good batteries?

[henley83]

i just traded a bunch of parts and stuff for my tmaxx with another guy for another bunch of parts. Sounds dumb i know but i had some stuff he needed and he had some stuff i wanted so it all worked out in the end. Anyways, on to my question. Included in this deal was pair of batteries. They are 6 cell 3000mAH NiMH. THe only thing is they are Radioshack brand. He said he traded for them and ended up never using them. Are these batteries any good? DOes anyone know anything about them? I currently use gp3300's anyway but I thought at the least they could be used as a decent set of backups while my others are charging.

Also will a dynamite mega peak charger recharge these as they are NiMH batts? I dont think it will on 4 amp but could I charge them on a 1 amp, kinda like a slow or tickle charge? Any help would be appreciated...

[offset]

They will charge at 4 amps. Those packs will work, but you will be disapointed compared to some HQ gp3300 packs. They can't put out the runtime/voltage/amps that the gp packs can, but theyll work nice for an ez start But seriosly, they will work fine in an e-maxx, just not 'great'.

Sounds dumb

Sounds like a great idea to me

[henley83]

Originally posted by offset
but theyll work nice for an ez start

thats probably where they will end up

[i_am_who_i_is]

i have a question about amps, does it matter how many amps i charge it at? or is it just that higher is faster?

[traxxastampeder]

If you charge at a higher amp the bat and charger will get hotter but it will finish sooner.

[FricFrac]

A general rule of thumb is...

NiCd - 2C
NiMH - 1.5C
Li-Poly - 1C

The "C" rating is your mAh of you packs. For instance if you have a 2600 mAh NiCd pack you can charge it at 2C -> 2 x 2600 mAh = 5.2 A. If you have a 3300 mAh NiMH pack you can charge it at 1.5C -> 1.5 x 3300 mAh = 4950 mAh (close enough to say 5 amps).

That being said there is something magical about the GP3300. They kind of fly in the face of the RoT (rule of thumb) and are often able to be charged at 6 or 7 amps - I know guys that peak at 10 amps! Some of these guys have packs that are two years old with this kind of blistering charging. They also use dischargers that bring the cells down to 0V (thats kinda a trick - there is still a charge in the cells) and claim that they get 2% more run time, etc....

[henley83]

ive never heard of that before fricfrac. thanks for the tip though.

[i_am_who_i_is]

cool thanks. i have some 3000 mAh NiMH packs -> 4.5 A
and some 3200 mAh NiMH packs-> 4.8 A

thanks!

[henley83]

i tried them out late this afternoon. they surprisingly had a lot of punch to them. runtime around 17-20 minutes in first gear, lotta crawling and goofing off. lot more than expected.

[offset]

I can't believe some people charge at 6 amps!!!! My gp's get too hot to touch i fi charge at 3.5 amps.

[fabryd]

How is it possible? I knew that the lower amp you use in the charge (0,5-0,8C) the longer you run....

[busted_emaxx]

I remember when I bought my batteries, they had instructions to never charge over 3.5amps. I think every battery can handle a certain charge current, and if you go over it, ur batteries will slowly degrade in performance, run time and how long theyll last. So, A higher charge current may charge faster, but it could damage the batteries...

[Jakey]

Originally posted by offset
I can't believe some people charge at 6 amps!!!! My gp's get too hot to touch i fi charge at 3.5 amps.

offset - The excessive heat you notice when charging at 3.5 amps is probably due to the peak voltage threshold on your charger being set too high. I nearly always charge my GP3300s at 6-amps. My battery temps immediately after peak are usually around 110 to 115 dF.

[offset]

Originally posted by Jakey
the peak voltage threshold on your charger being set too high.

Well i can't change that, i have a set everything charger (intellipeak twin pulse) is it bad that my batteries are being charged with a high peak voltage threshold? Also what is that?

[Jakey]

Voltage threshold or delta V is the drop in voltage that occurs after a battery pack is fully charged. When a battery is full the charger looks for that pre-determined voltage drop. Many chargers allow you to adjust the sensitivity of the voltage change the charger looks for.

[FricFrac]

Originally posted by fabryd
How is it possible? I knew that the lower amp you use in the charge (0,5-0,8C) the longer you run....

If you talk to the racers (not that they are always correct but most put a lot of extra effort in getting the most out of everything) EVERYONE I've ever talked to profess that you get more punch if you peak at a higher current (and more run time).

What you WILL get if you charge at a lower rate is extended life from your batteries. Always follow the manufactures suggested charge rates. NiCd typically have a life of 1000 cycles whereas NiMH is about 500 cycles.

[fabryd]

thanks a lot, so i will give a full of power to my new sanyo 3600 packs!!!

[granite]

Originally posted by offset
I can't believe some people charge at 6 amps!!!! My gp's get too hot to touch i fi charge at 3.5 amps.

I have the same problem with my twinpulse. It seems to miss the small peak that is characteristic of NiMH cells. NiCd cells have a more pronounced peak which is easier to detect. I'm thinking of putting a timer on the charger and setting it for an hour so if I'm not paying attention it won't cook the packs.