Random Electrical Question

[Moonstone2.0]

I am confused and need some help....

I have a solenoid that runs of a 9V battery which is button activated.

I had a Duracell Plus Power and it made the solenoid click from time to time but mainly just a weak noise came from it and it didn't work. At first I thought it was a solenoid problem but then tried an Energizer Ultra + and at first the solenoid didn't work but after a while it started clicking again and now clicks on every push.

I put the Duracell back in and it didn't work. Put the Energizer back in and it did work.

Curious, I checked the voltage of the batteries.

Duracell - 8.64V

Energizer - 8.60V

So how can a battery with lower voltage work better!?

So confused!

[Dave]

Under loads the batteries may behave entirely different, you're only measuring the voltage of the batteries off load, one could be almost dead and still give 8.4v, but as soon as you put a 100ma load on it, could drop to 2v.

[cully]

depends on the internal resistance of the battery
a battery with lower internal resistance will supply a higher current over a short time per volt
a battery with a higer internal resistance will supply less current for a longer time per volt

as it is powering a solinoid coil the coil requires a high inrush current to pull it closed but a small holding current to keep it closed

im guessing the Energiser battery is one of the types for light usage like remote controls

and the duracell is the type for cameras with heavey current demands

dont try to measure resistance of the battery with a multymeter you will probably kill it

[Moonstone2.0]

hmmm..cheers guys! That explains a bit.

Only measuring voltage with the multimeter. But may explain the incredible speed at which they are loosing power. Or its a faulty board...

Under load the energizer was in fact higher in voltage than the duracell...for a while anyway but now it's dropped and I have run out of 9v to play with.