Battery Question

kirk1827

First off I'd like to say hello. This is my first post.

I just recently got myself a AEG so I could got play with my friends. It's a EVOLUTION M4A1 SOPMOD FULL METAL (COMBAT SERIES) and it came with a 9,6v. 1300mAh battery (Crane style) with it's charger (9v 500mah).
http://eliteessex.co.uk/product.php?xProd=2545&xSec=1

So I get my AEG home and the first thing I due is charge the battery. I gave it a 3 1/2 hour charge and went to a meet and discharged it completely shooting. I got home and just out of curiosity, I used a multimeter to check what was left in my battery pack. To my suprise it say'd 10,45v. <---:eek:
I check the multimeter with a AA battery from my TV remote controller and the mutlimeter is good.

I then decided, hell I'll just charge it anyways. Charged it about 4 hours and then checked the voltage again. It says 11,05v.

The battery pack consists of eight (8) 1,2v 1300mah which mathwise comes out to the 9,6v it suposedly is.

I ask if it's not posible the chinese made batteries come in 1,5v and not 1,2v?

That would explain the volts I get. But since I'm new I'll ask.

Hope someone can help me.

Thanks

PS: If this is a question already answered in the forum, plz pass me the link.

Again thanks and hopefully I'm just crazy and my battery is all good.

Inari

If I remember correctly, a fully charged battery should read about 1.2x its declared voltage. NakedDex has posted a lot on this kind of subject, and has many informative posts - they're scattered across the forum though.

This one should answer your questions

NakedDex wrote: »

^^^ what he said.

The discharge curve for a dry-cell pack, like a NiCd or NiMH is a fairly consistent slow drop to "dead" voltage (each cell being nominally 1.2V, charged at 1.5V and discharged or "dead" at .8V).
The curve for a LiPo, and indeed exactly why they're so popular in electronics, R/C and airsoft, is a pretty straight line for it's life and a sudden and sharp drop toward zero.
Zero voltage in cells is never something that happens naturally and, depending upon the speed at which it heads toward zero, can result in a battery with reduced capacity or a puff of dark smoke where your pack used to be. If you keep the trigger pulled while the motor is clearly struggling under low power, you're going to mince the pack. It's unlikely to fail catastrophically, but you'll certainly notice it's performance will be gone to hell. You'll also notice a huge heat build up on the pack if you keep doing this, the heat being an indicator/side effect of the pack struggling with the current demand.

Given the above, and the discharge characteristics, once you notice a difference in rate of fire (and you will), change the pack. Ideally, you'd use a MOSFET with a voltage regulator on board. Cheap and simple to install, and really something I'd consider a necessity for running LiPo. It also improves trigger response, motor speed (fractionally) and reduces trigger contact wear (dramatically), and the more complicated models even offer you a three-round burst option. What's not to love?


Another thing I'd recommend is getting a multimeter. Seriously, every airsofter should own one. You can get a basic one in Maplin or Aldi/Lidl for a tenner, and it's exactly what you need for things like this.

Hope that helps

kirk1827

Thanks for the reply, but I don't understand.

"each cell being nominally 1.2V, charged at 1.5V and discharged or "dead" at .8V"

1.5v is = Charged
0.8v = Dead/dicharged
So 1.2v is = ????

Forgot to say my battery is NiMH.

So what that guy is saying, is that my battery says 1.2v (written on the surface) but charged it's 1.5v. Then my battery would be 12v?

Sorry for the newbie question.

I'm just trying to find out how this thing works so I can safely dicharge my battery after each airsoft game and then recharge.

I was looking for my batteries discharged voltage so I could make a good safe discharger since I know electronics (not batteries LoL), but discharged I got more then it's supposed to be.

Again thanks

I'll keep looking around see if I see anything.

Inari

Basically what it means is that the cell on average discharge (think bell curve) is 1.2v, but when it is fully charged it will be closer to 1.5v. When it is empty it is closer to 0.8v. Your battery's voltage is indeed 9.6v - but because of the chemical nature of batteries, the voltage is not consistently 9.6v.

So yes, when your battery is fully charged it will be closer to 12v than 9.6v, but that doesn't change that the voltage of your battery is 9.6v.

Don't get me wrong, I don't fully understand it either - I just take certain things for granted; I know that a fully charged battery is approx 1.2x the voltage stated, and I know that when dead it is approximately 0.8x the voltage stated. The rest is pretty grey to me

glicster

inari beat me to it..
dex posted this for me before...


Each cell has a nominal voltage of 1.2V in a NiCd or NiMH pack. A charged cell should read approximately .2V higher than nominal, and a depleted cell should read .2V lower.
A "dead" cell would read far lower, closer to 1V below nominal. These are cells that still provide connectivity within the battery, but don't actually contribute to the overall output voltage (which is also the most common reason for battery failures).

Going by this, a 9.6V pack should read 11.2V at maximum charge, and 8V when depleted. An 8.4V pack should read 9.8V at maximum charge, and 7V when depleted.
However, in normal operation, it's highly unlikely that you'll actually deplete a battery fully. On most 1J AEG's (discounting short stroke and "long-box" systems, as well as some high torque motors), your motor will require a minimum of .6-.8V below nominal to overcome the compression of the spring acting against it. This point should be taken as your effective depletion reading.

Again, going with the above, your 9.6V battery becomes ineffective at between 8.8V and 9V, and your 8.4V battery becomes ineffective at between 7.4V and 7.6V.

maciek87

And all the rest you can find here:

http://en.wikipedia.org/wiki/Nickel%E2%80%93metal_hydride_battery

including discharge curve.

glicster

maciek87 wrote: »

And all the rest you can find here:

http://en.wikipedia.org/wiki/Nickel%E2%80%93metal_hydride_battery

including discharge curve.

heres another linky, knock yourself out:p:)

http://batteryuniversity.com/learn/

kirk1827

Hahaha thanks.

I was just going crazy with the 11v I found in my battery.

When it dies forever I'll just get a new one. Need one anyways as 1300 mah is not enough.

“Scotty, we need more power.”

Thanks Inari

kirk1827

Thanks glicster

You explained it for me. I finally got it. + - 0.2v Perfect.

11.2v full. Good

Just didn't want to have a defective or or powered battery without knowing.

But now I got it thanks.

And thanks maciek87 for the battery universe. I'm gonna give it a good read and see what I like. Thanks

Thank you all.