Partial battery charging

[funkylyn]

Can anyone please advise me about partial re charging of batteries.

I have always been in the habit when doing an all day traffic free ride, like say the Tarka Trail, to stop for lunch, if possible,and plug in my battery for an hour.
However I have just noticed that when shops give their battery info they state usually a partial charge of between 2-3 hours....so does that mean that a 1 hour charge wont do anything.....or does every little bit help ??
(hope so )

Lynda

 

[lemmy]

From what I gather it's better to wait till the battery has lost at least 40% of its charge before replenishing it due to the wear and tear on the battery of the recharging process itself.

However, topping up as you suggest won't do any material harm since you aren't doing it all the time. But also, and more importantly in my view, the one hour will up the battery level and thus give you extended range over not topping up. That's what you need - and you are the master (or rather, mistress!).

 

[funkylyn]

From what I gather it's better to wait till the battery has lost at least 40% of its charge before replenishing it due to the wear and tear on the battery of the recharging process itself.

However, topping up as you suggest won't do any material harm since you aren't doing it all the time. But also, and more importantly in my view, the one hour will up the battery level and thus give you extended range over not topping up. That's what you need - and you are the master (or rather, mistress!).

Ah, Ok, thanks for that lemmy......usually by lunch time I would have done at least 15 or 20 miles so it probably comes within those parameters of 40% usage.
So thats a relief and justifies the pub stop

Lynda

 

[flecc]

At that discharge level it will gain quite a lot of charge, so definitely worthwhile. It's only in the late stages of charging that the charging rate drops to very low levels.

 

[funkylyn]

At that discharge level it will gain quite a lot of charge, so definitely worthwhile. It's only in the late stages of charging that the charging rate drops to very low levels.

Great !......kennet and avon canal here I come

Lynda

 

[flecc]

Great !......kennet and avon canal here I come

Lynda

Best wear a wet suit Lynda.

 

[funkylyn]

Best wear a wet suit Lynda.

Oh no......not ANOTHER accessory to buy

Lynda

 

[Jon]

I was reading a published paper from NASA on batteries the other month and they dont let their Lithium batteries drop below 8% or 9%. They were suggesting that by doing this it keeps the batteries in their satellites and earth applications healthier for longer and once the decay of the satellite battery reaches critical point, repair is not really an option although it has happened.

This was also confirmed from one of the ebike retailers i visited and i was told to keep the battery cool as possible without the use of a freezer lol and to keep it topped up where possible.

Now i doubt that this retailer read the paperthat i was sent as it came from some friends that work at the Clear Lake, Houston Nasa 1 site. Well, that said it was a published paper so he could have searched for it (not sure where it was published) but i doubt it.

 

[kitchenman]

Shouldn't it be said that different batteries have different rules? I have a NI-MH battery and have to leave it to cool down before charging it. (not quite sure how long so I always leave at least an hour ... must check with my supplier!) - fatboytrig was telling me that with his Toshiba battery it benefits from being charged directly after being used. He is currently carrying his battery with him and doing just that.

 

[Jon]

Shouldn't it be said that different batteries have different rules? I have a NI-MH battery and have to leave it to cool down before charging it. (not quite sure how long so I always leave at least an hour ... must check with my supplier!) - fatboytrig was telling me that with his Toshiba battery it benefits from being charged directly after being used. He is currently carrying his battery with him and doing just that.

Yes you are right.

The paper i read was talking about Lithium batteries LiPo and LifePo4. In my manual for my LiPo it is suggested to leave the battery for 30 mins to cool before starting to charge.

 

[flecc]

I was reading a published paper from NASA on batteries the other month and they dont let their Lithium batteries drop below 8% or 9%.

Not the whole story by far though. In fact the batteries only have one seventh of their capacity used in each dark period before the daily solar recharge phase. By only using that very small proportion of the capacity and ignoring the top and bottom of the charge extremes, they last for the ten year life specification, over 3500 daily charges.

 

[Scottyf]

Its all relative to application though really. Thats the one thing I've learnt about battery tech as it is with most things in life. You have to find the best compromise.

Lithium battery's work great on ebikes becasue generally the small size, less weight and the amount of life they give compared to other type of batterys in this application works well.

However if you needed more amp's or a higher discharge rate they are pants.

From reading for uni releases on batteries lithium types like those used in phones prefer little tops ups all the time. Much better than a huge discharge and replenishment that say Nicad need to keep them in a healthy condition.

Lifepo4 is looking pretty promising for ebike application though. Least for even cheaper running costs (Provided you keep the bike in use for 4 ish years)

 

[lemmy]

By only using that very small proportion of the capacity and ignoring the top and bottom of the charge extremes, they last for the ten year life specification

Since I can get 10ah or 18ah batteries for my Kalkhoff Tasman at only about £100 more for the extra 8ah, your post gives me a thought, Flecc. Here goes...

I reckon my 10ah Panasonic battery will give me another useful 18 months of life with a reasonable range. New, I got about 30 miles, now 18 months later, it's down to about 26 miles and I'd regard 22 miles as the least acceptable. I'd expect to be at that level and ready to replace the battery in 18 months. That's a 3 year life at £400 or £133 per annum.

Now, if I bought the 18ah battery, my idea of acceptable range does not change. Without doing detailed calculations, it looks to me like that would give the battery a greatly extended usable life (for my usage), out of proportion to the extra £100 in cost.

It would, in effect, be a great money saver. I would only need an extra 9 months of life to get the cost down to the same as the 10ah unit. If it would extend battery life to 6 years, for example, battery costs plummet to £83 per annum.

I'm applying the NASA logic that your post implies. I like a minimum range of 27 miles. By, in effect, over-specifying the battery, I can have the range I want for many years.

The only question would be if chemical change within the battery would limit the life, rendering my logic redundant. Having, as Ian Dury said, a doughnut for a brain, it may be my logic is redundant anyway

 

[flecc]

There is a but Lemmy. Basically for the very long life to be produced, the battery is 7 times the capacity that is needed, this to keep the discharge to capacity ratio low.

On the basis that your unit's design allowed for discharge from 10 Ah, implying that was the basic capacity needed, the 18 Ah battery is only 1.8 times, not the 7 times.

You would still gain of course, but the cost to gain balance is a bit debatable.

 

[Jon]

This is something that i was debating with the shop owner we came to the conclusion that to have a system as effective as NASA we would need huge batteries to reduce to quantity of discharge, if that makes sense therefore making the gains redundant in cost and weight.

My problem is this, if i invest in a battery that will last 5 or 6 years i may have the idea of saving money long term but realistically i wont. I wont keep my bike 5 or 6 years i know that im expecting 2 or 3 (that will be about 7500 miles) therefore i may as well stick with the battery i get as standard.

Interestingly when looking for ebikes Bob at Juicy is fitting the LiFePo4 15ah batteries to his sport range. If i remember rightly they should be in stock about now so it may be worth watching that space