2 9-volts for Emag Power?

[eMagnificent]

We all know the Emag's batteries suck. They DO have a memory effect, and they frequently die (refuse to take a charge at all).

I am probably just going to wire my own 14 AAA NiHh battery pack, using quality rechargables... but I was wondering about something else...

I often use 2 9-volt batteries for testing purposes (e.g. when my gun isn't firing in e-mode and I just want to make sure it's because my battery sucks.) I have tested, and have found that two 9-volt batteries would indeed fit inside the battery case. They'd be simple as heck to solder together (I usually just clip one of the males to the female and tape the wires on for testing). I was thinking that I could make a 2 9-volt batter pack just for backup. If my 14 AAA battery pack wasn't working, I could just unscrew, and switch out. Does anyone have an idea how long the power would last? I know it wouldn't last nearly as long... but how long? enough to get through 1000 rounds? I know I couldn't charge them through the charger... I was planning on using non-rechargable batteries for this.

[athomas]

The 2 nine volt cells wouldn't provide the instantaneous current required to operate the emag consistently for each shot, especially at high rates of fire.

If you are sure your pack is bad you are better off to build a new one if you can.


Emag battery packs use NiMH batteries which do not have a memory effect. The memory effect is an old wives tale that followed from the batteries used in the space program in the 60's. Most problems that people think is the memory effect is caused by a bad cell. Most often, a bad cell is created by overcharging the battery pack. NiMH batteries are best "quick charged" to 90% and then finished with a trickle. If the proper charger is used it senses the tiny voltage drop after the pack is charged and stops the charge process. This prevents the pack from overcharging and heating. Excessive heat is a sure sign that the battery pack is overcharging.

[eMagnificent]

I still hold that NiMh have a memory effect, even though it's nowhere near as bad as with the old school NiCads. The only batteries that have NO memory effect are LiIon batteries. The idea that NiMh batteries have no memory effect was propigated by the people who sell them.

http://www.zbattery.com/zbattery/memoryeffect.html

Other problems occur when the charger doesn't detect the slight drop (signalling the 90 percent area, and the start of the trickle). Overcharge. Sometimes the trickle is started too early (undercharge) and it will take much longer to charge the battery.

[hitech]

Originally posted by eMagnificent
I still hold that NiMh have a memory effect, even though it's nowhere near as bad as with the old school NiCads. The only batteries that have NO memory effect are LiIon batteries.

That has been my experence also. Although a friend of mine still swears that LiIon batteries have memory.

[Miscue]

2 9 volts have enough to turn on the board, but not enough to actuate the solenoid. Tried it... didn't work.

[Kevmaster]

wired in series or parallel?

[eMagnificent]

Mr

They must not have been charged, or else you wired them in parallel. They have to be wired like this:

---------(-)[9v](+)--------(-)[9v](+)--------

if you wire them in parallel, the gun would only be getting 9 volts, and thus would probably turn on, but would not activate solenoid.

[Miscue]

Brand new Energizers, soldered two 9-volt connectors together in series. Not enough amps...

[athomas]

That's correct. The nine volt cells do not supply enough peak current to actuate the solenoid. I'll bet if the battery output voltage was measured during the solenoid on cycle using an oscilloscope we would see a significant voltage drop.

Most nine volt cells only have a small amp capacity but they also have a greatly reduced C rating which is actually more important for this type of operation. If the batteies had been NiMH the nine volt series connection would have stood a better chance of working since most NiMH batteries have a higher C rating than similar alkaline cells. Even so, I don't think the nine volt NiMH have the capacity either.

[hitech]

Originally posted by athomas
I don't think the nine volt NiMH have the capacity either.

I've always wondered if the Plainview 9.6 volt NiMH batteries would work. They have a 170mah rating. Anyone what to try?

[athomas]

The Plainview batteries look quite impressive. It looks like the 9.6 volt rechargeables might work but I don't think they could handle a continuous 15cps for more than a second or two.

Now I am very impressed with the button cells which have a much higher maximum continuous discharge rating. I think we may be able to incorporate the button cells into a very compact round battery forgrip, especially when the ULE trigger assembly hits the market and we can reduce the current draw of the solenoid a bit. Check them out.