Kalkhoff Battery not charging

[Deleted member 4366]

The battery is healthy. Did you measure the voltage on the charger? It should be 29.4v, but my guess is zero!

 

[Tintaglia]

Good news that you think the battery might be healthy The charger is measuring 29.2 when plugged in with the battery connected and 25 when unplugged with the battery still connected. It measures 0 when the battery is not connected. I get the same measurements on two different chargers.

 

[Nealh]

The chargers outlet should read 29.4v before you connect it to the battery.

 

[Tintaglia]

The chargers outlet should read 29.4v before you connect it to the battery.

Measuring between which pins? Using the obvious + and - ones as marked on the charger I get nothing but on the outside pins (+ and charge monitoring?) I get a small voltage. I have checked 3 chargers and get the same result on all of them, except for a variation between 4v and 10v measuring the outside pins. They are all charging our other batteries perfectly.

 

[Danidl]

I've taken the readings again connected to two different chargers and they are all identical to when it isn't on charge. To confirm it is an 8ah 25.2v Kalkhoff lithium ion battery which is showing 2 charge lights and 5 battery condition lights.

.. well even that tells us something. I have no detailed knowledge of the Kalkoff charger so these questions are exploratory
.How many pins or connections does it have with the battery. It needs to. Have a minimum of 2 This question is to find out whether they're is a protection circuit which prevents any current or. Voltage from the charger in the absence of a connection.,

Is there a voltage present on any of these connections. If so what is it. . If it above the 25.3v , then it is a charging voltage. If it is about 5 volts it is probably part of a protection circuit used to energise the electronics in the battery.
If there is you should be able to follow it until it disappears In the battery

 

[Nealh]

Measuring between which pins? Using the obvious + and - ones as marked on the charger I get nothing but on the outside pins (+ and charge monitoring?) I get a small voltage. I have checked 3 chargers and get the same result on all of them, except for a variation between 4v and 10v measuring the outside pins. They are all charging our other batteries perfectly.

I'm not familiar with the multi pin charger so unable to a offer much more that may help. Though it sounds as if the charger is ok as in #22 you say it reads 29.2v when connected to the battery, so for some reason or another the battery isn't accepting a charge.
Could be an internal fuse if fitted has blown, fault wiring (dry or loose solder joint) or a faulty bms.

 

[Tintaglia]

It has 4 pins which according to Flecc's excellent article represent 1) charge monitoring, 2) negative, 3) battery meter and 4) charging positive. Without the battery connected there is only a small voltage between pins 1 and 4 and nothing between any of the others. With the battery connected there is a voltage of 29.2 between pins 2 and 4 but no change to the voltage on the individual battery cells when being charged. We have always suspected that the fault is that the battery is not taking the charge but don't know why. We have checked the obvious fuses and connections but don't know what else to check.
Thank you all for your help and suggestions. I'll have another look tomorrow and see if I can trace the route of the charge wire and get a reading where it joins the battery.

 

[Nealh]

At present the battery isn't a write off as the cell strings are well balanced which indicates the cells are healthy. The main issue is a failure to accept further charge, so tracing an testing the charge wires after the bms is next.

 

[Deleted member 4366]

Good news that you think the battery might be healthy The charger is measuring 29.2 when plugged in with the battery connected and 25 when unplugged with the battery still connected. It measures 0 when the battery is not connected. I get the same measurements on two different chargers.

OK, that sort of makes sense, but where are you measuring when you say that it's 29.2v plugged into the battery? Basically, you need to follow the voltage from the charge socket all the way to the BMS to check that it's arriving there. My guess is that it isn't arriving for whatever reason. Figure out which two wires carry the 29.2v from the charge socket and then stick a needle into the wire so that you can see that it's still there. If it's arriving at the BMS, we can only conclude that the BMS is faulty and not allowing charging. Maybe a faulty thermistor on the cell-pack (broken wire).

 

[Tintaglia]

The good news is that we've got the battery charging!! We've been fiddling about this afternoon checking voltages, the charging wires lead into a separate little circuit board and the upshot was that there is current on the wire coming in from the charger but not on the one leaving. We've checked the continuity of the wires through the circuit board and they appear to be ok so it must be somewhere else in the circuit board but that's where our knowledge grinds to an abrupt halt. We have no idea what to check on the circuit board to see where the problem might be.


