Low cost PCB & Smart BMS

Electric God: “Dumb” PCB are very cheap for good reasons. They don’t balance well or don’t balance at all and some are not very reliable. Also they can’t be monitored in any way, if you have expensive batteries and want to know how you are doing, than you need smart BMS. Otherwise when you need to service the packs, when you want to see what is going on / to see health of each cell, than the only way is to take the packs apart. For small batteries with a few dozen cells, it is practical to use “dumb” PCB if well chosen, if have packs with hundreds of cells better use smart BMS.grb1If you can not choose reliable PCBs, very cheap ones will just bite you in the ass. If I have one of these in my hands, I pull the covers off and then in seconds I can tell you if they are garbage or not. I’ve had several of this type of BMS fail me. I understand wanting to go as cheap as possible, but these BMS are not going to serve you very well. Each balance channel is isolated from all the other channels. There’s no way the BMS can tell if a cell is over charged or dead flat. It’s all based on wishful thinking in this type of BMS.
pcm not garbadge.jpgThis is a dumb BMS that I get in 16S, 20S and 24S. It’s pretty good and the charge controllers talk to each other. It’s about the best “dumb” bms I know of. One of the lovely things about this BMS is they use AOT290 mosfets, not some craptastic chinese POS. mitsumi.jpgThis PCB use intelligent IC’s made by Mitsumi that  can do cell management. Those tiny yellow parts right by the balance connector are LED’s. They flash when a cell is getting balanced. When a cell is over voltage, they go solid.

LED do all
3S to 20S – it does EVERYTHING you need in a single BMS (LIPO or LION)

LIPO or LION: For some “LIPO” BMS the balancing is actually set for LION or 4.1 volts max, which is just fine for LIPO. There is no great super secret mystery about lithium batteries. All that really matters is the low voltage and the max voltage per cell. choose bmsElectric God: As smart BMS have gotten so cheap, I’m ditching everything I have that’s dumb and switching to smart everywhere.sm1sm214S can be used as 13S. With the USB module you can use your PC to program it for 13S.16-20S smart BMS 7These settings are what says the BMS supports LION or LIFE or LIPO. Just set the voltages for the chemistry you have. Dumb BMS do this too, but this info is hard coded for specific chemistries. Smart BMS let you set them however you want.sm4sm3sm5.pngThe Smart BMS can show details / graphs /  trending data for each cell.
smol242243.jpg241244242The protection board support 8-24 cells any battery pack (lithium titanate, iron lithium, ternary, lifepo4, etc,  greater than 18v. The default is the li-ion parameters. When you connect the phone via bluetooth, can click and set up lifePo4 / LTO parameters.
7S -24S li-ion battery (24V-102V Lithium battery cell)
8S -24S lifePo4 battery (24V-88V Lithium iron phosphate battery cell)
10S -24S LTO battery (24V-68V Lithium titanate battery cell)
Single cell voltage detection range 1V-4.6V. High precision detection cell voltage error is less than 5MA. Charging current up to 50A. Discharge current can be choosed between 70A, 100A, 150A, 200A, 300A. Balance current: 200MA. Controlled equalization mode: when the charging is started, the pressure difference can be detected by the detected pressure difference to be greater than the set value. High-precision coulomb meter function, temperature control, Hall speed measurement.wtp.jpg200aBlowing up the image of this board, it looks like the Mitsumi chip I like so much .. Common port means you charge and discharge from the same port. Separate port means you charge at C- and discharge at P-. This is the better way to use a BMS and that is why I said you don’t want common.same portfdl


Leave a Reply

Fill in your details below or click an icon to log in:

WordPress.com Logo

You are commenting using your WordPress.com account. Log Out /  Change )

Google photo

You are commenting using your Google account. Log Out /  Change )

Twitter picture

You are commenting using your Twitter account. Log Out /  Change )

Facebook photo

You are commenting using your Facebook account. Log Out /  Change )

Connecting to %s