Monitoring individual cell voltages

ESK8 Electronics
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41

are the measurements given on their page wrong?

42

they have the smart bms up to 100A https://www.lithiumbatterypcb.com/product/14s-bluetooth-lithium-e-bike-battery-pcb-board-with-30a-constant-charge-and-discharge-current-2/

43

I just didn’t pay enough attention to sizes :slight_smile:

44

I used that one. Yes, it’s huge

45

There are two types.

  • 20A-60A; 108*65*10mm (or 108*65*15mm including the aluminum housing)
  • 60A-100A; 138*105*15mm
46

I got the 100 amps version. Worth It yet huge

47

Are you using it for discharge too? No issues?

One thing I found in ES is that some (not all) don’t go into the deeper sleep mode with bluetooth attached. If it doesn’t sleep, the drain is fairly significant, enough to worry about. So I’m constantly checking my builds that use these BMS.

48

I am still at the building stage. Didn’t really use It. So…the bt module does not sleep? Damn. Well i can use the pc and ignore the bt. All i really want is set 4.10 hvc

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49

yes, exactly that

50

The damn bt is not pairing anyway.

51

I was thinking about this the other day. Wondering if it would be worth putting a connector on the BT that is accessible from the outside of the enclosure. Would it be practical to only connect the BT to the enclosure when you need to change settings or check the individual pack voltage?

52

I would first do some measuring on how much power the BMS draws when idle with and without the BT connected. It can very well be that the difference is negligible. If there’s a significant difference, though, then sure, you could definitely route the BT connector outside of the enclosure. It’s 4 pin JST-XH and you could even change it to something waterproof.

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53

The measuring may be a bit tricky though. I think it doesn’t only draw power from the whole battery pack but from some sub-parts as well. Ideally you would put a multimeter on all balance leads. I only have two, one of which is this one. :smiley:

IMG_1105

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54

Yeah I had seriously considered putting a toggle switch in, and forgot :slight_smile:

Hacking "JBLTools" Chinese Bluetooth BMS boards | Endless Sphere DIY EV Forum has some data

But I think different units seem to have different behavior.

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55

When this happens to me I close the app, turn off bluetooth, start the app. app will start bluetooth, and usually can scan and bind.

56

I do not have any led lit. WTF? ae_1547568689627 Does It have leds or not?

57

Can someone that has an LLT BMS confirm if the ‘balance start voltage’ cannot be set lower as 4.17? In the datasheet it says min 4.17, typical 4.2 and max 4.23. But I kinda hope that I could put it to 4.1 :slight_smile:

Same for over-discharge protection voltage.

58

I’m using one with A123, and have balance start set to 3.4v.

IIRC I attempted to convert a lithium ion 10s one to A123 15s (failed), and was able to change all the values.

59

this conversation is why l like an external bms :slight_smile:

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Mr Smug. :slight_smile: I’ll take a bit of the shine off :wink:

One of the issues with a non-permanent balancing solution is the cycle life of the contacts for the balance leads.

For example JST-XH which is commonly used for lipo balance leads:

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