# Conversion to LiPO?



## 86Honda (Apr 15, 2009)

Well, it's time to take the plunge and get this EV working again.
I am going to replace my EV's current lead-acids with lithiums (possibly).
Current specifications:
Curtis controller, 400 Amp max, 96 V high voltage system
K+M charger, 110 V AC input, 96 V DC output
100 - 120 Amp cruising, 400 Amp max
1986 Hond Civic wagon, 5 passenger with storage area.
Power brake assist pump 
Heater (not hooked up)
Lots of battery space, high voltage wiring (00 welding cable) complete
Looking at either 60 Ah or 90 Ah with BMS and charger (if necessary).

I sent an information request to Elite, and here is their recommendation:

"Since your charger output is 96V, we recommend you use 26 cells in series (96V / 3.6V per cell). The nominal voltage of the 26 pack will be 3.2V * 26 = 83.2V. Please check if this is OK with your motor.

If you are crusing with 100-120A current draw, both 60Ah and 90Ah cells are OK. The concern is 400A max current draw, you will have to limit that to 15 secs for either cell type.

Our price is $1.70/Ah, $102 each for 60Ah cells, and $153 each for 90 Ah cells. We have 60Ah cells currently in stock, but 90Ah won't be available until late May."

I bring this before all you experienced people. Tracking down shorts on the battery pack is getting very old, since the charger is so finiky. Watering is also getting old. I finally have enough money to go to lithium, but I've also seen threads with folks using 12V LA (which this project was originally designed for) successfully.

I'd like to get about 30 miles again (like when the present International U1450s were new) or more, but with less weight and less work. No hills where I live.

Should I go with the 90s or the 60s, or something else entirely? I'd love to have the time to read all the threads on this site, but I'm hoping for a little newbie indulgence and have some of you advise me, or steer me to appropriate threads.

I can answer more specific question later, since I don't have my project book in front of me right now.


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## TheSGC (Nov 15, 2007)

What are the ratings of the batteries you have now?

You definitely want at least the 90 Ah, but I think a 120 Ah or 160 Ah LiFePO4 would be better. 

You would probably want 30 cells since the LiFePO4 are usually 3.2 volts nominal and a new charger/BMS. Your current charger will not work with Lithiums since they require a very special charger cycle. If you use your current charger, you will probably kill the new lithium pack.

You should look at the Sky Energy LiFePO4. They seem to quite a lot less expensive than the TS and the same in performance. They might even be the same battery sold under a new name.


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## 86Honda (Apr 15, 2009)

145 Ah, 12V

I've googled Sky Energy, but I get a wind power company. How can I get in contact with them?

I will continue to read threads here to find good chargers, LVC devices and battery management information.


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## judebert (Apr 16, 2008)

$1.70/Ah? Aren't we seeing $0.35/Ah in other threads? For that price, it'd better include a charger and BMS!

I converted a Honda Civic Wagon, too. Mine's an '88. I used 120V of Optima AGMs, and I only get about 15 miles. Of course, my batteries are 55Ah, compared to your 145! On the other hand, I don't need to water them, and I don't get ground paths because the batteries don't vent.

How in the world did you manage to stuff in so many batteries and keep the 4WD?


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## 86Honda (Apr 15, 2009)

judebert said:


> $1.70/Ah? Aren't we seeing $0.35/Ah in other threads? For that price, it'd better include a charger and BMS!
> 
> I converted a Honda Civic Wagon, too. Mine's an '88. I used 120V of Optima AGMs, and I only get about 15 miles. Of course, my batteries are 55Ah, compared to your 145! On the other hand, I don't need to water them, and I don't get ground paths because the batteries don't vent.


I'm still gathering wisdom from the folks here, and though I'm ready to buy, I'm waiting for more complete information. I have a lot to learn. 



> How in the world did you manage to stuff in so many batteries and keep the 4WD?


With a shoehorn! The 4WD does work, but is not practical at this time because during the cold weather, when it's most useful, the batteries don't cooperate. So the 4WD shaft is out temporarily (?).


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## dimitri (May 16, 2008)

> $1.70/Ah? Aren't we seeing $0.35/Ah in other threads?


