Recent content by gtxltd

Yes we should all leave charge enabled in BMS (except in emergency protection event). The charge source should be set up such that we never overcharge.

I don't. I'm a beginner but I would separate the parallel batteries and one at a time try to resurrect them. Apply a small amount of charge current and see if that brings them back. Apply a small discharge load and see if that works. Hopefully something you do will bring the BMS back to normal...

The important take away from this for all the beginners out there (including me) is that you can't disable the charging FETs without some ill effects on discharge. What I mean is there is a considerable amount of heat in the BMS if you have substantial discharge current with charge disabled.

I'm not sure why. The easy answer is capacitors inside the inverter/charger but who knows.

The fact that you have a inverter/charger hooked up is good information. That probably explains why you didnt see a drop before.

I made a crude diagram to show how this works. Inside my BMS (120 Amp) there are 30 FETs. 16 FETs are on one side of the PCB and 14 FETs on the other side. There are 15 discharge FETs in parallel and 15 charge FETs in parallel. My diagram represent one set. You can see how the discharge...

With the charge FETs disabled the power dissipated in the BMS is the discharge current x the voltage drop (about 0.5V). So if you pull 60 amps discharge with the charge turned off the BMS has to dissipate about 30 watts. You will feel the aluminum plates get warm for sure. With the charge...

I have two of those same BMS and I see almost exactly what SmoothJoey sees on both of them. I also know the schematic of the BMS well enough to know that what SmoothJoey is seeing is the expected effect. If you don't see the difference I would wonder if your charge fets are actually turning...

Hey Gazoo what are you using to read the voltage? If you are reading the app reported voltage that would explain it.

Not really for initial cooling. It's for motor startup which occurs every time the thermostat cycles on.

There is a difference between common port vs separate port BMS. My above response pertains to common port. A separate port BMS will not see the voltage difference. I have common port and I believe the OP also has common port.

Yes you should see lower voltage when you disable the charge FETs. The discharge current will now pass through the charge FETs by way of their intrinsic body diodes. You will see a diode drop worth of difference in voltage. It's important to note that your BMS will have to dissipate the power...

I did parallel top balance but only to 3.60 because I'm paranoid to avoid overcharging. It does look like Cell 2 and Cell 4 have a few more AH than 1 and 3 (at least to the untrained eye)

i think i see 9AM0000091 and 02YCB71717200J -- Looks like Jan 22 2019?

My test was a 12V 4S test so that did test all the cells. Two 300 watt 12V inverters feeding light bulbs and a 12v fan cooling the bulbs. Check out my other post today with the voltage of each cell plotted. I really thought that the voltage plot would generate more interest than fact that...