Battery Charging - Opinions Please

falmouthtony

Esteemed Pedelecer
When I get back from a longish ride with an empty Ezee 36v 14ah battery I usually do things 'by the book' and immediately put it on charge for 4.5 hours or so, then switch the charger off when fully charged.

However, for various reasons, there are occasions when I get back late and only have two options:
1) Put it on charge at 9pm, rely on the charger to to stop charging when the cycle is complete, and not switch the charger off again until about 10am the next morning.
OR
2) Leave the battery in a discharged state for 12 or 13 hours and charge it as normal the next day

Which is the lesser of two evils, or am I worrying unnecessarily in both cases?
 

trex

Esteemed Pedelecer
May 15, 2011
7,703
2,671
not much difference but 2) is better than 1).
 

Geebee

Esteemed Pedelecer
Mar 26, 2010
1,256
227
Australia
Lipo dont tend to suffer than being left patially charged, in fact they are best stored at around 50% charge but dont worry about that unless being stored for a long time (I just leave them fully charged).
I am paranoid and like to be around when charging :)
 

peerjay56

Esteemed Pedelecer
May 24, 2013
745
201
Nr Ingleton, N. Yorkshire
When I get back from a longish ride with an empty Ezee 36v 14ah battery I usually do things 'by the book' and immediately put it on charge for 4.5 hours or so, then switch the charger off when fully charged.

However, for various reasons, there are occasions when I get back late and only have two options:
1) Put it on charge at 9pm, rely on the charger to to stop charging when the cycle is complete, and not switch the charger off again until about 10am the next morning.
OR
2) Leave the battery in a discharged state for 12 or 13 hours and charge it as normal the next day

Which is the lesser of two evils, or am I worrying unnecessarily in both cases?
So long as it's not a lipo/homemade pack - Without being paranoid, just put it on charge and go to bed! In the morning it will be ready to go. Of course the best option is the timer, which will save energy.
There is a lot of unjustified paranoia re lithium batteries; a properly manufactured battery with the correct charger has as much chance of exploding/bursting into flames/morphing into a black hole as a tv or washing machine.
 

John F

Esteemed Pedelecer
Sep 3, 2013
435
55
For clarification, when my charger light goes green, does that mean it has completly stopped charging and is OFF apart from the light, or does it continue trickle charging? I am still nervous of leaving my bike on charge overnight in the garage.
 

Geebee

Esteemed Pedelecer
Mar 26, 2010
1,256
227
Australia
For clarification, when my charger light goes green, does that mean it has completly stopped charging and is OFF apart from the light, or does it continue trickle charging? I am still nervous of leaving my bike on charge overnight in the garage.
Depends :) one of mine trickle charges for a fair while and another cuts completely when the green LED lights. One of the timers as above set to cut off after a long enough period to fully charge would most likely be the best idea.
 

trex

Esteemed Pedelecer
May 15, 2011
7,703
2,671
For clarification, when my charger light goes green, does that mean it has completly stopped charging and is OFF apart from the light, or does it continue trickle charging? I am still nervous of leaving my bike on charge overnight in the garage.
when the charging light goes green, the charger regularly probes the circuitry - it does it by bringing the voltage back up to 42V for a second every now and then.
If the battery needs charging, the voltage will quickly goes from 42V then down to somewhere between 32V and 42V.
If the voltage is below 32V, the charger powers down (0V) and shows green, it's a fault condition. Some chargers will flash green/red, most don't.
If the voltage is 42V, the charger remains at 42V but reduces the current to zero and shows green, it's full charge condition. If the voltage is between 32V and 40V, the charger will maintain 2A charging current, the LED shows red. When the voltage reaches 40V or slightly above, the charger reduces the current and maintains 42V, LED is red.
The charger is processor controlled. It's probably the most reliable component of your bike, for not being exposed to the elements. The full charge state is as bad for the battery as when the battery is flat, so it helps not to not keep the battery full all the time.
 
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Geebee

Esteemed Pedelecer
Mar 26, 2010
1,256
227
Australia
Gosh, yes. :rolleyes: 3 out of 26000. Where are the similar recalls for ebike batteries and chargers?
"a properly manufactured battery with the correct charger has as much chance of exploding/bursting into flames/morphing into a black hole as a tv or washing machine."
LiPo issues are rare but a damn site more common than your description as that link shows, I have seen zero E-bike battery issues thankfully but have seen several phone and 1 camera LiPo swell severely and 2x LiPo chargers go up in smoke.
 