You are mixing AH with WH  , $0.35 was the Wh price, which translates to $1.12/Ah and that was for large orders, not single orders, but still Sky Energy price is better than Elite Power, but you dealing with shipping from China instead of Arizona, so you have to pick your risk level 

As for your pack, I would strongly recommend going over 100Ah, like 120Ah or 160 Ah, so you can sustain high starting current without killing the battery in the long term. Afterall, you want these to last 7-10 years, right?

You need 30 cells for 96V nominal, 30 x 3.2 = 96V. Your charger also is 96V nominal, not actual, so Elite's answer is wrong.

Depending on the charger you may or may not use it with LiFePo4, I am not familiar with your charger model. If it has a profile where charging current slows down at the end for "gassing" phase, then you may be lucky, but you might as well just buy new charger, its not that expensive for 96V anyway.

You definitely need cell balancers, check out www.voltblocher.com

Hope this helps

P.S. These cells take about the same room as your Lead Acid and they must be upright, just wanted to mention it.


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## 86Honda (Apr 15, 2009)

Yes, it helps. Steep learning curve. I'm visiting the wiki a lot lately, just to catch up. Started this conversion with Mike Brown's book before any of this newfangled Internet stuff was available. My charger does have the current slowdown, and it is able to be modified, but I am considering all options at this point.


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## TheSGC (Nov 15, 2007)

86Honda said:


> Yes, it helps. Steep learning curve. I'm visiting the wiki a lot lately, just to catch up. Started this conversion with Mike Brown's book before any of this newfangled Internet stuff was available. My charger does have the current slowdown, and it is able to be modified, but I am considering all options at this point.


Is it a K&W BC-20 or what? I know you said K&M, but I have never heard of such a charger. I do have a BC-20 for my Civic EV I picked up a few months ago and I love the thing. Of course, after I did some tweaks to it for 96 volts.


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## 86Honda (Apr 15, 2009)

TheSGC said:


> Is it a K&W BC-20 or what? I know you said K&M, but I have never heard of such a charger. I do have a BC-20 for my Civic EV I picked up a few months ago and I love the thing. Of course, after I did some tweaks to it for 96 volts.


You are right - a K+W (just an M upside down!). It works well when it works. It has a great aversion to any tiny grounding path, so it often doesn't like my flooded lead acids.


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## dimitri (May 16, 2008)

Do you have an EVAlbum page for your EV? Would be nice to see some pics of an old conversion 

Sounds like your charger could work with LiFePo4 if volatges and amps are properly calculated and cell balancers are used. But then again, if you spend so much on batteries, might as well spend few more bucks on a new charger, especially since yours seems to be finicky with ground issues...


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## dimitri (May 16, 2008)

Just Googled this charger, looks pretty decent. Since it has "gassing point" where constant current changes to constant voltage, I believe it can be used with LiFePo4 cells. For example, for 30 cell pack, I would set gassing point at 30 x 3.6 = 108V. At that time current will drop and cell balancers will allow the pack to balance using low "gassing current".

You may need to tweak voltage levels, but overall it should work. I strongly recommed Packtrakr to watch voltage on each cell.

Brian and I are also debating what cutoff voltage is better, depending on the charger and BMS you may want 3.6V or 3.8V cutoff on the balancers. My pack currently cuts off at 3.6V but I will change it to 3.8V to better suite my Zivan charger.


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## TheSGC (Nov 15, 2007)

86Honda said:


> You are right - a K+W (just an M upside down!). It works well when it works. It has a great aversion to any tiny grounding path, so it often doesn't like my flooded lead acids.


I take it your charger is installed in your car and the GFCI trips a lot. When it detects a ground in the car chassis it shutdowns. I solved that problem by not installing the charger in the car. The way my setup works, I have the entire chassis hooked into ground, that's how my Kelly works using the 12 volt system on the car. So I have place my charger outside, and I will get around to making a weather proof casing for it.


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## bblocher (Jul 30, 2008)

It's already been said twice but I'll say it again just for a third point of reference, get the 160Ah cells. 

Not only will this allow you to floor it all day long and be within your continuous amp rating for the cells but you also want to keep your SOC as high as possible too for cell life. Too many people try to size their cells to get just enough range to save money, but if your cells die early because you are discharging them to far then it will cost your more in the long run.

Just my two cents.


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