience with the kart, makes me question your info quoted below.
> 
> Quote,
> "first of all, you'll never see the motor taking full volts and full watts at the same time, second, (snip) (and volts at the motor only come up as RPM comes up, they go hand in hand)"
> ...


Max amps, yes. When the motor is stalled, volts cannot come up to maximum until the RPM threshold is exceeded, or at least this has been my understanding for years. I.E. if you can only turn the motor at a fraction of the RPM, it will only realize a fraction of the voltage, and will draw up to the maximum amps for that voltage. Full throttle will widen the PWM cycle, but the volts at the motor won't come up until RPM comes up. If it didn't then your motor would go from 0 RPM to max RPM instantaneously, and it does not.

This can also be observed by placing your shunt between the controller and the motor. As the RPM goes up, you can keep pushing high amps into it, but the power increases because the volts also come up with the RPM. The controller itself is not limiting the voltage, which I believe is your point, but the motor itself cannot turn faster than the torque output will let it. I.E. if you crank the motor down where it can only turn at 1000 RPM, you will reach the max amps output at that speed, but the amount of power from the batteries will match the amount of power (efficiency loss not included) being output to the motor... but if the battery shunt shows 200A and the motor shunt shows 500A, and if your (at sag) voltage input is 110V, then you know the watts input to the controller is 22kw. So, figure 22kw output to the motor with 500A, and you know the volts realized by the motor is 44v.



> Quote,
> "Third, increasing voltage on a motor that is not rated for that voltage could cause you to overspeed and destroy the motor. "
> 
> This is correct to a point, however, many EVers overvolt their motors. Theory being you don't run the motor at full voltage for long periods so the motor doesn't overheat, and the load caused by the vehicle prevents the motor from overspeed.


The heat is generated by amps input to the motor when it cannot efficiently convert the torque to motion. I too have overvolted many motors, and some motors can be overvolted quite a bit and even run at full voltage without a load without catastrophe. The forces imparted on the motor when it spins above its designed RPM can cause the motor to self destruct, whether that RPM is caused by outside force (I.E. towing your EV with the transmisison in low gear) or by applying a high enough voltage with too little load on the motor.



> My gokart with a 65 amp motor will draw 200 amps with the 36volt system
> when I hard accelerate from a stop. this current reduces as the kart picks up speed and the load on the motor is reduced. It will full speed cruise at about 40 amps. Now that I'm at 48 volts I expect a maximum current of 270 amps. Now I agree I'm probably abusing the motor, because this is a gokart and we drive it, ah well, like a gokart, as fast as we can!!


But, what if you measure at the battery and at the motor at the same time? The rating of your controller is typically the output current, not the input current. I.E. a Z2K at 336v isn't pulling 1600A from the battery, it's putting 1600A to the motor. You may wish to try what I described earlier, if you have only one shunt, set up a repeatable test and measure your readings, then move the shunt and repeat the test and measure again.



> Anyway just a little point of kwibble.
> Thanks again for the BladeZ posting.
> Mike
> PS. gotta work on my amp meter, with the 48v system I'm pegging the needle!


No problem on that. If I'm wrong, I simply wish to learn... but all I've said on this thread are related to first-hand experience, from my own projects, helping others with their projects, and reading years of dialog from countless others who have done the same.  Please help me understand, if I am wrong.


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## Qmavam (Aug 17, 2008)

Hi TX_DJ,
First, how do you insert comments into the quote?
I tried but it didn't work. So I'll Quote what you said in my text.


The gokart is great fun, lots of acceleration, little over 30 mph, but that seems fast when your butt is 3" from the ground!
I bought an old gokart and took the ICE motor off.

We have a different understanding of the motor operation, I hope we can get a proper answer.
Quote:
"Max amps, yes. When the motor is stalled, volts cannot come up to maximum until the RPM threshold is exceeded, or at least this has been my understanding for years. I.E. if you can only turn the motor at a fraction of the RPM, it will only realize a fraction of the voltage, and will draw up to the maximum amps for that voltage. Full throttle will widen the PWM cycle, but the volts at the motor won't come up until RPM comes up." 

First I'll describe my understanding of PWM. Basically it is turning a switch
on and off at a fast rate. The switch is often a Mosfet. Sometimes the PWM is run at 15Khz, That is a 66 microsecond (us) time period. When you turn the switch on full voltage is applied to the motor. If you had the throttle set for a 33us on time and 33us off time this would be equal to 1/2 of you battery voltage applied to the motor. It doesn't matter what rpm the motor is running it still has full voltage applied when the switch is ON, and 0 voltage applied when the switch is OFF.

Quote;
" If it didn't then your motor would go from 0 RPM to max RPM instantaneously, and it does not."

The motor doesn't go to max rpm because it has a load on it.

Quote;
"This can also be observed by placing your shunt between the controller and the motor."

I need to do this, I have seen the idea that battery current and motor current are different, I doesn't make sense to me. (excluding losses)
I understand there is a circulating current through the diode.

