Homebuilt ROVs Forum

AHarris wrote: Erm, not too sure as it is an old battery and the label has fallen off.
It is a 9 Volt Lantern Battery, I think it may be one of these Eveready batteries: http://www.rapidonline.com/Electrical-P ... ry-18-0249

Obviously it is nowhere near car or tractor batteries but it is just a battery to test with. In the future however, I was planning on getting this set:
http://www.rapidonline.com/Electrical-P ... rger-62263

As they are small, has everything I would need and most importantly they are cheap. When you say, 'is the battery capable of producing an amperage draw' would this one only be capable of putting out 1 Amp as it states 'Max Discharge current 1.0A'

Thanks again for all the help!

--NOTE--
Not sure whether this shows any information, but connecting the multimeter directly to the battery terminals and measuring the amps on it I get 3.57 Amps which I am guessing shows that it can put out a maximum of 3.57 Amps?

I'd definitely say that it's the limiting factor of your 9v battery that's producing the lower than expected 2.5 amp draw. To do the same thing with a battery capable of handling larger amperage loads you would definitely see a larger amp draw through your circuit, and possibly damage to your pump motor if there wasn't some form of current limiting protection in the circuit. The "1 Amp Max Discharge" current is the maximum that the battery can handle safely. Going higher than that value can cause the battery to overheat and could also cause damage to it. The 3.57 amps would be the maximum amperage load at it's current "charged" level. The difference between the 3.57 amps and the 2.5 amps through the pump is from the resistance in the wiring, the motor, any circuits included, etc. Also, I would never recommend putting your amp meter directly across the terminals of any battery. It's better to measure the amp draw through something that will create a heavy load on the battery, such as a halogen light or headlight. I hope this helps!

reHosea wrote:I'd definitely say that it's the limiting factor of your 9v battery that's producing the lower than expected 2.5 amp draw. To do the same thing with a battery capable of handling larger amperage loads you would definitely see a larger amp draw through your circuit, and possibly damage to your pump motor if there wasn't some form of current limiting protection in the circuit. The "1 Amp Max Discharge" current is the maximum that the battery can handle safely. Going higher than that value can cause the battery to overheat and could also cause damage to it. The 3.57 amps would be the maximum amperage load at it's current "charged" level. The difference between the 3.57 amps and the 2.5 amps through the pump is from the resistance in the wiring, the motor, any circuits included, etc. Also, I would never recommend putting your amp meter directly across the terminals of any battery. It's better to measure the amp draw through something that will create a heavy load on the battery, such as a halogen light or headlight. I hope this helps!

Thanks, it has helped a lot!
Shall do some research and attempt to get a suitable battery for the motors, and as you suggested, include some form of protection to help prevent the motors from being damaged.

Yes, make sure you include fuses - especially when you are testing. Learned that one the hard way.

The 3.25 amp draw is the current you get with the internal resistance of your ampmeter. If you had a more powerful battery you would blow the fuse in your ampmeter. Always mesure amps in series with the circuit, and volts in parallell.

Marcus