LiPo's and Chargers Demystified - At least for dummies like me....

[m102404]

First off...I'm a fair hand at working on different types of AEGs, GBBs and general mechanical bits. I'm pretty handy and can figure out most hands-on, mechanical type things. Good understanding of chemistry. My level of basic electronics is just above remedial.... I tend to learn from my mistakes...and I've done a whole lot of learning over the years .

I've built plenty of rifles...some were plain old field guns...others were tricked out high speed rigs just for kicks. High power to low power...etc... Mosfets or not.

But...batteries and chargers have always been a black hole to me...charge rates, discharge rates, C ratings, balancing, etc....

I have more of a "layman's" understanding of what works and what doesn't. Sums up to the following:
NiCad = good, less affected by cold
NiMh = good, no memory worries
Big Cells (i.e. Sub-C) = all day goodness, less affected by cold vs. small cells (i.e. 2/3A)
8.4v = normal, plenty good for stock -> M100 applications, small packs at this voltage really suffer at M120+
9.6v = good, plenty good for anything up to M120...which is typically more than what's needed for around here.

That brings me to LiPo's...mysterious and potentially dangerous. Bursting into flames, eating up gearsets, etc...mechbox destroyers. I've read just about everything I could find on this forum and a couple of others...but as I said above, I learn by doing and mistakes will happen.

So, without embarassing myself with technical errors, I'll describe in laymans terms what I've done with LiPo's in the last 24 hours....

I've been talking with Jugglez (Airsoftparts.ca) for the past couple of months and bugging him about bringing in a bunch of LiPo stuff. I did this for a couple of reasons:
1. I like fiddling with stuff
2. Jugglez is a top notch guy
3. Madbull and King Arms were/did come out with their LiPo products
4. Jugglez is always interested in seeing new stuff...which I then buy, which makes him smile
5. I hate ordering stuff from overseas/international...and it's pain free going through him.

So finally Jugglez brought in a bunch of King Arms and Intellec LiPos. Chargers were delayed. The King Arms batteries came in all types and sizes...from tiny ANPEQ packs, to sticks, to stock tube packs. The Intellect stick is pretty beefy...larger capacity with a longer length and slightly bigger "diameter" (i.e. the 3 slabs laid on top of each other and packaged).

He was bringing in "simple" chargers...with a low price point to reflect that...and a "do-everything" charger.

The day before the TAC09 convention, he got the "do-everything" charger...and I picked it up that night. It's named the "X-charger" and charges NiCad, NiMh, LiPo, LiFe and some other type I can't remember. It'll charge up to 5A and 6s LiPos. There's a whole wack of balancing ports (the balancer is built in) on the side. Some kind of USB thermal monitor as well (but I don't think you get the probe with it...haven't played around with that yet). It'll remember up to 5 or 6 specific batteries....I don't know, I just want to charge my stuff up and go shoot.

While at the TAC09 convention...I was talking about LiPos with Scooby and he was commenting on how the LiPos that Jugglez had were 20C, which was overkill (so Jugglez...you can punch Scooby for your lost sale that day...). Huang had some 11.1v 1100mAh 15C little stock tube batteries (about the same size as the King Arms one)....so I picked up 2 of these for my CQB M4.

That night I figured out how to charge the LiPo with the new charger...basically plug in the "normal" battery connector to the charging plugs of the charger and connect the little white balancer plug into the side of the charger...set a couple of numbers for the LiPo setting of the charger...confirm that it detects the right number of cells...and then wait while it charges. I did do it on the concrete floor of my workshop and checked it every couple of minutes...I envisioned this expanding pack bursting into flames and incinerating my workshop. Didn't happen...pack barely got warm to the touch. I could switch screens and see the voltage of the individual cells...neat.