As a very temporary fix we have bridged the two wires (see pic) and this is allowing the battery to charge. Obviously we know this cannot be a permanent solution, it is just to get some charge into the battery before it gets too low.

Does anyone know if you can buy these circuit boards separately or maybe we could get hold of an old non-working battery and transplant the board from that?
Thank you all so much for your help and giving us the confidence to get this far. We have also fixed another battery today by simply replacing the main fuse which we wouldn't have had the nerve to open up before (although what the point of putting the fuse inside where you can't get to it is beyond me).

 

[Nealh]

Good news at least there could be life yet.
Have a very close look at the wire solder joints using a magnifying glass if possible, a dry/Ioose solder joint would give an interruption in the current supply.
May be a case of carefully desoldering and resolderring the wire joint to rule it out.

 

[Tintaglia]

[QUOTE="Nealh, post: 365593, member: 12170
May be a case of carefully desoldering and resolderring the wire joint to rule it out.[/QUOTE]

That would be the logical next step, although not sure if Hubby's soldering will be any better than it's got now ;-) It's up to 28v now, I'm so glad we persevered, it would have been such a waste to have just chucked it away. Thank you all

 

[Danidl]

[QUOTE="Nealh, post: 365593, member: 12170
May be a case of carefully desoldering and resolderring the wire joint to rule it out.

That would be the logical next step, although not sure if Hubby's soldering will be any better than it's got now ;-) It's up to 28v now, I'm so glad we persevered, it would have been such a waste to have just chucked it away. Thank you all [/QUOTE]
.... Please publish close up photos of both sides of the board. Some of us with more time than sense may be able to assist at this last phase.

 

[Tintaglia]

Thanks again. Hope these are clear enough. We suspect the middle red wire and may try to resolder it tomorrow if we can dig out the necessary tools but generally any advice as to where we can check for current would be great but there's no urgency now we've got some charge into the battery.

 

[Nealh]

Probably won't hurt to do all 3if able too, from the looks of the end one on the left, looks possibly like salt/water has got in at some time.

 

[Danidl]

Thanks again. Hope these are clear enough. We suspect the middle red wire and may try to resolder it tomorrow if we can dig out the necessary tools but generally any advice as to where we can check for current would be great but there's no urgency now we've got some charge into the battery.

View attachment 18329 View attachment 18330View attachment 18328

Is the middle red wire the input from the charger? If so it should be connecting with the device c139 which looks to me as if it is a thermal fuse link and possibly defective. .. there should be zero ohms resistance accross it

 

[Nealh]

Is the middle red wire the input from the charger? If so it should be connecting with the device c139 which looks to me as if it is a thermal fuse link and possibly defective. .. there should be zero ohms resistance accross it

Good spot looks a bit unsightly in that area.

 

[Tintaglia]

Hi Danidl, the right hand red wire is actually the input from the charger, the middle wire is the output to the batteries. There is no transfer of the charge between the right hand and middle wires. The device c139 has no resistance between the two ends, does that sound right to you?

Nealh, if the resoldering of the middle wire goes well we will definitely do all three. The battery was wrapped in plastic and there was no sign of any water ingress, in fact it is immaculate in there. The white on the wires is just a little light powder which wipes straight off. It's amazing how much more you can see on the photos than on the actual battery.

 

[Danidl]

Hi Danidl, the right hand red wire is actually the input from the charger, the middle wire is the output to the batteries. There is no transfer of the charge between the right hand and middle wires. The device c139 has no resistance between the two ends, does that sound right to you?

Nealh, if the resoldering of the middle wire goes well we will definitely do all three. The battery was wrapped in plastic and there was no sign of any water ingress, in fact it is immaculate in there. The white on the wires is just a little light powder which wipes straight off. It's amazing how much more you can see on the photos than on the actual battery.

.. by no resistance do you mean 0ohm or infinite ohms . 0 ohm would be the correct value.

And sorry but my right and your right might be different, are you referring to the red lead closer to the edge of the board, which looks slightly thinner and more worn as the input wire , or is it the red wire closer to the middle of the board closer to the two black components

 

[Nealh]

Touchwood a battery nearly confined to the bin, now with a bit of tinkering a few solders to tidy up looks as if it may be ticketyboo and usable. A good save and 200 quid in pocket.
Let us know the final charge voltage and if it is holding ok and then the big test a ride out.