irregular power output

[SeanG]

Hi,

I have an urban mover with a lithium battery.
I had to get the rear wheel rebuilt (as spokes were breaking). So the battery was sitting uncharged for 2 weeks.
When I got the bike back the power output was irregular.
As the week went on the power output appeared to become smooth again (charged each night).
The bike wasn't in use for 3 days and the power is gone irregular again.

Only have the bike since Aug '08.

Do you need to keep lithium batteries on trickle/constant charge?

Is my problem battery dying or more likely caused by poor connection made when rear wheel was reinstalled (wires had to be soldered back to terminals).

thanks,
Sean.

 

[flecc]

No, they should never be on trickle charge Sean, as long as they are charged a minimum of every two months they should be ok. It's most likely an intermittent connection problem you're suffering from, since batteries normally only deteriorate, not fluctuate in performance.
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[SeanG]

Thanks for prompt advice.

Sean.

 

[Branwen]

Different kind of irregular power output

I haven't posted for a while, mainly cos my battery recell went wrong and I've been using the bike since before xmas without any battery on it. (A LaFree Twist Lite) Could this have damamged the motor? I ordered a new battery and charger, and brought it home today for the first time in ages with power.

1st and 2nd were great. It's a 9ah battery and the one I was used to was a 6.5ah one, plus, I hadn't had any power for so long, it felt rocket powered! But third gear things went wrong. The bike shot forward and then stalled, and the gears slipped, as power came on and off. Going more slowly and gently helped this, but trying to go faster brought it all on again.

I'll die if I spent all that money on a new battery and charger only to find the motor on the bike is now failing. Perhaps I should have stuck with the 6.5ah battery?

On another topic, I thought maybe I would get fitter without the battery, and might just move onto a regular bike, but to be honest, it didn't pan out like that. My asthma is way worse, because the battery made an aerobic exercise (bad for asthma) into a stamina one (good for asthma). On flat and downhill its a heavy bike, and with no power, harder to cycle than a regular bike. On uphill the motor took away that part which left me breathless and prone to attacks. So I better make electric work.

 

[Dynamic Position]

I haven't posted for a while, mainly cos my battery recell went wrong and I've been using the bike since before xmas without any battery on it. (A LaFree Twist Lite) Could this have damamged the motor? I ordered a new battery and charger, and brought it home today for the first time in ages with power.

1st and 2nd were great. It's a 9ah battery and the one I was used to was a 6.5ah one, plus, I hadn't had any power for so long, it felt rocket powered! But third gear things went wrong. The bike shot forward and then stalled, and the gears slipped, as power came on and off. Going more slowly and gently helped this, but trying to go faster brought it all on again.

I'll die if I spent all that money on a new battery and charger only to find the motor on the bike is now failing. Perhaps I should have stuck with the 6.5ah battery?

On another topic, I thought maybe I would get fitter without the battery, and might just move onto a regular bike, but to be honest, it didn't pan out like that. My asthma is way worse, because the battery made an aerobic exercise (bad for asthma) into a stamina one (good for asthma). On flat and downhill its a heavy bike, and with no power, harder to cycle than a regular bike. On uphill the motor took away that part which left me breathless and prone to attacks. So I better make electric work.

A higher capacity battery would not damage the motor. The bike works in 1st and 2nd. The problem could be mechanical wear (possibly dirt?) on the third gear. Your power combined with the motor power sufficient to cause the gears to slip. The electronics in the controller could sense the slipage and cut the motor assist accordingly. This would explain the power on off cycles you describe.

People with medical conditions like high blood pressure & asthma are unlikely to get fitter through more strenuous exercise unless they have had their condition cured by medical means first. I didn't know I had high blood pressure, but I now know I should have bought a pedelec sooner than I did!

 

[flecc]

The battery capacity won't make any difference to the motor which still sees it just a a 24 volts one. The motor cannot tell what capacity it is, the battery charge just lasts for longer range.

Riding the bike without power won't affect the motor unit since there's a freewheel just inside the chain sprocket drive which disconnects it from the rest of the unit.

There's no connection between the gears and the motor unit other than the chain, so I think your problem is one of two things. The first is the gear hub out of adjustment and gears slipping out of engagement, and to check if that's the case, make sure you pause pedalling when changing gear to see if there's any improvement. If you do already pause pedalling and we know you've had no gear trouble when riding unpowered, the second thing is possibly the cause.

That's the chain jumping over the motor sprocket teeth. It may be that wear of the motor sprocket and chain has made that easy to happen, and when it does it sounds just like gears slipping out of engagement. Having a new battery gives more power and that could have caused this to show up the problem. Have a look at the motor sprocket and see if the teeth are worn down and/or a bit hooked. Also make sure the chain is tensioned adequately and the chain tensioner on the motor is doing it's job of wrapping the chain around the motor sprocket properly.
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[Dynamic Position]

If you do already pause pedalling and we know you've had no gear trouble when riding unpowered, the second thing is possibly the cause.

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With the bike being heavy, I was assuming that third gear may not have been selected when riding without power. Branwen might be able to provide further details regarding his unpowered use.

 

[flecc]

With the bike being heavy, I was assuming that third gear may not have been selected when riding without power. Branwen might be able to provide further details regarding his unpowered use.

I didn't notice my post had crossed with yours Dynamic, duplicating the capacity advice. Apologies for that.

I think the main problem with the Panasonic unit with chain drive slippage is the torque sensor. When the drive slips the foot pressure comes off the sensor so the power drops, giving the impression of cutting out. The chain jumping problem I mentioned is very common with these units once the motor sprocket wears, which I why I bias to that, but the hub gear is still certainly a possibility.
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[Dynamic Position]

I didn't notice my post had crossed with yours Dynamic, duplicating the capacity advice. Apologies for that.

