Bottle Battery Repair.

[Fish36]

First thing is to get the cell voltages. They will determine what the next steps are.

Agreed as am a little perplexed. Unlike the bottle battery you were working on which showed an under-voltage after charging this one seems to be ok voltage wise showing 41v after a charge, leave the battery a couple of days and it remains fully charged as in it will not take anymore charging from the charger unit which within a few seconds shows a green 'fully charged' light.

Though go out for a ride on the bike and in under a mile there has been a low voltage cut-out and its the full leg power only cycle home.

Will try get out on the bike today and let the battery cut-out, then come back and open the case and measure the individual voltages via the balance wires and let you know what that throws up. Am curious to see what the results will be.

Cheers

 

[Deleted member 4366]

I had one battery that was totally worn out, Everything looked good after charging. Each cell was at about 4.1v and they stayed like that, but as soon as I tried to draw any current, all the cells sagged, and two went right down to LVC within a couple of minutes to cause a cut-out. When I stopped it, they all bounced back to over 40v. I had it on a test rig, so I was then able to check the voltages while it was going, which showed the problem. If you get the same, it would be worth temporarily wiring your voltmeter so that you can see how the overall voltage changes while riding.

 

[Fish36]

I had one battery that was totally worn out, Everything looked good after charging. Each cell was at about 4.1v and they stayed like that, but as soon as I tried to draw any current, all the cells sagged, and two went right down to LVC within a couple of minutes to cause a cut-out. When I stopped it, they all bounced back to over 40v. I had it on a test rig, so I was then able to check the voltages while it was going, which showed the problem. If you get the same, it would be worth temporarily wiring your voltmeter so that you can see how the overall voltage changes while riding.

Think your 'crystal ball' on this maybe being just a totally worn out battery is going to prove spot on, on this one. I have managed to test voltages, just need to write up the results and post them here which will do asap.

 

[Fish36]

Ok went for a ride on the bike, turned on the battery, used pedal assist for 100m then wound on the throttle, within 2 seconds the low voltage disconnects the battery, cycle home and open battery pack.

Check the underside of the spare balance wire connector i mentioned before, 10x black wires 1x red wire. Multimeter red lead onto the red wire in the connector then individually the multimeter black lead onto onto each of the 10 black wires.

Starting with the black wire next to the red and working away from the red, readings as follows:

1- 4.17
2- 8.34 (4.17 difference)
3- 12.52 (4.18)
4- 16.69 (4.17)
5- 20.3 (3.61)
6- 24.3 (4.00)
7- 28.0 (3.70)
8- 32.2 (4.20)
9- 36.4 (4.20)
10- 40.6 (4.20)

Battery charges to 41.1v maximum.

Interesting that the readout was cumulative. Also, reading 5 and beyond required the multimeter to be upped from 20v to 200v so lost the accuracy of the additional decimal place sadly.

D8veh, the BMS was where you indicated it would be at the top of the battery pack, thanks for the hint. Didn't unpack the BMS or battery pack any further as was getting the above voltage data without delving deeper.

Would seem there are a couple of under voltage cells though as the battery hits low voltage cut-off within a few seconds of any 'draw' being put on it, would it be fair to say this battery has just done its days? I'm not the first owner and know the bike has been well used and covered a lot of miles.

 

[Deleted member 4366]

It's a bit difficult to say without a test rig and a single-cell charger. I have that stuff, so I'd charge the lowest two cells back up to 4.2v, then connect a voltmeter to cell 5 to see what happens when I draw some current from the battery. With your extra connector, it's pretty easy to do the latter. you can charge the cells with a phone or USB charger, but you have to continuously monitor because you mustn't go over 4,2v. They'll take it all the way to 5v if you let them. If the cell is healthy, it'll take all day and night to charge up like that.

I use this stuff for connecting to the multi-pin socket:
http://www.ebay.co.uk/itm/Pin-Header-36-Way-SIL-Straight-2-54-Gold-0-1-x-20pcs-of-36pin-strips-720-pins-/231136233590?pt=UK_BOI_Electrical_Components_Supplies_ET&hash=item35d0cb0876

Opening up the cell-pack will give some idea of the chance of restoring the battery. If it's 18650 cells (cylindrical, there's a good chance. it might be one or two cells have leaked, Pouch cells are difficult to find and replace. If it has the thick prismatic Phylion cells, you can chuck them, and just keep the BMS and case.

 

[Fish36]

Thanks for the further input d8veh, appreciated.

The battery pack is rectangular with flat sides so the chances of the cells being cylindrical might be quite low. As you say 2x cells have issues and it looks like it could be difficult to replace these. Also, just as a precaution if I strip the battery pack right down i would wish to do that outdoors and it isn't really the weather for it right now.

