# Planning first conversion



## Moltenmetal (Mar 20, 2014)

For a 60-80 mile range, you need to reconsider lead acid batteries in my opinion. That is a lot of lead...If you go with lithium, you can estimate your battery capacity requirement as follows: final weight of car divided by ten is your estimated Wh per mile. Make sure that the resulting number of kWh is divided by 0.7 because you don't want to take your pack below about 70% depth of discharge if you want it to last. 

If you want performance, you can't beat DC for monstrous torque in an inexpensive package. If you want a long term practical car without a lot of maintenance, AC us the way to go.


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## IchibahnSLC (May 22, 2015)

Moltenmetal said:


> For a 60-80 mile range, you need to reconsider lead acid batteries in my opinion. That is a lot of lead...If you go with lithium, you can estimate your battery capacity requirement as follows: final weight of car divided by ten is your estimated Wh per mile. Make sure that the resulting number of kWh is divided by 0.7 because you don't want to take your pack below about 70% depth of discharge if you want it to last.
> 
> If you want performance, you can't beat DC for monstrous torque in an inexpensive package. If you want a long term practical car without a lot of maintenance, AC us the way to go.


Thank you for your response and the information. Currently however I have cheap access to those AGM batteries and thus would like to utilize them. I thought AGM batteries were safe up to a 50% discharge? I don't necessarily need the performace, just something drive-able as I used to drive a 3500lbs car with about 90 wheel horse and even less torque. The AC-20 motor I'm eyeing seems to put out about 25hp continues at 72v. 
I'm also wondering what else I will need besides:
Motor
Batteries
Controller
Wiring

Thanks in advanced!


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## jwiger (Oct 18, 2014)

The 70% discharge is actually depth of discharge. Basically you can run 100Ah batteries down to 30Ah of remaining charge without hurting them. With the AGMs you have a heavier battery pack to begin with and you can only run them down to 50% depth of discharge. If they really are that cheap go for it, but don't be surprised if you don't get the range you want. You will have a 72 volt system with a useable 50Ah, that's a 3.6kWh battery pack. And will maybe get you ten miles of range with that heavy of a car.


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## IchibahnSLC (May 22, 2015)

jwiger said:


> The 70% discharge is actually depth of discharge. Basically you can run 100Ah batteries down to 30Ah of remaining charge without hurting them. With the AGMs you have a heavier battery pack to begin with and you can only run them down to 50% depth of discharge. If they really are that cheap go for it, but don't be surprised if you don't get the range you want. You will have a 72 volt system with a useable 50Ah, that's a 3.6kWh battery pack. And will maybe get you ten miles of range with that heavy of a car.


I was going to do 3 rows of 6 batteries each, depending on what else I can fit under the hood maybe more.


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## jwiger (Oct 18, 2014)

Are these 12 volt 100Ah AGMs?


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## IchibahnSLC (May 22, 2015)

jwiger said:


> Are these 12 volt 100Ah AGMs?


They are, as this will be a budget build at the beginning I figured they would be fine. I'm really more worried about the AC-20 and whether or not it can handle 2900lbs.


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## jwiger (Oct 18, 2014)

With proper gear reduction you could drive dump truck with that motor, it just a matter of how fast you want to get there. 

I think this motor is too small for this application, especially if you want to try it on the highway. Do you plan on keeping the AWD system intact?


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## IchibahnSLC (May 22, 2015)

jwiger said:


> With proper gear reduction you could drive dump truck with that motor, it just a matter of how fast you want to get there.
> 
> I think this motor is too small for this application, especially if you want to try it on the highway. Do you plan on keeping the AWD system intact?


Yes, the AWD system is a must because of the winter here. I was hoping the motor would be good enough to get me by for a while until I got a WarP 9 or similar. I don't need it to be insanely fast. 0-60 in 8-11 second range is fine. I would need to drive it on the freeway, which is 70mph here.


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## jwiger (Oct 18, 2014)

If your winters are bad you will cold soak your battery pack and get even less range from it. The AC-20 will move the car, but not at highway speeds very well.

Realistically, how far do you need to drive each day? I have a 26 mile commute and I'm planning six times the battery pack you are planning.


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## IchibahnSLC (May 22, 2015)

jwiger said:


> If your winters are bad you will cold soak your battery pack and get even less range from it. The AC-20 will move the car, but not at highway speeds very well.
> 
> Realistically, how far do you need to drive each day? I have a 26 mile commute and I'm planning six times the battery pack you are planning.


I drive about the same, 26 miles per day. 300ah battery pack not enough for that? Even at the 150ah discharge I would think it would be enough. I used the EV source calculator to figure out a rough estimate and at 300ah it said about 57 mile range.


