Battery charge for storing through the winter?

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AndY1
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The manual says to fully charge the battery prior to storage and recharge it every now and then, but my friend, who has a lot of experience with batteries (Remote Control stuff), including NiMH told me, that NiMH should be stored at 40%-50% charge and should be recharged to that capacity every now and then.
He said, that leaving the battery fully charged for long periods will increase battery's internal resistance, thus decreasing it's performance and capacity.

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mikemitbike
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Re: Battery charge for storing through the winter?

Hi AndY1,
maybe your friend ment "leaving the Battery on a charger for long time". NIMHs "don´t like" being left in a charger for a longer time even if the charging curent is far below 1C. I´ll storage the bike with 90% charge. The selfdischarge is rather high, so it could be a problem tho leave the bike with only 50% charge for a time (some of the cells could drop to "zero".
Greetings Mikemitbike

AndY1
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Re: Battery charge for storing through the winter?

Thanx for the reply.

I found this, which pretty much confirms what you say. State of charge is not important as long as it's not below 1.0V/cell.

Quote:

Ni-MH batteries can give years of safe and reliable service if they are used in accordance with recommended procedures and are not abused. Batteries should be kept clean and dry both during use and storage. They can be stored for many months in a charged or discharged state without any detrimental effects as long as they are not exposed to extreme temperatures for any long period of time. After periods during which the battery has not been used, the battery should be charged before being placed in service. Extended overcharging or overheating of the battery should always be avoided.

Mik
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Re: Battery charge for storing through the winter?

AFAIK you do not have the recent Software (SW) update.

If you do, ignore this because I do not know how it behaves.

Whilst I have not been able to systematically test this, I firmly believe that the (old) Vectrix SW does not take self-discharge into account.

Maybe it will start a proper CP recharging cycle if the battery Voltage falls below some certain voltage, but I never saw it do this. In my experience the battery charge indicator will remain on "Full = 17/17" no matter how long you let it stand uncharged.
And then it only charges at "EC" current = next to nothing for 1 or 2 minutes when you plug it in.

You can find out if this is true by letting it self-discharge for a few months, then plugit in when you have time to watch and take photos or video of the recharging process.

If - after months of inactivity - there is no decent amount of CP and or CC charging happening when you first plug it in again, then you should assume that you have some empty cells in the pack and ride only the shortest distance which allows proper charging to commence. Then repeat it several times to equalize the cells.

Or, and this would be my recommendation if there was no WWW, you leave the Vectrix electronics and battery in about 50% SOC (State of Charge) so that a proper CP cycle will commence anyway once you first plug it in again for the first time.
But I would still do multiple shallow discharge/recharge cycles to re-balance the pack after that period of inactivity.

But there is a WWW, and you people in colder climates could answer the question (for everyone!) if or if not the stock Vectrix monitors self-discharge.
That would be important and a worth-while project. It can be done reasonably well with just a Vectrix (HAHA), a "Watts-up" or similar Watt-hr counting device of sorts and some effort for a few hours when you first plug it in again. And it has the distinct advantage of Nothing To Be Done During The Rest Period!

Whatever you do, do not assume your Vectrix is capable of the same performance as before the rest period right away.

Short trips, followed by full recharges including all charging stages, gradually increasing from 5km to full range (40-60km if you are lucky) could help to prevent reverse charging of the cells which might have self-discharged quicker than the others.

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