Quote;
"As the RPM goes up, you can keep pushing high amps into it, but the power increases because the volts also come up with the RPM. The controller itself is not limiting the voltage, which I believe is your point, but the motor itself cannot turn faster than the torque output will let it. I.E. if you crank the motor down where it can only turn at 1000 RPM, you will reach the max amps output at that speed, but the amount of power from the batteries will match the amount of power (efficiency loss not included) being output to the motor... but if the battery shunt shows 200A and the motor shunt shows 500A, and if your (at sag) voltage input is 110V, then you know the watts input to the controller is 22kw. So, figure 22kw output to the motor with 500A, and you know the volts realized by the motor is 44v."

Sorry, I understand what you said, but I don't agree with any of it.









Quote;
"The heat is generated by amps input to the motor when it cannot efficiently convert the torque to motion."

Heat is Current times the resistance of the wire in the motor. P=IxIxR
There are also some eddy current losses in the iron, but let's not complicate things with this, until we need to.

We might restart this discussion on a different forum and see if we can get some experts to give their ideas.

I'll really need to put the different battery and motor current thing to the test, I've seen the reference to many times. People describe it like it is a variable linear regulator outout. It's not, it's PWM.
Looking for knowledge, 
Mike


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## Qmavam (Aug 17, 2008)

Qmavam said:


> Hi TX_DJ,
> 
> I'll really need to put the different battery and motor current thing to the test, I've seen the reference to many times. People describe it like it is a variable linear regulator outout. It's not, it's PWM.
> Looking for knowledge,
> Mike


 I said "variable linear regulator", I should have said a variable voltage switching buck regulator.
Mike


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## Qmavam (Aug 17, 2008)

Here's a little info on PWM, it has some waveforms of Pulse Width Modulated voltage and current to a motor, and lamp. See section 12, waveform # 2, the 20Khz graph.
I'm a little surprised at how clean the waveform is.
Anyway it shows the full voltage on the motor during the on time.

http://www.picotech.com/applications/pwm_drivers/#chap1

Mike


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## TX_Dj (Jul 25, 2008)

To put the quotes in, you simply need to use the (quote) and (/quote) tags (replace the parenthesis with squared brackets, [], if I put those in place, it would have made a quote with only the word "and" inside it, like this:



> and




Keeping in mind, I am no expert, and I'm only human, so while many things I've read and/or discussed over the years were absorbed, they may have been misunderstood and/or mis-remembered...

My understanding about the motor voltage is that it has to do with the counter-electromotive force inside the motor (back emf). That may be far off, though.

Another thing to consider is that the PWM controller is not simply an on-off switch, but an on-off switch that will switch off prematurely if current exceeds the threshold.

I.E. If you hit 500A, the switch is cycled off, and the PWM will resume at the correct pulse timing. 

And yes, you're correct, P=I^2R. Just trying to keep it simple as well, but basically if you're trying to do the same work at lower RPMs on a motor, more heat is generated, largely because of the greater amperage required. Change the gear ratio so the motor spins faster, and less amps are required to do the same work, so less heat due to resistance to the current. Right?

I don't doubt that the motor controller will try and give full volts to the motor when the pulse width is its widest- however, also, if you cannot reach the widest setting due to current limiting, you also have the effect you mentioned where you get volts proportional to the pulse width, no? I.E. if I have this 66us pulse width that you mention, and hit current limit at 33us, then as you stated, 1/2 the pack voltage, yes?

There may be some differences between PMDC and Series Wound, and most of what I've learned over the years is directly related to Series... but you're more likely to hit your controller's current limit at 0 RPM than you are at 3000 RPM, unless you have a hefty load on the motor. 

I'm confused, yet in other ways I'm certain. LOL


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## Qmavam (Aug 17, 2008)

test of the quote system that must be at least ten words.



> Another thing to consider is that the PWM controller is not simply an on-off switch, but an on-off switch that will switch off prematurely if current exceeds the threshold.


You just had to throw in current limiting!
You only thought I was confused before.


> And yes, you're correct, P=I^2R. Just trying to keep it simple as well, but basically if you're trying to do the same work at lower RPMs on a motor, more heat is generated, largely because of the greater amperage required. Change the gear ratio so the motor spins faster, and less amps are required to do the same work, so less heat due to resistance to the current. Right?


(Don't know why this won't go into quote mode, Mike)

I think so, your reducing the load on the motor by changing the gear ratio so less current is required to turn the motor. So less heat is produced.


> I don't doubt that the motor controller will try and give full volts to the motor when the pulse width is its widest- however, also, if you cannot reach the widest setting due to current limiting, you also have the effect you mentioned where you get volts proportional to the pulse width, no? I.E. if I have this 66us pulse width that you mention, and hit current limit at 33us, then as you stated, 1/2 the pack voltage, yes?


