Nimh discharge rates

[AaronF]

Hi all,

I'm pretty new to RC trucks, I have the Granite Mega 4x4 with the NiMh batteries. One observation I have, but no evidence of, is that the Dynamite Speedpack2 3300mah battery that comes with it seems to have better performance than the gens-ace-r-spam 5000mah battery that I also have. Its like it has a better discharge rate or something but I haven't been able to find anything out about discharge rates of NiMh batteries.

I'm going to convert it to 3s lipo at some point anyway, which is part of the reason I didn't get the BLX, so I could learn how they work.

Anyone had a similar experience or know about this? The truck appears to have more punch on the 3300mah battery.

Part numbers for anyone who wants to know
DYNB2071EC (Dynamite)
GEANM50007SDH (Gens)

 

[grihn]

Does your gens battery have a deans connector? Are you using an adapter? That could be factor. It also could just be the quality of battery. I've had really good luck with Dynamite batteries and consider them pretty good quality. I haven't had bad luck with Gens, but my Gens lipos seem a bit weaker than my CNHLs and Dynamites.

 

[slick2500]

A fully charged 7 cell nimh has more voltage than a 2s lipo 10.5v vs 8.4v. Nimh just has a wicked power curve compared to lipo, performance drops off as the pack depletes more than with a lipo.

 

[AaronF]

Does your gens battery have a deans connector? Are you using an adapter? That could be factor. It also could just be the quality of battery. I've had really good luck with Dynamite batteries and consider them pretty good quality. I haven't had bad luck with Gens, but my Gens lipos seem a bit weaker than my CNHLs and Dynamites.

The Dynamite has the IC3 and the Gens has a EC3, that's about the only difference.

A fully charged 7 cell nimh has more voltage than a 2s lipo 10.5v vs 8.4v. Nimh just has a wicked power curve compared to lipo, performance drops off as the pack depletes more than with a lipo.

yeah i have read that somewhere, I'll have to pay more attention next time I take it out. Could also be the cells in the Gens might not be as good, kind of like the Silicon lottery with graphics cards.

 

[slick2500]

The Dynamite has the IC3 and the Gens has a EC3, that's about the only difference.



yeah i have read that somewhere, I'll have to pay more attention next time I take it out. Could also be the cells in the Gens might not be as good, kind of like the Silicon lottery with graphics cards.

If you have more voltage you will have more performance. The performance drops off a lot faster with the NIMH though.

But what charger are you using to charge each battery? Does your charger have a way to test the internal resistance of the cells?

 

[AaronF]

It’s just a cheap charger but better than the one it comes with. GT Power SD4-I it’s pretty basic so doesn’t Have that feature

 

[Hector_Fisher]

If you have more voltage you will have more performance. The performance drops off a lot faster with the NIMH though.

But what charger are you using to charge each battery? Does your charger have a way to test the internal resistance of the cells?

Yeah i remember when lipos first started getting big, there were people still using nimh because of the extra boost right at the beginning of the pack.

The Dynamite has the IC3 and the Gens has a EC3, that's about the only difference.



yeah i have read that somewhere, I'll have to pay more attention next time I take it out. Could also be the cells in the Gens might not be as good, kind of like the Silicon lottery with graphics cards.

Not all batteries are created equally. I've seen some pretty poor quality lipos, some that held less than half their rated capacity and had voltage sag so bad I never needed to storage charge the battery after use because it was only at 3.8v (on a granite voltage). A high quality nimh pack, while it doesn't stack up to the average lipo nowadays, is still pretty decent.

 

[AaronF]

I think the Gens battery has died... took it out about an hour ago and it seemed slower and less lively than usual. Put it on my charger and it goes up to about 9.7 - 9.8v then says charged after about 30 mins, it usually takes a couple of hours to charge. The voltage starts dropping and stops about 8.04 volts.