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## jwiger (Oct 18, 2014)

My apologizes, my head isn't right. You mentioned 3p6s (3 parallel x 6 series) of 12v 100Ah AGMs. You are right, that is 72 volts at 300Ah. At 50% DoD that is about a 10.8kWh pack. You said the car weighs about 2900 pounds, lets round that to 3k. Most cars would average about .300 wh/mile in that weight range. That gives you 36 miles. I would expect a 5-8% loss pushing the AWD so conservatively that brings you down to about 33 miles. Which cuts it real close. Will you have the opportunity to plug in at work?


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## IchibahnSLC (May 22, 2015)

jwiger said:


> My apologizes, my head isn't right. You mentioned 3p6s (3 parallel x 6 series) of 12v 100Ah AGMs. You are right, that is 72 volts at 300Ah. At 50% DoD that is about a 10.8kWh pack. You said the car weighs about 2900 pounds, lets round that to 3k. Most cars would average about .300 wh/mile in that weight range. That gives you 36 miles. I would expect a 5-8% loss pushing the AWD so conservatively that brings you down to about 33 miles. Which cuts it real close. Will you have the opportunity to plug in at work?


I should be able to plug in most places I go. I'm hoping to fit more batteries under the hood, the eventual goal is to cut and re-weld a floor on the car for the batteries to fit in and so I can run a flat bottom to help with aerodynamics. I figure in under the hood I could possibly fit another 6 batteries. I'll have to look for a stronger motor then the AC-20, but the deal on it seems pretty good. Since the final drive is 3.919 to 1 I should Ideally be getting about 100hp to the wheels at 72 volts right? Or did I do that math wrong?

Thank you for all the info so far!


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## jwiger (Oct 18, 2014)

IchibahnSLC said:


> Since the final drive is 3.919 to 1 I should Ideally be getting about 100hp to the wheels at 72 volts right? Or did I do that math wrong?


Gearing doesn't give you horsepower it simply exchanges torque for rpm or vice versa. The AC-23 is advertized at 65hp, at 96 volts. Do you know the cranking amps of these AGMs? I will have to dig into the voltage sag on AGMs but, if you know the CAs we can determine battery horsepower, and plan a better motor.

Additionally I show your car having 185/70R14 tires stock. with a 3.919 ratio you are spinning the motor at 3763 RPM at 70 MPH. Will you use some of the gears in the transmission?


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## IchibahnSLC (May 22, 2015)

jwiger said:


> Gearing doesn't give you horsepower it simply exchanges torque for rpm or vice versa. The AC-23 is advertized at 65hp, at 96 volts. Do you know the cranking amps of these AGMs? I will have to dig into the voltage sag on AGMs but, if you know the CAs we can determine battery horsepower, and plan a better motor.


The battery model number is 31hr4000. I will try to find some numbers for it. 
Here is what I found initially:
http://www.power-solutions.com/batteries/deka/unigy_ups/deka-unigy-high-rate-series-hr4000


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## IchibahnSLC (May 22, 2015)

jwiger said:


> Gearing doesn't give you horsepower it simply exchanges torque for rpm or vice versa. The AC-23 is advertized at 65hp, at 96 volts. Do you know the cranking amps of these AGMs? I will have to dig into the voltage sag on AGMs but, if you know the CAs we can determine battery horsepower, and plan a better motor.
> 
> Additionally I show your car having 185/70R14 tires stock. with a 3.919 ratio you are spinning the motor at 3763 RPM at 70 MPH. Will you use some of the gears in the transmission?


I will be using the stock transmission and whatever gear suits it best.


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## jwiger (Oct 18, 2014)

That's a 74 pound battery, 18 of those will weigh over 1300 pounds!  A similar capacity pack in LiFePo would weigh 272 pounds.


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## IchibahnSLC (May 22, 2015)

jwiger said:


> That's a 74 pound battery, 18 of those will weigh over 1300 pounds!  A similar capacity pack in LiFePo would weigh 272 pounds.


Yeah, I see that now. I found a different spec sheet before that said 54lbs, oh well. They are still very cheap. I might go with a lower voltage or lower capacity then. Maybe 10 batteries in 5p2s and then run a 60v system.


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## IchibahnSLC (May 22, 2015)

So I have found another motor that may be better suited. It's FB1-4001A. 
http://www.cloudelectric.com/product-p/mo-fb1-4001a.htm

What do you guys think of that one instead? I know it's DC instead of AC but I may have found a killer deal on one.

Thank you.


