E-Bike Battery

Electrically assisted bikes, trikes, etc.
Olliespilot
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E-Bike Battery

Postby Olliespilot » 24 Sep 2017, 7:11pm

Does anyone know if this is true? A friend took her e-bike into Halfords for its' 6 week check. She was told that if she leaves the bike unused during the winter and the battery is left at 50% charged or less, it will go to sleep and never wake up. rendering it useless. Doesn't make sense to me, but I'm no expert on this. Interested to know of other's opinions please.

landsurfer
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Re: E-Bike Battery

Postby landsurfer » 24 Sep 2017, 7:17pm

Possibly one of the issues with LI-PO batteries .... they suffer badly from cell memory .... come on Leckies fill in the detail ..
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UAVDave
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Re: E-Bike Battery

Postby UAVDave » 24 Sep 2017, 11:52pm

Yes - Lipos have cell memory. Not as bad as NiCad's in the old days but still an issue. Lipos should be charged to storage level - approx 60% - if not in use for 3-4 weeks or more. Less time than that isn't really an issue. So the the best solution for your friend is why not give the bike a ride once a week or so over the winter? That would partially discharge the battery and allow 100% charging with no problems.

Dave
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NATURAL ANKLING
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Re: E-Bike Battery

Postby NATURAL ANKLING » 25 Sep 2017, 1:35am

Hi,
Also recommended that you do not leave stored at 100% either, safety IIRC.

Tho I have always stored my spare phone batts at 100% :?
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Olliespilot
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Re: E-Bike Battery

Postby Olliespilot » 25 Sep 2017, 7:01am

Thanks very much everyone. Like the idea of a regular ride the best.

groberts
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Re: E-Bike Battery

Postby groberts » 25 Sep 2017, 9:09am

Never heard of this before but understand such batteries can be fickle.

I will be away later later thus year for six weeks - without my eBike - so what do I do, presumably leave the battery charged at +60%? I am a little worried that by then it will also be cold, which of course batteries don't like either

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al_yrpal
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Re: E-Bike Battery

Postby al_yrpal » 25 Sep 2017, 10:15am

I leave my strimmer battery constantly on charge. As it expires the charger automatically tops it up. Reading the reviews of the strimmer people who dont do this are all complaining about having to buy a £75 replacement after 12 months. I also regularly recharge my drills battery regularly.

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Mick F
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Re: E-Bike Battery

Postby Mick F » 25 Sep 2017, 10:26am

Same here.
I keep all rechargeable batteries topped up - and some on charge permanently.
Drills, circular saw, all the many AA and AAA cells, the laptops, the Garmins ........... and until recently, the Fiat500 as their batteries are prone to Stop/Start failure after three years.

All batteries are happier being fully charged ........... but you need an intelligent charger so you don't over-charge.
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NATURAL ANKLING
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Re: E-Bike Battery

Postby NATURAL ANKLING » 25 Sep 2017, 10:55am

Hi,
In my understanding that lithium batts do not suffer the problems other battery technology does.
So no need to keep fully charged.
Lipo pros - can be made in any shape unlike li-ion which has to be similar to what you see in mobiles, cons are not so good on energy density (volume)
Low capacity (%) can ruin them quick, which is probably why letting them run down by not charging soon enough will shorten life.
http://www.androidauthority.com/lithium ... nce-27608/
http://batteryuniversity.com/learn/arti ... _batteries
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Ruadh495
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Re: E-Bike Battery

Postby Ruadh495 » 25 Sep 2017, 11:15am

As I understand it if the voltage per cell drops to below a certain level (think it's 2v) there is a risk of lithium whiskers forming which can short the cell, resulting in a particularly nasty fire when recharging is attempted. For this reason the battery management system (built in to larger lithium batteries) will not allow the battery to charge unless all the cells are at 2v or above. The B.M.S. should also prevent discharging to below this level, but if a discharged battery is left "leakage" could drop some of the cells below 2v.

A battery which has died in this way may be "resurrected" by taking it apart and bypassing the battery management system. This, of course, introduces a risk of a battery fire / explosion and should only be attempted if you know what you are doing.

Not sure a ride would be necessary, topping off charge every couple of weeks should be enough. Maybe a "smart" charger on a timer?

atlas_shrugged
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Re: E-Bike Battery

Postby atlas_shrugged » 25 Sep 2017, 1:11pm

Li batteries will self-discharge - this happens even if they are not used. Many Li batteries will be damaged if they become deeply discharged. Good battery protection circuits should stop use of a battery when deeply discharged.

Keeping a Li battery topped up when not being used is a good plan. In most cases it should be possible to get a deeply discharged battery back to life by recharging but that will not mean that the battery is completely OK.

Like all things there are variations with different battery types. The best plan is to check the detailed instructions with the battery. If the company does not provide detailed battery care instructions then you have probably bought the wrong battery.

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[XAP]Bob
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Re: E-Bike Battery

Postby [XAP]Bob » 25 Sep 2017, 3:48pm

Ruadh495 wrote:As I understand it if the voltage per cell drops to below a certain level (think it's 2v) there is a risk of lithium whiskers forming which can short the cell, resulting in a particularly nasty fire when recharging is attempted. For this reason the battery management system (built in to larger lithium batteries) will not allow the battery to charge unless all the cells are at 2v or above. The B.M.S. should also prevent discharging to below this level, but if a discharged battery is left "leakage" could drop some of the cells below 2v.

A battery which has died in this way may be "resurrected" by taking it apart and bypassing the battery management system. This, of course, introduces a risk of a battery fire / explosion and should only be attempted if you know what you are doing.

Not sure a ride would be necessary, topping off charge every couple of weeks should be enough. Maybe a "smart" charger on a timer?



OR by touching both terminals with an arc welding rig apparently.... Not that I'm going to try that....
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Olliespilot
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Re: E-Bike Battery

Postby Olliespilot » 25 Sep 2017, 5:18pm

Thanks again to everyone - Forum members sorts everything every time. Nice to know that Halfords advice stacks up.

pete75
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Re: E-Bike Battery

Postby pete75 » 26 Sep 2017, 11:07am

al_yrpal wrote:I leave my strimmer battery constantly on charge. As it expires the charger automatically tops it up. Reading the reviews of the strimmer people who dont do this are all complaining about having to buy a £75 replacement after 12 months. I also regularly recharge my drills battery regularly.

Al


£75??? My mate has one of those strimmers with a battery to start it and it cost him nearly 300 quid and that was in a sale at a machinery supplier that had gone bust. Doesn't matter if the battery screws up because they still have pull cord starters.

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[XAP]Bob
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Re: E-Bike Battery

Postby [XAP]Bob » 26 Sep 2017, 12:36pm

pete75 wrote:
al_yrpal wrote:I leave my strimmer battery constantly on charge. As it expires the charger automatically tops it up. Reading the reviews of the strimmer people who dont do this are all complaining about having to buy a £75 replacement after 12 months. I also regularly recharge my drills battery regularly.

Al


£75??? My mate has one of those strimmers with a battery to start it and it cost him nearly 300 quid and that was in a sale at a machinery supplier that had gone bust. Doesn't matter if the battery screws up because they still have pull cord starters.

Probably a battery powered trimmer, not a petrol one with a battery starter.
A shortcut has to be a challenge, otherwise it would just be the way. No situation is so dire that panic cannot make it worse.
There are two kinds of people in this world: those can extrapolate from incomplete data.