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John F

Esteemed Pedelecer
Sep 3, 2013
435
55
when the charging light goes green, the charger regularly probes the circuitry - it does it by bringing the voltage back up to 42V for a second every now and then.
If the battery needs charging, the voltage will quickly goes from 42V then down to somewhere between 32V and 42V.
If the voltage is below 32V, the charger powers down (0V) and shows green, it's a fault condition. Some chargers will flash green/red, most don't.
If the voltage is 42V, the charger remains at 42V but reduces the current to zero and shows green, it's full charge condition. If the voltage is between 32V and 40V, the charger will maintain 2A charging current, the LED shows red. When the voltage reaches 40V or slightly above, the charger reduces the current and maintains 42V, LED is red.
The charger is processor controlled. It's probably the most reliable component of your bike, for not being exposed to the elements. The full charge state is as bad for the battery as when the battery is flat, so it helps not to not keep the battery full all the time.
Interesting info. So you are saying it does keep trickle charging depending on the voltage level, which I am assuming is dependant on its age/condition? ie if it's in perfect condition - no charge?

I am surprised by your comment that a full charge is bad - other posters disagree?!
 

peerjay56

Esteemed Pedelecer
May 24, 2013
745
201
Nr Ingleton, N. Yorkshire
"a properly manufactured battery with the correct charger has as much chance of exploding/bursting into flames/morphing into a black hole as a tv or washing machine."
LiPo issues are rare but a damn site more common than your description as that link shows, I have seen zero E-bike battery issues thankfully but have seen several phone and 1 camera LiPo swell severely and 2x LiPo chargers go up in smoke.
You're missing the point.
http://www.theguardian.com/money/2014/jan/11/kitchen-flames-domestic-appliances If you're not paranoid about your tv/washer/tumble dryer, why be paranoid about charging your properly constructed ebike battery? A sense of proportion helps.
 
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flecc

Member
Oct 25, 2006
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a properly manufactured battery with the correct charger has as much chance of exploding/bursting into flames/morphing into a black hole as a tv or washing machine.
That theory is correct, but the real world reality is somewhat different. The possibility of manufacturing battery cells with a potential fire causing fault is much greater than that of manufacturing a TV or washing machine with such a fault.

Ergo, a current lithium battery has a greater potential for fire than a current TV or washing machine, though still being generally very safe and reliable.

Recent domestic appliance fires have normally been a result of a design fault, which once rectified causes no more problems. The chemical mix of cell contents is permanently at the mercy of defects in raw material or human error.
 
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flecc

Member
Oct 25, 2006
52,765
30,351
I am surprised by your comment that a full charge is bad - other posters disagree?!
No disagreement John, the greatest stress a battery suffers is at the charge extremes. However, the e-bike's electronics prevent either the peak charge or empty being reached, so the battery does have some degree of protection against the worst situations.
 

RobF

Esteemed Pedelecer
Sep 22, 2012
4,732
2,311
That theory is correct, but the real world reality is somewhat different. The possibility of manufacturing battery cells with a potential fire causing fault is much greater than that of manufacturing a TV or washing machine with such a fault.

Ergo, a current lithium battery has a greater potential for fire than a current TV or washing machine, though still being generally very safe and reliable.
Or put another way, the gadget in your house most likely to burn it down is your ebike battery/charger.

I'm not too worried about that happening, but the precaution I do take is only charge when I can keep an eye on the battery.

Easy with the Bosch ones because they charge in a couple of hours.

More of a fag with the Brompton Nano because its battery takes several hours to charge.
 

OldBob1

Esteemed Pedelecer
Oct 11, 2012
355
117
Staffordshire
Just put on charge and disconnect if you go out or to bed and reconnect the next day.
I feel safer if I am around to keep an eye on things.
 
D

Deleted member 4366

Guest
I'm sure it can happen, but I've never heard of a normal ebike battery catching fire. We had one DIY battery that caught fire because the guy charged it without a BMS.
 

flecc

Member
Oct 25, 2006
52,765
30,351
I'm sure it can happen, but I've never heard of a normal ebike battery catching fire. We had one DIY battery that caught fire because the guy charged it without a BMS.
Certainly seems true today, the only cases I've known of a manufacturer's e-bike battery catching fire have been historic with batteries using the old non-compound cobalt cathodes. They were the cheapest ones too. The last one was probably be all of six years ago now and batteries have come a very long way in that time.