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

I have "Start Balance Voltage" now and the default is 1.5

There is also something called "Con. Wire Res. Settings"
There are 24 inputs that I assume is for a resistance adjustment for balance leads

ArthurEld said:

Here's one - https://diysolarforum.com/resources/user-manual-for-heltec-jk-bms-with-active-balance.95/

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Thank you very much, this is perfect!!

smoothJoey said:

I just had a look and this model https://heltec-bms.com/product/4s-8s-12s-13s-16s-200a-210a-250a-330a-bms/
This spec stood out Discharge protection voltage: 2.1V
That's even lower than the Daly.

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It was looking like a good one until I looked at specs. can't take the risk. However, great to have folks searching. Hopefully some good ones at a reasonable price will turn up as time goes by. We need to figure out how to help support and encourage Steve at Overkill to get a 48v configured with much larger amp capacity. This 'problem' really needs a solid solution.

ArthurEld said:

I have "Start Balance Voltage" now and the default is 1.5

There is also something called "Con. Wire Res. Settings"
There are 24 inputs that I assume is for a resistance adjustment for balance leads

Click to expand...

You will likely want to raise the "Start Balance Voltage" so that when the cells are low it stops trying to move power around. I would be sure to set it a bit above your low voltage protection cutoff voltage. I have my Balance Start Voltage set up at 3.2 volts on my NMC cells, so it does stay balancing down lower than I will use them in normal operation, but the batteries are safe down to 3.0 volts even, so it will stop balancing before it will hurt any cells.

The "Con. Wire Res. Settings" is the resistance of each balance lead. This becomes important when it is trying to move 2 amps of current between cells. Even a very low resistance can results in fair amount of voltage drop. If you are trying to balance to within 5 millivolts, and the wire lead has 0.1 ohms, at 2 amps, that is a 0.2 volt drop, or 200 millivolts. That is a problem. So once it knows the resistance, it can calculate the wire voltage drop into the measurements to maintain accuracy to about 5 millivolts. You can manually adjust the values, but it you start with a decent charged pack, do a factory reset and set the number of cells, on the next power up cycle, it actually runs a self test and measures the voltage drop and calculates the resistance of each lead for you. I have not seen it try to recalculate it though, so it may only be a one time thing after a factory reset. My system measured them out to all be between 0.130 and 0.136 ohms. I did my best to keep all of the wires the same length and it looks like I did pretty good.

GXMnow said:

You will likely want to raise the "Start Balance Voltage" so that when the cells are low it stops trying to move power around. I would be sure to set it a bit above your low voltage protection cutoff voltage. I have my Balance Start Voltage set up at 3.2 volts on my NMC cells, so it does stay balancing down lower than I will use them in normal operation, but the batteries are safe down to 3.0 volts even, so it will stop balancing before it will hurt any cells.

The "Con. Wire Res. Settings" is the resistance of each balance lead. This becomes important when it is trying to move 2 amps of current between cells. Even a very low resistance can results in fair amount of voltage drop. If you are trying to balance to within 5 millivolts, and the wire lead has 0.1 ohms, at 2 amps, that is a 0.2 volt drop, or 200 millivolts. That is a problem. So once it knows the resistance, it can calculate the wire voltage drop into the measurements to maintain accuracy to about 5 millivolts. You can manually adjust the values, but it you start with a decent charged pack, do a factory reset and set the number of cells, on the next power up cycle, it actually runs a self test and measures the voltage drop and calculates the resistance of each lead for you. I have not seen it try to recalculate it though, so it may only be a one time thing after a factory reset. My system measured them out to all be between 0.130 and 0.136 ohms. I did my best to keep all of the wires the same length and it looks like I did pretty good.

Click to expand...

Man oh man all this chatter is making me want one of these ‘smart’ BMSes.

My ‘dumb’ 300A Heltec BMSes arrived along with a 5A Heltec active balancer and I’m impressed by the quality of what I’ve seen.

My issue with their smart BMSes like the ones you’ve both got was the limited charge current. The 300A dumb BMS will handle up to 100A of charge current, while my 2kW solar charger is going to be putting out 80A or more (I’m mulling putting in a 2.25kW array or possibly even 2.5kW).

