LLT 20s 200A BT bms- gets 71.3v in, but 51.8v out?!

[Hertzelz]

Hey Guys

My first battery build, LG CHEM N2.1 cells, they're connected to each other with hand made aluminum clamps (with liquid insulation on top of them - the red color you can see in the video).

So all of the balance wires are correct (nowhere to be mistaken honestly as its only 20s1p), each wire jumps from 3.5-3.6 all the way to 71.3 in the end (same as the B- wires that clamped to the BMS)

but the weird thing is, when I measure the P- ports I get 51.8v ?!?!?!

I even uploaded a video (sorry for the angle, only 2 hands) that shows the difference between B- ports and P-........
https://youtu.be/ug5PbUNQQj0

needless to say that the BT is a complete shit, doesn't work on my new Samsung Note10+, so I got an LG G5 with older android version,
and its not stable at all, in the beggining i successfully connected to the bms and got this screen:
https://imgur.com/a/bjLdjlV

but that app is for view only, you cant change anything in it, tried the xiaoxang app, it doesn't recognize the bms.
tried the JBD pc application (tried all of the different ports even though im a pc wiz so I know a thing or two) - nothing, the program doesn't identify the bms no matter what COM or port in the PC I try (windows 7).

I contacted James from LLT and no answer for 3 days. I doubt he'll be helpful.

The only thing that i can think about that they forgot to wire the bms internally to 20s and kept it 14s

Anyone have an insight for me? Already ordered an ANT bms, but the ANT's are 30% the size of the LLT which makes me wonder how they claim its 120-130A const and 400A peak.

 

[amberwolf]

but the weird thing is, when I measure the P- ports I get 51.8v ?!?!?!

This means the output FETs are turned off.

Usually that means the BMS has shut off the output FETs to protect the pack against overdischarge or overcurrent. This means that either something is set wrong in it, or it's reading too low a voltage on a cell or cells, or a cell sense wire is disconnected or wired to a wrong group, or it's just plain defective.

My guess is that until you can get into it's setup to make sure all th esettingsa re right, you won't know which one of thoas it is.

 

[Hertzelz]

but the weird thing is, when I measure the P- ports I get 51.8v ?!?!?!

This means the output FETs are turned off.

Usually that means the BMS has shut off the output FETs to protect the pack against overdischarge or overcurrent. This means that either something is set wrong in it, or it's reading too low a voltage on a cell or cells, or a cell sense wire is disconnected or wired to a wrong group, or it's just plain defective.

My guess is that until you can get into it's setup to make sure all th esettingsa re right, you won't know which one of thoas it is.

Apparently the temp sensors weren't connected and thats what caused it (?!) because when i disconnect them the P- port jumps back down to 51.8v

That doesnt make any sense at all, and Apparently that bms (because its the 200A version) doesn't support the xiaoxiang app, only other android app which only allows to view and not change anything. damn