Perhaps I have misunderstood Myles' suggestion, but when putting anything in series, balance becomes important. If the four twelve volt pumps are identical and loaded identically, then each will see 12 volts. However, if 3 are dry and one is wet, the wet one will have a higher load and its voltage will drop causing problems. If the pumps are tied to each individual battery, then some of the problem goes away, but the original objective of keeping all four batteries balanced still hasn't been achieved since the four loads can vary by quite a bit unless all four pumps are loaded equally (all pumping water of equal depth to outlets at the same height).
Pat
--- In electricboats@yahoogroups.com, Hans Kloepfer <hanskloepfer@...> wrote:
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> Myles,
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> I think your idea is great to use multiple bilge pumps in series. Many of the commercial bilge pumps are rated to run at 12 OR 24 volts. I probably would not have a need for four bilge pumps, but I already have two.
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> I currently have a small cheap separate voltage converter soley for the bilge pump, but I like your idea much better.
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> Cheers,
> Hans
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> --- On Sun, 2/13/11, Myles Twete <matwete@...> wrote:
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> From: Myles Twete <matwete@...>
> Subject: RE: [Electric Boats] 48V to 12V
> To: electricboats@yahoogroups.com
> Date: Sunday, February 13, 2011, 2:34 PM
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> I use an ebay-purchased used GE 36v-12v converter, but as folks have mentioned about continuous drain if the DC/DC converter is in the loop, I never did connect my bilge pump back up to automatic operation since converting to electric…not good, but that’s what’s the status.  Another bilge pump idea: You could avoid the constant drain on the DC/DC by having a dedicated DC/DC for the bilge pump, then rewiring the bilge pump switch to instead switch the input power to the DC/DC when water is detected or you manually switch it on.  Or how about this whacky idea: Why not place four 12v bilge pumps (for 48v), in the bilge at different stations along the length and perhaps width of the boat.  You’d want any one of the switches to turn all 4 of them on (assuming it’s okay to dry run them) and so you’d need to parallel all 4 switches up, then have the parallel bank of these switches placed electrically in series with all 4 motors. If any
> switch detects water, all 4 bilge pumps turn on, running on 48v.  Of course, both of those ideas require disconnecting the switch from the motor…  -MT
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