So the 50A charge limit on Heltec’s current smart BMSes is a showstopper for me.

But MAN, does all that programmability sound nice! (jealous)

GXMnow said:

You will likely want to raise the "Start Balance Voltage" so that when the cells are low it stops trying to move power around. I would be sure to set it a bit above your low voltage protection cutoff voltage. I have my Balance Start Voltage set up at 3.2 volts on my NMC cells, so it does stay balancing down lower than I will use them in normal operation, but the batteries are safe down to 3.0 volts even, so it will stop balancing before it will hurt any cells.

Click to expand...

I can see how balancing at both ends would be a waste of energy so I will adjust the "Start Balance Voltage" to only balance the upper limit.

GXMnow said:

The "Con. Wire Res. Settings" is the resistance of each balance lead. This becomes important when it is trying to move 2 amps of current between cells. Even a very low resistance can results in fair amount of voltage drop. If you are trying to balance to within 5 millivolts, and the wire lead has 0.1 ohms, at 2 amps, that is a 0.2 volt drop, or 200 millivolts. That is a problem. So once it knows the resistance, it can calculate the wire voltage drop into the measurements to maintain accuracy to about 5 millivolts. You can manually adjust the values, but it you start with a decent charged pack, do a factory reset and set the number of cells, on the next power up cycle, it actually runs a self test and measures the voltage drop and calculates the resistance of each lead for you. I have not seen it try to recalculate it though, so it may only be a one time thing after a factory reset. My system measured them out to all be between 0.130 and 0.136 ohms. I did my best to keep all of the wires the same length and it looks like I did pretty good.

Click to expand...

I left all of my balance wires the same length and I checked resistance.
But as I said above, I got more variation than you. I will start paying more attention to those values and try the factory reset to see what happens.
Thanks GXMnow.

fafrd said:

Man oh man all this chatter is making me want one of these ‘smart’ BMSes.

My ‘dumb’ 300A Heltec BMSes arrived along with a 5A Heltec active balancer and I’m impressed by the quality of what I’ve seen.

My issue with their smart BMSes like the ones you’ve both got was the limited charge current. The 300A dumb BMS will handle up to 100A of charge current, while my 2kW solar charger is going to be putting out 80A or more (I’m mulling putting in a 2.25kW array or possibly even 2.5kW).

So the 50A charge limit on Heltec’s current smart BMSes is a showstopper for me.

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The Heltec Smart BMS with Active balance doesn't have a 50A charge limit. Mine is the 200A version and it has 200A charge current limit.
There is a 300A version as well.

Specs are here- https://www.alibaba.com/product-detail/14-24S-200A-Smart-BMS-with_62544207027.html

fafrd said:

But MAN, does all that programmability sound nice! (jealous)

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Can confirm. I have several 100A versions and these can handle 100A charge and discharge. It's all configurable as well.

ArthurEld said:

The Heltec Smart BMS with Active balance doesn't have a 50A charge limit. Mine is the 200A version and it has 200A charge current limit.
There is a 300A version as well.

Specs are here- https://www.alibaba.com/product-detail/14-24S-200A-Smart-BMS-with_62544207027.html

View attachment 32758

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Forgot to mention I’ve got an 8S 24V battery. If I ever step up to 16S / 48V that looks like a nice option!

upnorthandpersonal said:

Can confirm. I have several 100A versions and these can handle 100A charge and discharge. It's all configurable as well.

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I’m pushing the limits of what an 8S battery can do (and that’s probably the reason products of this class are not widely available at 8S).

but if I ever decide it’s not going to work out and step up to 16S, it’s good to know there are good smart BMS options available...

I ordered 3 more Heltec 200A Smart BMS with 2A active balance.

I was a little hesitant since people are finding JK for cheaper and JK appears to be the manufacturer.

But Michelle reduced the price to $155 each so I went for it.

The 2A active balance won't be used for squeezing more Ah. But should do quite well top balancing cells that gradually lose capacity or that slowly get out of balance for whatever reason.

Besides that even without the active balance these BMSs are excellent. That is just my opinion and I don't have experience with other BMSs. ?

$155 is a very good price. I paid $178 for my JK branded 200 amp unit. Just about $200 flat after shipping and taxes.

