Battery packs from 18650 li-ion cells

waylander · October 10th, 2014, 11:32

Hello All,

Tried to do a search here and they all came back related to flashlights....

Has anyone made or used a 3S (9.9v) 18650 pack in an AEG? Just wondering if they would fit in a stock designed for nunchuk style batteries? I checked the dimensions and they are 18mm dia. vs 17mm dia which a standard 2/3A nimh cell is. I used to make my own sub-c packs for RC so wanted to try this but don't want to spend the money and time if I know it won't work.

Advantage? 3200mah (looking at good panasonic ones not the cheap china clone ones) cells vs 1600mah.

Thanks!

Styrak · October 10th, 2014, 15:21

Single 18650's usually have voltage cutoff circuitry for charging and discharge.....not sure putting them in series would work.

waylander · October 10th, 2014, 16:33

Hmmm... I'll have to see whether it's possible. I have some cheap chinese made ones that I can try on without too much loss.

As they're li-ion I think I might be able to charge them through a balance connector like lipos have. Then each cell is effectively being charged individually. I have a Hyperion charger that can do that and spare balance connectors around. I'll give it a try and see what happens.

Edit: did a bit of research and it looks like it's fine to put them in series, you just have to be aware of total voltage vs individual cell voltage. A balance connector as used in lipo batteries should help with the charge part of this issue. I typically run voltage alarms set for well above the minimum so not too worried on the discharge side either. Using good quality cells with good QC should alleviate the issue of cells that charge and discharge at different rates but it would be easy enough to match them as well. I'll probably buy 10 individual cells, charge them all up, discharge using a flashlight for x number of hours and read voltage. Which ever 3 cells most closely match I'll put in a pack.

ThunderCactus · October 10th, 2014, 18:57

That would make a 7.4v ~2200-3000mah lithium battery that slid perfectly into a magpul STR stock, right?
I think you're on to something.

slntdth93 · October 10th, 2014, 19:59

Check the max current output of those Panasonics although, don't want to overdraw from them.
There's some high discharge ones that go up to 25A, capacity of those is 2500mAh. I think average LiPo does 30A burst

ThunderCactus · October 10th, 2014, 22:41

25A is fine for AEG's
Unless you have motor issues or your running some crazy high ROF builds, you should only be drawing 12-16A

waylander · October 11th, 2014, 00:03

Those Li-Ion cells should be 3.6v making a 3S 10.8v. I think that's perfect. For discharge, that is a concern, I'll have to see how hot the cells get.

I'd actually perfer using A123 cells but they are too damn big! I think they might make smaller ones than those I'm used to in RC but I'll have to do some hunting. They would actually be perfect

lurkingknight · October 11th, 2014, 01:04

18650 is just a size format isn't it? you can get them in life or lipo can't you?

waylander · October 11th, 2014, 01:47

I've never seen a lipo in cylindrical format before but maybe...

life is available in 18650, a123 makes cells that size but they are low capacity, 1100mah although they do have higher C ratings. I'm hoping to double the capacity of current 1600 nimh packs so they last a whole day. i have a few 2000mah lipos but they don't fit all my guns...

I'd also like something between the 9.6v nimh and 11.1v lipo so I get faster rates of fire in auto compared to 9.6v but not as high as 11.1v.

ThunderCactus · October 11th, 2014, 02:03

Why not just get a mosfet that limits the rate of fire?
My 249 fires around 1400rpm at full throttle, but I typically scale it back to 1200rpm

waylander · October 11th, 2014, 20:45

Actually I do have programmable mosfets. The biggest thing for me is the capacity. I want 2000mah + and the only way to get that right now is with a full stock which I don't like.

I'm a tinkerer at heart, I did RC for years so that's just what I do

Used to make my own A123 and sub-c packs for RC so was looking for viable options for airsoft that would work in the limited space we have.

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October 10th, 2014, 11:32	#1
waylander Trader rating Join Date: Aug 2014 Location: Edmonton, Alberta	Battery packs from 18650 li-ion cells Hello All, Tried to do a search here and they all came back related to flashlights.... Has anyone made or used a 3S (9.9v) 18650 pack in an AEG? Just wondering if they would fit in a stock designed for nunchuk style batteries? I checked the dimensions and they are 18mm dia. vs 17mm dia which a standard 2/3A nimh cell is. I used to make my own sub-c packs for RC so wanted to try this but don't want to spend the money and time if I know it won't work. Advantage? 3200mah (looking at good panasonic ones not the cheap china clone ones) cells vs 1600mah. Thanks!

