New battery tech for battery replacement (2 9volts)?

[custar]

Yes, I know this thread is kind of old, but the subject comes up every once in a while.

Is there any reason linking the two batteries sold here sequentially wouldn't work? They should provide more than the 650mah, and $30.00 including the charger isn't bad.

custar

[drg]

Where?

[custar]

Link fixed.

custar

[flyingpootang]

Great info on the batt packs.

[Chrishew09]

Yes, I know this thread is kind of old, but the subject comes up every once in a while.

Is there any reason linking the two batteries sold here sequentially wouldn't work? They should provide more than the 650mah, and $30.00 including the charger isn't bad.

custar

they should work just wire them in series, remember you need to disconnect them from the series connection to charge them separately, so use some kind of battery clip for that you can get them at radio shack. with that charger it will take approx. one hour to charge each battery, food for thought.

I also should mention that the capacity will NOT be 800mAhr it will be only 400mAhr, when you put batteries in series the voltage goes up but the capacity stays the same, when they are in parallel the capacity goes up and the voltage stays the same.

[Covjek]

noob question

If i were to put together a pack like the one uthomas has would i need to do anythng to the rest of the internals and elecronics or is it just put it in and shoot?

[Chrishew09]

If i were to put together a pack like the one uthomas has would i need to do anythng to the rest of the internals and elecronics or is it just put it in and shoot?

you got it, its that easy.

[custar]

Thanks for the info. I don't shoot that much in a day, so the weight savings and lower cost would be worth it.

custar

[athomas]

Yes, I know this thread is kind of old, but the subject comes up every once in a while.

Is there any reason linking the two batteries sold here sequentially wouldn't work? They should provide more than the 650mah, and $30.00 including the charger isn't bad.

custar

These batteries won't work. The discharge capacity is only 80ma and the max discharge is only 800ma. The required max discharge is about 3000ma. There are other lithium batteries that are quite small that will do the trick. There was a thread here on AO not to long ago.

[Chrishew09]

These batteries won't work. The discharge capacity is only 80ma and the max discharge is only 800ma. The required max discharge is about 3000ma. There are other lithium batteries that are quite small that will do the trick. There was a thread here on AO not to long ago.

Where does the 3A discharge current come from?
I find this hard to believe, maybe the peak currents to the solenoid are around 3A but that peak current is coming form the capacitor on the board.

The peak currents for any batteries are directly related to the heat that the cell generates during its chemical reaction, between the anode and cathode. They rate cells based on the temperature rise of the cell under a certain load. These ratings are based on a constant current type application, ours is not. We run peak currents with very low duty cycles, and give much time between cycle for cooling. I have not measure nor have i crunched the numbers but I would imagine that our RMS currents that the battery sees would be in the 100mA to 150mA range with duty cycle around 5% max, this is not hard on any cell at all.

But then again what do i know.....

[athomas]

Where does the 3A discharge current come from?
I find this hard to believe, maybe the peak currents to the solenoid are around 3A but that peak current is coming form the capacitor on the board.

The peak currents for any batteries are directly related to the heat that the cell generates during its chemical reaction, between the anode and cathode. They rate cells based on the temperature rise of the cell under a certain load. These ratings are based on a constant current type application, ours is not. We run peak currents with very low duty cycles, and give much time between cycle for cooling. I have not measure nor have i crunched the numbers but I would imagine that our RMS currents that the battery sees would be in the 100mA to 150mA range with duty cycle around 5% max, this is not hard on any cell at all.

But then again what do i know.....

The 3A discharge comes from quotes from AGD. Others as well as myself have verified them and I actually posted the math for them in a post quite a while ago. They are the reason the battery pack is so large, using AAA cells instead of smaller 9v batteries.

Even when the duty cycle is averaged out, the continuous average draw is still larger than the capability of the the rechargeable 9v batteries.

30ms/cycle x 15cps = 450ms of "on" time per second
3A current draw based on solenoid specs.
.45 x 3A = 1.35A continuous draw

Lets prove this:

The Emag battery was 650mAh rating with approx 20000 shots per charge.

30ms/shot (AGD dwell) x 20000shots = 600 total seconds of on time = 10 min = 0.17hrs

650mAhr/0.17hr = 3.82Ahr current draw. This would be the continuous current draw if the solenoid was turned on for the entire 600 seconds. The draw is actually higher than originally thought. I guess maybe the number of shots per charge could be higher than given.

At partial duty cycle; 0.45 x 3.82A = 1.72A

If the rate of fire goes up, the continuous draw also goes up which puts additional load on the batteries.

Even though the batteries are rated at continuous load, they also have a rating for instantaneous output for a percentage of the duty cycle. It is usually several times higher than the C rating but can be a limiting factor when using the cell for a specific high demand and can decrease the usefulness of the battery for that application.