So...what do LiPo batteries do for the layman?
1. Fit in pockets, pouches, etc...taking up very little space...adding very little weight.
2. Fit my stock tube so I can run my CQB M4 with a Magpul CRT stock...sweet. The battery actually fits exactly...but the plug and the wiring sticks out past the end of the stock tube about an inch...no big deal for me since a fully collapsed stock is too short for me anyways. NOTE: King Arms is coming out with a stock tube that has the bearing ring inside the stock tube set "shorter"...so their LiPo and wiring will fit completely, thus allowing a fully collapsed stock.
3. Fits my AKS74U (that can take up to a 12v NiMh mini stick)...with hoards of room to spare...I wasn't worried about the length...I was worried about the "diameter" of the pack. No problems. Previously I was using a 9.6v 1400mAh Intellect stick battery. This little beast currently shoots 396-398fps w/ 0.20g bbs (that's stock out of the box). It's awaiting the next AEG workshop where the participants are going to mess with the mechbox.
4. The 11.1v 1100mAh 15C "Hot Power" stock tube pack that I have...acts almost identical to a 9.6v 1400mAh 2/3A cell brand new Intellect stick pack. ROF is about 10rpm faster (mid 900's). If your setup can take the speeds of a "normal" 9.6v mini pack...you shouldn't have any issues.
5. That LiPo is a little quicker than a 9.6v 2300mAh large (subC) relatively new Intellect pack (it was a rectangle pack that I modded for a Crane stock for the CQB M4). Trigger response with the LiPo is pretty much instantaneous. Lightly modified KWQ M4 mechbox....stock KWA motor. It's a noticeable hair quicker ROF than with the large 9.6v pack. This rifle shoots 344fps with 0.20g bbs. I haven't bothered to test ROF...it's too fast to be field usable, you're mid cap will be empty before you know it...semi-auto only with this one. Again...if your mechbox can take it a big 9.6v battery...it should be ok with this LiPo.

So...no ruined mechboxes...no incinerated workshop. I've only put 400-500 shots (semi and full auto) through each rifle so far (come on...it was only last night that I did this...). Nothing insane like Alfred's 16v rigs...but plenty fast enough for me.

I'll try a 20C lipo next...one with a larger mAh rating. I haven't gamed them yet...so I have no idea how long these batteries will last in skirmishes/mil-sims etc... I'm a bit nervous about over-discharging them with use...but I'll just be a bit careful for now. But...if they prove out at Soldier Gear, Op Broadsword, etc...they'll be keepers.

BTW...If you see my rifle burst into flames and you get caught in the backdraft...stop, drop and roll.

Tys

[jesster202]

Im running 20c lipo, whats the diffrence i find it spits out hard fast and no delay at all? what is the diffrence between the 12c and 20c? also great short great write up, you should add the basic's of charging and do's and dont's and i don't think u will blow it up only if you leave it alone while charging lol.

[KND]

11.1 v, 1200 mah , 15 C should give you about 1500 rounds then you must change a new one and stop using the lipo when you notice your roof get slow because discharge the lipo under 3 v will be cause to fire.

You should get a lipo lower voltage detector to test the voltage of Lipo because Lipo battery never discharge lower than 3 v.

[wildcard]

Knowing my luck with AEG, I'll stick to the tried and true "normal" Battery for now.
The last thing I need is bugging Jugglez for three extra V3 box for my three pigs before the March 21st game and BW3.

[LUTNIT]

King Arms makes a cut off circuit for 11.1V LiPo's, its a pink heat wrapped thing, really small.

[Roughneck]

And on that note, I'll be getting a lipo for my M249

[ILLusion]

The "C" rating is generally the maximum current load that the pack can safely dump at any one given time.

If you draw a current higher than that and the battery blows up beside your face, the packaging can only say "I told you so."

If your gun is properly upgraded with internals balanced properly (between the spring, gearset torque level, motor torque level and battery voltage), then your gun shouldn't ever draw more than 10-15 Amps for <400fps setups.

I can only think of 550fps setups ever requiring a 20C setup (think PTW M150 spring.)

Besides that, I'm not aware of whether a 20C pack will shoot out a higher ROF than a 15C, but the higher current ceiling definitely does imply that it is capable of unleashing a faster dump (due to less internal resistance.)

I haven't tried the two to find quantitative proof for myself, but based on that assumption, you can equate it to an 8.4v 600mAh mini Ni-Cad pack compared to an 8.4v 2400mAh sub-C Ni-Cad pack. The large pack will DEFINITELY dump a higher current load and increase ROF dramatically, which is why it is not recommend for bone stock 275fps guns, whereas an 8.4v 600mAh mini pack is perfectly fine.

[Watase]

Originally Posted by KND

because discharge the lipo under 3 v will be cause to fire.

From what I've read on LiPo's, discharging a battery below 3v won't cause a fire, it will just basically kill the battery.

Now, if you try to charge that battery, will it cause a fire? Maybe, but you dont have to worry about your gun blowing up in your face because of over discharge..

