Lipo batteries - safe or death traps?

drifterex

Hey there.

I'm considering getting a Magpul PRS stock for my SR25 (if I get it sorted, but thats another story) and believe you can fit a slim lipo battery in the stock tube. But I heard nothing but horror stories about lipos that if you look directly at them, you anger them and they burst into flames
Seriously though, I have heard about house fires, and have seen videos on youtube as to how volatile they can be? Does anyone on here have any first hand experience with them, and i so could ye offer any advice, as to how to handle them, where to store them, etc.

Cheers,
Mark.

Vents

It's true, Lipo's used to be very unstable and didn't like bumps.:( But, consider this. You have lipo's in your mobile phone and laptop without them bursting flames. This is due to the hard shells that are casing the cells and the charge discharge process of he unit. you can buy lipo's that will fit your AEG that have hard shells if that is a concern to you. As fo the charge,discharge and storage charge of lipos. Thas just somthing you would have to manage yourelf with a balance lipo charger.

I would also recomend not jumping straight into the 11.1v club, as a good 7.4v with a healthy Mah and C rating might run your AEG closer to it's optimum.

drifterex

Vents wrote: »

You have lipo's in your mobile phone and laptop without them bursting flames.

I didn't know that... ok well that puts my mind at ease some bit, so as long as you use decent charger/discharger you're laughin. So now all I have to do is sort my gun out. And buy a PRS stock. And find a magical money tree.

Mark.

Puding

Do I have common sence? if yes carry on
Attention span greater than that of a kitten? If yes carry on
Do I look after my gear and not abuse it? If yes carry on

if all yes you can use lipos safely

there is a lot of rumor and mis information about lipos best bet is to read the great thread pm armies about lipos, unless your going for simple block lipos you will not be able to get hard cases any of the strange shapes like for stock tubes do not come with hard covers, but you have to stab or break the internal sections to creat the run away chemical reactions, also do not buy cheap lipos as quality of the build can be bad also make shore you buy a good quality smart charge that will do lipos do not use cheap wall chargers

drifterex

The ones I was looking at are G&P, as the dimensions are just right. Now I know G&P rifles are good, but what about the batteries?

MerryDespot

Puding wrote: »

Do I have common sence? if yes carry on
Attention span greater than that of a kitten? If yes carry on
Do I look after my gear and not abuse it? If yes carry on

if all yes you can use lipos safely

there is a lot of rumor and mis information about lipos best bet is to read the great thread pm armies about lipos, unless your going for simple block lipos you will not be able to get hard cases any of the strange shapes like for stock tubes do not come with hard covers, but you have to stab or break the internal sections to creat the run away chemical reactions, also do not buy cheap lipos as quality of the build can be bad also make shore you buy a good quality smart charge that will do lipos do not use cheap wall chargers

Puding was good enough to answer my worry wart thread a while back -
http://www.boards.ie/vbulletin/showthread.php?t=2055855754

here's the site he linked me to, which sorted me out completely.
Thanks again Puding - and hope this helps OP as well.
http://www.arniesairsoft.co.uk/forum...4&st=0&start=0

drifterex

Deadly, thanks bud. That article does help with a few more questions. It seems a 7.4 lipo can have equivalnent output to a 8.4 or even 9.6 nimh, which I didn't know. Another reason not to jump on the 11.1 bandwagon straight away. Shouldn't need it for a semi only rifle anyway.

Mark.

Puding

You can work it out a lot of it comes down to the c tarring , a lot of the cheaper lipos have a low c rate of 12 or so , the lowest I would go for is a 20c lipo

for me a rule of thumb is a 7.4v 2000mha 20c is about the same or better that a 9.6v 3500mja large battery ( depending on cell quality)

it's interesting wi

drifterex

I see, I see. 20c minimum helps too. The stock tube in the Magpul PRS is tight, approx 25mmx260mm. Length is fine but width/diameter will be pretty snug, and any of the 7.4's I've been looking at, that will fit, are all 1200mah, 15c maximum, so perhaps a 11.1 might suit me better (mah are slightly higher but cell count seems to be 20 on most), or as it's a semi only rifle would that matter? What brands would recommend? The 2 brands I was lookin at were G&P and Firefox..any good or a waste of money?

Mark.

extremetaz

For the record guys, what we tend to refer to here as Li-Po is the second gen Lithium Ion batteries - these do NOT have a hard shell as standard, they have a foil shell.

The simple reason for this is that in the event of a failure, the foil shell allows the cell to expand and vent rather than the older hard shell units which used to burst violently.

Hence, whilst I've no doubt that there are hard shell versions of the latest gen batteries available - I'd be inclined to stick with the foil packed ones.



