Trouble understanding/picking LiPo (C-rating, power, etc)

[-Shade]

Hey all,

I'm looking to get into LiPo batteries, but after sorting through some interesting threads on here, I can't really determine which one is right for me based on my setup. I'm worried what I choose may not provide me with enough power.

I have a guarder infinite torque up motor shooting an SP110 at 430fps - soon to be an SP100 which I'm going to guess will be around 400fps. An 8.4V nimh will not spin the motor/spring - and a 9.6v does a good job. On a side note, the internals are all upgraded and using low resist wire and deans.

I was looking at the turnigy batteries listed on airsoft store canada, more specifically the Nano-Tech 7.4V 1200mah 15C Stick Battery. I've heard conflicting opinions that a battery with a low C rate like 15 won't work well for a higher demand setup like mine (sort of) is. Is this a totally wrong assumption? I'm looking for good trigger response as I will be using this gun mostly in semi and sometimes 3rd burst from the MERF3.2 mosfet installed.

Any recommendations on what battery I would get the most out of would be most appreciated!

Thanks

[ThunderCactus]

Race guns won't use more than 20A unless something goes wrong, so just aim for 20A or more
1.2A * 15C = 18A continuous draw, which should still be fine

And just TRY a 7.4V lipo, they're only $10 or so, you're not losing much if it doesn't work

[Azathoth]

Originally Posted by ThunderCactus

Race guns won't use more than 20A unless something goes wrong, so just aim for 20A or more
1.2A * 15C = 18A continuous draw, which should still be fine

And just TRY a 7.4V lipo, they're only $10 or so, you're not losing much if it doesn't work

In this case I would opt for more "C" value or more MAH to get that COntinue amp closer to 25-35. That C value is the maximum sustained rate and you would be getting close to the limits of the pack.

@ Thundercactus
UR Hoppin?
No, cuz ER hoppin

[ThunderCactus]

Don't forget, LiPo's have burst rates too.
The continuous rating is a good safety margin, but it's really meant for things like RC cars where the motor is operating constantly. Not airsoft guns where it's primarily used in short bursts.
Really comes into play with LMGs though

[Freudster]

I have a few friends into RC Cars. One of their race batteries was 90C at 5A. I was curious to see how much it would melt stuff.....

[-Shade]

So what your saying with a burst of 25C it should be able to handle my high torque motor at 425fps? And you're right - I really don't have anything to lose with buying a lipo since they're cheap and can be resold at essentially their original value if it doesn't work, lol.

[Kos-Mos]

Originally Posted by Freudster

I have a few friends into RC Cars. One of their race batteries was 90C at 5A. I was curious to see how much it would melt stuff.....

Quite much...

But not as much as the 150C 8000mAh 28.8V pack that goes into my friend's electric Baja. That battery is monstrous.

On topic, if you can fit a "large" type battery, a 8.4v will spin it no problem.
It's not the voltage that is the problem here, it's current. Especially with high-torque motors.

With that said, 7.4V 2000mAh 25C should pull your spring no problem. If not, redo your mechbox work, there is something wrong.

[ThunderCactus]

Yep.
LiPo's have significantly higher amperage output than NiMH. Most will tell you that a 9.6v mini NiMH is just about the same RoF as a 7.4v LiPo.
But the LiPo has more amperage, which means more torque, which means it can drive a higher ratio gear set, achieving the same or better RoF with lower voltage

Your RoF may be a bit different, you may have to change gear ratios or try out an 11.1v to see how it handles. Again, the batteries themselves are dirt cheap so it doesn't hurt your wallet to try them out!

[-Shade]

Originally Posted by ThunderCactus

Yep.
LiPo's have significantly higher amperage output than NiMH. Most will tell you that a 9.6v mini NiMH is just about the same RoF as a 7.4v LiPo.
But the LiPo has more amperage, which means more torque, which means it can drive a higher ratio gear set, achieving the same or better RoF with lower voltage

Your RoF may be a bit different, you may have to change gear ratios or try out an 11.1v to see how it handles. Again, the batteries themselves are dirt cheap so it doesn't hurt your wallet to try them out!

I currently run this:
http://www.airsoftparts.ca/store2/in...oducts_id=2156

It's a small type I'm assuming - so the lipo I mentioned earlier should outperform this? Or at least spin my motor, lol?

[Freudster]

I'm sure it will be fine. As Kos-Mos said, just make sure nothing is binding first and it should pull the 100 spring no probs.