ConnieH wrote:Your last post kman brings up something I've been thinking about - a battery backup for the solar panel, in case it gets damaged, or in case of a really cloudy day. Do you (or Figgy or anyone who knows this stuff
) think a 6v alkaline lantern battery could run the HF pump? Or I could connect 4 1.5v batteries in a series to come up with 6v, if my math is correct. I'm just not sure how long it would last, I had a hard time deciphering the data on the Energizer battery site as to amperage.
I've toyed with idea of hooking the pump to rechargable batteries and rerouting the solar panel to charge the batteries, but I'm not exactly sure how involved something like that would be (still learning about all this electricity stuff!). Plus I'm really reluctant to start hacking on the HF pump this late in the game, but thought packing along a lantern battery "just in case" might not be a bad idea. If the pump dies, I'm f*cked, so I'm considering buying a spare like you did - we have a 400w inverter, so I could pick up an AC pump at the local HF and return it later if I don't use it, which hopefully I wouldn't need to
Hmm, several things going on there.
1) I'm fairly sure the lantern battery (or even bundled alkalines) would indeed power the HF pump. That's certainly an easy way to deal with it. Another option would be to just pick up a small lead-acid 6v battery, which would be pretty cheap. They're readily available, look for sealed AGM batteries. Same sort of batteries you use in a UPS, roughly the size of a lantern battery. No idea how long the alkalines or lantern battery would last, but the lead acid batteries will all have amp-hour ratings, so it's easy to figure.
2) I thought this same issue through (parts failures), however, and ultimately I decided that $21 (shipped) for a fully-spare pump seemed like a better idea than spending money (close to the same, actually) on a 6v spare power solution. A spare pump runs at 12v, too, so no wasteful inverter needed, it's very efficient to run right off the same battery you already have powering the fans. It's not just the power source that can die, after all, if the pump itself gives out it doesn't matter if you've prepared a non-solar power pack.
3) Another option, I'd note, is you could get a power adapter that converts your existing 12v battery into 6v juice the HF pump can use. But that's likely to cost the same as the fully-spare pump, bringing us back to point #2.
4) Hooking the pump to rechargeable batteries and running the pump off the batteries, then charging the batteries from the solar, is a great way of doing it (that's how most solar xmas lights work, too) but I think it's more complicated than I want to get into. A spare pump was a really simple choice, requiring very little work to be 100% ready to go. (just have to connect that cigarette plug, or even could connect the wires directly)
I had taken it all apart to install the float valve and intended to cut a bit bigger piece of shade cloth since the one I had was a little too small, then got in a hurry to get it running to test the float and forgot. It didn't leak badly, but I'd rather it didn't leak at all, especially since it'll be close to my yurt and I don't want any water leaking under my walls, so I'll use shade cloth on the playa. Of course I could put a coaster under it to collect any leaks (and probably will just as a fail-safe), but I want all the water to stay IN the cooler because our water sources are limited. 
