Heltec BMS' (up to 350A) with Active Balancing & Independent Active Balancers

[ArthurEld]

I'm still waiting for an answer about a CPU warning on one of mine.
It won't let me turn on charging or discharging but it will balance.

Hopefully we'll get answers next week.

 

[GXMnow]

I actually got a human response from the Ali Express store where I purchased my JK (Heltec) BMS unit. They are on a Spring Holiday until Feb 20th though, so they were not able to help right now, but they will contact me when they get back to work in 6 days.

Meanwhile.... I am looking at other BMS solutions. I was spoiled by the functions on the JK BMS. I really like how it worked and the data it reported. When it was working properly, it is an excellent design. But I need a BMS that is going to last years, not months. It went online last June, and quite in February. That was 8 months of service for about $200, so that is not a very good return on investment. It is such an odd failure, I am still hoping I can find a flaw on the PC board and get it working again. I have my battery bank charging without a BMS right now, and it does make me nervous. I have been out to the garage about every 30 minutes to measure cell voltages. So far they are staying dead on balance. My Fluke meter is showing every cell within 0.005 volts of each other. And I have the XW-Pro stopping charge at just 57 volts, so it will take a pretty big imbalance to get me into any trouble. The fuses are still there for over current protection. And the XW-Pro will also shut down if the voltage drops below 50.5 volts, which is 3.6 volts, or about 45% charge. So the chances of anything going too wrong are very slim.

 

[Steve_S]

I actually got a human response from the Ali Express store where I purchased my JK (Heltec) BMS unit. They are on a Spring Holiday until Feb 20th though, so they were not able to help right now, but they will contact me when they get back to work in 6 days.

Meanwhile.... I am looking at other BMS solutions. I was spoiled by the functions on the JK BMS. I really like how it worked and the data it reported. When it was working properly, it is an excellent design. But I need a BMS that is going to last years, not months. It went online last June, and quite in February. That was 8 months of service for about $200, so that is not a very good return on investment. It is such an odd failure, I am still hoping I can find a flaw on the PC board and get it working again. I have my battery bank charging without a BMS right now, and it does make me nervous. I have been out to the garage about every 30 minutes to measure cell voltages. So far they are staying dead on balance. My Fluke meter is showing every cell within 0.005 volts of each other. And I have the XW-Pro stopping charge at just 57 volts, so it will take a pretty big imbalance to get me into any trouble. The fuses are still there for over current protection. And the XW-Pro will also shut down if the voltage drops below 50.5 volts, which is 3.6 volts, or about 45% charge. So the chances of anything going too wrong are very slim.

It is ironic that I started this thread but went with the Chargery BMS simply because I wanted Contactors over FET base. I have a JBD Fet Based which I will be using for my 12V Pack for the small RV Furnace in the Powerhouse (it is independent with own solar).

After a few months of testing & tweaking, including the hard Thrash Tests I've gotten the QNBBM Active Balancers and Charger BMS with partial Passive Balancing activated singing in proverbial Harmony and singing along nicely. It's good enough that my comfort level reached a point where I even sold off most of my spare BMS', Relays, Contactors (although I do still have 2 full spare sets until I complete everything to 100%). gotta have backups way out here.

 

[ArthurEld]

I actually got a human response from the Ali Express store where I purchased my JK (Heltec) BMS unit. They are on a Spring Holiday until Feb 20th though, so they were not able to help right now, but they will contact me when they get back to work in 6 days.

Meanwhile.... I am looking at other BMS solutions. I was spoiled by the functions on the JK BMS. I really like how it worked and the data it reported. When it was working properly, it is an excellent design. But I need a BMS that is going to last years, not months. It went online last June, and quite in February. That was 8 months of service for about $200, so that is not a very good return on investment. It is such an odd failure, I am still hoping I can find a flaw on the PC board and get it working again. I have my battery bank charging without a BMS right now, and it does make me nervous. I have been out to the garage about every 30 minutes to measure cell voltages. So far they are staying dead on balance. My Fluke meter is showing every cell within 0.005 volts of each other. And I have the XW-Pro stopping charge at just 57 volts, so it will take a pretty big imbalance to get me into any trouble. The fuses are still there for over current protection. And the XW-Pro will also shut down if the voltage drops below 50.5 volts, which is 3.6 volts, or about 45% charge. So the chances of anything going too wrong are very slim.

