Nimh to Lipo in AER & AEP - straight swap?

Point Two Balls

Point Two Balls

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Hi All,

Am I right in thinking that if I don’t get a crazy large and powerful Lipo, it’s a straight swap…..

Or is there more to it?

Pat.

 
Point Two Balls said:
https://www.airsoftworld.net/world-exclusive-lithium-polymer-aep-battery-li-po-lipo-7-4v-550mah.html
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Should be fine in a CM.128.  I run my CM.123 off of 1200mAh 7.4V stick lipo brutally shoehorned in and with a Deans connector replacing the standard contacts, but that was more just for the fun of it.  A drop in replacement makes sense and I found even a tiny 7.4V lipo gave a far snappier trigger response than the stock NiMH.

Point Two Balls said:
What’s the max safe Lipo I can put into a entry level Cyma (513) ?
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I'd stick to 7.4V for a very specific reason.  CYMAs come with higher powered springs as stock, and the cheapest way for a seller to get them down to UK power levels is just to lop some (or actually a lot) of coils off.  My CM.516 came shooting bang on 1J, but the spring had been cut down so much that it was barely long enough to return the piston fully.  Not a problem with 7.4V, it shoots quite nicely.  But when I dropped in an meaty 11.1V 2600mAh highish-C battery, I got significant overspin on semi, double-shooting on most trigger pulls.

Unless you're sure that yours already has a full length M100 or heavier spring in it, I'd go with 7.4V.  Capacity and even C rating won't matter that much with a stock CYMA, as the draw from the motor will be the limiting factor rather than supply from the battery.

 
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Careful with the li-po.  The tops pull off the damn things if you are too forceful when inserting them into the adaptor.   

They are a huge improvement though.  

 
I only run 7.4v lipos in my electric guns and none of them have chewed through their internals. I don't really see the need for 11.1v batteries, but then again I don't really use AEGs at all outside of a TM mp7 AEP, and that runs suuuuuper nice on a 7.4v lipo!

 
So....my stock battery was an 8.4v 1100mAh nimh.

The only lipo I could find that would fit in the stock buffer tube was a 7.4v 600mAh Lipo.

The gun just seems not as sharp and full auto is definitely slower with the Lipo fitted.

Is this normal ???

Thanks

Pat.

 
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Probably is cause you have lost a volt. Mah is only really a measure of how long the battery will last. 

Not a scientific explanation but I'm sure someone will explain properly lol

Regards 

 
A good 7.4v LiPo will deliver as much or more power to the motor than the 8.4v NiMh

As @Shamal said, the MilliAmp Hour (mAh) is how much electrical power the battery can deliver in one hour. (Basically how much it can store)  You'll need one bigger than 600mAh.  (1300mAh or larger)

You also need to look at the 'C' rating.  This indicates the maximum power delivery and should be as high as you can get.  20C is standard 25C is better.

This should do the trick but check the size fits

Make sure to get a decent charger to keep it in good condition and fire free ?

 
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Ah - ok - makes sense that dropping 1V would slow things down.

I wanted to loose the crane stock and fit a slimline stock, so that means my battery had to fit completely inside the buffer tube so I opted for this one:

https://www.patrolbase.co.uk/specna-arms-7-4v-600mah-20-40c-battery-for-pdw-mini-tamiya

No way will anything else bigger fit.

Not sure A 25C will be much different even if I could find one to fit.

So I guess this is the limitation of a slimmer stock.

Pat.

 
That's disappointing, I've always got better performance out of even modest 7.4V lipos than 8.4V NiMh, but reality is reality.

That Lipo you're running is 600mAh (i.e. 0.6Ah) and 20/40C which means that it can notionally deliver 12W sustained and 24W peak.  I'd want more for an AEG, and I'd also expect to go through at least two of those during a full auto day, maybe three and into the fourth if you get a lot of play in.   This is why dummy PEQ boxes and rewiring to the front are fairly popular.

Of course, there's always the possibility that it's just a duff battery. One of the few actually worthwhile posts I've seen on Facebook was a chap demonstrating that the internal cell resistance on airsoft batteries was far higher than it should be, and higher than cells sold for RC use.  I strongly suspect that we get the bad cells, since our power requirements aren't as high as RC.

HobbyKing let you search by dimensions, if that's any help to you:

https://hobbyking.com/en_us/batteries-chargers/batteries/lipo.html

You'll want to filter by "Number of cells" first, i.e. 2, then you can start looking for skinny sticks.

I agree with going to Deans: if you only solder one thing on your gun, it should be that.  Mini-Tamiya does work, but it's not great, and airsoft mini-Tamiya polarity is reversed compared to typical RC which limits choice.

 
I have a suspicion the battery wasn't fully charged when tested.

It should produce enough power to cycle properly if only for a short time.

 
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