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## jwiger (Oct 18, 2014)

Looks like the old Advance 9". That would definitely motivate your car. Is your deal much cheaper than the going rate for the Netgain Warp 9"?


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## IchibahnSLC (May 22, 2015)

jwiger said:


> Looks like the old Advance 9". That would definitely motivate your car. Is your deal much cheaper than the going rate for the Netgain Warp 9"?


Yes, a crazy amount cheaper. I don't know what it is with my area but the few motors that I did find were really cheap.

Update: This guy says the motor is new, hard to believe that. He wants less then 500 for it, let's put it that way. Really hard not to pull the trigger immediately.


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## IchibahnSLC (May 22, 2015)

IchibahnSLC said:


> Yes, a crazy amount cheaper. I don't know what it is with my area but the few motors that I did find were really cheap.
> 
> Update: This guy says the motor is new, hard to believe that. He wants less then 500 for it, let's put it that way. Really hard not to pull the trigger immediately.


Update 2: Getting a checklist together for the build. So far I have:

Motor
Batteries
Controller
Wiring

What else am I missing?


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## jwiger (Oct 18, 2014)

motor to transmission adapter
DC to DC converter
Heater
Charger
Contactors

You need to physically bolt the motor to the transmission. There may be an adapter on the market already or you may have to get one fabricated, also an adapter to fit on the motor shaft to attach your flywheel. 

Is your car a manual transmission? Keeping the clutch will make it simple to adapt.

The DC to DC converter takes the place of an ICE car's alternator. It supplies power to your 12 system to run your lights, wipers, etc. 

The heater should be obvious. Most all liquid cooled ICE cars used engine heat to heat the passenger compartment. You won't have that source any more, so that is one more thing to run off your battery pack.

The charger should be pretty obvious too. And there is two criteria you need to look for here, luckily there is a lot of flexibility. The first is a suitable voltage range, if possible get one that will give you room to grow, the second is how fast you want to charge. Some people consider this in miles per hour, since we can loosely plan that your car will burn 300wh per mile then a 1500w charger will charge your car at roughly five miles per hour. If you can leave it plugged in for ten hours each night you will have about fifty miles of charge window. A larger charger will move power quicker, but at a greater cost. 

Finally Contractors, I'm going to lump these in with other safety and instrumentation devices. fuses, volt meter(s) amp hour meter(s) etc. These are the little items that the devil hides in. It would be a shame to loose a $10k car because you skipped a $100 contactor, or a $40 fuse.


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## IchibahnSLC (May 22, 2015)

jwiger said:


> motor to transmission adapter
> DC to DC converter
> Heater
> Charger
> ...


Thank you for the info! As far as the adapter is concerned I will have to have it fabricated. 
List now is:

Motor - great price
Batteries -$650
Controller -$600
Wiring -$150

DC to DC converter
Heater
Charger
Contactors

I have pricing ideas for the motor, batteries and controller. I would guess $150 in wiring, what do you think the rest would cost. I don't need the heater yet.

I like the idea of converting the PC PSU to use for the EV. I have several really good 400w ones laying around and have taken one apart to build a sound system with.


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## jwiger (Oct 18, 2014)

IchibahnSLC said:


> I like the idea of converting the PC PSU to use for the EV. I have several really good 400w ones laying around and have taken one apart to build a sound system with.


I personally don't like the idea, the PC power supplies are designed for an AC input, they are not meant to survive in a dusty, wet, vibration prone environment that is a car. That being said. If you want the cheap route, you can run a belt drive off the secondary shaft of a dual shaft motor to drive an alternator. It's not the most elegant way to do it, but it would keep you going, you could also drive A/C, Power Steering, and a vacuum pump (for your power brakes, and possible HVAC functions) in this fashion.

Take a look at Matt Hauber's video below:


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## IchibahnSLC (May 22, 2015)

jwiger said:


> I personally don't like the idea, the PC power supplies are designed for an AC input, they are not meant to survive in a dusty, wet, vibration prone environment that is a car. That being said. If you want the cheap route, you can run a belt drive off the secondary shaft of a dual shaft motor to drive an alternator. It's not the most elegant way to do it, but it would keep you going, you could also drive A/C, Power Steering, and a vacuum pump (for your power brakes, and possible HVAC functions) in this fashion.
> 
> Take a look at Matt Hauber's video below:


I saw that and thought about it. Seemed like the more expensive route. I was going to use manual steering and no a/c. I used to go all summer without a/c here but during winter will have to have the heat (that will eventually be added). I'll have to add a brake booster to this list too.


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## jwiger (Oct 18, 2014)

I don't see any listings for that platform with manual steering, If your plan is to simply unplug the hoses you are in for a major arm workout!

