Opportunist Battery top-ups

[Eaglerider]

During some recent research into local rides I can plan, it occurs to me that the range could be considerably extended by en route top-ups. I'm thinking about, perhaps ride 20 miles, visit friend for tea, perhaps a 40 minute top up.

Then perhaps another 5 or 10 miles, stop at pub/restaurant, 1 or 2 hour top-up etc. This way I can plan extended routes but have the luxury of riding on max assist mostly, because that's the most fun for me. Then a blast home of, say 25 miles without so many worries about running out of charge. A sort of day long adventure.

My question is, are these very short top-ups doing any damage to the battery, even if the charging process has not finished and may be only a partial charge?

Is there any way to estimate how much charge the battery will take on if the charging was just say 20 minutes, or is just not worth it? I am wondering if a high charge rate would take place in the early stages of a charging cycle?

Is this a silly thing to do with little benefit to range, or is it a practical means for me to enjoy a day long ride with plenty of 'max assist', visiting friends/pubs and enjoying perhaps 50 to 60 miles over the day.

Any suggestions welcome.

 

[flecc]

My question is, are these very short top-ups doing any damage to the battery, even if the charging process has not finished and may be only a partial charge?

Is there any way to estimate how much charge the battery will take on if the charging was just say 20 minutes, or is just not worth it? I am wondering if a high charge rate would take place in the early stages of a charging cycle?

This can be perfectly practical to do. Lithium or SLA batteries are not harmed by reasonable quantity top-ups, indeed they are best used cyclically in this way. However, topping up a battery when it's already quite full does increase the chemical stress on the cells somewhat.

A good choice for this type of usage would be a bike with an SCiB lithium battery. This is a type developed by Toshiba that is rather low on capacity but is suited to fast charging. Quite a substantial charge can be taken up in a 30 minute stop. Only some Schwinn and Claud Butler e-bikes have these at present and they are on the low powered side, using the Tongxin Nano front hub motor.

On any battery, estimating the charge that will be absorbed during short periods is difficult, since it varies according to the current charge level. Charge rate is highest in the early stages but can be very low in the late stages of a charge. Probably best to use a battery with an integral meter so that the readout of that can be used for judgement.
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[Jimod]

It would work if your friends and the pub were all in range and along the route. Also they'd need to be in when you called. I bought a spare battery for my bike for when I feel like going further. So far the furthest I've gone is 37 miles and the battery went flat about 2 miles from home I could have made it without the spare but I had it and it would be rude not to use it.
I reckon a spare is the best bet when out 'playing' . I doubt I'll ever be more than 30 miles from home so my spare would always bring me home with no effort from me.

 

[lemmy]

I charge the Panasonic battery on my Kalkhoff whenever I please, after 2 miles or 30. It's two years a old and still going strong, so I can't have harmed it much.

 

[Scottyf]

Lithium based batteries are absolutly fine with "top ups" no matter what state they are in.
The same as your mobile phone for example.

Even a 20min charge is still something. You can get higher amp chargers for slightly quicker top ups.

Most standard chargers (Ac to dc convertors at a set voltage) are any where between 1 to 5amp.
Most likely your standard charger will be around 2amp.

So in an hour (for a 36v battery) you will put in 2amps @ 42v (42 is the highest point of volts for a 36v battery of 10cells in series).
If your battery is 10ah thats a good 20% battery power you've topped up with.

Even a 30min charge can put appx 10% back in. Which maybe another 3-4miles depending on your bike / terrain / use.

The powerful charger is the faster it will charge. However the faster it goes the more thermal stress the cells under go and the shorter their life span.


So top up to your hearts content. Its all worth something. An it free.

 

[Deleted member 4366]

Two alternatives:
1 Forget about the tea. Ride 5 miles to a nice pub; drink a couple of pints while you top up the battery; ride to another nice pub; drink a couple of more pints while you top up the battery; repeat these steps until both you and the bike are full; glide home - you'll be surprised at how smoothly you bike glides along. If you're lucky, you'll make it all the way home, but if you don't, it wont be for lack of battery power.. Try not to choose pubs that are all in a line because you'll have less chance of arriving home.
2 Get a 20aH Ping battery and then you won't have to worry about topping it up. Was I pleased that I had one today when my pedal came loose 14 miles from home so I had to throttle all the way back after using maximum speed on the out leg?

 

[Scottyf]

I think that's the real bonus with electric bikes. If one method of pedal power fails you have the motor to pick up. Or visa vera.

I had my rear derailer go. Due to a cable left it stuck in last gear. No problem with electric. It became a single speed for 2weels lol

 

[Hackney Andy]

I have similar dilemma on topping up the battery. My return trip to work is 6 miles and I tend to top up every day, but should I be topping up every 3 days, say? The battery is a 3 year old 16Ah Li-Ion on a wisper 905se, which I bought second hand recently. (As a test when I first got the bike I used it on throttle only and it took me 12 miles before the medium led light went out, so I assume the battery is in decent condition - unlike me who's 18 stone.) What's best practice under these circumstances to prolong battery life?

 

[flecc]

I'd say continue to top up every day in those circumstances. That won't harm the battery and will give you the optimum performance every day. You could try doing it every second day, and if you find the bike's performance to be the same both days, then that would also be ok.

Once every three days could take a three year old battery to a fairly low charge state, possibly stressing the cells and giving less performance on the third day, so I'd personally avoid that.

 

[Hackney Andy]

Many thanks for your advice - I'll stick with the daily charge. The maximum distance I've ever gone on the bike is 30 miles and that takes me to the low indicator - I won't risk taking it any further.

 

[flecc]

Although that 30 miles you once had indicates two daily would be ok, battery performance drops off markedly at the low temperatures we can expect for the next 3 months or so, so daily is sensible for the present.

 

[Wisper Bikes]

I'd say continue to top up every day in those circumstances. That won't harm the battery and will give you the optimum performance every day. You could try doing it every second day, and if you find the bike's performance to be the same both days, then that would also be ok.

Once every three days could take a three year old battery to a fairly low charge state, possibly stressing the cells and giving less performance on the third day, so I'd personally avoid that.

Hi Andy, of course Flecc is absolutely correct, even though your battery would last for three days it causes far less stress to the battery to top up when possible, especially in the cold weather. You will of course also benefit from that "just charged" feel.

All the best

David