Battery Life

[davidw]

This may sound stupid (I am strictly non technical) but how do you know when a battery is coming to, or is at the end of its time. Do you just get less miles per charge?
Is that a gradual process, or does the mileage suddenly drop off? Or does the battery completely give up one morning and refuse any more charging?

 

[banbury frank]

Hi most battery's it is a gradual decline in RANGE


So a Lithium - ion battery which is the most supplied because it is the lowest cost should still hold 80% capacity at 800 to 1000 full charge discharge cycles if it goes dead faulty battery or charger

I count the BMS as part off the battery

Frank

 

[morphix]

This may sound stupid (I am strictly non technical) but how do you know when a battery is coming to, or is at the end of its time. Do you just get less miles per charge?
Is that a gradual process, or does the mileage suddenly drop off? Or does the battery completely give up one morning and refuse any more charging?

I think it's a gradual process and the range gets less and less as the charging cycles get shorter (time between charges).. some people I've heard say their bikes perform less well with an aged battery, particularly on hills. There will no doubt come a point where the battery just isn't able to provide enough power or power for long enough to be useful.

 

[tangent]

As batteries age the internal resistance also rises. This shows up as increased voltage drop under load and so reduced current delivery to the motor and reduced power. You may have noticed that a battery that is 2/3 discharged does not provide as much power as a fully charged battery for instance. This is due to a drop in voltage as the battery discharges, but the feeling of the bike is the same.

 

[Scottyf]

Either way its still cheaper than petrol lol. Seriously though i'd be happy with 600 cycles and replacing every two years. Don't think i'd ever use up the 2000cycles that some chemistrys advertise.

 

[flecc]

In addition to the decline that others have mentioned, there's the issue of cutting out. To protect against the voltage dropping too low and causing battery cell damage, the bike's systems cut the power at a safe low level, for example at about 32 volts on a 36 volt system.

Once a battery has reached the point where it can no longer always deliver enough current due to the effects of age and usage, the system will cut out under high load so often, you'll have to change the battery, even though the shortened range may still be enough otherwise.

With some of the most powerful bikes, cutouts can happen under very high load such as when climbing very steep hills, even though the battery is still perfectly ok for most use. The answer then to get more battery life is to either; avoid the steepest of hills, use less throttle during the climb if on a throttle controlled bike, or give more help to the motor on the climb with more pedal effort.
.

 

[davidw]

Thanks for all those responses.
Flecc, I'm on the panasonic system (Easy Glider ) so throttle doesn't come into it.
Is there anything similar to 'cut out' in my situation?

 

[flecc]

I've never come across it on those, their battery managemnt is excellent so it's likely that only the decline in range will apply. That was certainly true of their earlier unit, on which I ran one battery down to barely 8 miles range at well over four years old without cutouts.
.

 

[tangent]

My experience on a Panasonic based system is similar to Flecc's. My original 8 year old NiMH battery is still good for 5 miles or so, I have never experienced a cutout, but the bike does feel sluggish with old batteries in it after a few minutes use.

 

[davidw]

Thank you for those helpful replies.
The reason for my query is that I will be going off to a remote part of Extremadura in Spain in mid May to spend the summer there as I usually do and didn't want to find myself without assistance from my Gazelle. At 79 I can't walk far these days but on my 'magic carpet' the world is my oyster. It also helps as I do my regular 20kms circuit into the local village that the terrain is only undulating (and not straight up and down as it is here at home in the northern Pennines) Plus the weather of course. Apart from the very occasional thunder storm it seldom if ever rains and the wind tends to be no more than a breeze most days. Week after week ...cycling heaven for this old crock.
So all being well I'll have a spare new battery with me this year and can see with a relaxed eye just how my 3 year old battery performs.