I finished up a Chevy Volt lithium conversion about a month ago and the car has been sitting in the garage more than I like because of the holidays and the weather. Every day or so, I’ll pop in to check the BMS mostly out of curiosity and because I think it’s cool… and to make sure nothing is crazy going on. I’ve noticed that the DIFF between my high and low cells seems to be drifting further apart. Wondering if I just have something configured wrong, the balance feature isn’t working, or if this is normal. When I finished the install, the DIFF was around 50 mV; now it’s up to 155mV
My setup
4 Chevy Volt 48V batteries
Chargery BMS-24t
Delta Q charger with lithium profile
2000 4 seater w/ t2 controller.
Originally I just had balancing on Charge and Storage. Flipped on Discharge to see if that would make a difference.
Thoughts? Anyone have a good description on how balancing works? Is it just drawing power from the highest cells to bring them down to match the others?
I just finished up a bolt install and I’m new to the Chargery BMS as well. If I’m not mistaken the BMS is powered by the first 16 cells in the pack. You’ll notice cells 17-24 are at a higher voltage than 1-16. You mentioned the cart had been sitting for a bit so the BMS was draining 1-16. I think the new hardware version of the Chargey BMS draws power from all 24 cells.
You have the “Diff of Cell Voltage” set to 150mV. I believe that threshold must be crossed to trigger balancing. Once triggered it will balance the cells to within 12mV, the “Balance Stop Diff Voltage”.
Ah… so i need to go lower vs. higher. let me try that.
Think I set it higher because I was having trouble with getting the charger to enable. I thought the charger wouldn’t kick on if any alarms were going off. Will report back
It may only balance when display is on.
I set “always on” so I can see when I walk by.
For storage, unplug bms and a power cable. It can then sit for a couple years without draining.
You can see in the Upper left corner it says “Storage” so that tells me the settings are to low OR you need to reset “turn the balancer off and then on again” the green light on your charge control leed. Comming off the BMS should turn on and the charger will kick on.
That is if your charge parameters are set correctly 4.0 or higher
I updated the firmware to V1.22 for LCD and V1.18 for main unit which looks like it adds the option to balance in storage. If I kick "Over Charge Release Voltage " above the lowest cell voltage, the charger will enable and do its thing. I did notice on other folks’ postings of their settings, that they didn’t have the balance in storage as an option which came in with recent firmware updates. So now there’s Balance in Charge, Discharge, and Storage… all which I have ON. (I guess just because its on the display, doesn’t necessarily mean it works)
I tried to cycle them all to OFF, exited the menu mode, and then went back in and put them to ON. We’ll see if that makes a difference in the AM.
I have been ripping around in the car between rain storms here in SoCal trying to see if I’d get better balancing in discharge and when it’s back on the charger. I’m still stuck around 150mV. Secondarily, being inspired by some of the SkiTracks postings people have been putting online (@Tyson_Davis), I wanted to start doing some data collection of my own and posting to see if it’s consistent with the performance others are getting.
I had a good laugh on this ride, had a mini cooper pull over and let me pass climbing the 9% hill.
I have an email out to Jason Wang with all my settings too to see if he has any ideas.
Current status, I have the display configured to always on and lowered Difference(Diff) of cell voltage to 50 to see if that will get it balancing. As of now, haven’t move that much since messing with settings 12 hours ago.
Overnight no real change in Storage mode. That’s with the cell DIFF lowered to 30mV, Display always on, and balance start voltage at 3.60. It went down maybe 3mV
I bumped up the "Over Charge Release Voltage " to 3.95 to see if being in Charge mode would get this sucker balancing with 4.0 at the top. Actually got further apart
I drove it 2 miles down to the park to go for a run. Rebooted it there. I’ll have some discharge, charge, and storage all happening. See where it’s at when I get back home
