LLT SmartBMS questions

[fessyfoo]

@glyphiks

Did you disconnect the balance wires or main negative at any stage?

nope.

[fessyfoo]

is the charging turned off for any reason by chance? the app should show this.

[Acido]

Maybe the charge port has a diode so you can’t measure the voltage because of that, if it charges normally I wouldn’t worry.

[fessyfoo]

@Acido

Maybe the charge port has a diode so you can’t measure the voltage because of that, if it charges normally I wouldn’t worry.

I’m able to pull current out through the charge port. (it shows up as discharge in the app) so I don’t think there’s a diode. and think P- and C- are connected on the board.

[Linny]

Charging is turned on, yea

[fessyfoo]

how to calibrate voltages.

@Pecos

I haven’t messed with it but you should be able to set offsets in the voltage calibration menu to correct for that

@leadBreather

That worked perfectly. I was expecting 41.92v after calibration, and got exactly that. Thanks.

[fessyfoo]

@frame

LLT BMS auto detect version wiring guide
JBD BMS auto detect version wiring guide

[fessyfoo]

@fessyfoo

When does the LLT smart bms clear counters like low voltage alert?

I’ve found it at least clears them each time you write the config.

[GnomeMeansNo]

I don’t get what this LLT in my LaCroix is doing…

It says it’s at 100% but 18s pack is only at 73V.
FreeSk8 reports 73.3V as 86%.

The LLT seems to be toggling charging on and off every 5 seconds because when charging is on at least one cell quickly goes above 4.25V:

Is this pack OK? Does it just need to stay plugged in an balance for a while?
The LLT does seem to be balancing for about three seconds before it kills charging for another five seconds.

[Acido]

Why is your cell 15 at 4.3v?

Thats the reason the bms is not charging

[frame]

@GnomeMeansNo

Is this pack OK?

very much not ok, u got pgroup at 4.07 and 4.32, that’s a huge difference and bms has to work very hard to try and balance it out. if u keep charger plug in it will probably take weeks to get all pgroup to 4.2

[GnomeMeansNo]

Yeah it’s wierd the cell that is high jumps about tho it’s not always that one.
Hmm I let it go for a few hours and eventually the charger clicked off and the batteries look balanced:

…at 4.1V per cell… still only a level FreeSk8 calls 94%

It seems like when it’s charging the cell voltages bounce around which cause the BMS pvervolt to trigger every few seconds but then once the charger cuts the juice all 18 settle at the same level.

[frame]

I suggest u check p5, 11,14 and 15. It’s not normal when bms reporting them higher than rest, but it goes back down that fastand in line with the rest when charger is off

[GnomeMeansNo]

Hmm I ran the pack down to 25% but llt still reports 100%.

[me_ashman]

I manually set my voltage percentages and that fixed the 100% charge always showing

[tech.shit]

If your BMS isn’t wired into the discharge the reported percentage will almost always be incorrect unless charging, at least in my experience with a half dozen LLTs

[fessyfoo]

lil cross linking

@vegr0

Cant get an answer from LLT. i got their 10-17s bms. first time using it and i can’t get the settings to write anything other than 13s… You can see the extra cell group. its a 12s pack.

I followed the harness wiring correctly, stopping after the first 13 wires.
Any idea?

@ShutterShock

You did not follow the diagrams, you have to solder together a number of the leads to make it 12s. You should be able to get the diagram from the product page in a pdf

@vegr0

yea thats the issue, There is no diagram for this unit.

36V 48V 60V Li ion or Lifepo4 smart Bluetooth BMS with 40A 60A 80A constant current for 10S to 17S Battery – LLT POWER ELECTRONIC

Normally the first black wire is for battery -

then the first white wire hits the positive of battery -

then each wire hits the next positive terminal of every group. - I used a total of 13 wires for this 12 pack.

Which part did i mess up for this unit as it obviously isn’t wired the same as their standard 12s bms.

edit - i see now theres a text link hidden on the page that shows the diagram…

@ShutterShock

There is a diagram for it, you just posted it

It doesn’t have a 12s one, but it’s a reasonable assumption since all the others are like this, to think that 12 should be the last connection on the end (17)

Then 11 should combine 16, 15, 14, 13, 12, 11.

@glyphiks

It does have a 12s one

Search terms LLT diagram 10-17s bms wiring

[fessyfoo]

Troubleshooting “fluctuating balance readings”

LLT BMS cell values fluctuating

Hey everyone, I’m mid way through swapping an original Lacroix nazare over to 18s using the internals I bought second hand from someone parting a supersport. The battery is in, powers up without issue, but the BMS is constantly fluctuating the voltage on a few cells from 1-2V up to 6V. Anyone seen something similar or have any ideas? [Screenshot_20231105_165857_XiaoXiangElectric] [Screenshot_20231105_165903_XiaoXiangElectric] [Screenshot_20231105_165907_XiaoXiangElectric] [20231105_171049] …

[fessyfoo]

reference

@ablairlamb

Hi all, finished building my 18s6p P45B pack and did my BMS wiring yesterday. I am using a JBD SP22S003 BMS and everything seemingly went fine except for my final readout. The diagram shows leads BC16-17-18-19-20 as getting combined, however on my connector there is no lead for where BC20 would be - it skips and has the last 2 leads. I combined the 4 wires 16-19 and finished it off per the diagram, however I am getting an odd readout on the Xiaoxang app. Not sure if I should add a lead where there is one missing, and add it to the other combined leads? Even though the BMS model number is SP22, it’s listed as a 21S BMS (and the missing wire would confirm that also).

Any thoughts? Thanks in advance and happy holidays all.

@Skyart

What i normally do is remove the black plastic cover on the back of the BMS and solder those pins together at that location.

@ablairlamb

I just ran all 4 leads to the 16th P group since it wasn’t a long run. Do you have any idea what might be up with the funky reading? I haven’t used this BMS in particular before, only the 10-17S one before.

@Skyart

The weird reading comes from the missing lead messing up the way the BMS reads voltage. You could just solder that one to the reatbof the group, but i recomend soldering all of them together at the back of the BMS and removing all but one of those leads that go to your group 16.

After that you should be able to plug everything in and it will read lile it should. If it doesnt you will need to go into the settings menu and charge the BMS from 21s to 18s

@ablairlamb

Thanks, ended up jumping them on the back of the BMS and all is reading well now Now need to ride it!

[fessyfoo]

@glyphiks

JBD is the manufacturer. LLT is a reseller. They are the same bms.