October 10th, 2014, 15:21	#2
Styrak Trader rating Join Date: Jan 2007 Location: Saskatoon, SK	Single 18650's usually have voltage cutoff circuitry for charging and discharge.....not sure putting them in series would work. __________________ Airsoft Sales and Repair/Upgrade Services

October 10th, 2014, 16:33	#3
waylander Trader rating Join Date: Aug 2014 Location: Edmonton, Alberta	Hmmm... I'll have to see whether it's possible. I have some cheap chinese made ones that I can try on without too much loss. As they're li-ion I think I might be able to charge them through a balance connector like lipos have. Then each cell is effectively being charged individually. I have a Hyperion charger that can do that and spare balance connectors around. I'll give it a try and see what happens. Edit: did a bit of research and it looks like it's fine to put them in series, you just have to be aware of total voltage vs individual cell voltage. A balance connector as used in lipo batteries should help with the charge part of this issue. I typically run voltage alarms set for well above the minimum so not too worried on the discharge side either. Using good quality cells with good QC should alleviate the issue of cells that charge and discharge at different rates but it would be easy enough to match them as well. I'll probably buy 10 individual cells, charge them all up, discharge using a flashlight for x number of hours and read voltage. Which ever 3 cells most closely match I'll put in a pack. Last edited by waylander; October 10th, 2014 at 16:43..

October 10th, 2014, 18:57	#4
ThunderCactus Not Eye Safe, Pretty Boy Maximus on the field take his picture! Trader rating Join Date: Feb 2007	That would make a 7.4v ~2200-3000mah lithium battery that slid perfectly into a magpul STR stock, right? I think you're on to something.

October 10th, 2014, 19:59	#5
slntdth93 Trader rating Join Date: Jul 2010	Check the max current output of those Panasonics although, don't want to overdraw from them. There's some high discharge ones that go up to 25A, capacity of those is 2500mAh. I think average LiPo does 30A burst Last edited by slntdth93; October 10th, 2014 at 20:02..

October 10th, 2014, 22:41	#6
ThunderCactus Not Eye Safe, Pretty Boy Maximus on the field take his picture! Trader rating Join Date: Feb 2007	25A is fine for AEG's Unless you have motor issues or your running some crazy high ROF builds, you should only be drawing 12-16A

October 11th, 2014, 00:03	#7
waylander Trader rating Join Date: Aug 2014 Location: Edmonton, Alberta	Those Li-Ion cells should be 3.6v making a 3S 10.8v. I think that's perfect. For discharge, that is a concern, I'll have to see how hot the cells get. I'd actually perfer using A123 cells but they are too damn big! I think they might make smaller ones than those I'm used to in RC but I'll have to do some hunting. They would actually be perfect

October 11th, 2014, 01:04	#8
lurkingknight "bb bukakke" KING! Trader rating Join Date: Jul 2011 Location: Ottawa	18650 is just a size format isn't it? you can get them in life or lipo can't you? __________________ I futz with V2s, V3s and V6s. I could be wrong... but probably, most likely not, as far as I know.

October 11th, 2014, 01:47	#9
waylander Trader rating Join Date: Aug 2014 Location: Edmonton, Alberta	I've never seen a lipo in cylindrical format before but maybe... life is available in 18650, a123 makes cells that size but they are low capacity, 1100mah although they do have higher C ratings. I'm hoping to double the capacity of current 1600 nimh packs so they last a whole day. i have a few 2000mah lipos but they don't fit all my guns... I'd also like something between the 9.6v nimh and 11.1v lipo so I get faster rates of fire in auto compared to 9.6v but not as high as 11.1v.

October 11th, 2014, 02:03	#10
ThunderCactus Not Eye Safe, Pretty Boy Maximus on the field take his picture! Trader rating Join Date: Feb 2007	Why not just get a mosfet that limits the rate of fire? My 249 fires around 1400rpm at full throttle, but I typically scale it back to 1200rpm

October 11th, 2014, 20:45	#11
waylander Trader rating Join Date: Aug 2014 Location: Edmonton, Alberta	Actually I do have programmable mosfets. The biggest thing for me is the capacity. I want 2000mah + and the only way to get that right now is with a full stock which I don't like. I'm a tinkerer at heart, I did RC for years so that's just what I do Used to make my own A123 and sub-c packs for RC so was looking for viable options for airsoft that would work in the limited space we have.

Battery packs from 18650 li-ion cells

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