LLT bms end user configuration?

DIY Builds Battery Builds
#1

I bought a couple of 12S charge only LLT BMS’s, and have been installing them as part of my upgrade cycle.

The first one I never could get the Bluetooth connection to work so I didn’t configure it at all, and I’ve been running it since last spring without a problem.

The second one I just installed, and I notice that the charge complete voltage is different than the first one.

So I’m wondering should I have gone in and meticulously configured these things before use?

Thanks,

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#2

Probably a good idea to just give the parameters a once-over whenever using a fresh one. That’s what I do anyways

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#3

I never touch them unless i’m diagnosing/troubleshooting a sick battery, you good to leave them as is!

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#4

I have a few parameters I tweak and set but nothing major or at all necessary, they seem to respond well to plug and play. Always a good idea to look and see that it isn’t set to life or lipo or something. If the xaioxiang app doesn’t work a bunch of solar focused apps will interface with them well depending on your os

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#5

If one BMS connects and the other doesn’t, and they’re both the same it would suggest to me that one BMS may be faulty.

How much is a BMS worth?, Compare that to your house, car or any other place you might leave your board.

#6

Thanks for the feedback everyone, I’ll continue to research. I might replace one of them, but I want to watch the charge process via the app (which works now that I’ve gotten a new phone) and see if I can discern the difference.

Tangential question, has anyone seen, or written code to query the LLT via the UART port? A quick Google didn’t turn up much.

#7

On GitHub there are some projects
Search" “ESP32 JBD BMS”

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#8

I have had issues similar to the bluetooth issue you mentioned, where certain features would not work off the bat. I could not fix it with android or iphone. I had to buy the pc connection cable. After configuring via PC it worked as expected.

I agree that the stock configuration is good. I prefer the preset li ion poly light, which uses a max of 4.2V instead of 4.25V.

The completed charge voltage should really be regulated by your charger so that amperage is reduced as you approach the target (full charge) voltage. I would take a look at your charger output and run the numbers to see how that is lining up with individual cell voltage. Then adjust the configuration if needed.

#9

LLT and JBD are the same BMS (or share the same interface)?

#10

Xiaoxiang, JBD, LLT… all the same

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#11

you just made my life so much easier.

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#12

I Use the overkill solar app

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#13

JBD is the manufacturer, the rest are just resellers

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#14

It’s kinda funny, I have 2 LLT BMS’s, both 12S and I use a Cycle Satiator. On the first board (F2) it terminates the charge fine, but on the second board (F1, recently rebuilt) it errors out with a “power cycle error” message.

There’s a 90% chance this is my fault. I have (3.5A) inline fuses on all the balance leads, but not on the Positive and Negative leads. The Cycle Satiator is a 4A charger but I can’t imagine I would ever see 4A on a balance lead.

I put a 2A charger on it, but I think the LLT thinks it’s charge complete so it’s not doing anything.

Perfect excuse to run the board today, then charge with the (dumb) 2A and see if it charges to a different voltage.

All the chargers say they terminate at 50.4, but I can’t get it above 49.5. I’ll have to re-check the final voltage on F1, I’ll do that later this week.

#15

I agree I don’t think there is any way to blow those fuses in normal operation, but I don’t have experience using fuses on the balance leads. I have two suggestions. 1. The pack could be out of balance so that one cell group is higher than the others. If you can’t get the BMS to display I would just measure these directly to see if that is the case. But you said another BMS worked so maybe not this. 2. The BMS has an unusually low voltage cutoff like 4.15V or so. You’d have to change the setting if this is the case. You could potentially set your charger to the lowest output amps, like .1A if that is possible. Then ramp up the voltage from 49.5 to wherever it cuts off. That would tell you more accurately what the cut off is set at but wouldn’t really solve the problem.

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