7s80p Balancing

Hello again;
I have 2 - 24V ~160Ah, in parralel,battery that I am charging with a EPSolar Charger.

I have Battery Management Protection setup.

I need Battery Balancing (7 packs).

I am doing this on the cheap (cannot afford Batrium).

all the 7s Balancer boards I can find do 63mA current balancing.

From this website, I think I need about 1A Balancing Current. http://liionbms.com/php/wp_balance_current.php

I was watching this youtube video ().

The above video makes it looks like I can purchase a fairly inexpensive 7S balancing board and slap on a low Ohm resistor to by-pass the resistors on the board to get a a High Current Balancing board. With some heat control added.

Am I looking at this the right way?

Check out this diy bms
https://github.com/stuartpittaway/diyBMS

Jason Morris said:

Check out this diy bms
https://github.com/stuartpittaway/diyBMS

Click to expand...

Yep. I'm basing my bms off his work and expanding upon it.

I am using these 1S balancers and now have 7 of them. My original though was only to get two of them and only balance on the highest and lowest voltage. Then I would use relays to pick the cells with the highest voltage on one balancer and another relay to pick the lowest voltage with the other balancer. I thought that would be very simple, almost like those ABCD switch boxes for serial/parallel cables back in the days, but after figuring how many relays I would need, I ended up with needing 28 relays just to do this simple task, so I gave up on it, until someone comes up with a Dual Pole Seven Throw relay for cheap

if your pack is severely out of balance, 1 amp isn't going to help you unless you are only charging your battery pack at 4 amps. I had a 3s20p li-ion 11.1 voltpack that was severely out of balance, when I was charging at 6 amps I had to bleed one of the cells at 4 amps to get it to charge without triggering the bms, as it got full I reduce the load on the cell. But this I had to do manually and adjust as it was charging I use one of these. It did work, got the battery charged at 6 amps in about 3 hours, normally it take all day to charge at 1 amp with a balance charger.

USB Electronic Load Adjustable Constant Current Resistor 35W Capacity Tester
This one is adjustable, by turning the knobs.




I also tried to use one of the 3in1 balancers like in the youtube video, but I knew that 1 amp balancing wasn't going to help. Looking at the circuitry you need a small solder tip and steady hands.

I was going to use overvoltage relays to control the usb load testers on each cell but couldnt get it to work because each cell is grounded to the other and was interfering with the overvoltage relays.

Ardino is beyond my knowledge level, batrium too expensive and more than I need.

For the li-ion battery packs, I added more series connections (nickel strip) and that fix that balancing problem. For my 4s lifepo4 110ah battery I couldnt fix the out of balance condition using more series connectors.

I fixed it by using active balancers (6 amps) , that was an excellent fix for the battery, I been using for almost 3 months and my solar charge controller is chargingthe battery at up to 12 amps until my overvoltage relay disconnects the solar panel. Since I had the balancers not once has the bms triggered because of an out of balance condition. With the balancers, I don't have to do any more adjustments during the day on the solarcontroller, before I had to adjust the bulk/float throughout the day to avoid triggering the bms.
The4s balancer cost about 90 dollars, they sell for different battery configurations.
That is an option, cheaper than batrium but still expensive. Electriccarpartscompany sells them.