Your pack is so well balanced that it would stay balanced without the balancer.
You could turn off the balancer and use a different one.

If I can't get a replacement for my bad one, I'll get a different BMS. The Overkill sound pretty good. Their guarantee says they will replace it even if you break it by doing something stupid.
I'd probably go with the balancer Steve mentioned and put it on my worst pack. Sounds like fun anyway.

 

[GXMnow]

The funny part is the FET protection section, and even the active balancing section are all working perfectly. It is just the voltage measuring on 2 of the cells went to zero. I am trying to trace the board and see if it is a simple component failure. But the traces are so tiny, and it appears to be more than a 2 layer board. I think I found the transistors that seem to select which cell is being measured. To go further, I need to test it with voltage on and see what it is doing. I know it samples, so it is going to be constantly switching from cell to cell. My guess is one of those transistors failed, so it can't connect to the lead between cells 3 and 4. I was hoping to find a bad solder joint. No luck yet. I may be getting a 60 - 100 amp dumb BMS just to monitor the system until I decide n a permanent fix. My current demands are staying under 60 amps. I may parallel 2 cheap 45 amp units. They are only about $30 each. I am also looking at what BMS units the Schneider will talk to. So far it is just one built into a battery module.

Yes, the cells are staying in balance without an issue, but I am still not going to chance it running without me here without active protection. I am also

 

[upnorthandpersonal]

I wish I could get one of mine to fail like that. I want in on the fun to figure out what broke...

 

[Horsefly]

After a few months of testing & tweaking, including the hard Thrash Tests I've gotten the QNBBM Active Balancers and Charger BMS with partial Passive Balancing activated singing in proverbial Harmony and singing along nicely. It's good enough that my comfort level reached a point where I even sold off most of my spare BMS', Relays, Contactors (although I do still have 2 full spare sets until I complete everything to 100%). gotta have backups way out here.

Hey @Steve_S - I thought you were no longer happy with the QNBBM Active Balancers. I can't find where you said it though, so I may be mistaken. If they are on your good list, I'll put them back on my list. ?

 

[Steve_S]

I'm NOT happy with DeliGreen. The QNBBM's have been working a treat. I only wish they had a UI that would allow for changing settings and monitoring the Balancing activity of the device. Once Jason releases the new Chargery B series with Active Balancing I hope to get into one and if happy with what I see I may switch my fleet over.

 

[Horsefly]

I'm NOT happy with DeliGreen. The QNBBM's have been working a treat. I only wish they had a UI that would allow for changing settings and monitoring the Balancing activity of the device. Once Jason releases the new Chargery B series with Active Balancing I hope to get into one and if happy with what I see I may switch my fleet over.

Ahhh, OK. I misunderstood.

Do you have any idea when the Chargery series B will be available?

 

[Steve_S]

Nope, twas supposed to be just before CNY but they were thrashing & abuse testing.
Also this is OFF TOPIC, so no more Chargery Babble in here.

 

[Stepandwolf]

Your pack is so well balanced that it would stay balanced without the balancer.
You could turn off the balancer and use a different one.

If I can't get a replacement for my bad one, I'll get a different BMS. The Overkill sound pretty good. Their guarantee says they will replace it even if you break it by doing something stupid.
I'd probably go with the balancer Steve mentioned and put it on my worst pack. Sounds like fun anyway.

Wish Overkill offered a larger BMS, i.e. 250a vs. 120A. As an aside, Daly said they would have active balancing in about 2 months. Is there another active balancing offering besides Heltec? Heltec doesn't make an 8s so they aren't an option for me.

