Battery charger

[Oregon Bob]

Is there any reason to not use a battery charger to power your bilge pumps? It seems like that would be the easy method when your working at home. I've read some comments that you should only use a batter charger in a pinch.

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[okbasspro]

I have done it but the new electronic chargers will not work

[russau]

i use my charger at home and if i need it to slow down for the finer gold, i just switch it to 6 VDC .it seems that useing a valve to turn down the flow just increases the water pressure.

[Old Radio Tech]

Look at it from the pumps point of view. If I'm a 12VDC 750GPH pump, I want to pump at 750GPH. Any restriction makes me work harder. A battery charger puts out between 13.6 and 14.5VDC, making me turn faster and work even harder still against the restriction. Matching the pump to the job also helps the pump last longer. At home on the blue bowl I'm down to using a 160GPH 110Vac pump, my flow control is much better, and even that little pump is running half throttle.

[Oregon Bob]

Thanks everyone for your responses.

[russau]

ORT my point exactly! on my Miller table i try to use smaller bilge pumps with lower GPH rather than useing a valve as my main way to restrict the water flow. and it does work better that way like you stated!

[Old Radio Tech]

Another advantage I've found of using smaller pumps on the blue bowl is there is less turbulence in the line caused by the pump so the length of the lead in hose needed to smooth out the turbulence is shorter. I've coupled that with a six turn valve and get controlled, smooth, gentle flow.
Sorry about hijacking your post Oregon Bob.

[PYRATE]

Is there any reason to not use a battery charger to power your bilge pumps? It seems like that would be the easy method when your working at home. I've read some comments that you should only use a batter charger in a pinch.

Chargers using a lot of 110v electricity for the amount of 12v energy produced and many chargers have a limited lifetime. A 110 pump is cheaper than a charger and will use less power.

i use my charger at home and if i need it to slow down for the finer gold, i just switch it to 6 VDC .it seems that useing a valve to turn down the flow just increases the water pressure.

Mount the valve in a different location or add more pipe after the valve. The valve limits the flow, but will act like a jet if there isn't anything to contain the water being forced out of it.

I'm not an expert on such things, but as I understand it running a 12v pump on 6v power will double the current draw and overheat the motor.

Look at it from the pumps point of view. If I'm a 12VDC 750GPH pump, I want to pump at 750GPH. Any restriction makes me work harder. A battery charger puts out between 13.6 and 14.5VDC, making me turn faster and work even harder still against the restriction. Matching the pump to the job also helps the pump last longer. At home on the blue bowl I'm down to using a 160GPH 110Vac pump, my flow control is much better, and even that little pump is running half throttle.

Again, not an expert, but restricting the outflow of a pump shouldn't make the motor work harder or reduce the life of a pump (restricting the inflow will)

[Old Radio Tech]

Not an expert either. Bilge pumps pump water up and out using a hose the size of the output. It's a pull/push operation. Any output restriction and the pump has to work harder to get the water out. It's pushing against the restriction. Any lessoning of the amount of rise will lesson the amount of work the pump has to do. I've also noticed that the depth of water above the pump (head), changes the flow(GPH).

[stevemc]

Just hooking up a battery charger to a bilge pump is not a good idea. The battery charger sees it as a dead battery and tries to push the max amount of volts and watts into the pump, early breakdown of the charger and the pump. Plus it could heat up and cause a fire. A better way is to actually have a battery, and have it hooked to a trickle charger if needed. You could use a small 12 volt battery. Or you could use a 115 volt to 12 volt power supply, in the correct amperage. Check at Radio Shack, and try for a controlable power supply. Check your bilge pumps for wattage.

[PYRATE]

Not an expert either. Bilge pumps pump water up and out using a hose the size of the output. It's a pull/push operation. Any output restriction and the pump has to work harder to get the water out. It's pushing against the restriction. Any lessoning of the amount of rise will lesson the amount of work the pump has to do. I've also noticed that the depth of water above the pump (head), changes the flow(GPH).

A typical bilge pump is a centrifugal pump and has a spinning operation versus the push/pull operation some other types of pumps.

When the discharge is restricted, the pump mechanism will still spin and while it won't operate as efficiently (as measured in output volume) it isn't working any harder and won't damage the pump.

Best link I could quickly find on this matter: Cycle Stop Valves, Inc.

[Old Radio Tech]

Centrifugal pumps are sensitive to overheating under low flow. A way to deal with this is smaller pumps, more flow. And having a speed control on the pump rather than a valve on the output would help according to the article.

[Old Radio Tech]

When I first started trying to master the blue bowl I used a battery alone. I found that as the battery voltage settled from 13.6vdc to 12vdc the pump output changed and my water level changed. Not good. So I then used a charger. As stevemc stated the charger overworked itself trying to charge the pump. I put the charger(tried trickle charger as well) on the battery with the pump as well, and the combined resistances of the pump and battery was not what the charger wanted to see. That's why I now use an 110vac pump. And it was cheap -$16.

[PYRATE]

Centrifugal pumps are sensitive to overheating under low flow. A way to deal with this is smaller pumps, more flow. And having a speed control on the pump rather than a valve on the output would help according to the article.

I agree, but only when dealing with highly restricted flow, high capacity pumps &/or fluids other than water, but we're talking about the use of a 12v bilge pump pumping water for processing gold on a small scale.

I'll reword my initial response: Again, not an expert, but restricting the outflow of a pump (ie. installing a valve into to fine tune the flow of water while still allowing a steady flow) shouldn't make the motor work harder or reduce the life of a pump.

Heartily agree with your advice to use a 110v pump vs. a 12v pump & charger or 12v pump & charger/battery combo

[Oregon Bob]

Thanks guys. Real good info in these posts.

[Old Radio Tech]

The 750gph or higher that many use to run their blue bowl is way over sized and hard to control. The bowl may need 60gph. So that 750gph needs to be highly restricted to feed the blue bowl, and may overheat. I never did feel it to find out when I was using the 750gph. How about someone who is see how hot it is after 2-3hrs of constant running and let the rest of us know? And I wouldn't call that nasty stuff running through my pump water. It would be in the "fluids other than water" category.