Furthermore, on the note of durability - I recently had a 7.4V 1600mAh unit strapped to my SYMA 9086 helicopter (stock unit is a 7.4V 800mAh) when it lost radio contact at about 20meters altitude and came down in quite a hurry.

Most of the impact was taken by the canopy and battery, such that one corner of the battery was quite notably squished in. The battery was in a high state of charge at this point but when I recovered it, it was not in any way warm so I gingerly pressed it back to shape.

I then discharged it and recharged it in an isolated environment (sealed metal container) just in case - but it came back perfect and has been working as well as ever since then.

SO - these things ain't anywhere near as fragile as they're made out to be (as also proven by the Austrian airsoft crowd video - there's a link flying around somewhere).


It's worthwhile investing in a good, digital balance charger no less - I got mine on ebay for a pittance and it's a fantastic piece of kit for charging anything.

extremetaz

drifterex wrote: »

(mah are slightly higher but cell count seems to be 20 on most)

The 20C figure isn't a cell count - the "C" is a moniker for the charge capacity of the battery, the value preceeding it, is a scalar multiplier denoting either the maximum safe peak discharge rate, or the maximum safe constant discharge rate (to the best of my knowledge, there's no standardisation yet so which it is depends on the manufacturer - in any case, given the burst fire nature of airsoft, this isn't much of an issue. It comes into play far more where RC cars and planes are concerned).

For example - a 7.4V 1600mAh 20C battery can safely supply current at 20x1.6A == 32Amps. Whether this rating applies to peak or continuous discharge would, as stated, depend on the manufacturer and would have to be researched.


As regards comparison to 8.4V or 9.6V units - the above posts are correct in so far as that it all comes down to the discharge rate.

The larger 20C+ packs at 7.4V will easily match a 9.6V, the cheaper 10C ones will be closer to an 8.4V.



Beyond that, personally - if your rifle is semi-only, I'd consider that an argument FOR and 11.1V rather than against it. The 11.1V will considerably decrease spin-up time, giving you a far better trigger response, and if you're only using it in semi then you don't have the same level of concern regarding stress on the gearbox that you would have otherwise (Some of the gearbox guru's on here may disagree with me on this point - if so, then take their word over mine as my gearbox knowledge is competent but not expert).

drifterex

Ah, feel a bit of a dope now, thought the c was for cell count. Yeah, thats kinda what I was thinkin as regards it being a semi only rifle, so prob will be an 11.1 I'll get. Just a matter of finding a charger now. Whats a good brand of charger to get?

extremetaz

I use this one - can't speak highly enough of it either. Fantastic piece of kit.

Clicky

Puding

Had never used hard shells myself but never thought about the safety and allowing it to expand

11,1 in a semi only is nice for fast trigger responce but I would say a MOSFET with active breaking is a must

would recommend the IMAX b6 as well

extremetaz

Puding wrote: »

never thought about the safety and allowing it to expand

Yup - it's the sole reason for the foil casing.

Puding wrote: »

I would say a MOSFET with active breaking is a must

That's a very good point!

drifterex

Thanks lads. I have one of those chargers on it's way. €31 and free postage. Result. And I'm planning on starting RC ducted fan jetting soon, so at least I'll have a charger that will cover me for that too. The mosfet would be handy, but I dunno where I'll fit it in a Magpul PRS is the only thing. Hope I'm not gettin on over my head here...I need a cheap hobby

Mark.

Puding

Hope I'm not gettin on over my head here...I need a cheap hobby

wrong hobby then step away :P

drifterex

Yeah, well it's the cheapest of all of them. Retsoring an old beetle - or moneypit as I prefer to call it, and then there's my skyline which has had more money spent on it then I'd car to admit or remember. Ah well, could be worse.

stephenshields2

Oops wrong thread, sorry!!

MerryDespot

Puding wrote: »

wrong hobby then step away :P

What he said.
As I've said on these pages a few times, a serious smack habit would be cheaper and less addictive!

drifterex

Yeah, exactly :D:D

Ah well, I'll persevere anyway. I can't see myself kicking this habit anytime soon. Although, I prob am more of a collector, than a skirmisher, I love it all the same.

Drachnien

one thing with using lipos is that an AEG lacks a Low voltage cutoff that you find in RC vehicles. what this does is it stops the power flowing if the battery voltage gets too low (over deischargind a lipo can damage it and stop it taking a charge again). to be honest it's not such a huge issue as most of the time the battery won't have enough power to pull back the spring before it gets to an over discharged state but if you wanna make sure pick up somthing like these LINK very simple .. green light means the cell's ok red means it's not .. total voltage output gets too low the buzzer goes off. it's handy for noticing a dodgy cell too (as if one is always hitting a low voltage before the others there out of balance)

As i said - not necessary but usefull

drifterex

Great, thanks. Must invest in one of them too.