Batt not charging - help!! (52V 14S 4P - JBD BMS - 14S 50A UART BT / JBD-SP14S004)

[m0rg5]

EDIT: added the missing/updated settings screenshots

Hey all - long time lurker, first time poster here.

I'm a noob that's been going through a hardcore learning curve around all this, what with bad advice I got early on that led to a lot of confusion and mistakes. I've now rewired the balance wires a redonkulous amount of times, there's been a crap ton of confusion and frustration, and still haven't found a manual () yet I may well be becoming somewhat less of a noob as I pull more and more hair out and approach bald guru .

My setup:
- **Configuration**: 52V 14S 4P
- **Cells**: 56 total 18650 cells
- 43 saved from a damaged pack.
- 13 reclaimed cells (I ran full charge/discharge tests with a LiitoKala Lii-M4S, and ended up discarding about half of those).

**BMS Specs:**
- **Model**: JBD BMS 14S 50A UART BT (JBD-SP14S004)

Now, I think I finally have it set up correctly, have tested voltages, continuity, input, etc and everything seems in order.

The BMS seems to be working, showing all settings, can see it balancing and settings are editable via xiaoxiang and overkill bms apps (overkill so much clearer, without erroneous, double entries ("cell num" I'm looking at you), so based on OKB now.
I can see BMS balancing, and have manually got all the cells pretty close (see img).

There are 2 key things I'm seeking help on:

1. The BMS isn't allowing any charge input. This could be due to my settings, that my cells were too far from each other (closer right now than they've ever been), or something else - I'm charging with a 54.6 3a charger as I try to find the laptop power supply i will canabilise to become the 52v charger.

2. Any advice, gotchas, etc on my BMS battery settings (see img).

Thanks in advance for any help you can offer!

 

[amberwolf]

Some (possibly many) BMS have a limit to how different the cells can be, since having cells that are different from each other**** means that (since BMS are designed around using new cells) that they are no longer matched and have aged too much and should be replaced, so it disables charge and/or discharge, so you don't end up damaging cells (which can result in a fire). The difference setting, if it is user-accessible (it isn't always, not even to see what it is), is often 0.1v.

You'd have to manually charge each cell (or group) so that all of them are within the BMS limits for difference to overcome this. (it's easier to charge them all to the *same* voltage so that they are at least equal at the intiial pack build point).

If the BMS has a balance function, then once youve overcome the difference limit and can begin charge, you can leave it on the charger for however many hours, days, or weeks that it takes to make those differences go away and balance the pack (something you'll have to do every time you charge it, to get the most out of the pack each time).

If it doesn't have a balance function, then it cannot make the differences go away, and every time you charge/discharge they will grow worse until it exceeds the BMS difference limit and it prevents you from using the pack. You would have to manually and individually charge each cell (or group) every time to balance them.



****If cells are not the same, they will not charge/discharge the same, and will become more and more unbalanced, so that there is less and less usable capacity (even though the cells aren't actualy changing in capacity).


Also, balanced does not mean the cells are equal in anything other than voltage. If they are not identical, matched-characteristics cells, they will perform differently from each other in both charge and discharge, and they will always grow *more* different over time, making the pack behave worse and worse.


We can't see what your settings are to tell you if they are ok or not, since none of them are visible in the screenshot.


Laptop PSUs are rarely suitable as chargers. Most are not CC/CV, but simply turn off the output entirely as soon as current limit is exceeded, or simply just fail (blown fuse, fet, diode, etc) when exceeded. (one or more of these is true for most PSUs in general; not a very high percentage of PSUs are designed as CC/CV output).

LED PSUs (meanwell HLG and ELG, etc) are CC/CV and suitable for charging.

 

[m0rg5]

Hey @amberwolf , thanks for the detail in yr reply.

I am aware of much of it, all the 18650's were tested (full charge, recharge, IR test, mah measurement on a liitokala m4s) before selecting the compatible, from the cells that survived, for the pack w' similiar IR and mah ratings (~2500mah).

