[NSRCA-discussion] NiMH follow up

[George Kennie]

Hi John,
Thanks for the kind words, but I have the same struggles grasping
some of this stuff as anybody else (probably quite a bit more). Take
this battery stuff. I can't understand why it is that if I take my
500 ma pak and connect it to my 50 ma wall charger for 10 hours it
isn't fully charged?????  Why is it necessary to charge it for 16
hours and try to stuff 800 ma into that little package
(hmmm,......maybe that's why those lipos swell up that way??? BG ).
I'm aware that when I fast charge my Tx pak, if I can get it off the
charger about 3-5 minutes before that buggar reaches peak, the
voltage will read 12 volts, but if I leave it on past peak the
voltage will be depressed to 11.4 or even 11.2. So why the heck
would we want to charge for 16 hours when the max voltage probably
occurs somewhere around 10 hours?????????(I'm guessing).
You and Ed have a really good handle on this stuff, but I don't !!!!

Georgie


John Pavlick wrote:

>  Jay, Yeah, I guess I forgot to point that out. The time applies
> to a fully discharged pack (.9 ~ 1V  per cell). At C/10 it's
> pretty hard to hurt anything by "overcharging" i.e. charge a
> partially discharged pack for 16 hours. At the higher rates it
> becomes a very real possibility. Normally for "Fast" charging
> you'd use a good Peak detect charger: 0 delta V  or negative delta
> V depending on the cell chemistry. For C/10 you can get away with
> a low cost constant current charger - but you do need to shut it
> off! Ed also pointed out that new packs generally need a full 20
> hours on the charger at C/10. I would agree that this is a good
> thing to do, but do remember to stop charging them at 20 hours.
> It's easy to forget. Better yet use a timer, but if you go this
> route, make sure that the charger won't turn into a "discharger"
> when the input power is removed.
>
> John Pavlick
> http://www.idseng.com
>
>      -----Original Message-----
>      From: nsrca-discussion-bounces at lists.nsrca.org
>      [mailto:nsrca-discussion-bounces at lists.nsrca.org]On
>      Behalf Of Jay Marshall
>      Sent: Tuesday, February 28, 2006 4:23 PM
>      To: NSRCA Mailing List
>      Subject: Re: [NSRCA-discussion] NiMH follow up
>      You are correct on the rate. The time is dependatn upon
>      how much of the original charge remains. A good charger
>      will charge only as long as necessary to meet its full
>      chare specification (voltage, etc.).
>
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