This could work though:
http://www.buyautoparts.com/buynow/...anual_Steering_Rack/80-70110_R.html?xref=2766


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## Moltenmetal (Mar 20, 2014)

Ok, you've reduced your range requirement to something sane. The rest is just design- and lots of reading. 

You need a good Ah meter, shunt and likely an ammeter or at least a display of controller amps. A potbox for your throttle. A main contactor and an emergency disconnect. Heavy cable, terminals and something to crimp them with. A main fuse. You need some interlocking, so you don't forget and start driving while the controller is plugged in. A DC/DC converter is nice unless you want to carry and charge another 12V battery. If you go with lithium, I recommend a BMS- a charger with a complicated curve is less essential as I generally terminate charge when one cell goes high anyway.


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## IchibahnSLC (May 22, 2015)

Moltenmetal said:


> Ok, you've reduced your range requirement to something sane. The rest is just design- and lots of reading.
> 
> You need a good Ah meter, shunt and likely an ammeter or at least a display of controller amps. A potbox for your throttle. A main contactor and an emergency disconnect. Heavy cable, terminals and something to crimp them with. A main fuse. You need some interlocking, so you don't forget and start driving while the controller is plugged in. A DC/DC converter is nice unless you want to carry and charge another 12V battery. If you go with lithium, I recommend a BMS- a charger with a complicated curve is less essential as I generally terminate charge when one cell goes high anyway.


Ok, I will add those to my list. What is a good controller that won't break the bank for a 120v system? 
On another note I found some 12v 165ah AGM batteries for $80 each that have probably 75% ah left. Might pick up some of those instead of the 100ah ones.
Interlocking?
Anyone know a good meter to use to test these batteries to see what juice they have left ah-wise?


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## AntronX (Feb 23, 2009)

IchibahnSLC said:


> On another note I found some 12v 165ah AGM batteries for $80 each that have probably 75% ah left. Might pick up some of those instead of the 100ah ones.


You know, 10 of them will weigh 1200 lbs, will be unusable in a year and only give you 25 miles of range. Seriously, save up for some lithium or don't bother with the project. Edit: If they have 75% capacity left in them, that means they are very very used and past their life. I came across some free 55Ah AGMs that were used in high voltage UPS. Even though they were hooked up in series, they were very out of balance. Some could not even sustain 100A load for few seconds. Some had 80% life left, some had >50%. I ended up giving them away for free on craigslist. 



IchibahnSLC said:


> I don't need it to be insanely fast. 0-60 in 8-11 second range is fine. I would need to drive it on the freeway, which is 70mph here.


LOL, Nope. Not happening. Think 30 - 60 sec. to 60mph if you can even get that fast. Hell, Nissan leaf with 80KW motor and 3400lbs total weight barely gets 9 seconds. At 72V that's 1111A. But you will not get 72V at 1KA. Likely not even 50V due to voltage sag.


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## Moltenmetal (Mar 20, 2014)

Interlocks are logic, provided by relays or other devices such as the controller itself or a BMS, which protect you against known problems. I have only a couple: one is a relay that makes it impossible to turn on the controller while the charger is running, thereby making sure that you can't drive away while you're plugged in. In the same circuit I have an inertial switch which shuts off the controller if you're in a collision. 

My BMS trips the charger when one cell goes high- essential if you have lithium cells to avoid damage due to over-charging. Some have a low voltage cutout which puts the controller into "limp mode" (limiting max current) when the BMS detects one cell going low voltage, but I don't expect to come anywhere near the bottom of my pack so I just have a very loud alarm under the dash. I won't be lending my car to others and the investment in the batteries was crushing for me, so there's no danger that I'll ignore that alarm!


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## IchibahnSLC (May 22, 2015)

Moltenmetal said:


> Interlocks are logic, provided by relays or other devices such as the controller itself or a BMS, which protect you against known problems. I have only a couple: one is a relay that makes it impossible to turn on the controller while the charger is running, thereby making sure that you can't drive away while you're plugged in. In the same circuit I have an inertial switch which shuts off the controller if you're in a collision.
> 
> My BMS trips the charger when one cell goes high- essential if you have lithium cells to avoid damage due to over-charging. Some have a low voltage cutout which puts the controller into "limp mode" (limiting max current) when the BMS detects one cell going low voltage, but I don't expect to come anywhere near the bottom of my pack so I just have a very loud alarm under the dash. I won't be lending my car to others and the investment in the batteries was crushing for me, so there's no danger that I'll ignore that alarm!


