I had the chance to purchase 24 (actually 28) LifePO4 150Ah cells on the cheap, so I bought them. My plan is to put 24 cells in my E2 using one 24s Smart BMS. Can anyone advise of any problems that I may encounter along the way or offer advice on the setup? I am told by the GEM dealer that I should get about 70+ miles per charge with this setup.
What cells did you end up getting?
Remember to take pics along the way and post your progress.
I see there was quite a bit of activity around LifePo4 cells a while ago but the real hotrod guys have moved on to other things now. You can find the threads in the archives(if you didn’t know that already). There are still some guys here running them tho. I am surprised they have not chimed in. I think they don’t drop in every day.
I got BLMPOW cells. Supposed to be 150Ah Grade A and New. I have not taken possession yet so I have not tested them to see if they are really what they were listed at. Is there anything you can advise me to look out for? I searched the forum for information and found that some are putting 25-28 cells in their cars. Also found a comment about taping or otherwise securing the packs together to prevent swelling. I use lipos in my RC equipment and the only time the swell is when you do not take care of them. Using a BMS with BT so I can monitor the system better.
should work fine. You will need to reprogram your charger. 24 cells is the minimum. Below that the voltage will be too low and the Gem a dog. If you add more the Gem will respond well. much faster acceleration and top speed. For longevity don’t charge cells to max voltage.
I am running the 6 x 12v - 100Ah SMART batteries now. Charging to about 86 volts, I have plenty of power and get about 50 or so miles per charge depending on how fast I want to run. I was thinking that I should get similar power but more mileage using 24 x 150Ah batteries. Any suggestions on how to use more than 24 cells without a problem?
Use the 32s smart bms, or skip the bms and use a balance board at each cell. 25s is a good number for a gem.
Compression is only needed with certain cell types. Can’t hurt though. Build 5 x 5s batteries.
Price wise, anything around $100 each is a good price. Any less, I will buy some. The last lifepo4 I got were 16pcs 280ah and $150 each delivered.
Lifepo4 cells fall back to 3.34v when done charging. so 24 would be 80v, about what stock is. With the weight reduction and lower sag your gem will be faster. Now if you add voltage your motor will respond well to it. Us high voltage guys are 96v, It’s like adding a turbo. So the more cells you add the faster a Gem becomes. If you are happy with your current performance stay with 24. You also have an E2 so speeds over 35 get squirrely.
Also the default on your charger will overcharge your batteries. It will go up to 96v. It is currently trying to overcharge your cells. No way of knowing how the built in bms in handling it. For sure it is taking them to 100%+ which is hard on you batteries and will decrease life span and range. Get your charger set to what you are installing.
If I go with all 28 of the cells, can I use the cell balancers, from Inwo, and 32 cell smart BMS together? I only want the BMS for the BT information it provides. Inwo suggests 5 cell packs, is there a reason for 5 and not just filling up the available space with cells. I already have the 32 cell BMS.
The 5 cell packs is just packaging. You can use cell balancers with the bms
You will need a spoof for the controller. Inwo has them
Yes, using both is a great idea. The boards are much higher current than the smart bms.
David, and the gang, I have been working too much on my day job. I need to get all these cars here converted. Went a bit crazy and acquired 2 Salvage Model 3s to play with. Been thinking about the balance boards. How much are they?
Tesla3 needs bms. Boards are for lifepo4.