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Can someone tell me how do you know when a battery is fully charged, for
example, if you want to
give your car battery a boost once in a while, or some old rechargeable
batteries you've not used for some time, and they have become completely
flat. How do you estimate how long you should leave them on charge. I have
a multi-tester but I'm not to sure how to use it. I don't want to
over-charge them, as I have ruined quite a few leaving them on charge to
long.

Any decent battery charger will tell you when the
battery is fully charged; it should also have decent
documentation, that you should take not of.


On Fri, 28 May 2004 19:39:18 +0100, in
<UyMtc.345$ZT5.184@newsfe2-win>
Scottie scrawled:

>Can someone tell me how do you know when a battery is fully charged, for
>example, if you want to
>give your car battery a boost once in a while, or some old rechargeable
>batteries you've not used for some time, and they have become completely
>flat. How do you estimate how long you should leave them on charge. I have
>a multi-tester but I'm not to sure how to use it. I don't want to
>over-charge them, as I have ruined quite a few leaving them on charge to
>long.
>

--
Basic computer maintenance
http://uk.geocities.com/personel44/maintenance.html

Most modern units will only charge till they are full, therefore not
overcharge.
Depending on the type of battery, constantly charging, over a period of
time,can lead to a deteriation in the battery charge life. It used to be
said that you should fully discharge a battery, from time to time, in order
to lengthen the life, as such the better charging units also featured a
discharge facility. As to whether that is still true??

"Scottie" <> wrote in message
news:UyMtc.345$ZT5.184@newsfe2-win...
> Can someone tell me how do you know when a battery is fully charged, for
> example, if you want to
> give your car battery a boost once in a while, or some old rechargeable
> batteries you've not used for some time, and they have become completely
> flat. How do you estimate how long you should leave them on charge. I have
> a multi-tester but I'm not to sure how to use it. I don't want to
> over-charge them, as I have ruined quite a few leaving them on charge to
> long.
>
>

Scottie wrote:
> Can someone tell me how do you know when a battery is fully charged,
> for example, if you want to
> give your car battery a boost once in a while, or some old
> rechargeable batteries you've not used for some time, and they have
> become completely flat. How do you estimate how long you should leave
> them on charge. I have a multi-tester but I'm not to sure how to use
> it. I don't want to over-charge them, as I have ruined quite a few
> leaving them on charge to long.
1.For your/a car battery read this, it covers the topic quite well and you
can research further, should you so wish
http://www.indiacar.com/index2.asp?p...aintain_od.htm
Follow the makers instuctions!
2."Old rechargeable" is not helpful, if they are NiCd then they are probably
borked, but it may be possible to recondition them. Fot that you would need
a good quality charger that is able to fully discharge, recharge & then
trickle charge them. Personally I would say it's probably not worth it. If
they are NiMH or polymer batteries then a recharge will suffice.
Follow the makers instuctions!( there may be an echo in here ere ere re
e e )
HTH & HAND

"anon" <> wrote in message
news:q4Ntc.202$...
> Most modern units will only charge till they are full, therefore not
> overcharge.
> Depending on the type of battery, constantly charging, over a period of
> time,can lead to a deteriation in the battery charge life. It used to be
> said that you should fully discharge a battery, from time to time, in
order
> to lengthen the life, as such the better charging units also featured a
> discharge facility. As to whether that is still true??
>
> "Scottie" <> wrote in message
> news:UyMtc.345$ZT5.184@newsfe2-win...
> > Can someone tell me how do you know when a battery is fully charged, for
> > example, if you want to
> > give your car battery a boost once in a while, or some old rechargeable
> > batteries you've not used for some time, and they have become completely
> > flat. How do you estimate how long you should leave them on charge. I
have
> > a multi-tester but I'm not to sure how to use it. I don't want to
> > over-charge them, as I have ruined quite a few leaving them on charge to
> > long.

car batteries are not the same as home rechargeable device batteries.
car batteries use lead acid solutions, home rechargeables come in different
flavours (NiMH,NiCd,Li-Ion, and those limited recharageable alkalines).

car batteries will hold a stronger charge if it is trickle charged (low
(2)amps) overnight. Letting it drain completely is not recommended. car
batteries are normally charged around 13.5v
if a trickle charger is not used, an hour should be a good estimate on
charging time.

NiCd batteries are notorious for loosing their full charge (memory charge).
full drain is recommended.
the others i've listed do not require full discharge.

an overcharged battery will give off excess heat. this heat is what causes
damage and reduced battery life.
so monitoring the heat is a good indication of full charge.

-a|ex