BMS Problem With ADAPTTO System

[APNIC]

Hi,

I'm wondering if someone might be able to point me in the right direction with a problem e-bike I have. Just to clarify I'm a complete novice and have absolutely no idea what I'm doing (honesty is always the best policy lol)

Recently my brother passed away and I ended up inheriting a Qulbix Raptor Q140 e-bike.

The bike had been stood for a long time (1.5 years) and so the first problem was a totally flat battery, when I turned the key, nothing happened at all, the bike was dead. I got around this by pulling the battery appart (it's dozens of 18650 batteries) and charging them individually and putting the battery back together.

This worked as in the bike can now be turned on at least. BUT....

When I twist the throttle nothing happens, I think the bike has shut down into like a protection mode.
On the bike's LCD screen I have a !BMS! warning symbol at the top.
Finally on the BMS circuit board there are 3 little red lights, which I'm assuming is a warning something is wrong.
The circuit board has 7 slots in total and I am using 5 of them as in the picture attached. If I move all the connectors 1 to the left, then the 3 red lights vanish and the bike turns on OK, but again I get the BMS warning error and the throttle does not respond.

Does anyone have any ideas about what I should try next ?

Thank you very much

 

[Nealh]

You don't say what voltage system is in use possibly 48v ?
Also what is the voltage of the battery when fully charged ?
The warning lights probably indicate that the cell bank/banks indicated are either not charged or will not charge and the voltage is at or below the lvc (low voltage cut off).

 

[APNIC]

Hi,

Thanks for the reply.
The battery is 72 Volt and 20 Amp Hours.
At the moment the battery is showing around 69 Volts
According the e-Bike's manual the minimum required is 55 Volt

Thank you

 

[Nealh]

My bad as I didn't open the pic to see the 5 groups of sense wires,
72v is 20s ( in series) 55v is way way too low so ignore that.
69v means it's not charged the pack as a whole is sitting at 3.45v per cell average so sitting at lvc level.
A charged pack should read 83 - 90v, 69v is why you are seeing red lights a cell group or two are low indicatied by the leds adj to that sense wire connection.
If you place your meter probes on the sense wires you should get 20 voltage readings incrementally rising by about 3.4/3.5v each time, the bms is fine it's just not detecting the voltage it needs to see.
In all probability after 1.5 yrs standing the cells/battery may be knackered.

 

[APNIC]

Thanks so much for your input, it's greatly appreciated as I'm honestly way out of my comfort / knowledge zone here.

When I stripped the battery down to component level, eg single 18650 batteries. I tested each one individually and charged them up.

I used to be in the e-cig business so had plenty of chargers and testers for these batteries. There were a handful that were toast, but I replaced these with a new one. Each battery was charged, discharge tested and then charged again.

My plan was to try and get enough power to turn on the bike (Which was acheived) and then use the bike to charge the battery up to the top. On these bikes you plug the charger into the bike and then select the charging option through the bikes menu. But it looks as though being in this BMS error mode is preventing me from doing this as the charging isn't happening when I enter charge mode.

Thanks again though for your help.

 

[Nealh]

Although you have managed to bring low cells up to voltage they may have bled back some, with the new cells what voltage did you charge them to ?

 

[APNIC]

I had 10 x 18650 chargers in my old e-cig store room, so all the batteries went into these chargers which would charge them right up to full. I think it was to 4.3v although I can't honestly remember.
I was thinking if I could get the bike at least turned on, I could then charge and balance the battery through the bikes charging / BMS system.

 

[Nealh]

There may lie the likely issue if the new cells were fully charged they will be far superior to the older cells and will hold all their charge whilst the older cells may not hold their charge so well (4.3v is to much). It is these new cells that are likely preventing the bms to allow charging as it reads their full voltage so will not allow the current to flow. Ideally you need charge/discharge each cell in each parallel group to a respectable like voltage of about 3.6 (72v) - 3.8v (74v) then you should see charging applied only after this will you find out how well balanced the pack is and whether the cells will hold up.

 

[APNIC]

Oh yes I see what you are saying. I never thought of that, but it makes sense. I will have another look into the battery in the next few days and take it from there
Thank you ever so much for your help on this one. It's very appreciated.

 

[Deleted member 4366]

It doesn't add up. if you charged all the cells to 4.3v, 4.3 x 20 =86v, but you only have 69v. Where has the 17v gone? You need to measure the voltage on each pin of the edge connectors. They should go up in equal increments of about 4.2v if that's what they were when you assembled them. Any discrepancies will show you where the problems are. I'd say that the cells are knackered and self-discharging. Did you check them for that? Also, measuring their internal resistance can give a good idea of their state too. Knackered cells can go very saggy when you use them.

 

[APNIC]

Hi d8veh,

Yes I agree with what you are saying.
I was assuming that as it took me so long to charge up all the batteries and rebuilt the battery back up, that during this time I might have lost some of the power ?
It's taken a few weeks to strip down and rebuild the entire battery pack.