Picture of Solar powered bilge pump
I've had water seep through my basement window quite a few times in the past two years. While I've done what I can to prevent this (clean gutters, divert downspouts) water stills builds up within my basement window well occasionally, and eventually seeps into the basement - wrecking havoc on my day.

Last year, I added a bilge pump to the window well which was powered by a couple of 6V lantern batteries. This worked - until the batteries died.

So - I decided to up my power source to an AGM (absorbed glass mat) Lead Acid battery which gets charged via a solar cell.

DISCLAIMER: Be careful when using tools - protect your eyes - think twice before doing anything. With batteries, you can't unplug them - they're always 'hot' - watch where you put your tools - avoid possibly shorting out the terminals. Keep the protective terminal covers on the battery until you actually connect it to your circuit, and when you do, make sure a fuse is the first thing to get connected. Batteries can be dangerous - they can explode - leak acid.

Step 1: The Bilge Pump

I purchased the bilge pump and float switch at a wally world - I think it was for around $35-50. Sorry for the lack of detail here - did this at 3am after cleaning out my basement all night :(.

The bilge pump is designed for small boats to expel water within their hauls and keep them afloat, it's not an industrial pump by any means. The accompanying switch is a small float switch which closes the circuit once the water level is at a certain height.
Great idea, I'm building something similar and wonder if you might know how/what could be used to turn on/off your pump at 1-2-3-4 designated times 7 days a week. This switch must be battery operated, economical/cheep and no bigger then a common paperback book?????
Any answers out there?????
joeinventor2 : Just buy an automatic bilge pump that runs whenever water is detected. Would you still need a switch for this? You could still add a SPDT switch, one that has "On/Auto/Off" positions (the center position is Auto). OR, buy an (expensive, about $80 ) DC timer . Those have lots of settings.

I just installed a solar powered 100ah battery system to run my 12 volt sump pump (we often get a LOT of rain). It is a Rule 360 GPH (gallons per hour) 12 volt bilge pump, requiring 2 amps at 12.3 to 13.6 volts, assembled basically as jedi27's is. The solar panels provide about 3 amps per hour unless it is raining (which is where the battery comes in!!).  If the pump runs about 3/4 of the time, it's using 1.5 amps per hour. 100 ah / 2 (max. recommended discharge) = 50 ah. 50 / 1.5 = 33 hrs. In other words, if it rains for 1 day and a half, the sump pump probably will run the battery too low to do much pumping. Add to that: the solar controller has a disconnect setiing of 12.2 so you just won't get even that far! I have been forced to connect a 2 amp battery charger to the battery pack at times to keep the voltage up.

Next task for me is to find the user manual for the controller to see if the LVD is user adjustable.

I hope this is all of some use. I'm a new guy, liking this forum very much.
jedi27 (author)  JoeInventor25 years ago
The battery operated portion makes it more complex, otherwise I'd say grab a timer from big blue and have done with it...

You COULD look up a 555 timer based circuit - have a small counter circuit - calc that out to run every so many hours - have it activate a relay for so many sec /.mins - which would then power your pump.

This would be better suited for a micro controller... a lot of folks use the arduino (look them up in instructables) - it's a great hobby level pic that would allow some interfacing to things such as a relay - low power consumption, small, $35ish?  depends on model...  this would allow a lot of flexibility.  You could modify the logic to only run if moisture detected within the allotted periods - perhaps warn if low battery - log run times, etc... 

(I'm curious how this will be used... the requirements are a bit off kilter...)

Good luck!!!! 
baudeagle6 years ago
I have heard that if you do not add a diode into your circuit the battery will discharge through the solar panel at night. I am not that familiar with this but maybe someone else can enlighten me.
jedi27 (author)  baudeagle6 years ago
I suppose the panel could do that, but I left the original solar panel circuit intact - which is (probably) designed to disallow that type of discharging. I didn't poke around the circuit too much - looks like it's just a cap, resistor, LED, plus another diode (the LED is a diode too!). Keep in mind that my cheapo panel was designed to trickle charge a car battery - even noted in the manual that it wouldn't drain the battery at night - so I'm putting some faith into that! (i believe) The purpose of the diode is prevent current from flowing the wrong way - in that case, from the battery to the panel.