Help needed please on BMS ?

[Thorls1]

Hello,
Can anyone help me please, I have purchased a Carrera Crosscity bike at a low cost because the owner said the battery needed renewal charger reading charged all the time ( bike is a 2020 model) I took the case apart as pics and bumped the battery using the outputs which then allowed a normal charge to take place until it read fully charged.

The charger reads 41.8 v and the battery reads 41.3 reading taken direct without BMS as if I read it from the BMS it reads a quickly dropping voltage from about 18 v to 0.6 in a matter of seconds ?

I have tested the cells individually on the pin connector and they are all apx 4.13…see pics…is the problem the BMS ? It is a Powercore DXB 31, is it possible to get a replacement ? Have sent Powercore a email but had no reply

many thanks for any help or advice

 

[Nealh]

Is the BMS in sleep mode , some of those batteries have to be woken up.
I think a a 30sec press of the on button is a method of waking them up.

 

[Thorls1]

Is the BMS in sleep mode , some of those batteries have to be woken up.
I think a a 30sec press of the on button is a method of waking them up.

Thanks Nealh, I did try a press of the controller button on the bars and it lit up for a second then went off…I will reassemble the battery and try it for 30 seconds

 

[Nealh]

Does the battery have it's own switch, this is the one to long press.

 

[Thorls1]

Does the battery have it's own switch, this is the one to long press.

It only has an on off rocker switch and charger port..no other switches

 

[Thorls1]

It only has an on off rocker switch and charger port..no other switches this is a copy of the battery by Greencell you can see the red Rocker switch at the top of the battery

 

[Bikes4two]

Have sent Powercore a email but had no reply

I'm thinking the Chinese New Year holidays may be the cause for no reply as yet.

I'm awaiting a replacement BMS for my bottle battery as not only is the BMS not alowing a full charge but the discharge mode fails to operate sometimes too.

I have twice now got the battery to fully charge by charging through the outlet connector rather than the charging port (I'd read this somewhere and thought, what the hell, I'll give it a go and so far so good).

Obviously charging in this way bypasses the balance function but I'm checking each cell bank for balance and so far problems.

When you read the e-skateboard forums, you find that it is not uncommon to modify the BMS to operate in Charge Only Mode and bypass the Discharge mode as BMS lockup on skateboards can lead to nasty accidents.

As to whether bypass mode on ebike batteries is something to consider, I'd look to other more wiser forum members to comment on that one.

 

[Thorls1]

I'm thinking the Chinese New Year holidays may be the cause for no reply as yet.

I'm awaiting a replacement BMS for my bottle battery as not only is the BMS not alowing a full charge but the discharge mode fails to operate sometimes too.

I have twice now got the battery to fully charge by charging through the outlet connector rather than the charging port (I'd read this somewhere and thought, what the hell, I'll give it a go and so far so good).

Obviously charging in this way bypasses the balance function but I'm checking each cell bank for balance and so far problems.

When you read the e-skateboard forums, you find that it is not uncommon to modify the BMS to operate in Charge Only Mode and bypass the Discharge mode as BMS lockup on skateboards can lead to nasty accidents.

As to whether bypass mode on ebike batteries is something to consider, I'd look to other more wiser forum members to comment on that one.

View attachment 45586

View attachment 45587

Thanks…lots of videos on you tube where people build packs without BMS our more experienced members would know if this is a bad idea…doyou mind letting me know where you ordered your BMS from please…just incase I have to try and get one…thanks

 

[wheeliepete]

It could be the switch at fault, check the solder joints or bridge the connection and see if that gives you full pack voltage at the output connector. You could replace the BMS with a generic one, but you may have to resolder the balance wires if the connector/sequence does not match.

 

[wheeliepete]

i've got a pack with a BMS that stopped providing output voltage about a year ago. I've carried out the modification in #7 and it has performed fine since, still charges and balances well. I do keep an eye on the voltage, but all controllers I've come across have a LVC, this will prevent the pack from over discharge, so I don't view it as a dangerous mod. I do however see potential danger in doing this on a high power setup with a cheap battery that cuts power, as this could put the cells under extreme stress and could end badly, although this does not apply in your case.

