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Mad Hatter · 11-30-2005, 09:12 AM

I just purchased a charger that ha a temp probe and allows one to set the temp alarm to a certain temp. Since this will be used for my on-road car only charging nmhi batteries, how hot is too hot for the batt? IE, what do I set the temp alarm at?

EeePee · 11-30-2005, 02:13 PM

Google must hate you...

http://www.rccaraction.com/articles/NiMHbatcare1.asp

Mad Hatter · 11-30-2005, 07:33 PM

Quote:

Originally Posted by EeePee

Google must hate you...

http://www.rccaraction.com/articles/NiMHbatcare1.asp

I have read that article. However, I am being told it is incorrect that the temp shut off should be around 133-138 degrees. So which is right? I would just like some more info before I burn a good 90$ pack to a crisp. Maybe I should have worded the ? differently.

What temp do you consider a safe charging temp for your nimh packs and why/where did you get your info?

EeePee · 11-30-2005, 07:42 PM

Why not let the peak detector detect the peak?

floogldood · 12-01-2005, 01:18 AM

some will say that 135 deg F is max. Some use 35 deg F over ambient temp.

I find that smaller radio batts like the max to 110 and good sub C batts can go 130 or so.

Mad Hatter · 12-01-2005, 02:20 PM

Quote:

Originally Posted by EeePee

Why not let the peak detector detect the peak?

The charger I am using has an adjustable temp alarm and temp probe on it. I have some packs that are getting up there in temp before the peak and shut off. Just trying to protect the investment.

floogldood · 12-01-2005, 06:33 PM

This is a sign of charge rate too high for the battery. If you can step it down towards the end it may not heat up.

If it is getting hot only at the end then it is unequal / unbalanced cells or the battery is full regarless of the peak.

jardiniboy · 12-01-2005, 06:38 PM

100 degrees should be good enough. Also, for amps charge at 3-4 amps you don't want to damage your batteries. The rccaraction website is mostly for grip racing. For crawling would you charge your batteries at 5 or more amps, discharge at 30 amp, build your own packs. Heck no.

Mad Hatter · 12-01-2005, 08:02 PM

Quote:

Originally Posted by jardiniboy

100 degrees should be good enough. Also, for amps charge at 3-4 amps you don't want to damage your batteries. The rccaraction website is mostly for grip racing. For crawling would you charge your batteries at 5 or more amps, discharge at 30 amp, build your own packs. Heck no.

For crawling I use ready built stickpacks and charge them at 4 amps. I can get a lot of run time and decent power fom them. I build my packs for racing and charge them at 5-6 amps.

JohnRobHolmes · 12-01-2005, 11:51 PM

nimh will take quite a beating on charge cycle if you want the voltage out of them. I have all my cells zapped, then I custom build them, charge them at 5 amps, and wheel the snot out of them. I cant stand using cheaper tin strip packs. Batteries are usually the weak link in a power system, not the motor. The best way to have quality punch and long runtimes is to pay attention to all the electrical details.

If you want to spare your packs for many a year of use, charge them at 1C or less (so 3000 batts are charged at 3 amps). They will still peak over 100 degrees F though. It doesnt matter how slow you charge them, a peaked cell acts like a peaked cell.

11-30-2005, 09:12 AM	#1
Mad Hatter Pebble Pounder Join Date: Oct 2005 Location: The arm pit of the universe Posts: 176	Batt temps while charging ? I just purchased a charger that ha a temp probe and allows one to set the temp alarm to a certain temp. Since this will be used for my on-road car only charging nmhi batteries, how hot is too hot for the batt? IE, what do I set the temp alarm at?

11-30-2005, 02:13 PM	#2
EeePee MODERATOR™ Join Date: Jul 2004 Location: Ohio Posts: 18,928	Google must hate you... http://www.rccaraction.com/articles/NiMHbatcare1.asp

11-30-2005, 07:42 PM	#4
EeePee MODERATOR™ Join Date: Jul 2004 Location: Ohio Posts: 18,928	Why not let the peak detector detect the peak?

12-01-2005, 01:18 AM	#5
floogldood Quarry Creeper Join Date: Nov 2005 Location: Planet Earth Posts: 350	some will say that 135 deg F is max. Some use 35 deg F over ambient temp. I find that smaller radio batts like the max to 110 and good sub C batts can go 130 or so.

12-01-2005, 06:33 PM	#7
floogldood Quarry Creeper Join Date: Nov 2005 Location: Planet Earth Posts: 350	This is a sign of charge rate too high for the battery. If you can step it down towards the end it may not heat up. If it is getting hot only at the end then it is unequal / unbalanced cells or the battery is full regarless of the peak.

12-01-2005, 06:38 PM	#8
jardiniboy Newbie Join Date: Jun 2005 Location: waipahu Posts: 9	100 degrees should be good enough. Also, for amps charge at 3-4 amps you don't want to damage your batteries. The rccaraction website is mostly for grip racing. For crawling would you charge your batteries at 5 or more amps, discharge at 30 amp, build your own packs. Heck no.

12-01-2005, 11:51 PM	#10
JohnRobHolmes owner, Holmes Hobbies LLC Join Date: Nov 2004 Location: Volt up! Gear down! Posts: 20,290	nimh will take quite a beating on charge cycle if you want the voltage out of them. I have all my cells zapped, then I custom build them, charge them at 5 amps, and wheel the snot out of them. I cant stand using cheaper tin strip packs. Batteries are usually the weak link in a power system, not the motor. The best way to have quality punch and long runtimes is to pay attention to all the electrical details. If you want to spare your packs for many a year of use, charge them at 1C or less (so 3000 batts are charged at 3 amps). They will still peak over 100 degrees F though. It doesnt matter how slow you charge them, a peaked cell acts like a peaked cell.

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