early battery install

[cobra1336]

Preping for Red Glare, any problem with installing my 9V battery 3 weeks in advance? Fresh battery but I would like to prep everything so it's ready to go.

 

[troj]

Preping for Red Glare, any problem with installing my 9V battery 3 weeks in advance? Fresh battery but I would like to prep everything so it's ready to go.

Depends... Is anything going to be drawing power from it during the wait? If the answer is anything other than "No", I'd wait.

-Kevin

 

[rdbones]

With that length of time I would wait - even if there is not "supposed" to be any draw !

 

[cobra1336]

OK thanks, I will change it just before launch.

 

[JDcluster]

What kind of batteries are they?
You can install them then; just disconnect the negative side as you would your car.

I use Rechargeable Nickel Metal Hydride and check them periodically to make sure they still have enough juice. I still have one prepped from last RG wasn't able to fly it last weekend either

I have since pulled the batteries out and charged them about a week or so ago.

JD

Preping for Red Glare, any problem with installing my 9V battery 3 weeks in advance? Fresh battery but I would like to prep everything so it's ready to go.

 

[Handeman]

If it's a 9V battery, just check it with an amp meter before flight. If it puts out over 5 amps you should be fine.

I had a battery that read 8.9 volts only fire the drogue match, and later fire the main match when touched directly to the battery. It was only putting out 2.2 amps when measured even though the voltage was what it had been when new.

I don't worry about the voltage on the batteries any more. Check the amps they will output.

 

[G_T]

Do you really want to draw 5A from such a battery as a test?

https://data.energizer.com/PDFs/522.pdf

(If that times out as it generally does for me, try one of these links or do a google search):

https://www.google.com/url?sa=t&rct...sg=AFQjCNE8AOaAIq-8qy9-tg-wl1t2XjdPVQ&cad=rja

https://docs.google.com/viewer?a=v&...SLeUlV&sig=AHIEtbSNMEGjNF_9EqAf6aUMgc9TExSK8Q

Look at the Constant Current Performance graph (about 2/3 down on the right), and extrapolate out to 5A. Your battery is dead rather quickly, and likely this much current draw (if it will even do it - I didn't look up the internal resistance but it is high for 9V alkaline) would damage the battery in short order.

These batteries are not of a design/chemistry suitable for high current draw.

IMHO, of course.

Gerald

PS - From a non-authoritative source, the internal resistance of a 9V alkaline cell is about 1.5 ohms. Max current available from the battery would be on the order of 6A if new and then shorted. I'd expect a damaged battery after this test.

PS - This link may be of interest as well, as these tests were done at current levels that begin to approach our usage: https://www.powerstream.com/9V-Alkaline-tests.htm

 

[Handeman]

Do you really want to draw 5A from such a battery as a test?

https://data.energizer.com/PDFs/522.pdf

(If that times out as it generally does for me, try one of these links or do a google search):

This is the only one that didn't time out.
https://www.google.com/url?sa=t&rct...sg=AFQjCNE8AOaAIq-8qy9-tg-wl1t2XjdPVQ&cad=rja

https://docs.google.com/viewer?a=v&...SLeUlV&sig=AHIEtbSNMEGjNF_9EqAf6aUMgc9TExSK8Q

Look at the Constant Current Performance graph (about 2/3 down on the right), and extrapolate out to 5A. Your battery is dead rather quickly, and likely this much current draw (if it will even do it - I didn't look up the internal resistance but it is high for 9V alkaline) would damage the battery in short order.

These batteries are not of a design/chemistry suitable for high current draw.

IMHO, of course.

Gerald

PS - From a non-authoritative source, the internal resistance of a 9V alkaline cell is about 1.5 ohms. Max current available from the battery would be on the order of 6A if new and then shorted. I'd expect a damaged battery after this test.

PS - This link may be of interest as well, as these tests were done at current levels that begin to approach our usage: https://www.powerstream.com/9V-Alkaline-tests.htm

I agree that high current draw from a 9V is not a good thing, but I touch the meter probes to the battery just long enough to get a reading, about 0.5 second, if that.

Does this shorten the life of the battery, proabably, a little, but without the test, do I put a brand new battery in everytime? I will still test the new battery that way.

Beside, the Stratologger says to not exceed 10 amps, and that the amps is battery dependant. This that until the match fires, you're putting out the max amps the battery is capable of. I'm not sure the quick tests I do are any worse on the battery then actual use is.

I would rather get a few less uses out of a battery then have one come down without the charges going off.

 

[plano-doug]

I agree that high current draw from a 9V is not a good thing, but I touch the meter probes to the battery just long enough to get a reading, about 0.5 second, if that.

That still stresses the battery.

The common way to test a battery is to first measure the voltage with no load (open circuit voltage, OCV). Then apply a load and measure the voltage again (closed circuit voltage, CCV). For a 9V battery, I'd use maybe a 50 or 100mA load (ie, ~180 or 90 ohms, respectively). As long as it stays above ~8.5 volts with the load connected, it should still be good.

This stresses the battery adequately enough to reveal if it's weak without over-stressing it.

The key is that even a near-dead battery may measure 9V OCV, but only a good one will hold up under load.

But placing an ammeter across a battery with no other load is presenting a dead short. That's a poor way of testing any battery. While in this case it's not destructive testing, since it's only a half second or so, it still borders on that. And it does dump a bunch of charge for a short time, on the order of ½% of the battery's entire capacity (assuming a 300mAh capacity).

HTH.

Doug

.