 

[Bikes4two]

.…doyou mind letting me know where you ordered your BMS from please…just incase I have to try and get one…thanks

It was greenbikekit.com - I order on 29th Jan - I wasn't given a shipping/delivery forecast but I'm anticipating a couple of weeks.

 

[Thorls1]

It was greenbikekit.com - I order on 29th Jan - I wasn't given a shipping/delivery forecast but I'm anticipating a couple of weeks.
View attachment 45591

thank you

It could be the switch at fault, check the solder joints or bridge the connection and see if that gives you full pack voltage at the output connector. You could replace the BMS with a generic one, but you may have to resolder the balance wires if the connector/sequence does not match.

Many thanks, will check the switch

 

[Thorls1]

thank you

Many thanks, will check the switch

It could be the switch at fault, check the solder joints or bridge the connection and see if that gives you full pack voltage at the output connector. You could replace the BMS with a generic one, but you may have to resolder the balance wires if the connector/sequence does not match.

I checked the switch today and it appears to be the problem…switched it on and off a few times and it works…will replace the switch…many thanks to all for your help

 

[Bikes4two]

I checked the switch today and it appears to be the problem…switched it on and off a few times and it works…will replace the switch…many thanks to all for your help

Just to say that in my bottle battery I suspected the switch as initial observation seemed to point that way but the problem turned out to be the BMS after all.

As you probably know, switching the battery on and off is usually acheived by sending a control signal to the BMS rather than directly switching the main connections, thus operating the switch and getting power back can lead you to think that it's a switch problem when it could be the BMS.

As said above, it's worth bridging out the switch, ideally at the BMS end, to see if the problem goes away for sure (this is what I eventually did and the powering down problem persisted, hence a new BMS). If is does go away then that just leaves the switch and wiring from the switch.

If your switch is like the ones I bought from Ali Express (before I realised it was a BMS issue), you're welcome to one for free (10 cost me a couple of quid and I've no particular use for the spares) - just PM me.

 

[Thorls1]

Just to say that in my bottle battery I suspected the switch as initial observation seemed to point that way but the problem turned out to be the BMS after all.

As you probably know, switching the battery on and off is usually acheived by sending a control signal to the BMS rather than directly switching the main connections, thus operating the switch and getting power back can lead you to think that it's a switch problem when it could be the BMS.

As said above, it's worth bridging out the switch, ideally at the BMS end, to see if the problem goes away for sure (this is what I eventually did and the powering down problem persisted, hence a new BMS). If is does go away then that just leaves the switch and wiring from the switch.

If your switch is like the ones I bought from Ali Express (before I realised it was a BMS issue), you're welcome to one for free (10 cost me a couple of quid and I've no particular use for the spares) - just PM me.

View attachment 45650

Many thanks, I spoke to soon yesterday the out put kept coming and going on inspection of the BMS it looks like a SMD resistor has burnt out see picture in red circle….need to try figure out which BMS I need to get now !! I know its a 10s, 36volt and 20amp discharge but unsure

 

[Nealh]

One could try replacing the 511, nothing lost by doing so.

 

[Thorls1]

One could try replacing the 511, nothing lost by doing so.

Thanks Nealh, do you know where I could source one from ?

 

[Nealh]

They are so small one doesn't just one, they usually are sold by the 10's/ 100's and are pennies each.

 

[Nealh]

They are pennies to buy, one has to buy them in larger quantities.
(511 Ohm, 25 pcs.) SMD resistor 0805 Values: 112 Ohm to 953 Ohm on OnBuy

 

[Thorls1]

They are pennies to buy, one has to buy them in larger quantities.
(511 Ohm, 25 pcs.) SMD resistor 0805 Values: 112 Ohm to 953 Ohm on OnBuy

Many thanks for your help