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

[ArthurEld]

Here's my Help About -



And this is the QR code I got from Heltec- https://heltec-bms.com/wp-content/uploads/2020/09/heltec-bms-2.6.0.build30.apk_.1.1.zip

 

[fafrd]

GXMenow and ArthurEld

The only possible interest I have in getting a ‘smart BMS’ from Heltec versus their ‘dumb’ Active-balance BMS is the increase the active threshold voltage from 2.9V to well up into the knee such as 2.4V.

Can both of you confirm that the Active Balance only becomes active when voltage mismatch to an adjacent cell exceeds 100mV (which seems to be a common spec in all variants of Heltec Active Balance technology that I have seen)?

If only active with 100mV mismatch, this Active Balance Technology is only realistically get activated we’ll up the knee past 3.4V (unless one cell is basically degraded to the point of needing to be replaced, meaning 50% capacity or less).

 

[upnorthandpersonal]

@ArthurEld Interesting, the below one is mine. So I have an earlier build date, but a later revision. Something doesn't add up...

 

[upnorthandpersonal]

when voltage mismatch to an adjacent cell exceeds 100mV

I think I can put mine to 10mV. Let me check... yes, the lowest I can put it to is 0.003V, so 3mV.

 

[fafrd]

I think I can put mine to 10mV. Let me check... yes, the lowest I can put it to is 0.003V, so 3mV.

View attachment 28419

Didn’t realize the app allowed that parameter to be changed as well.

What is the read precision of the BMS?

Have you ever used a mV-precision multimeter to check the accuracy of the BMS single-cell measurement precision against a common reference (the multimeter).

Most BMSs I’ve seen state +/-5mV precision (meaning a worst-case of 10mV error cell-to-cell).

 

[dRdoS7]

Hi,

Here are a couple of screenshots:





Mine came from here: https://heltec-bms.com/support/

An earlier version from here: https://www.jkbms.com/support/

I think you might be correct. And I bought mine more recently and got my app direct from Heltec.
Where did you buy your BMS and where did you get your app? And when?

Link to Ali Store is back a page.

dRdoS7

 

[upnorthandpersonal]

It's funny, because I'm pretty sure JK are the original manufacturer this BMS.

@fafrd The claimed accuracy on these is supposed to be +/-5mV. I did check this some time ago, but I just deemed it close and good enough at the time.

 

[ArthurEld]

Hi,

Here are a couple of screenshots:

View attachment 28420

View attachment 28424

Mine came from here: https://heltec-bms.com/support/

An earlier version from here: https://www.jkbms.com/support/



Link to Ali Store is back a page.

dRdoS7

Yours is newer than mine. I guess these apps don't update

 

[dRdoS7]

Hi,

Yours is newer than mine. I guess these apps don't update

But the info probably relates only to the BMS, not the app. We have different a VendorID to upnorth... Don't know about GXMnow.

Maybe different between BMSs, as to whether that Start Balance Voltage setting is available.

dRdoS7

​

 

[fafrd]

It's funny, because I'm pretty sure JK are the original manufacturer this BMS.

@fafrd The claimed accuracy on these is supposed to be +/-5mV. I did check this some time ago, but I just deemed it close and good enough at the time.

Thanks. I’d see little point in balancing to 3mV accuracy if read accuracy is +/-5mV (unless you confirmed with a precision multimeter that the actual read accuracy is at least +/-1.5mV, at least for the cells you care about).

I’m in touch with Heltec and most here who have purchased from them seem reasonably happy, but if JK is the original manufacturer and similar products can be purchased directly from JK at similar prices, I would prefer to go that route - do you have a link to their store?

 

[digitalsteve]

Quick shipping from China to Southern California Heltec 16c BMS and active capacitor balancer, ordered on 16th received via Fedex on the 23rd. Also great communication and help.

 

[fafrd]

Quick shipping from China to Southern California Heltec 16c BMS and active capacitor balancer, ordered on 16th received via Fedex on the 23rd. Also great communication and help.

Did you order through Heltec’s website or through AliExpress?

Link appreciated (it’s so difficult to identify the real manufacturing companies versus the trading companies repping those manufacturers on AliExpress...).

 

[digitalsteve]

Did you order through Heltec’s website or through AliExpress?

Link appreciated (it’s so difficult to identify the real manufacturing companies versus the trading companies repping those manufacturers on AliExpress...).

Heltec's website, Echo Zhao was quick to answer my questions (evenings, pacific time, probably morning for him?)

Company Name: ChengDu Heltec Automation Technolohy Ltd,Co.,
Contact Person: Echo Zhao
Email: echo@heltec.cn
Skype: echodongmei
Tel-Number: +8618123313360

 

[ArthurEld]

I called Echo a him too and was informed that Echo is a her

 

[upnorthandpersonal]

if JK is the original manufacturer and similar products can be purchased directly from JK at similar prices, I would prefer to go that route - do you have a link to their store?

I'm not sure they have one - the links on their website seem to point to different stores, but don't have the BMS. Maybe it's worth contacting them directly and ask, but somehow I don't expect a real answer.

 

[Dzl]

What makes you think JK is the manufacturer?