The BMS does seem to be active balancing, albeit slowly (~150mv IIRC) I've added a new screenshot and all cells are all now within the 0.1v, though still not charging with the 48v charger.

And thanks to u I'm onto getting a more suitable charger.

 

[docw009]

The 13S 3A charger should still get you up to 53 or 3.8V/cell, The charger will revert to constant voltage as it approaches full voltage but I've watched my 13S 3A charger still pushing 3A at 54V.

I think you have to play with the balance settings. It appears from your settings that you .have enabled balance but shut off balance when charging. I've never used that kind of BMS, but it sure appears that it's balancing around 3.6V and can't go any higher very fast.. Maybe disable balance entirely or raise the balance voltage to 4.1. Anyway, try playing with those settings,

What sticks in my head is I recall seeing similar posts, and the answer was a quick "oh heck, you forgot some slider button"

.

 

[m0rg5]

The 13S 3A charger should still get you up to 53 or 3.8V/cell, The charger will revert to constant voltage as it approaches full voltage but I've watched my 13S 3A charger still pushing 3A at 54V.

Yes, my understanding too, but it aint charging.

I think you have to play with the balance settings. It appears from your settings that you .have enabled balance but shut off balance when charging. I've never used that kind of BMS, but it sure appears that it's balancing around 3.6V and can't go any higher very fast.. Maybe disable balance entirely or raise the balance voltage to 4.1. Anyway, try playing with those settings,

I've actually tried all types of settings to try and get it to work, inc balance when charging only (only the OKB app shows this as "balance only when" charging, xiaoxiang just has balance and balance when charging side by side), but none have made any difference.

What sticks in my head is I recall seeing similar posts, and the answer was a quick "oh heck, you forgot some slider button"

Here's to hoping!

 

[eee291]

If I had to guess based on the info, I'd say you soldered the black wire to the B- instead of the blue one.

 

[m0rg5]

If I had to guess based on the info, I'd say you soldered the black wire to the B- instead of the blue one.

The blue one is B-.

I soldered the black wire (B0) to S1 negative as per diagram

 

[eee291]

So you've got the thick black wire from the BMS going to charger -, and charger + going to Cell 14 positive?
If so, then the only explanation left would be that your charger actually needs to see voltage from the battery to actually start charging.
So turn the Discharge slider on and the battery should start charging.

 

[m0rg5]

So you've got the thick black wire from the BMS going to charger -, and charger + going to Cell 14 positive?
If so, then the only explanation left would be that your charger actually needs to see voltage from the battery to actually start charging.
So turn the Discharge slider on and the battery should start charging.

Sry for delay, and thx for detail.

I'd accidentally put charger[-] onto S1[-] (connecting to B-) instead of C-.

It's now spliced into C- which then becomes OUT[-].

But still nothing is doing .

Is this coz my series' are now more unbalanced? (There might have been a short and a blown fuse, that was possibly, maybe entirely my fault).

Did I read that it needs a minimum 3.6 to charge? (Even tho there's option to set it lower than that). I have been manually bringing them up ~3.6v.

It remains working in all other respects and is active balancing right now after changing the Balancer Config/Start Voltage: 3400mv (BMS was disconnected since last reply).

 

[eee291]

Is this coz my series' are now more unbalanced? (There might have been a short and a blown fuse, that was possibly, maybe entirely my fault).

JBD BMS doesn't care if the cells are unbalanced. If it's blocking charge port, it would tell you.

I think there is some other issue you/we are overlooking completely.
I'd like to see actual pictures of how the battery and BMS are wired up.
Another thing to check would be the charger output, with a multimeter, for example.

 

[docw009]

Sry for delay, and thx for detail.

I'd accidentally put charger[-] onto S1[-] (connecting to B-) instead of C-.

It's now spliced into C- which then becomes OUT[-].

But still nothing is doing .

