LiPo Ready - Is My Rifle LiPo Ready? How can I tell?

[ThunderCactus]

If you're getting a MOSFET you need to redo all your wiring anyway. And if your getting an SW-COMP like the triggermaster, you won't need a seperate PCB.

Mah in LiPo works the same as it does in NiMH. It's the measure of your battery's 'gas tank'

[lurkingknight]

is the ratio of 1mah:1BB more or less still applicable to lipo or is it skewed more in another direction? figure if lipos cost less, it wouldn't matter as much to carry several batteries vs 1 with more juice, except for changing them out, but the m14 is a pretty quick change, as is a p90.

[ThunderCactus]

Actually, they're generally MORE efficient than NiMH, especially at 7.4v.
You're draining a battery with more Mah less quickly, but it's providing more amperage so you maintain your RoF.
The reason LiPo's are significantly less expensive is due to their manufacturing process, they're just WAY easier to make than NiMH.

If you're going to do a before and after, you'll have to rewire the gun and install your MOSFET first. Then compare NiMH to LiPo back to back.
To give you an idea, on my LMG I was getting about 700mah/box with 9.6v 4200mah NiMH, now around 400mah/box with 11.1v 4900mah LiPo, at the same RoF (triggermasters allow you to slow down your motor speed)

[m102404]

Re. practical what works in the field...

1. LiPo's are typically more compact and lighter compared to the "same" NiMH/NiCd battery...so they're easier to take a spare with you for even the longest games

2. They're typically more efficient at providing power. It's HIGHLY dependant on your setup/power/wiring...but in general you will see many more shots out of a LiPo vs. a NiMH/NiCd of the same "size". Size refering to the physical dimensions since a "large" LiPo tends to have generous MAh ratings and will go for a long, long, long time.

In short...I suppose you can say "this MAh rating will = this many shots"...but you need to take your personal setup into consideration. And in general...you'll get more shots out of a LiPo than another battery in your gun...not because of the MAh rating itself...but rather because the LiPo that you happen to tuck into the gun will probably have a larger "reserve" of power than a normal battery. Hope that makes sense.

[lurkingknight]

I not really concerned with a before/after, just that it works safely without blowing up internals or up in a fireball. Only reason I'm looking into it is because my new p90 would benefit by converting to lipo since battery space is limited. My g&g needs a mosfet to prevent trigger contacts from burning up. Converting that to full lipo friendly just makes it easier for me to field both on the same day and not have to carry around multiple types of batteries.

[m102404]

Gotcha. With any LiPo you want to watch for a couple of things:
1. Heat. The batt will get warm...it should not get HOT. If it's HOT HOT and puffing...that's no good.

2. Sizing. Matching a batt to the power requirements of your setup will help to prevent the battery from over heating.

3. Charging/Discharging. When the shots slow down...STOP. Switch out the batt and measure it if you can. When charging...ALWAYS balance charge and keep an eye on it to see that each cell is charging evenly. If they're a little off from each other as they charge...that's ok. More than that and I'd call the pack suspect.

4. Damage. If your pack/wrapping/wires/connectors/etc...are damaged....DO NOT USE. The integrity of the pack is essential. DO NOT compromise the pack by squeezing/jamming/stuffing/etc...into places that are two tight for it.

All that is VERY, VERY important when using them....especially so when you're getting a feel for how they work/last in your setup.

[lurkingknight]

there shouldn't be too much of an issue with space, with the g&g, there might actually be too much space cause even my 8 cell 4000 mah nimh can shift around inside the stock. What I need to determine at this point is the power draw for the 2 different guns to find the right battery. Since I'm a firm believer in not halfassing things that can be dangerous, I'll have a good charger that can balance charge.

The rest of the stuff like the triggermaster should give good warning that the battery is dry enough for a charge.

What's the usual method of determining how much power a motor draws? Once I find out the draw I should be able to pick a battery that puts out enough amps for the strongest motor of the 2 and I should be fine, right?

[ThunderCactus]

Unless you've got a motor problem, most upgraded guns don't draw more than 15A.
Anyway my 7.4v 1600mah LiPos are 20C (handles up to 32A continuous), and they're the size of a NiMH 6 cell mini battery.
Only place where you might have trouble is your motor. I've installed many triggermasters, and they just WILL NOT work with un-insulated systema magnum motors. Any motor that has a bent armature, short, or draws too much amperage, will constantly overheat your triggermaster, either on long bursts or excessive semi-auto.
That being said, if you have a GOOD motor, you'll have nothing but good times lol

[Noob7_0]

I understand that a 11.1v lipo should only be fired on semi but what about a 7.4v lipo? Can a 7.4v be fired on auto in a controlled burst?

[ThunderCactus]

You can use an 11.1v LiPo in full auto, just as long as your internals can handle it.
For example, my G&P M249 is capable of long sustained bursts at 11.1v no problem, because I've set up the internals to handle it.

A 7.4v LiPo, depending on your gear ratio, will give you almost the same RoF as a 9.6v NiMH mini battery.
In addition, because the LiPo offers higher amperage, you're able to get more torque from your motor, and therefore run a higher ratio gearset, increasing your RoF.

So on a stock AEG, install a simple MOSFET switch, an appropriate fuse, and possibly a voltage monitor, and you can abuse your trigger same as you would with a NiMH battery!

[Noob7_0]

I purchased a pair of 7.4v sticks for my buffer tube from an online retailer. When I received them and plugged them in my charger declared them to be low voltage and wouldn't charge them. I spoke to the retailer and her recommended charging them at 0.1A on NiMH. I very carefully did this and they now have sufficient voltage to charge correctly. However they don't seem to hold a charge. I charged both to 8.4v and checked them a few hours later and they dropped to 8.15v.

Is this normal? I am planning to exchange them regardless (unless I am convinced otherwise) but I would like to know what voltage drop I should expect as I though Lipo's held there charge for a long duration.

[ThunderCactus]

They should drop about 5-10% per month
I HIGHLY recommend safely disposing of those packs and getting new ones.
If your LiPo was under 3.0v/cell when you first got it, you never should have put it on a charger to begin with, you very well could have ignited the packs.

You DO have a proper LiPo charger though, correct?

[haven.hatty]

If you're getting a MOSFET you need to redo all your wiring anyway. And if your getting an SW-COMP like the triggermaster, you won't need a seperate PCB.

[Daiviet]

Always been told to not to let the cells drop below 3.0v, due to damaging the pack. Recently I came across an 11.1v that was over discharged and showed as 2.0, 2.0 and 2.9. It was sitting in my ammo can for a while and with my spare time today decided to see if it would recharge. Took everything to the garage, stood by with a fire extinguisher, and it seems like the battery is fine. After a while of slow charging (0.2A) it's gotten back up to 3.7v ish per cell no problem and after a few hours is still holding up fine.

So my question is, what real damage does discharging past 3.0v per cell really do? I've always read and been told that it damages the battery, but everything *seems* fine...

[ThunderCactus]

An over discharged battery CAN safely be charged, but the damage caused can limit the max charge the pack can take (so charging over it's diminished limit is like over-charging) and cause the voltage to drop sharply under load.

Like all batteries, the state of yours is prone to circumstance. It could very well be fine, or it could catch fire next time you charge it at 1C to full capacity

Honestly when it comes to LiPo's, you can get a high quality pack for $9-$40, so why bother taking the risk? lol