I think the main problem with the Panasonic unit with chain drive slippage is the torque sensor. When the drive slips the foot pressure comes off the sensor so the power drops, giving the impression of cutting out. The chain jumping problem I mentioned is very common with these units once the motor sprocket wears, which I why I bias to that, but the hub gear is still certainly a possibility.
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No problem flecc, I think cross posts are quite common. I will need to watch out for motor sprocket wear when the time comes. Do you know if the sprockets can be changed easily or is this a job best left for 50 Cycles to do as part of a planned service?

I found out today that I could fit my ProConnect S in the back of my ageing Renault Laguna Estate. Plan was to leave the car at the garage for the mechanics to look at, but it didn't make it leaving me stranded on a roundabout! The car has since been recovered and I am just waiting to find out how much the repair bill will be. The grinding metal and oil leak sounded very expensive! Just as well I have the e-bike.

 

[flecc]

They are very easy to change, and I have a page on my website for changing the motor sprocket of the Agattu, the principle the same. There's also a tip there for continuing with a worn sprocket until a new one arrives. Here's the webpage:

Changing the motor sprocket

I believe 50cycles will be stocking sprockets and may already have them.
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[Branwen]

Thanks for all the help. I'm going to print it all off for the bike shop. They checked the gears were set up right at the service but it still had this slipping problem.

I think maybe I wasn't pausing long enough between gear changes because I had been cycling it so long without power, and pausing longer does make a slight improvement now I've tried it.

The problem is getting worse though, and shows up with and without power now. Third gear isnt catching at all sometimes, its freewheeling as if still in second, and if I slow enough to be at the speed for second, you can feel second grab. Sometimes when you think its grabbed, you realise it's just still in second, not third.

I am dropping it off Thursday, along with your webpage FLECC. Thanks. I am with a new repairer now, not like the one that did my battery and was asked to follow your re-celling instructions exactly, but who told me they were idiot instructions and he had a better way of doing it. Yeah, but the battery didnt actually work his way, so who was the idiot. (Probably me, cos he never gave me my money back).

 

[Branwen]

Well, I've seen the sprocket, didn't know what it was. It's corners were worn down to nubbins compared to the one in the pics on your website.

There was good news and bad news though. The sprocket came off okay, but turned over, it doesnt fit. There's a spline(?) that doesn't line up. So back to putting it on the right way round and waiting for the part, right? Wrong. Once off the thing didn't want to go back on, so the mechanic put self tappers in to get it back on, and it makes a terrible clunking noise now. Apparantly, on the LAfree Twist Lite, they aren't reversible, and if you try, are damn near impossible to get back on.

Good news was, apparantly I was asking Giant shop a year ago what would happen if this bit wore down, and they got the part in at prices back then, for when it did, cos the bike is 6 years old and it was bound to go soon enough anyway. So the part is in stock and mine if I want it. Putting the bike in for repair on Monday.

 

[Branwen]

Bike was repaired, new sprocket set and chain ect.... new battery holding a charge...

Took it out, engine worked for 5 minutes then packed in. Think my Lafree has finally died.

 

[flecc]

Sorry to hear that Branwen, some do just die like that, usually a main circuit board failed which cannot be repaired.

A Lafree sprocket can be reversed, I've done it and so has David at A to B magazine, but it cannot have the circlip replaced since a flange on the sprocket stops that fitting so it's only a temporary fix. It seems yours may have had some spline damage.

The later Panasonic unit on the Kalkhoffs etc has a motor sprocket which can be reversed and secured since it has no flange.
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[Branwen]

I'm guessing replacing the whole motor is out too.

Guess I have a bike for parts, a brand new 9ah battery and charger and an old charger and battery case for sale...

 

[flecc]

The motor units should still be available, but were £450 plus fitting last time I knew a price, so not worth it really.

It's certainly worth advertising what you have and there will be lots of takers for the battery, the 9 Ah being rarely available. Some like the failed bikes for spares too and the sprocket set will be desirable as well.
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[Branwen]

Odder and odder. I kept using the bike without power, I'd been doing it for ages anyway so it let me save up for another bike. Plus it had new sprockets so was usable anyway. The bike still did the thing like it was missing the gear though, even after the new sprockets were on. It was way less though, maybe 'cos I was back to no power. Other thing I noticed about new sprockets was the pedals don't free wheel backwards easily anymore. Before you could kick one and it spun for a few seconds. Now it has to be moved backwards by hand. but that's probably nothing.

The weirdest thing is this. I decided to put the battery in to get it from my locker at work, where I had left it, back home. Lo and behold, the motor works. I don't expect it will last, but hey ho, not complaining right now.

Odd, huh?

 

[flecc]

Yes, it seems like there's an intermittent fault in a circuit board component, like all intermittents though, a nightmare to identify.
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[Branwen]

OK, well, some time and some experimentation later, and it seems I've found what sets off the stall no power thing. I charge the battery, and when its full, switch it off. But I then wait and switch it on again in case it isn't quite full. That's fine, but if I do it again, for instance right now it might be a day or two before I then go out so I might charge it again to make sure its REALLY full, it doesnt like that. It seems to gain a memory and stops after only a few minutes riding, as if its flat. Last time I walked home, dishcharged it a bit, and it was fine. The first time it was off the road and must have discharged a bit over time. Dunno if thats it, but its the only thing I do which guarantees it will stop dead after a few minutes, like it did the first time when I thought the motor was gone.

 

[flecc]

That could be triggering the trouble. I don't think lithium batteries like trickle charging, and that sort of topping up is rather like that.
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