battery charging issues

[Headshok]

I have a 400W Linea panier rack style slide in/out battery about 2 years old
I stupidly let it run flat over 2 months and now it won't charge
Firstly when I plugged the charger in it stayed green ( on the charger) and I wasn't getting any spark, so I tried to clean up the contacts with 2000 grit paper, and started to get a yellow/orange spark, and the charger would go red - but only for about 30 seconds then green again. So I don't think its charging.
Anyone else had this type of issue?




So I tried to

 

[vfr400]

You should never leave a battery flat. Most likely, one or more cells have gone below the minimum 2.5v, where the management system won't allow charging.

You might be able to save the battery by opening it up, measuring the cells, then either charging them individually or charhing for a short time in front of the management system. You can confirm the problem by measuring the voltage on the charge port. Anything lower than 30v for a 36v battery or 21v for a 24v one indicates a high probability that's the cause.

 

[Nealh]

Tell us the discharge voltage, if reasonable it may be ok. As vfr has said if a cell group drops below a certain voltage then the BMS senses a error/fault and for safety will not let charging occur. If a cell group is between 2.5v - 3.2v then it will be recoverable if lower then 2.5v it may still charge but may be weakened.
We can guide you safely to manually recover the battery if you are practical and undaunted at giving it ago, a voltage meter is essential.

 

[Headshok]

I think it must be a 36V as the charger is outputting 41V and the battery is on 28.1V (it actually fluctuated a little from 27.9 but settled on 28.1.

I am happy to tackle anything you recommend, (nothing to loose!) I had to magyver an old charger to safely get a reading on the charging terminal!

For prep I did remove all the screws this morning and the rear cap came off ok, but the front end (where the charger and light are) didnt budge - with the 2 screws out - so I think it must be on some sort of top clip?

 

[vfr400]

With 28v on the charge socket, you should be able to charge it. It means that there is a connection to the cell-pack and the BMS has the charge port switched on and your cells are probsbly OK. If it were switched off, you'd see something like 18v or lower.

Have you got any other charger that can get it over 30v? Maybe there's a cut off in the charger you were using.

Or maybe try keep plugging in your charger to get a bit of charge in before it cuts off. You won't need much to get it over 30v, when it should start charging normally.

 

[Headshok]

the charging cuts out after 30ish seconds so I am unplugging it and reconnecting - and seeing if that works.

 

[Headshok]

I dont this is working - it cuts out after 2 seconds now! and is on 27.8V

 

[vfr400]

It could be that the battery is charging the charger. The only thing I can suggest is to try a different charger.

 

[Headshok]

I got it locally and spoke to the shop today - taking in tomorrow to try a different charger.

 

[Nealh]

Whether at 28v it charges is down to the BMS and it's lowest LVC value, some may allow charging some don't. Some of the BMS I have don't allow charging if a cell group is below 3v.
Undo both end covers to the battery and look to see if the cell pack is siliconed in at all, if so you will need to prise out the silicone so the pack can slide out. From there one can access the BMS to check the 10 cell group voltages.

 

[vfr400]

Whether at 28v it charges is down to the BMS and it's lowest LVC value, some may allow charging some don't. Some of the BMS I have don't allow charging if a cell group is below 3v.
Undo both end covers to the battery and look to see if the cell pack is siliconed in at all, if so you will need to prise out the silicone so the pack can slide out. From there one can access the BMS to check the 10 cell group voltages.

That's right, but he's able to measure 28v on the charge port, so the charging mosfet must be switched on.

 

[Headshok]

thanks neal - have you ever had one of these apart before. on the end with the charger port/switch/ Light ect there are 2 screws underneath, but the end cover won't come off - it feels like there are more screws holding it but i can't see them. I popped out the light but still can't see any more screws?

 

[Nealh]

thanks neal - have you ever had one of these apart before. on the end with the charger port/switch/ Light ect there are 2 screws underneath, but the end cover won't come off - it feels like there are more screws holding it but i can't see them. I popped out the light but still can't see any more screws?

No, sorry not that type.

 

[Headshok]

Finally got it out without doing any damage - the batteries just had a blue heat shrink cover..

So what should I check first?

its got 50 cells

 

[vfr400]

As always, lovely photos, but they don't show what we need. We need the BMS, it's connections and the wiring to the charge socket and terminals.

 

[Headshok]

thanks this is the first one I have taken apart so thanks for being gentle..

In photo 2 the red and black cables come from the charging port, the black one goes the bms and the red one goes to the other end of the cell pack, where it connects with the red wire to the main fuse and the red wire from the BMS connection which lokos like a pc hardware connector.

the 2 thin white (rH of pic 1 ) are the mains switch

 

[Nealh]

Lets see if we can rule out any cell group anomalies with a series of 10 cell readings..
4010.JPG Disconnect the multi sense wire connector, 1 x red, 9 x White and I think I can see 1 x Black on the very end.
With your meter (set to 20v)place Black probe on the Black wire pin and the Red on the White next to it, write down the voltage.
Next move along to the very next pin the Black probe on the the first White and Red probe on second white again write down the voltage.
Now do the exact same to all the others until you have ten individual voltage readings.
When done show us all the readings.

 

[vfr400]

Put your red probe on the position where the red is soldered to the cell-pack, then probe where the black is soldered to it, then to the negative terminal, then to the charge negative. If all have the same voltage, there’s nothing wrong with the BMS.

If your charger allows it, you should be able to get the cell-pack voltage up by maling a temporary bridge between where the negative attaches to the back of the charge socket to where the thick black is soldered to the cell-pack. Once the voltage goes up above 30v, it should charge normally.

All this is assuming that it's not your charger or its connection that's the problem.

 

[Headshok]

ok back now- had to get a new volt meter,

down to 17V on the pack

trying your suggestion so I have soldered a wire from the charger black wire to the black on the pack and its recieveing 42V so fingers crossed

 

[Headshok]

Its been getting 42Volts now for 17 hours and wont go any higher than 25.5V

Any more suggestions please?