Not sure what you meant by S1. If you meant B1, that In the first case, you had a 54.6V connected directly to 13 of the cells, And if you meant B-, then across all 14 cells. Either way, the charger is able to charge what cells it contacts to its max voltage. You cannot shut it off. If the balance circuits only bleed 50 ma, and with 2 amps going thru the cells, I can't see the balance holding back charge though,

Sure you have a good charger?. I just had to toss two 52V chargers. Hadn't used them for a year and they just never woke up. Went to cycle my little used 52V battery up to full and then down to storage and nejther would charge it, Did get it to 54V with the 48V charger.

 

[m0rg5]

Crikey moses - it's charging!



Yesterday I figured I should replace the worn fuse holders and while I put a fuse in the charge fuse holder [FH_2], I didn't in the primary+ OUT fuse holder [FH_1]* - thinking I didn't need to coz FH_1 showed the full pack voltage on both fuse points* (detail below for other noobs that may be confused too).

Not sure what you meant by S1.

S1: series 1 of 14 (14s), S1- : S1 negative.
Important detail was that charger[-] was incorrectly connected to B- not C-, it's fixed and working now.

Thanks @eee291!

Seems we made it!

---

* FH_2 splices to FH_1 cable, after the fuse.

TBH the no-fuse voltage sitch kinda breaks my , after googling this seems to be the counter-intuitive way of fuses - they only stop current-flow when there's a broken-fuse/no-fuse + current-flow? Or am I still confused?

 

[m0rg5]

EDIT: removed, jiggled and plugged back in temp sensor, all ok now. Leaving the below for any other poor soul that may find themselves tearing their hair out.

---

Just left house so unplugged charger.

On return I open overkill app, plug batt back in (charger shows red: charging), app disconnects showing "connecting" on app.
Will then not connect on xiaoxiang (just white screen I've never seen before) or overkill apps.
Unplug charger and reconnects in both apps, plug charger back in and disconnects.

In 'Event Counts':
Charging low-temp times: 1058
(charging under temp set to -8.0c)
All others: 0

I'm in oz, start of summer, 30c right now - WTAF!?

 

[Zambam]

EDIT: removed, jiggled and plugged back in temp sensor, all ok now. Leaving the below for any other poor soul that may find themselves tearing their hair out.

---

Just left house so unplugged charger.

On return I open overkill app, plug batt back in (charger shows red: charging), app disconnects showing "connecting" on app.
Will then not connect on xiaoxiang (just white screen I've never seen before) or overkill apps.
Unplug charger and reconnects in both apps, plug charger back in and disconnects.

In 'Event Counts':
Charging low-temp times: 1058
(charging under temp set to -8.0c)
All others: 0

I'm in oz, start of summer, 30c right now - WTAF!?

Hi,

Good job getting your battery charging!

What is the overkill app? What does it do? Will it be useful in addition to the XiaoXiang app? I will be building my first battery pack soon, two of them actually (LiFePo4 22S 1P, 15 Ah cells) , each with it's own BMS (JBD SP22S003A). Parts on order.

 

[m0rg5]

Good job getting your battery charging!

Thanks!
Been a bloody unprecedent trial, but now: VICTORY!

What is the overkill app? What does it do? Will it be useful in addition to the XiaoXiang app? I will be building my first battery pack soon, two of them actually (LiFePo4 22S 1P, 15 Ah cells) , each with it's own BMS (JBD SP22S003A). Parts on order.

Overkill sells branded, maybe custom?, JBD kits (for solar, off-grid setups, etc) and have developed their own app for the kits they sell.
The app talks flawlessly to any JBD BMS, as far as I know, and is maintained by English speakers, with much clearer sensical settings.

Oh, one related thing I've been meaning to add here: the 'protection locking' showing in xiaoxiang is disabled simply by enabling charging and discharge. Just one example of confusing settings in xiaoxiang (another that caused me to need to reset BMS: 2 x 'cell num' in 'parameter view', still don't know what the 2nd one does, the first is not cells but series').