Thank you for the information. I am looking into used lifepo4 cells currently. The AGMs I was looking at have about 15 cycles on them but are still very heavy. I am also looking into lighter vehicles for the conversion. Was thinking perhaps a older VW golf or similar.


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## jwiger (Oct 18, 2014)

I feel a golf would be a much better car for your budget. There are adapter plates out there already. If you don't mind giving up the rear seat, and doing some sheet metal work you can place a lot of the batteries there and have amazing weight distribution. It would be a lot of fun in the snow!


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## IchibahnSLC (May 22, 2015)

jwiger said:


> I feel a golf would be a much better car for your budget. There are adapter plates out there already. If you don't mind giving up the rear seat, and doing some sheet metal work you can place a lot of the batteries there and have amazing weight distribution. It would be a lot of fun in the snow!


Yeah, I always wanted an older golf as well. The reason I was going the DSM route is because the aftermarket parts market is very large, so any more weight reductions or mods would be easier. Plus I have worked on them before. 

I'm not afraid to learn a new car though so the golf is def. on the top of my list. Those adapter plates are pricey though, I think I would still have one made locally. The weight on the golf without engine should come in around 2000lbs so that will be about 500lbs lighter then the mitsubishi.

Edit: Found a local company that makes them. Anyone deal with these guys before "Electric car Parts Company''?


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## nimblemotors (Oct 1, 2010)

I have an adapter plate and clutchless taperlock coupler from my Boxster that will also work on a Jetta/Golf with a 9in dc motor for sale.
There is a nice Jetta for sale here $500 that includes a dc motor. 
Can't beat that.



IchibahnSLC said:


> Yeah, I always wanted an older golf as well. The reason I was going the DSM route is because the aftermarket parts market is very large, so any more weight reductions or mods would be easier. Plus I have worked on them before.
> 
> I'm not afraid to learn a new car though so the golf is def. on the top of my list. Those adapter plates are pricey though, I think I would still have one made locally. The weight on the golf without engine should come in around 2000lbs so that will be about 500lbs lighter then the mitsubishi.
> 
> Edit: Found a local company that makes them. Anyone deal with these guys before "Electric car Parts Company''?


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## IchibahnSLC (May 22, 2015)

nimblemotors said:


> I have an adapter plate and clutchless taperlock coupler from my Boxster that will also work on a Jetta/Golf with a 9in dc motor for sale.
> There is a nice Jetta for sale here $500 that includes a dc motor.
> Can't beat that.


Yeah, that is a great price. How much would you want for the adapter? Would it work if I kept the clutch on the golf?
I'm still debating if the golf is the way to go. Unfortunately they are kinda pricey here even for the old ones. ( I was looking at a 91)


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## IchibahnSLC (May 22, 2015)

This golf is looking like the one I'm going to go for. The gearing seems pretty good and the weight advantage is fantastic. The weight should be enough with the batteries to give me enough traction in the winter with winter tires on.


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## IchibahnSLC (May 22, 2015)

I will be buying the motor either today or tomorrow. Will be going to the local battery recycle places to get some laptop batteries to put together a lithium ion pack while I use the old school agm ones.


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## jwiger (Oct 18, 2014)

You will go through hundreds of laptop battery packs to find enough cells. Unless you have access to a healthy chain lightly used laptop batteries, Tesla will probably have the Giga Factory working before you have enough.


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## IchibahnSLC (May 22, 2015)

jwiger said:


> You will go through hundreds of laptop battery packs to find enough cells. Unless you have access to a healthy chain lightly used laptop batteries, Tesla will probably have the Giga Factory working before you have enough.


I understand that. I have time to do it. In the meantime I will run on the AGM platform with enough range to do my daily commute.

The batteries will be more of a ongoing project.


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## jwiger (Oct 18, 2014)

Okay, my hats off to you for attempting a very daunting and frustrating task.


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## IchibahnSLC (May 22, 2015)

jwiger said:


> Okay, my hats off to you for attempting a very daunting and frustrating task.


I know it will be but it will help me learn. Thinking of setting up my 3D printer as a spot welder to speed along the process of assembly. I'm calling local recyclers right now to see how much they've got. I figure I'd need about 600 packs to get enough good cells. 
That'll be fun!

I found a few items for sale used on ebay that I will eventually have to purchase. Hope they are still available when I have the money.


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## jwiger (Oct 18, 2014)

I think de-soldering and testing of individual cells will be your first big hurdle. Just remember each group of cells is only as strong as the weakest one. If you have a mix of Ah around 2-3Ah, and there is one cell in there that is only 1800mAh you have to consider the whole pack 1.8Ah. 

It would be wise to spend a few hundred dollars on a really good R/C Lipo batter charger/discharger.


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