When I originally looked into things, I didn't find enough info to conclusively determine who the actual manufacturer was, but Heltec seemed the more likely of the two from what I remember.

 

[ArthurEld]

What makes you think JK is the manufacturer?

When I originally looked into things, I didn't find enough info to conclusively determine who the actual manufacturer was, but Heltec seemed the more likely of the two from what I remember.

Why does the vendor ID have JK in the name? There are other indications that JK is the manufacturer.
I bought this direct from Heltec



edit:
The name of the device.

 

[PeterBC]

Head swimming again in all the info here. I now realise the link I was following (with the lugs for battery connections) was a 'dumb' BMS, not configurable, and no monitoring or displays. That sounds dangerous to me. I want to see whats going on at least. Also some of the parameters seem wrong ? Isnt a cutoff voltage of 3.75v too high ?
The Smart version with an App etc seems to be passive balancing only ?

72.49US $ |Smart BMS 40A 80A 300A 400A 8S ~ 20S Lifepo4 li ion Lipo Battery Protection Board Bluetooth APP 10S 13S 14S 16S 20SBalance|Battery Accessories| - AliExpress

Smarter Shopping, Better Living! Aliexpress.com

www.aliexpress.com

"Charging current: 50A Equilibrium current: 100MA"
The charging current text doesnt change for different versions from 40A up to 400A. I'm assuming it can handle charging and discharging at the same rate as these are common port ?
If passive, what about the option of just adding their simple active balancers to another BMS ? Of course all the discussions of when is active balancing really useful are relevant and what parameters to use.

 

[Steve_S]

With the "Dumb" BMS' you have to be careful to get the one for the chemistry being used. LiFePO4, LITO, etc are all very specific. The devil is IN the details and it takes a careful & cautious eye. The Dumb BMS' are fine for their intended purposes such as a completely enclosed battery assembly that is set & forgotten for ages... I most certainly would not use these with the current crop of Commodity cells. With those you most certainly would be better off with Matched & Batched cells I would think.

HelTec could certainly stand to hire a proper English Speaking Writer to Edit their Docs for Clarity & Readability.

Common-Port use the same DC wires to the battery for charge & discharge. Separate Port uses a separate DC line that comes from the charger system (think of an EV parked getting charged by it's internal charger... no solar or other charge methods as one example. IMO, THis is not a BMS I would use in any EV as such, unless it was my Converted Lawn Tractor. LOL.... E-Lawn Tractor races coming soon ! \\WooHoo//

HelTec is a Known Good Active Balancer system producer. They have BMS' with Passive or Active balancing as well as stand-alone Active Balancers including some with communications interfaces. You can use a Regular (non-Balancing) BMS and have it work in conjunction with an Active BMS. You can even use a BMS with Passive Balancing in it & an Active Balancer BUT the active balancer will confuse the passive balancing so better turned off.

For example, I am running with QNBBM's (Active Balancer) with my Chargery BMS' (x4). BMS is wired to the QNBBM which is then wired to the cells with 14g wire in my case. I've plaing with the passive balancing on as well just for fun to see what's happening with that... The passive is more or less pointless with big cells and I run 2 packs of 24V/175AH & 2 packs of 24V/280AH so it became pretty obvious passive would not cut it at all...

QNBB with BMS leads going in, and Batt leads going out to cells. Pic Below along with the two types of connectors.
Heltec's can be setup similarly. Many choose to use a MOLEX connector and others choose to use a Fused Connector with appropriate sized fuses to protect each cell (I don't know if that is "needed" TBH, it's more a piece of mind thing I think.

I hope I've answered your questions., at least I hope it helps a bit anyways.

 

[Dzl]

Isnt a cutoff voltage of 3.75v too high ?

Yes and no, its higher than you want to consistently charge to but fixed 'dumb' BMSes are often set to 3.7-3.8 to allow the full bandwidth to be used 2.5V to 3.65V, expecting that you will limit charge bandwidth at the charger and inverter + DC disconnect. Setting the BMS at 3.75 allows an end user to use a charger that charges to 3.65V with a little cushion to prevent disconnects. My limited understanding is that with healthy cells slightly exceeding 3.65 on occasion may have some effect on cycle life, but won't cause significant immediate damage. Considering that most people here are buying cells of somewhat questionable quality and health, it seems reasonable to be a little more conservative. This is one of the benefits of a programmable BMS, you can set more conservative limits if you choose too.

The Smart version with an App etc seems to be passive balancing only ?

The BMS you linked to is a different make/model (Ant BMS), it is not the smart version of the Heltec BMS

"Charging current: 50A Equilibrium current: 100MA"
The charging current text doesnt change for different versions from 40A up to 400A. I'm assuming it can handle charging and discharging at the same rate as these are common port ?

Not sure if they are all 50A, but the AntBMS is not technically a common port BMS (even if it looks like one), it can control charging and loads separately and is limited in the charge current it can handle.

If passive, what about the option of just adding their simple active balancers to another BMS ?

Many people do something similar to that. Heltec does make an active balancing BMS though, you just haven't found it yet. I don't have a link handy, but it has been linked to multiple times throughout this thread, you might have to dig back a bit.