[ILLusion]

Originally Posted by KND

stop using the lipo when you notice your roof get slow because discharge the lipo under 3 v will be cause to fire.

You should get a lipo lower voltage detector to test the voltage of Lipo because Lipo battery never discharge lower than 3 v.

That is an incorrect/incomplete statement.

The level you need to stop at is dependent on the size of your pack.

You can not drop below a NOMINAL voltage of 3.0v PER CELL of your PACK, otherwise, you will encounter permanent damage to your pack, if not a fire.

That means, if you are running a 7.4v PACK, then you will have two CELLS in your pack, which means you can not drop below 6.0v.

If you are running an 11.1v PACK, then you will have three CELLS in your pack, which means you can not drop below a nominal voltage of 9.0v.

There are some Li-Po cells out there that do NOT carry a nominal voltage of 3.7 volts, but are 3.6volts instead, which would effectively create a 10.8v pack from three cells. These types of packs will also have slightly lower minimum discharge limits, AS WELL AS maximum charge limits! If you try to charge/peak a 3.6v cell as if it were a 3.7v cell, YOU WILL BLOW THE PACK UP AND POSSIBLY BURN YOUR HOUSE DOWN.

You need to know all of these differences when dealing with Li-Po.

[Cheesevillage]

Originally Posted by ILLusion

...which is why it is not recommend for bone stock 275fps guns, whereas an 8.4v 600mAh mini pack is perfectly fine.

I'd just like to pipe in and say I've run a 3300mah large in my v2 TM box since day one. We had it apart last week and there was minimal/expected wear on the internals. This after at least 40k BBs.

I would go so far as to RECOMMEND a "high power" battery for stock setups.
Guns don't feel like guns if you have to wait for them to wind up.
(And going to a 600mah mini you do unless the battery is freshly charged - my large goes months without charging)

[ILLusion]

Originally Posted by Cheesevillage

I'd just like to pipe in and say I've run a 3300mah large in my v2 TM box since day one. We had it apart last week and there was minimal/expected wear on the internals. This after at least 40k BBs.

I would go so far as to RECOMMEND a "high power" battery for stock setups.
Guns don't feel like guns if you have to wait for them to wind up.
(And going to a 600mah mini you do unless the battery is freshly charged - my large goes months without charging)

I'm not talking about Ni-MH. I'm referring to Ni-Cad (sorry, I should have specified that in my statement. It has been corrected.) There is a very good reason why Tokyo Marui only suggests 1300mAh sub-C Ni-Cad packs for stock guns. If you run a stock Tokyo Marui with an 8.4v 2400mAh Ni-Cad pack in full auto for any length of time, you will kill that piston soon enough. I've seen them go in less than 2 months (from a moderate user who loved full auto fire.)

Also note, that stripping in this situation will occur only with full auto fire. You do not get these problems if all you do is semi-auto fire, so you can not equate it that way. If all you do is semi-auto fire, heck, go nuts and throw in a 36 volt 10,000mAh Ni-Cad hot pack for ultra-instantaneous wind up and fire.

Ni-MH does not suffer the same type of internal resistances that Ni-Cad do, and generally have more consistent current dump capabilities compared to equivalent Ni-Cad cell sizes. In general, Ni-MH packs will have a lower ROF compared to Ni-Cad, as they are not designed to provide huge capacity loads in a moments notice, like Ni-Cads. Li-Pos are even more so.

[Cheesevillage]

I didn't realize the difference was so huge! Thanks for the insight.

[m102404]

Thank you everyone...for putting your comments and helpful advice. I had avoided LiPos until now because I didn't want to spend more money on a charger (but it's totally worth it) and the "unknowns" of LiPos.

I'll take some multimeter readings if I get a chance...probably in the next week or so.

Originally Posted by LUTNIT

King Arms makes a cut off circuit for 11.1V LiPo's, its a pink heat wrapped thing, really small.

Ahem....Hello Jugglez...are you listening?

Now...onto a MOSFET for it...heehee.

[Scarecrow]

Isn't there a safety circuit you can install into your AEG to stop the lipo battery at a safe level?

[KND]

Originally Posted by Scarecrow

Isn't there a safety circuit you can install into your AEG to stop the lipo battery at a safe level?

I don't think they do have it right now but you can put a buzzer which has the alarm when the Lipo battery go under 3 v. My friend make one for me and it's really save me last time when my 3 cells lipo and two of them getting under 3 v and it's getting hot also.