Anybody know if this active balancer can be enabled/disabled via a switch?
I want to leave it connected along with my bms and only turn it for scheduled maintenance as required.
UPDATE: provide link for clarity

smoothJoey said:

Anybody know if this active balancer can be enabled/disabled via a switch?
I want to leave it connected along with my bms and only turn it for scheduled maintenance as required.

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There's a on/off switch in the options.
It has an option for turning it on at a certain delta. Mine is currently set a .008V so it won't turn on unless delta is over .008V.
And there is an option for the balancer to only turn on above a certain voltage in case you only want balancing done near the top.

You might be able to put your own switch on the negative balance lead. I'm not sure if that is the kind of switch you are talking about.
That might be risky. Steve S is always talking about burning up BMSs by messing with balance leads while the harness is plugged in.

edit: you are probably talking about the separate balancer which I think has the same software and options.

ArthurEld said:

There's a on/off switch in the options.

Click to expand...

That means the active balancer(not a bms) that I linked has an smartphone based management app, confirm?

ArthurEld said:

edit: you are probably talking about the separate balancer which I think has the same software and options.

Click to expand...

Yes the discrete active balancer not a bms, see link in previous post.
Going to double check the link now.

smoothJoey said:

That means the active balancer(not a bms) that I linked has an smartphone based management app, confirm?



Yes the discrete active balancer not a bms, see link in previous post.
Going to double check the link now.

Click to expand...

I don't have that separate active balancer but I think someone mentioned that it uses the same app.
I could only find one app on the Heltec site.

I think a few people here are using those 10 amp active balancers. Hopefully someone will reply.

Hi,

I have 18 x 280Ah cells, and have the Ah capacity set as 260Ah on both the JK & Classic apps.

I have noticed over the last 3 weeks that the indicated remaining capacity shown on the Enjpower app is falling compared to the reading on the Classic app. The Midnite Classic will usually get to 260Ah before going to Float, while the BMS app is a few Ah less. Because it never goes to 260Ah, it's falling behind the SCC. Yesterday it was about ~50Ah lower.

Just to confirm which is reading correctly (I don't want to believe the SCC, and then run out of electricity sooner than expected), lunchtime yesterday after reaching Float, I turned off solar to both the SCC & the inverter/SCC. Also switched off the grid input to the inverter. I'm going to run the bank down until either it reaches 48V, or the BMS shuts off discharge at 2.6V on any cell. I have an ATS, so the grid will supply the house when the inverter or BMS shuts down.

This morning @ 8am, the BMS app indicated 0Ah, the Classic 44Ah remaining. Bank was down to 58V BMS, 57.5V SCC., inverter 58.6V.

I don't know if it's the updated app, but previously I'm sure the 2 values were roughly the same after the charge cycle. I may try the earlier app in a couple of days and see if it's the same.

Wondering if anybody else has notice this.

I have a 3rd Ah meter, but currently it's in the cable to the inverter and only measures what is going in/out of that. I'll move it to the BMS cable soon, and see if that's reading the same as the SCC (WBJr Ah shunt).

dRdoS7

I have to ocassionally trigger a reset by doing a full charge when the percentages on my BMS and inverter get out of sync.

That's interesting. I have both apps too but never checked between them.

Hi,

I was able to extract 254Ah on my test before #1 cell triggered the 2.6V Low BMS trip. It had dropped rapidly once it approached 3V, took about 35mins, so looks like it's faulty. It was 531mV lower than the highest. 3 other cells also ended up lower than the others, but nowhere like #1. I'll have to contact Mr. Basen. Hopefully I can get a replacement for at least #1.

Drawing about 10A over most of the test. Ran the oven & evap. coolers for a time late afternoon. Started at noon, finished 10:40 next morning.

Took about 5 hours to re-charge to 260Ah.

I now have a red band across the top of the app, also the capacity set itself to 252Ah, from my 260Ah setting, which prevented the reading going higher. I had to change it back to 260, then cause the BMS to above the high trip and set the remaining Ah to 260.

dRdoS7

UPDATE: The red Band disappeared once I closed the app, and restarted it. Must be a warning that a fault condition has occured, and to check to log. Don't recall seeing that before. Maybe only for major trips?