Leaving NiMH's / NiCad on Trickle?

[Dukester]

Leaving NiMH\'s / NiCad on Trickle?

My instructions to my charger states that NiMH's or NiCad's can be left in the charger on the trickle charge mode indefinitley or until used again so they will be always topped off. Is there a rule of thumb to use? I mean I have mine in trickle mode for a couple or three days, can they be left in this mode longer you think?

Thanks,
Dave

 

[cheesehead]

Re: Leaving NiMH\'s / NiCad on Trickle?

If the batteries feel warm on trickle, then I wouldn't do it. Some batteries can take a small continuous charge, but it will still degrade them a little.

Well, actually, this link summarizes it nicely,

http://www.vencon.com/articles/nicd2.html

I've been partial to using a timer to turn off the charger, but it seems that some chargers will allow the batteries to discharge very slowly if left plugged in.

cheese

 

[batterystation]

Re: Leaving NiMH\'s / NiCad on Trickle?

If the charge rate is 10% or less of the cell capacity then no harm can be done to the cells with the exception of possible "memory" trouble with a nicad. Cordless phone chargers work this way. They are just a constant slow charge. True that an unplugged charger can become a load on a battery too as cheese has stated.

 

[MrAl]

Re: Leaving NiMH\'s / NiCad on Trickle?

Hello there,

I like the timer method best. I got a timer for $5 and
plugged my charger into it. I set it for 1/2 hour per
day and it keeps the battery pack charged up good.

Like some of the other posts say, your particular charger
could draw current from the batteries when it's not
plugged in (or when using a timer that turns off the
ac power going to the charger). To find out, simply
measure the current from the batteries when the charger
is unplugged and the batteries are fully charged.
If the current is very low ( like 200ua ) then it
wont be a problem. If it's something like 2ma i would
think about it a little more.

Take care,
Al

 

[Dukester]

Re: Leaving NiMH\'s / NiCad on Trickle?

[ QUOTE ]
batterystation said:
If the charge rate is 10% or less of the cell capacity then no harm can be done to the cells with the exception of possible "memory" trouble with a nicad. Cordless phone chargers work this way. They are just a constant slow charge. True that an unplugged charger can become a load on a battery too as cheese has stated.

[/ QUOTE ]

I have a strong hunch that you are correct. I mean of all people you should know since you are in the battery business. /ubbthreads/images/graemlins/smile.gif

The batteries that are in question are 9amp D-Cell NiMH's. My Charger states the following. "While the unit is in trickle mode the AT-5798 is charging at 1/10th to the contant pulse rate." (constant pulse = 800 ma) The instruction's also go on to say. "You may leave the batteries on trickle for an added extra topping off charge or just to maintain them in a fully charged state until you need them."

With your comment it just backs up my instructions so I can sleep better. /ubbthreads/images/graemlins/sleepy.gif

Touching the batteries with the back of my hand do not feel warm at all while in trickle mode.

Thanks,
Dave