Weight against Voltage?

[Nick]

A question about Lipos/Cells.

My Triton only does 14.8v Lipo (5s). I don't want to charge 2 seperate packs, as waiting upto 2 hours for both to be done isn't worth the effort in my opinion.

So a Lipoly 4200mah 2S2P 7.4V Pack, if I used 2 (meaning 4s right?) I could charge them both and get 14.8v and some nice mAh.

However if I got 16 cells of IB3800. Which is 19.4v (in Triton limits). Which is best? The Lipos are lighter and powerful but I'm restricted by the charger but the 16 cells gives more volts?

Also, what to people think of GP2200s cells?

Any general explination would be really useful, thanks.

[Gustav]

A 4s(1p) pack is 14.8 volts,the 2s2p is 2 2s in parallel,only giving 7.4 volts.EDIT; i see you said using 2 of them,sorry.

How many NiMH cells can you charge at once? For example charging 2 10 cell gp2200 packs would take alot less than 2 hours and weigh about the same as 16 sub Cs.Maybe about an hour at 3 or 4 amps?

What setup/truck do you have in mind?

[Nick]

Triton can do 24cells.

Maxx with 7XL/9920.

[Gustav]

If you could keep the weight down enough,i think the runtime wouldn't be too bad on 18 gp2200s.Fast as hell aswell.

If you could stretch to another motor,an 8XL on 20 gp2200s would give awesome power and respectable runtime (considerably longer than the 7XL on 18 2200s i'd bet) since you have more cells and lower amp draw,wouldn't take too long to charge either, the capacity is much lower than 3700s so it takes less time to charge the same no. of cells at the same current.(i know you know but it's a fair point.)

[Nick]

Hmm, I'm intrested in the GP2200s, but what would be the best, 18x GP2200s or 18x IB3800s? I can imagine the NIMH 3800s would give more punch but would it not matter with the extra weight?

[Gustav]

I've no doubt the 2200s would be quicker but obviously without the runtime.

The theory behind using gp2200s is that it's best to use more of them to reduce amp draw (and gain power obviously) to offset the lower capacity.That's why i think if you could stretch to the 8XL or 9XL it would be more ideal.Basically they're good for gaining alot more power at the same weight whilst maintaining runtime.

You mentioned buying 2(2s2p) lipos,would an 9XL and 20 2200s cost more? I know which i'd choose between 24volts vs. 14.8 volts.

The runtime is my only concern with the 7XL on 18 2200s, a 9XL on 20 2200s would give alot more run time.

So if your'e sticking with the 7XL it's probably better to use the bigger cells if runtime is important,but to answer your question the 2200s would be quicker.

[squeeforever]

i would recommend the lipos. you said that your triton can charge 14.8 volts or 5s but 14.8 volts is 4s. if it can charge 5s i would definately go with 5s on the 7xl. you can always charge both at the same time. just connect them in series.

[Gustav]

That's what i was thinking,if it's 5s go with the lipos and the 7XL.

[MetalMan]

The Triton can only charge up to 4s Lipo (which is 16.8v fully charged). The Triton can only charge at up to 2.5amps with Lipo, so charge times would be long. If you want a 5s (18.5v nominal) pack, you could get a 2s and a 3s, charge them separately, and then connect them in series to run them.

[RC-Monster Mike]

I think the 18 IBC3800s would be punchier and ultimately faster than 18 gp2200 cells, along with a longer runtime. The disadvantage is the weight. The cells can definately carry thier weight, but the whole truck will handle differently and the extra weight will put more stress on all the parts. The 7xl on 4S Lipos will be a nice performer also IMHO.

[starscream]

I totally agree with Mike.

IMO, if you have the money, the skyvolt lipos look to be the best packs available right now. You could get a 1p4s pack and charge it to 90% in 20 minutes. You would need to get the skyvolt charger to utilize all the benefits of cell balancing etc but you could you still use your triton charger along with a fma charge protection module. (You would need the CP Module because it has a battery plug adapter installed)

I mainly use GP2200's because I race my MT. Sacrificing runtime for weight is worth it to me because the less weight ultimately provides more control of the vehicle at high speeds and better overall performance. We race 5 minute heats and 12-15 minute mains. It only takes ~20 minutes to charge the packs back up after each 5 minute heat. If I can make it to the A Main without bumping up from the B, I can go an entire night using one set of packs. Although I can't even remember the last time I was in a B main ;)

[Nick]

Can any one reccomend a good Lipo charger?

I'm really intrested in Lipos, just don't want to buy a small one just because I'm restricted by my Triton and charging 2 Lipo packs seperatly is too time consuming.

I'm sure my Triton could fetch abit, if I was to get a Lipo charger.

[Dafni]

I am also looking for a good Lipo charger. Would be great if it could handle 6S.

Sugestions welcome!

[Rtsbasic]

The Astroflight 109 is a popular one I think..1-9 cell lipo.

http://www.aeromicro.com/Catalog/ast...er_2691678.htm

[Gustav]

Nick,you were asking about weight against voltage and thinking about running 2 (2s2p) in series, i would say is that if you ran 20 gp2200s this would give you the best of both worlds since the weight is very similar and the voltage much higher.Would 20 gp2200s and a 9XL cost much more than the lipos?

Also,running a single 4s pack or a pair of 2s1p with your 7xl would half that battery weight and charging time and still give you a fair runtime.Although much less power than 24 volts.