Is it possible to connect a BMS to 2 batteries?

[Kagamoosha]

I just recently bought a triangle shaped battery from Calibike.com that came with a BMS installed. It is a 48 volt 13 series 9 parallel made of 18650 cells. My other battery is a 48 volt 15 series 10 parallel also 18650 cells. Is there a way of connecting these two batteries using the 14 pin connection so I can manage and charge both batteries in parallel. Even if I had to remove 2 of the cells, so both batteries have 13 cells in series, but my ideal situation would be to have both batteries fitting inside the frame bag I have. I know that if I just connect the two batteries in parallel they have to have the same voltage or they will not work correctly, so any suggestions would be greatly appreciated.

http://calibike.com/?product=48v20t-electric-bicycle-ebike-48v-20ah-lithium-triangle-pack-battery-and-charger-1-yr-warranty

 

[999zip999]

Just use as two different batteries when charging and use the chargers that came with each battery. Connect for discharge. Many, many reasons. One they are of two different chemistry. Let us know how the cali battery works out.

 

[Wheazel]

Short version its a bad idea.

Also:
You claim both batteries are 48v labeled, while one being 13s and the other 15s.
This would mean that the individual cells differ too much to be used under the same bms, even if you would rebuild the two pack into one.


Doesnt the 15s pack have its own bms?

 

[dnmun]

do you know if the chemistry of the 15s pack is lifepo4 or is it li ion?

we know the calibike pack is li ion so if your 15S is lifepo4 then you can charge them up at the same time but using a different BMS for each pack.

we would have to see the BMS of the two packs too in order to know if they could be connected at the drains while charging.

 

[Kagamoosha]

I Thought calibike was using LifePo4? That is what my other cells are made of, and to answer the question about my other BMS it was damaged making a wooden frame box and the company that sold me the battery sent me the wrong BMS and told me how to hook it up which ended up killing one of the cells, so now I'm left with a 15 cell battery and I also had to find a charger to charge 15 cells, because my charger also got damaged! I still have no BMS for my other battery.

 

[dnmun]

the calibike batteries are limn2o4 and they have a lipo BMS so charge to 4.20V/cell and if you will post up a picture of your lifepo4 battery and the BMS we may be able to show you how to fix it and if you did not push current through the lifepo4 cells at low voltage then they may recover yet too.

or we can show you how to wire up the two packs in parallel using 15S of the lifepo4 and charging it to 3.63-3.64V/cell.

the charger can be repaired and voltage adjusted too.

 

[999zip999]

You can not use one bms with two different types of cells with different hvc and lvc levels as one big pack. It will damage one of the two packs. Two 15s lifepo4 packs yes if of the same quality. Two 13s packs of same cells and quality yes. One new pack and one older pack not a good idea.

 

[Kagamoosha]

Thanks for the help. I purchased another of the Calibike batteries and plan to sell my used battery on Ebay. Rafe told me to put the batteries in parallel to make sure they are charged and have the same voltage before putting them in parallel. Now I will have a 48 volt 40 amp hour battery. Sick!

 

[999zip999]

Before pulling in parelle be sure they are of same voltage first.

 

[Kagamoosha]

I used my Calibike battery for the first time today. Had to say pretty impressed so far. I did 25 miles in the wind today and it was still at 47 volts when we were done. Not bad for my Fat Tire Ebike. I reprogrammed my Lyen controller for a lower cutoff voltage, since these cells can be pulled much further than my battery without a BMS. I set it for 40 amp max phase limit and 20 amp battery limit. I was doing a solid 25 mph and only using up about 8 amps according to my Watt meter. I was surprised.