Anyone running NiMH cells over LiPo?

[10kman]

I'm still playing with my recent MGT conversion, scrapping together a few more bucks for good cells, and am wondering if anyone is using NiMH cells by choice. If so, was it due to cost savings over LiPo? No noticeable performance gains for your application?

I've been toying with old, and junky, NiMH cell packs, ranging from 8 cells, to 12 cells, and then to 2 8 cells in series with my connector, giving me 16 cells to play with at one test session.

I've settled on 4s Lipo for my voltage range, which is a smidge more than 12 cells. 12 cells isn't much to carry around for a MGT, or a Neu 1515 1/y with a Quark 125B, but in the game of electricity and RC, lighter is better.

But, at what cost? I can get almost 3 12 cell packs by shopping around for the same price as one 4s2p LiPo pack, so I'm stuck in the middle. Runtime will be increased by the LiPo pack, and weight halved, so bonus there, but again, the cost....

Just bouncing around ideas in my head, and now the board. Oh yeah, what's the max range temp for the Quark 125? I had it warm to the touch, but will bust out the temp gun to tune in my voltage next time I'm out.

Thanks,

10k

[BrianG]

One of the major advantages lipos have over NiMH is the weight savings. For an equal weight of lipo vs NiMH at the same voltage, you can get up to three times the runtime. Also, for the same voltage/capacity, lipos are generally smaller in physical size. Yeah, they cost more, but I think they're worth it really. I was in the same boat as you about 6-8 months ago; NiMHs were working fine for me, but I took the plunge and happy I did.

[Finnster]

I personally got tired of the crappy runtime and the gradual reduction of power. My GPs in my Revo always had alot of power at the start, but a few min in they had calmed down a bit, and by 10-12 min they were dogging.

I moved up to cheap lipos, and the consistent power and long runtime is awesome. Bashing around I get ~1hr, and playing hard is like 20-25min.

These were 2*2S 6400mah lipos from TrueRc @ $80 ea. Not bad at all really. I won't go back.

[BrianG]

I'm still running 14 cell GP3300 packs in my Revo and am trying to find an excuse to get a 5s 10Ah pack. Triple the runtime, a little less weight, and more voltage - too bad they're just so darn pricey.

TrueRc's 8000Ah 4s pack is very good for the price ($140). I have 2, and have put them through hell and they have never failed me. I even rounded the end of the cells a little and they are fine. I hit a pot hole I didn't see with such force, that it bent the end of the cells against the battery box and shifted the cells in the pack. The lipos are ok though.

[pb4ugo]

As far as bang for the buck, I don't think anything beats the A123 cells. DeWalt packs can be had for $110 and will net you 10 cells. A little time on your part and materials and you can have two 5s packs (that will perform simialarly under load as 4s lipo) for $125.

[Finnster]

I have some of the 8AH TrueRcs as well. They are really nice, but they are just a bit too wide @50mm fit everywhere. Other than that they are great.

I like the idea of hte A123s too, just they are a bit too big and heavy and low runtime for me to take the plunge with them now. The next gen ones should be really awesome tho. They have great potential.

[Procharged5.0]

Originally Posted by BrianG

I'm still running 14 cell GP3300 packs in my Revo and am trying to find an excuse to get a 5s 10Ah pack. Triple the runtime, a little less weight, and more voltage - too bad they're just so darn pricey.

Exactly my issue I have (6) 6-cell GP3300 packs and (2) 8-Cell Gp3300's currently. I want to go Li-Po and will eventually....just hard to make that big of an investment right now. Too many other things come first!

(I keep trying to pursuade my wife the RC should be priority #1, but to no avail LOL! :019: )

What ever way you go, I'd get away from nimh as some point. My big problem with the nimh is two fold. First they are heavy. Second, then start to degrade very quickly, relatively speaking. I've seen nimh cells start to degrade after 10 cycles. The lipos and li-ions are more cost effective in the long run and they perform better to boot.

The A123 cells are nice. They'll take a beating and charge quickly. The downside is that they are large and heavy with limited capacity. My 5S2P 8Ah pack isn't much heavier than a 5S2P A123 pack and has almost twice the capacity and lots more power. The 5S A123 pack is a closer comparison to the 4S2P 8Ah pack in both weight and power delivery, but you get more runtime with the lipo pack.

As was said above, you can build yourself a 5S2P A123 pack for about $140, if you consider the balancing tap, cells, wire, etc. Although I'm very interested in the A123 cells and will likely get some in the near future, the ease of just buying a 4S2P 8Ah lipo packs keeps me coming back for more.

[MetalMan]

I switched to Lipo almost 2 1/2 years ago, and have never regretted doing so. I'm always on the prowl looking for the best deals on Lipos to maximize the bang-for-your-buck factor. For my Revo, I chose A123 packs because they are so cheap (in Dewalt packs), and because they still outperform NiMh by quite a lot. Here are advantages of A123 over NiMh as I see them:
-MANY more cycles
-greater power
-less weight (5s2p A123 weighs ~720g, 12 NiMh weighs ~800g)
-higher voltage (5s=16.5v)
-higher capacity (2p=4600mah)
-VERY consistent power until the last second
-FAST charge times (with the right charger)
-safer (won't "explode" at all like NiMh can)

But for competition, Lipo definitely has A123 beat for power and energy density. That's why my Hyper 8 is running a Maxamps 4s 5000HV Lipo pack.

[10kman]

Being a tech freak, I know that LiPo is the way to go in the long run, which is a huge reason why I did an electric conversion, electronics have way more room to grow vs. gas. Internal combustion can only do so much or else it has to get bigger and bigger, electronics get smaller and smaller, with same or better power.

I'll keep saving for a 4s2p pack from maxamps, plopping down 275 bones for a battery better be worth it........

10k

[jnev]

10kman - have you seen the True-rc lipo packs? They are way cheaper, and from what I hear from other members is that they have worked great for them and the customer service is great too.

+1 for the TrueRc lipos!...

Bye:027:

I don't have any of the truerc 4S packs, but I do have a couple of 5S packs. They are the 8Ah and although they are rated at 10C, I've never had any issues with them at all. For a change, I believe that the truerc packs are under rated. At around $150 a pop, they hurt a bit less than the maxamps packs. Just be sure to check the balance taps. I think that you have to add them to your order to get them; I don't remember.

[10kman]

Thanks for the tips for TrueRc, I will check those out as options. I'm trying to avoid buying twice, so if my reading shows a noticeable performance difference between those and the maxamps packs, I will just keep saving for the good stuff.