 

[GXMnow]

After a bit more testing, finally brave enough to power up the board with it unmounted. 57 volts fused at 200 amps can be a bit daunting. It appears the problem is in the wiring harness. If I measure across pairs of cells at the connector to the BMS, I am getting 8.4 volts with both cell 3 and 4, but if I measure 2 and 3, or 4 and 5, I am only getting 6 volts. Yet 1 and 2 is 8.4, 5 and 6 is 8.4 etc. The lead between 3 and 4 is very high resistance and showing some voltage drop with just the load of my Fluke meter. With the BMS connected, it get's far worse. I need to pull the harness off of the batteries and check it. I think it is the crimp on the actual pin inside the connector at the BMS end.

 

[upnorthandpersonal]

I think it is the crimp on the actual pin inside the connector at the BMS end.

That would be interesting - any idea how this could have happened? It's not something I would expect on a system that is sitting in a corner without stresses applied to those wires.

 

[fafrd]

That would be interesting - any idea how this could have happened? It's not something I would expect on a system that is sitting in a corner without stresses applied to those wires.

Heat and/or corrosion...

That’s the reason I prefer soldered leads - if there is no movement involved, once a soldered connection is validated, there is little short of corrosion if the underlying wire itself that can lead to change in resistance...

[edit: see it is on the BMS side of the harness, so not a DIY crimp connector on the battery side. A poorly-made crimp connector by the supplier can easily result in non-stable resistance...]

 

[ArthurEld]

I took a couple of those pins out of the connector. I messed up a couple wires and had to put heat shrink on them.
They were kind of a pain to get out and I wasn't thrilled with putting them back. They didn't seem as good as new.
I am still using that harness but plan to replace it with a new one.

It is good news that your BMS seems to be ok now.

 

[fafrd]

I took a couple of those pins out of the connector. I messed up a couple wires and had to put heat shrink on them.
They were kind of a pain to get out and I wasn't thrilled with putting them back. They didn't seem as good as new.
I am still using that harness but plan to replace it with a new one.

It is good news that your BMS seems to be ok now.

Has anyone found a good source of reasonably-priced replacement harnesses?

I think I need a longer one than the one bundled with my BMS...

 

[ArthurEld]

Has anyone found a good source of reasonably-priced replacement harnesses?

I think I need a longer one than the one bundled with my BMS...

I want to buy one like the original. I will try to get it from Heltec unless someone comes up with a better source.

Some people make their own. They even buy the plugs.

Digikey probably has the pieces.

 

[GXMnow]

CONFIRMED!

The problem is in the wire harness, seems to be the crimp in the 15 pin JST connector. It is intermittent. I was measuring cell volts with a 100 ohm load resistor. That was pulling the voltage down to just 2 volts on the bad cell lead, so it is not open, but very resistive. About 100 ohms. I pulled out the pin for cell 24 that I will never use, and was going to replace the failed pin. Trying to pull the pin out, I was putting a bit of stress on it, but still didn't get the tab pushed in enough, but when I checked it again, it is working, the BMS powered up and is reporting all cells are good now. I am going to order a new set of JST connectors and make up a new harness. My guess is the crimp is partially on the wire insulation and not holding tight on the conductors.

The JK (Heltec) BMS is still working fine and actually did it's job shutting down when it saw bad cell voltages.

 

[ArthurEld]

CONFIRMED!

The problem is in the wire harness, seems to be the crimp in the 15 pin JST connector. It is intermittent. I was measuring cell volts with a 100 ohm load resistor. That was pulling the voltage down to just 2 volts on the bad cell lead, so it is not open, but very resistive. About 100 ohms. I pulled out the pin for cell 24 that I will never use, and was going to replace the failed pin. Trying to pull the pin out, I was putting a bit of stress on it, but still didn't get the tab pushed in enough, but when I checked it again, it is working, the BMS powered up and is reporting all cells are good now. I am going to order a new set of JST connectors and make up a new harness. My guess is the crimp is partially on the wire insulation and not holding tight on the conductors.

I looked up how to get those pins out and thought I was following the instructions but it didn't work like the instructions said.
And when I put the pin back in it was damaged. I had to bend back the part that is supposed to let the pin go.

Now I want to replace my crappy leads with the ones I don't use. It would be nice to just remove all of the ones I don't use.

 

[Haugen]

Anyone have the PN or the series of the JST connector Heltec is using?
There is a chance that I can get my hands on a crimper and make replacements