Battery problem

Ajaym

Finding my (electric) wheels
Feb 10, 2016
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I own a Kudos Duke which I keep at a holiday home in Corfu. I tend to go out there in spring and autumn so the bike is unused for 6 months or so over the winter. In light of what I had read I therefore asked a friend who lives there if he could put the battery on charge once a month which(I trust) he did.
So in May 2014 I arrive and try the bike and whilst the led on the charger indicates the battery is fully charged it's flat and nothing I try will get it going. I decide therefore to take the battery into a shop which sells electric bikes and see what they can do. With my limited Greek and his limited English I explain the problem and leave it with him. When I return he says he's fixed it and it was a loose connection. This doesn't seem entirely convincing but if it's fixed who am I to complain and for the rest of the year the bike works fine.
So fast forward to May 2015. Same problem. So into the shop and leave it with him. When I return he says this time he can't fix it and that the battery may be dead. I asked what he'd actually done and it seems he'd taken one end cap off which only gives access to the back of the charge plug and led display and that his sophisticated test equipment was a torch bulb with two wires soldered to it.
Anyway back home I thought I might as well try it on the bike and noticed that the leds briefly lit up. I connected the charger and bingo the battery started charging and once again worked fine for the rest of the year.
So any idea what is going on? It seems my Greek friend can fix the problem without knowing that he's doing it. If when I get there this year I have the same problem any suggestions? And anything I can do to prevent this happening in the future.
Thanks in advance for any help you can give.
 

trex

Esteemed Pedelecer
May 15, 2011
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your battery seems to be out of balance because of long period of inactivity.
The battery is composed of 10 cell blocks, the BMS runs from one block. Over time, that block has much lower voltage than the other 9, causing the BMS to shut down. What that guy on the island did was to connect his light bulb directly to the cell pack and discharges your battery a bit to get the BMS to reset itself. Topping up the battery each month helps but it's best to ride the bike a bit each month.
 

Ajaym

Finding my (electric) wheels
Feb 10, 2016
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Thanks for the prompt reply. I'm not sure I can persuade anyone to ride the bike whilst I'm not there. If the problem does repeat is there anyway I can duplicate the Greek guy's effect?
 

trex

Esteemed Pedelecer
May 15, 2011
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yes, you can.
 

Ajaym

Finding my (electric) wheels
Feb 10, 2016
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Sorry if I'm being stupid but do you mean I should do as he did and try connecting a torch bulb to the charger connections which is what I think he did.
 

trex

Esteemed Pedelecer
May 15, 2011
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2,671
on some batteries (I presume also on yours), the battery meter is connected to the cell pack via a two pin JST plug.
He probably connects his torch bulb there. You will probably need a better bulb than a torch bulb, but the principle is still the same. Next time, charge the battery to half full (36V) before hibernating the battery, you are less likely to unbalance your battery even after 5 months without topping it up.
 

Kinninvie

Esteemed Pedelecer
Oct 5, 2013
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Teesdale,England
Where on Corfu?
 

Ajaym

Finding my (electric) wheels
Feb 10, 2016
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Agios Matheos.At the top of a big long hill hence the electric bike!
 

Ajaym

Finding my (electric) wheels
Feb 10, 2016
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71
Just to return to the original question I also own another Kudos bike(a Tourer) here in the UK. It appears to have the same battery. Looking inside there are two wires going from the charge socket via a fuse to the cells and two wires going to a small pcb where the battery level leds are mounted. So the idea is to connect some kind of load(ie a bulb). As it might be easier to buy something here any suggestions as to what I might get via ebay? or Maplin?
This does all seem to me slightly crude,though as I said if it works I guess I shouldn't complain,but would there be anything else to try if it doesn't solve the problem?
Maybe I should return to this thread once I'm out there in May if plan A doesn't work.
 

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