Not much spare money laying around at the moment so will look at getting a rack/bottle battery now (was thinking the approx. £200 36v x 10AH LiFePO4 rack mount battery from Kudos Dave might be the best option?) as that is the best value, already in the UK, LiFePO4 I have found. Am aware Whoosh Hatti has the 'Big Bear' Samsung cell'd 36v 15ah Li-Po battery for £350 inc VAT and P&P though that may be out of my budget

Think i will strip the existing battery case in summer and confirm if it can be repaired or not. If not, i can keep the case until the rack/bottle battery starts to run its course and then look at getting Ping battery to make a bespoke 10ah+ LiFePO4 battery configuration that will fit inside.

Would like to try a 2WD conversion if funds improve in the near'ish future. So a rack/bottle battery now and a Ping battery inside my old case and job done as I would then have 2x 36v 10ah batteries and just need a front wheel kit

Seem like a reasonable plan?

 

[Fish36]

ps...

Current battery is Wisper 36v 14ah Lithium Polymer.

Wisper replacements on the PowaRider website:

36v 11ah £449
36v 16ah £525

 

[Deleted member 4366]

Thanks for the further input d8veh, appreciated.

The battery pack is rectangular with flat sides so the chances of the cells being cylindrical might be quite low.

This is a similar battery to yours (externally) This photo shows the cylindrical cells onside. The ones marked had leaked, so had to be replaced. I had three like this, so I made a serviceable one out of the three. I could probably have made three, which would have involved much more cutting and shutting.



This one shows a complete string about to be soldered in:

 

[Fish36]

ah, thank you for that d8veh, photo's very much appreciated. So please bear with me as am a total newbie. It looks like I have 8x 'good' cell groups (good as in they are 4.2v per group though no idea if they can take a current draw) and 2x u/s groups (which are already way under voltage). So if 2x groups wiped out immediately under a current demand, that would still leave me with 8x 4.2v (33.6v) going into the controller. I gather my controller actions cut-out at 31.5v so the bike should still operate, though we are on the very fine line of ordinary voltage drop under load of the 8x good cells triggering the cut-off? Though having said that, the other day i measured overall voltage output after cut-off at 17v for the whole battery. So is there a chance even the 'good' 4.2v cell groups are worn out also?

My pack could very well be just like the ones in your pics and I suspect there is a leak also which would explain the low reading from 2x cell groups. Anyones guess at the moment how many individual cells are u/s as the photo shows in your example 14 individual cells per 'unit'. So it could be from 2x to 28x cells gone.

I didn't measure the actual battery pack itself though the inside measurements of the battery casing are 97mm x 88mm (the length of the battery pack itself is about 260mm including the BMS on top, so the battery will be about 220mm in length and is 36v 14ah). Take about 6mm off each of those width & depth measurements for external foam packing (between inside of case and pack), then remove say 3mm for the tape wrapped around the battery pack/any sheet material keeping the cells in place and that would make the actually cell pack measurements 88mm x 79mm...is the height of the cells in the pics anything like either of those measurements?

If it is like above, sadly I do not have any surplus cells to replace the malfunctioning ones with and as much as I am maybe capable of soldering the cut individual battery connectors as you show above am not sure i would wish to as am a bit cack-handed at times! I also do not have any of the diagnostic equipment that might be required to kick-start individual cell groups.

Even though this is Lithium Polymer battery which I gather has a good service life, I know the battery has been used hard (long hilly journeys) and the pack is now 3 to 4yrs old. Do you think it is worth repairing? Am in no hurry to spend £200 on a new pack though to repair this one I would need a kind soul like yourself to do the repair which means covering the cost of replacement cells and labour inputted. Then there is posting the battery there and back so the costs will soon add up I really like to recycle when at all possible, but it has to be cost effective and the end result be worthwhile.

It feels a bit debatable on whether it is worth trying to repair?

 

[Deleted member 4366]

It isn't 17 volts. If you connected anything to it, it would immediately go to zero. The BMS cut's off the negative when it trips. The 17v is only residual charge - nothing to do with the pack voltage.

You'd need to test further to determine whether you can do anything with it. You can only tell what's what my observing the individual cell voltages under load. At most, you could get a bit more life out of it, but I'd say that it's past its sell-by date. If you had some spare cells, it would be worth having a go,but it wouldn't be worth spending any money on it. The best you could do is charge the low cells in an attempt to re-balance it. That might get you a reasonable range. I have a battery on test now that has one cell-string very slowly self-discharging. If you used it every day, it wouldn't be a problem, but leave it a week and it'll be like yours. It's new, so I'll have a go at repairing it.

 

[Fish36]

Thanks for the clarification on the 17v reading d8veh.

Think it is more than likely those 2x low voltage cell groups do have u/s individual cells in them so as you say the only way to restore them would be a full strip down and replace.

Point understood on testing the 10x cell groups individually under load to see what the voltage drop is on each of them under load to assess overall health of each group and the battery pack as a whole.

