Solenoid trouble - inadequate electrical power

[billthebutcher]

I feel like a clown asking you guys this, but I've been co-opted into someone elses project, and electrical engineering isn't my field. This is not a "homework question," and I'm not a troll. I'm not looking to waste anyone's time. I have a solenoid that applies a load to actuate a part in a machine. The solenoid works fine with a 12VC, 5Ah Lead-Acid Battery. The problem is that the battery is physically too large to fit into the machine. Is there any way to acheive the same results using a combination of physically smaller batteries wired in series? I have A23 (12V) batteries at my disposal.

I am incredibly ignorant about electronics, so I apologize in advance if this is a silly question. I have attached a specification sheet for the solenoid. I would greatly appreciate any help you guys could give me.

Thanks,
Bill

 

[billthebutcher]

Here is page 2 of the spec sheet.

 

[davidbeach]

If you have a 12V battery that is too large, and you want to use multiple 12V batteries that are smaller, you have to connect the batteries in parallel, not in series. Wire them in series and you will have too much voltage at the solenoid and probably not enough current for long enough. Wire them in parallel and you only get 12V, but the sum of the battery currents.

 

[ScottyUK]

You could of course use a couple of 6V batteries connected in series. You could possibly look at NiCad equivalents and see if their cylindrical shape is better suited to where you need to mount them. You'd need 10x 1.2V cells, but cells are available in sticks of 2, 3, and 4 cells, and in 12V blocks. There are probably 5 and 6 cells sticks too if you look.


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If we learn from our mistakes I'm getting a great education!

 

[billthebutcher]

So once the voltage requirement is met, any additional voltage beyond that will do no good - so it's a question of amperage then?

 

[israelkk]

There is another issue to consider. You have to make sure that the multiple batteries can supply the desired current because the inner ohmic resistance of the multiple batteries can be larger than the large battery inner resistance when the desired current flows in the solenoid.

Solenoid force is only the result of the current flowing in the coil!! the voltage only determine how fast the current reach its peak.

 

[billthebutcher]

Well, we go the thing to work. A single 9V battery appears to be able to actuate the part as long as it is allowed to "ram" the part - with a little gap (about 0.1 inch), the plunger can build up enough speed to hit the part and actuate it, instead of attempting to gently accelerate it.

We were using coated wire before, which is why we couldn't get the solenoid to do anything, even with no load applied. We were both aware that it was coated but had forgotten since we last used it. Please forgive our breathtaking stupidity, and thank you all for being incredibly helpful.


-Bill

 

[electricpete]

So once the voltage requirement is met, any additional voltage beyond that will do no good - so it's a question of amperage then?

It's a question of deliving Amps without having too much voltage droop or for that matter too much internal heating of the battery. (As irealkk said, the battery has in internal resistance.)



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(2B)+(2B)' ?

 

[itsmoked]

SOOOoooo. You really did waste our time!

You promised you wouldn't.





















Keith Cress
kcress -

http://www.flaminsystems.com

 

[oldfieldguy]

"A single 9V battery appears to be able to actuate the part as long as it is allowed to "ram" the part - with a little gap (about 0.1 inch), the plunger can build up enough speed to hit the part and actuate it, instead of attempting to gently accelerate it."

Common problem, common fix. You're allowing the solenoid plunger to pick up and store some kinetic energy in that first 0.1 inch of travel.

In my days as young tank commander, we had a similar issue with the electrical firing solenoid on a 90mm gun. Setup required a certain measure of free travel before it would trigger the gun reliably. Said measure of free travel was the thickness of a US Army dogtag.

Just make sure that the object of the solenoid impact is up to the hammering.

old field guy

 

[billthebutcher]

itsmoked: Yeah, sorry! I know some very, very basic electrical stuff, but this was out of my league. The other guy I worked with discovered the ramming solution.


Thanks, old field guy. I'll have to keep that in mind for the future.