Basic Programmable BMS

[NCPW]

Good option agpfl. Are you still using the stock lead acid charger and just controlling the cut-off voltage through the BMS?

[agpfl]

I am using a cheap Chinese charger set to cut off at the proper voltage. The BMS is my safety net. I sold the Lead acid charger and it almost completely offset the price of the Li-on charger.

[PingEye3]

Originally Posted by agpfl

Just google 14S smart bms. I used one like this: https://www.aliexpress.com/item/14S-...794186005.html

Hi agpfl,
I just googled that page. That looks very much like the BMS supplied by Nick at EV battery. The PC software pages shown are identical to the PC software I use with the usb-serial programming cable on one of Nick's BMS. Nick did not allow that much control of the BMS parameters by the typical user so he did not supply that cable. His WiFi app showed cell voltages, pack voltage etc., very generic. This looks to be a pretty good BMS to give a try.

What amperage rating did you choose to order from them for your pack? They show on their drawing that all pack discharge current passes thru the BMS. I would choose this one at 320A for 14 cells.

https://www.aliexpress.com/item/80A-...9-bfeb6b43f417

[agpfl]

Originally Posted by PingEye3

What amperage rating did you choose to order from them for your pack? They show on their drawing that all pack discharge current passes thru the BMS. I would choose this one at 320A for 14 cells.

I use the 30A version, but could probably get by with 20A because my charger does not charge over 15A. I don't connect the load because I don't need/want the BMS to shut down the pack. The only connection I have to C- is the charger. Depending on the controller I use, it will either shut down or go into limp mode, so I don't need the BMS to perform that function.

[Volt_Ampere]

I just have a very annoying alarm on my cart for undervoltage protection.

[BobBoyce]

I have the same thing. I keep the charger control relay unplugged until I am ready to plug the charger in, so if the battary charger malfunctions the BMS can shut it off. After it is charged, I unplug it again, and I have the annoying beeper to alert me of low battery. So far, it has never sounded because I tend to charge it when it gets down to around 54 volts. I then turn on the reset/override switch when I drive it. If the keyswitch power is turned on without it being configured correctly, it sounds the annoying beeper. Like an alarm...

[DaveTM]

Originally Posted by Volt_Ampere

I just have a very annoying alarm on my cart for undervoltage protection.

I have an annoying one as well. The cart just shuts off. That's annoying!!!

[Riso]

I have the chinese bluetooth bms shown above. My charger shuts off at 50.4 volts on my Chevy Volt batteries. My Alltrax is set to 38 volts on the low side. I use my cell phone to monitor the individual cell voltages. I lost a battery earlier to over voltage. I think this was do to regenerative braking. I replaced the bad battery with a new one and turned off regenerative braking and have not had a problem since. The cell balancing is a joke. The highest drain I have seen of any bms is 1.3 amps. This would take days if not weeks to balance cells. I think you should use the bms to cut off charging on the high side or to cut off load on the low side but balancing should be ignored. My batteries are in perfect balance since turning off regenerative braking. Just my opinion

[agpfl]

There should minimal balancing necessary anyways if all the modules came from the same leaf battery pack. The volt cells should be similar because they are all in one block.

I think I have the balancing set to keep the cells within 0.12v. I believe I have balancing active when the cell voltage is above 3.9v, so its pretty much always active, but I never see it running.

Sent from my SM-G950U using Tapatalk

[brad2388]

how long does it take to get them from ali? i like the bluetooth to just be able to check on them from time to time.

looks like imma need 2 sets of leaf batteries. one for the txt and one for the rxv cart now.