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View Full Version : Psuedo matching/testing RayOvac 15 min AAAs


ipattie
2004.12.25, 03:18 PM
As an old electric guy, used to (why I switched to nitro, BTW) buying matched battery packs, I was curious about the consistency of the Ray-O-vac AAA rechargeables most local guys use for mini-z here in Houston.

I rigged up a single cell discharge station, with a digitial voltmeter hooked up, and measured discharge voltage to 5 min for 16 batteries. My goal was to find the highest voltage set for Stock class, and weed out any duds.

Ignore the volages, there are way too many drops in the setup, but the relative findings should be good.

Of 16 batts, after 5 min:

1) No duds, but 2 were down to 1.000 v
2) Most (8) were an 1.020 volts.
3) Rest were maybe bell shpaed (remember your statistics!) around 1.02.

Best was 1.035, worst 1.000. So the range is 3.5 percent, so just stay off the wall one time in that 5 minutes and forget about it!

In mod class, none of this matters, too much speed already.

Ian

madf1man
2005.01.04, 08:18 AM
Thanks Ian confirming what I was assuming.part of the beauty of these litte guys!!!!!!!

THRC Dan
2005.01.09, 06:11 PM
Good research Ian...

I agree with you... the mod class's are just way too fast... But its cool, alot of the guys like it. I will probably stick more with the stock or maximum X-Speed classes and just play with the rockets.... lol

Ian... If you dont mind... write me up a report regarding your battery testing and I will post it in the "Tech" section of the website...

ipattie
2005.01.10, 08:27 PM
Good research Ian...

I agree with you... the mod class's are just way too fast... But its cool, alot of the guys like it. I will probably stick more with the stock or maximum X-Speed classes and just play with the rockets.... lol

Ian... If you dont mind... write me up a report regarding your battery testing and I will post it in the "Tech" section of the website...

Danny, pretty easy:

1) Get a single AAA cell battery holder, or just use one slot of a multi-cell holder.
2) Get a 0.5 to 1.0 Ohm wire wound power resistor at Radio shack, these are the big square sugar cube like things, about a 10-25 watt should be ok ($2). I used two 10 watt 1 ohms in parrellel, they only got warm.
3) Hook up a digital voltmeter ($10) and the power resistor to the cell holder.
4) Charge your cells fully, then pop each one in, and using a watch, measure the voltage as often as you like. I sorted them based on their voltage after 5 min.

You can adjust the resistance by using more resistors in series or parrallel. I.e., at 1 volt, a 0.5 ohm resistor, will give a 2 amp load. An 800 mAhr cell would then be flat after 0.8/2 hours, or 24 minutes.

ruknd@aol.com
2005.01.10, 10:54 PM
Danny, pretty easy:

1) Get a single AAA cell battery holder, or just use one slot of a multi-cell holder.
2) Get a 0.5 to 1.0 Ohm wire wound power resistor at Radio shack, these are the big square sugar cube like things, about a 10-25 watt should be ok ($2). I used two 10 watt 1 ohms in parrellel, they only got warm.
3) Hook up a digital voltmeter ($10) and the power resistor to the cell holder.
4) Charge your cells fully, then pop each one in, and using a watch, measure the voltage as often as you like. I sorted them based on their voltage after 5 min.

You can adjust the resistance by using more resistors in series or parrallel. I.e., at 1 volt, a 0.5 ohm resistor, will give a 2 amp load. An 800 mAhr cell would then be flat after 0.8/2 hours, or 24 minutes.
would this work for 1:10 too? Let's say 3300s?

ipattie
2005.01.11, 05:39 AM
would this work for 1:10 too? Let's say 3300s?

You need to be careful with your choice of resistor and the cooling of it for high amp loads. For a 3300 sub-c, a resonable amp load for 5 min of juice, is on the order of 30 amps, so R = V / I, = 1/30 = .0333 Ohms. This low of a resistance is close to a short circuit, so be very careful about heat, explosions and other bad things happening that could blind and burn you.

I don't think the method above can be applied safely to sub C cells.

ruknd@aol.com
2005.01.11, 01:29 PM
You need to be careful with your choice of resistor and the cooling of it for high amp loads. For a 3300 sub-c, a resonable amp load for 5 min of juice, is on the order of 30 amps, so R = V / I, = 1/30 = .0333 Ohms. This low of a resistance is close to a short circuit, so be very careful about heat, explosions and other bad things happening that could blind and burn you.

I don't think the method above can be applied safely to sub C cells.
anyone ahve any idea on how do make a 1:10 unit? The CE one is wayy pricey....