C-Forum

Has anyone tried the batteries that come with battery drills for their pump for Oc1? thanks D-Caption

I haven't used powertool batteries, but I do use LiION batteries in my pumps.

LiION has a serious quirk to keep in mind when using with a pump system. The batteries will have a built in fuse/ limiter that shuts them off when the drain is too fast. Mine turn off at 7amps, smaller batteries shut off at 3-4 amps.

If you're running a single pump that draws just under 5 amps, and your power tool battery shuts off at 4amps, you won't have a working pump.

Eric, do you have a link to your pump building plans?

No real plans needed, it's a very simple wiring job.

Start with the pump, then find a battery that will power it, followed by a waterproof case to hold the battery (lead acid can get wet, the others need to stay dry).

Decide on how you want to mount the battery/ pump/ switch. On the most recent boats I've been mounting twin Mayfairs behind the saddle, running into a thru-hull that's a couple inches behind my footpedals.

On the Mikey saddles I put the battery on the front of the saddle and the switch directly on the waterproof case. A rubber waterproof switch cover from Lowes/ Home Depot seals the switch and I can reach it by just putting my hand down between my legs.

On the Esquif bulkhead saddles I put the battery in front of the saddle but run the switch through the bulkhead so that it's just behind the thwart. For that I use a submarine switch from West Marine (totally waterproof, expensive, but works great).

Beyond that it's just wiring the battery to the switch to the pump and letting the juice run. At some point if I remember I'll post photos, the Esquif bulkhead saddle setup is probably the most colorful (used dymondwood to make the switch plate and thwarts).

Ezwater,

Colin (cmnypny) put together a nice document on the whole system. You can find the thread at http://cboats.net/cforum/viewtopic.php? ... light=pump

The link in question is http://www.riverjunkies.net/howto/openb ... system.pdf

Another good place to look is CanoeColorado http://www.canoecolorado.com/canoeing/bilgepump/

Marc

Thanks, I vaguely remember those thread but hadn't yet searched to find them.

[quote="Eric Nyre"]No real plans needed, it's a very simple wiring job.

Start with the pump, then find a battery that will power it, followed by a waterproof case to hold the battery (lead acid can get wet, the others need to stay dry).

.....snip.....

quote]

Ummmm, sorry, this isn't true for LiIon Batteries. They are the best battery for the weight, have no memory, etc, but they are the worst choice for starting up a DC motor. LiIon batteries that are large (i.e. have a high Amp-hour rating) typically have built in electronic fuses that shut off the battery if you try to pull too much current out of them. Why? Because an LiIon battery can be permanently damaged, or cause an ugly failure if you short them out.

Here's the rub -- a motor when starting up is virtually a short-circuit, so you can run into real issues with LiIon batteries. What most people do is 'slowly' turn on the motor in a controlled way. Doing this requires more circuitry. Not doing this will either trip your electronic fuse (those crappy glass fuses are way to slow to protect your battery), or you risk losing your investment in the LiIon battery.

So I caution you to either choose NMh batteries, NiCad (which suck for other reasons), or SLA. Personally, I use LiIon, but I've controlled the turn on for the motor which is a tad more complicated that most people want to deal with. Those of you who like soldering are welcome to use the startup circuit.

BTW, there's another good pump building link. It is in french, but you can use a translator. This pump relies on many rechargable AA cells (NMh), so doesn't have a tonne of capacity, but it pretty good none the less.

http://www.cartespleinair.org/Canot/Div ... ulombe.pdf

Been running LiION batteries in pumps for 3 years. So far so good.

If your battery is too small for the pump, it's going to trip the fuse. That's why you choose your pump first, then get the correct sized battery to go with it. If your pump draws 5 amps on startup, get a battery that can handle 7 amps and then no worries. Larger batteries bypass the need for a startup circuit and you can wire them just like any other battery.

FYI when we're talking large LiION battery, we're still in the range of something around 14oz in weight. They'll run your pumps for a week long trip without needing to be recharged and still have juice to spare for a few days trips before you need to top it off again.

Yes LiION can explode into a cloud of green smoke. However that's most common when a model airplane suffers rapid decelleration. Get a good battery, make sure your pump draw is under what the fuse will trip at, and enjoy.