mark in wi

Ok First I have been away from RC for awhile. When I was last racing the NiMH packs were just comming out. My question is about the mAh ratting on batteries. If a Nicd has the same mAh rating as a NiMH will they run the same time if all else is constant? I know this sounds dumb but would run times be different? I don't even want to start thinking about Li. I need new batteries and as with most people money is tight and I want to keep it simple. I was thinking about "upgradding" to NiMH over NiCd but price wise I would only gain 1-200 mAh. Some of the Lipo packs cost the same as NiMH so this adds to the confusion. I know I will have to get a new charger but will be another thred. Any pos/neg about the different types of batteries. These would be for 1/10th car and hopefully something for the kid to bash with.

Thanks for the help!

Mark

JeromeK99

iTrader: (3)

Well.. first off you are going to be hard pressed to find NiCad race grade batteries.. The last packs I saw were 3000mah, but they came out the same time 3000mah NiMh were released.. The main difference is that NiMh do not really have a "memory" like NiCads did. The downside is that you can't charge them with too high of an amp rate without heating them up too much, which can damage the cells fairly easily. You are pretty much stuck with 4-6amps.. not like the old days when you could step on your NiCad at 10amps in a pinch! The NiMh also take a more delicate and specific charge profile. So you would need a new charger if it was made for NiCad only... You basically get the same runtime based on the mah of the battery, NiCad vs. NiMh. As with NiCad, you get the best performance using them only once a day.

Now.. moving up a few more years... LiPo... no memory... no need to discharge... run them back to back all day.. you get about 1.3x the runtim in mah over NiMH.. So if you have a 3200mah LiPo (3200 x 1.3), you get about 4160mah compared to NiMh.. I've tested my early 3200mah LiPo vs. 4200mah NiMh race cells... almost identical power curve and runtime. The LiPo packs also weigh about half as much.. a 4200mah NiMh is about 16oz.. while the 3200mah LiPo is barely 8oz! You actually have to add weight to the car when using LiPo to get it to handle correctly. Best thing about that is that you can distribute it where you want! Best thing ever, IMO is that you can use 1 battery all day long.. I actually race 2 classes with only 2 LiPos. I just put them on the charger right after my race and they are ready by next heat! I've been doing this for over a year now! So even though some LiPo packs cost more than NiMh, you don't need as many. Just have one pack and one charger for each car you race!

Couple LiPo with a brushless motor/esc and you can get even longer runtimes!

Welcome back! Today in R/C it is more racing than working on stuff in the pits. That's why I race more than one class a night!

Jerome