Battery Advice

[cogs]

i recently purchased an Alien 36v kit, which has been fitted and running for a couple of weeks. So far i'm pleased with it (i'll post an assessment after a bit more time).

My method of charging accords with Alien advice, and involves sticking it on to charge after each journey, long or short. My habit is to do about 18 miles each day, but some days i dont use it at all, and occassionally i'll do about 25 miles, which exhausts the charge completely, it being somewhat hilly around here. It has been used to complete exhaustion twice.

The bike lives in a cold shed, and is also charged there.

A couple of questions arise. If i charge on day one, then leave it unplugged overnight in the cold shed until day two before i use the bike, should i anticipate some loss of efficiency due to temerature?

If i leave the charger plugged in and connected to the battery through the night would that avoid such a 'problem' arising?

If i use the bike for a short journey, maybe 5 miles, should i still charge up immediately thereafter, or perhaps wait until i have used the bike again and added to the accumulated milage before i recharge?

Any answers would be appreciated.

 

[flecc]

Like all batteries it's efficiency suffers at low temperatures, and after very cold nights the drop in performance will be noticeable. Leaving the charger plugged in will not help, since once full charge has been achieved, the battery's internal management disconnects the charger supply circuit anyway.

Normally with lithium batteries the advice is to charge with every use, but if the usage is at less than a quarter of it's range/capacity, it's worth skipping it and charging after the next similarly short trip. Avoid completely emptying the battery if you can though.
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[cogs]

Thanks Flecc. i read somewhere that battery life is extended by keeping them in a cool environment?

It sounds as though the best thing to do would be to charge in the house where ambient temp is somewhat higher than the sheddie, and then transfer to bike when it is required for use?

 

[flecc]

Cool is better for storage cogs, but not for a battery in use. Lithium batteries lose capacity with time whether used or not, and storing at lower temperatures reduces the loss. For example, storing at zero degrees C reduces the capacity loss to about 2% a year.

When a battery in in use it's going to lose capacity anyway, so then it's best at a good operating temperature. Charging indoors and keeping it there until use is better for performance, but only charge it when you are in the house. Although they are reasonably safe, battery overheating and fires are not unknown so they are best charged when you are in the house and awake.
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[cogs]

Clear and to the point advice Flecc.

Much appreciated, especially the health and safety aspect, which had not occurred to me.

 

[Rod Tibbs]

Phenomena

Following on from the battery discussion, could I ask about a strange phenomena which has shown up on my Mistral? I ride it largely for pleasure around well defined routes in the Newmarket locality. I know exactly how far it goes on a full charge before one light drops out, then another and so on.

Twice my son has borrowed it to do an eight mile journey into Newmarket and back. The bike has then been on charge for no more than an hour.

When I have then gone out on the bike the charger is still showing red, ie the bike is not fully charged.

But out on a familiar route it is now doing far better than it would have starting with a fully charged setup with a green light on the charger. In other words the short one hour booster charge seems to envigorate the battery to a much greater extent than a straightforward charge to automatic switch off.

I know this sounds odd but I am very familiar with both the battery and its state over various distances. Today when I got back at least two more lights than usual were showing over a journey which would normally take them out.

Any ideas or advice would be most welcome.

Rod

 

[flecc]

That's very odd behaviour Rod, and it shouldn't be the case with everything working as it should. The only vague possibility I can think of is the charger overcharging and stressing the cells in the battery, leading to poor following performance. The battery's internal management system should prevent that happening. It may be unique to your battery since no other Mistral owner has mentioned this before.

That's just a guess though, as I've never known anything like that before, and I can only suggest you cut short the charges in future to get the better performance.
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[Rod Tibbs]

That makes a lot of sense and I will definitely try it it out. When I take the bike out for a 15 mile run I know almost to the minute when the charger is going to switch to green and signal 'enough.' So next time I will give it an hours less charge and then see what it does over the same course.

Will let you know - and again thanks for the suggestion.


Rod

 

[bogmonster]

i recently purchased an Alien 36v kit, which has been fitted and running for a couple of weeks. So far i'm pleased with it (i'll post an assessment after a bit more time).

My method of charging accords with Alien advice, and involves sticking it on

Hey, keen to know how you are getting on with the kit. I am on the edge of ordering one but think the battery will be too small for my needs. It would be good if Alien could provide the kit minus the battery and rack but I don't think this will happen. I would then add a 15ah Lifepo4 battery. I may just get the kit and buy a Lifepo4 battery if the supplied battery does not work out.

I need to do 22 miles between charges and it is hilly around here. I can put a fair degree of effort in (currently I ride my pushie the 22 miles each way once a week). Even if the battery was OK to start with I think with full discharges twice a day it will quickly start to degrade.

Anyway, keen to know if you are happy.

Cheers, BM.