Will go with the new rack mount battery for now as the price is very fair from Kudos Dave and take a look at the old battery pack in the summer when i can work on it outside in the warmer weather

Thanks once again for all the input, very much appreciated

 

[mike killay]

The problem that I envisage is that unless it is known that the battery is reasonably new and just a few calls have failed, what is the likelihood of say a repaired 3 year old battery lasting for another 3 years?

 

[Fish36]

Hi Mike, agree with your thoughts...so will go with a brand new rack mount 10ah LiFePO4 battery and leave my original unit as a summer 'perhaps take a further look inside' project

Though hope my taking a look at this battery and d8veh's excellent very helpful input might assist other electric bike newbies in deciding what best to do when a battery fails and is very expensive to replace via the OEM.

Can always buy an upright behind seat post battery of the universal silver casing type at a point in the future if I go ahead with a 2WD project, though for the time being would just be happy to have the bike on the road in standard one wheel drive at an affordable price and the rack mount battery will achieve that admirably.

 

[Deleted member 4366]

Will go with the new rack mount battery for now as the price is very fair from Kudos Dave

Kudos to Dave. What a fine fellow. I expect that's saved you a bit.

You can gut your old case and use it to store tools, spares, lock, waterproofs etc. On my Cyclamatic one, I left the lock in the top. but didn't screw it to the case. When You operated the lock, it would clamp it in place to make a handy lockable top for the storage unit.

Here it is locked in place:

 

[Fish36]

Thanks for the pic of the Cyclamatic, yup that is exactly how I intend to mount the new battery, maybe in a small on-top-of-the-rack mount pannier to hide it away though cable tie the battery to the rack through the pannier for security. And yes, the Kudos team are really helpful and their battery prices are very fair. Their willingness to help owners of other brands is very nice also.

Sadly my battery case splits open like a 'suitcase' so it has a seam next to the long downtube all the way down the case and another opposite the rear wheel though will certainly use the free space where the old pack used to sit for my nice chunky waterproofs as as suggested, ideal place for them

So soon it will be a very discrete electric bike with nothing much electrical really visible.

One quick question please if I may. I have removed the battery terminal connector that used to sit in the base of the frame for the original battery to slide into and will use this on the rectangular Kudos battery pack (cutting the 2-pin connector from the terminal so it can simply click in to the connector that goes into the controller). So great, that just leaves me needing to add a foot or so of similar guage wire to reconnect it all....BUT...

The rectangular rack mount battery packs, unlike the behind the seat post ones don't look to have the on/off key switch in the battery pack (looks to be in the plastic box the battery slides into on the OEM bikes which i presume holds the controller etc) so this leaves me needing a way to connect and disconnect the battery current, yes?

I thought about using a 'rally car' battery cut-off switch as these are high amp rated (Ebay uk item number 181308173871)...is there a better/cheaper way to fit an on/off switch between battery and controller please d8avh?

 

[neptune]

I have been following this thread with interest. d8veh, you talk about charging an individual cell to bring the voltage up. It occured to me that it might be feasible to use the charger from an electronic cigarette for this. The advantage would be that the charger is specifically designed to charge a single lithium cell, and to cut off at a safe voltage.I would like your opinion on this please.

 

[Deleted member 4366]

It should work perfectly, but it'll take approximately 10 times as long to charge the ebike cell as your e cigarrette

 

[Deleted member 4366]

The rectangular rack mount battery packs, unlike the behind the seat post ones don't look to have the on/off key switch in the battery pack (looks to be in the plastic box the battery slides into on the OEM bikes which i presume holds the controller etc) so this leaves me needing a way to connect and disconnect the battery current, yes?

A couple of suggestions:
1. Put a pair of Deans connectors on the wire from the battery. They're very easy to to connect/disconnect, although you get a bit of a spark and a "snap" noise when you connect, that takes a bit of getting used to.
2. Temporarily recycle the key-switch. It only takes a minute to remove. You could mount it in any plastic box from Maplin, ans cable-tie it to the seat-post or wherever convenient.
3. Make one of these switches, which allow you to use any small switch to switch the batteryon/off. It works like a sort of relay. You can get some fake IRFB4110s from Ebay for a couple of quid, and the rest from Maplin. At 15 amps, you only need two FETs. The four in the diagram is for 30 amps. you don't need a PCB for it, but make sure the wires can't short and you must use 15 amp wire where it shows thick lines.

 

[Fish36]

Thanks d8veh, good food for thought there

Sadly my on/off switch is moulded into the battery case so would mean cutting it out of the case and as I may yet in the future re-cell the case am reluctant to do that...idea 3 looks great though a bit beyond my skill level sadly (but thanks for the diagram)...and yup, had thought of the Anderson connector, so similar thing to the Deans but not sure on that spark and crackle each time it is unplugged!

Might go with this idea if you think it would be ok? Ebay uk item 360790724566 mounting the terminals inside a Maplin box as you mentioned above...this should be ok?

 

[Deleted member 4366]

That'll be more than OK, but I'd try the Deans connector forst to see if you can get on with it. Deans are better than Andersons for frequent disconnecting and a lot easier to install.