 1/2 the pack voltage, ah no, full pack voltage for 1/2 the time.
Oh, ok yea volts proportional to pulse width.
Regarding current limiting, I haven't got into how that is implemented yet.
Probably as simple as turning the switch off, but haven't looked at it yet.
I hope I can get some more info on this,
Later, Mike


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## Qmavam (Aug 17, 2008)

Hi TX_Dj,
I posted my questions to an electronic design newsgroup, 
sci.electronics.design Subject; Understanding PWM of Motor (current problem) In case you would like to look.
You have a much better understanding of the current and voltage than
I did! But I'm starting to get with it.
Later, Mike


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## TX_Dj (Jul 25, 2008)

Mike,

Now that's an interesting statement, because I'm No Expert!(TM)

The current limitation simply watches the current being fed to the output, and if it reaches a threshold, the controller prematurely switches off the power.

A Curtis controller will switch the PWM frequency down to 1.5 kHz at "low speed", because it's easier to control current limitation at a slower rate, otherwise the controller tries to turn the pulse back on before the amps have fully dropped below the threshold.

This is the reason why Curtis controllers "whine", because of an audible resonance that's set up when it's in this stage. But- the whine is exactly the reason why the Curtis does not fail (usually) in high-amp, low-speed situations, unlike Kelly, Logisystems, etc who do not switch frequencies. Those lesser controllers are more likely to try to switch the power back on before amps have truly dropped where they need to be.

Zilla is one of the few controllers that qualifies as "still on the market" (for a limited time) which does not switch frequencies and does not suffer from the current limitation at low speed... and this may or may not be related to the fact that it's an IGBT design and not Mosfet. I don't know.

I would like to read the thread from sci.electronics.design, but unfortunately I don't have a newsgroup reader right now. 

Any chance you could post the thread contents here (of course removing email addresses so as to protect those posters from bots that scour our forum here)?


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## Qmavam (Aug 17, 2008)

TX_Dj said:


> Mike,
> 
> 
> Any chance you could post the thread contents here (of course removing email addresses so as to protect those posters from bots that scour our forum here)?


 I found the thread on google groups, here is the URL.
http://groups.google.com/group/sci.electronics.design/browse_thread/thread/abb7b7fdbb3aa31f?hl=en&ie=UTF-8&q=Understanding+PWM+of+motor+(current+problem)#d91f8fa586e266df

I hope that link works!
Near the end of the thread is a poster named John Larkin, I think he helped most although others did too. And some thought like I used to








Later, Mike


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## Qmavam (Aug 17, 2008)

Qmavam said:


> I found the thread on google groups, here is the URL.
> http://groups.google.com/group/sci.electronics.design/browse_thread/thread/abb7b7fdbb3aa31f?hl=en&ie=UTF-8&q=Understanding+PWM+of+motor+(current+problem)#d91f8fa586e266df
> 
> I hope that link works!
> ...


 I realize now I was thinking about the motor being driven like a lamp or a resistor. As in waveform 3 and 4, here. 
http://www.picotech.com/applications/pwm_drivers/#chap12
However since the motor has inductance there is current flow during the off time through the freewheeling diode. I think I'm up to speed on this, thanks for jerking my chain







.
Mike


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## TX_Dj (Jul 25, 2008)

That's a great thread you linked to there. Thanks for asking those questions there, and sharing it here.

I'm not so certain that I fully understand all that was said in there, but it's nice to see that their opinions match my limited understanding, even if I was technically inaccurate on several points.


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## TX_Dj (Jul 25, 2008)

Pardon the thread necromancy... just wanted to toot my horn here for a sec...

It's been 19 months since the re-conversion of this scooter, and while it doesn't get nearly as much use as it did before the re-conversion (as I don't commute downtown by train for work anymroe) it has held up quite well. I won the championships in both 2008 and 2009, with no changes to the design for 2009.

Also, a couple weekends ago, I rode the scooter from my house to the Live Green Expo in Plano (almost 5 miles each way) and rode it all over the show instead of walking (standing around talking about EVs is rough on my knees). I figure I easily put 12 miles on it, and only once did the currie diagnostic panel drop into the red during acceleration, and held a reasonable top speed on the flats and up hills, riding it WOT most of the time I was out of the show.

I've thought a few times about riding it all the way out to the office, which is almost 9 miles on the most direct route, but even still that would be a long hard ride, and I still wonder if I could get both packs to recharge in the 8-9 hours at the office for the return trip.

I wouldn't think twice about it if I still had a seat and two chargers to charge both packs at once (I never did finish designing/building the custom charger). I still have the seat, and the old receptacle for it... Maybe I could custom-fab something off the motor mount, which I need to beef up because the single-plate twists a lot under torque. 

Early summer, though, we'll be moving to an office that I think is outside the range of the scooter, 12 miles by freeway, much farther on side streets. Maybe that, plus EV Racers 2010 (the new version of NTEAA Scooter Challenge) will give me cause to switch to a small LiFePO4 pack.


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