Hi Tony, > Tony VE6MVP <t...@...> wrote: > Folks > I've been reading the low voltage disconnect thread with > a great deal of interest. Thanks for the tips and suggestions. > We're putting up a VHF repeater and two UHF link radios on > a solar/wind power site.
The event will be quite the learning experience... > Given Alberta winters what would you folks suggest as a low > voltage disconnect value to avoid the batteries freezing in > winter? Which can hit -40 for a few days. Are you planning to disconnect the batteries based on low voltage, (low/high) temp or both conditions? > Also we're thinking of having a backup power generator being a lawn > mower motor hooked up to an auto style alternator and a roughly > eight or ten hour fuel tank. If the batteries get too low then > we'll just attempt to get into the site, fire up that home made > generator and walk away. We'll make sure it looks like a rusty > piece of garbage so no one who wanders by is likely to steal > it. Any comments? The Gas Genset is kind of an inconvenient popcorn fart but heck any port in a storm when you've got nothing better. You might find a... or convert the gas motor to propane, try and find an electric start engine and have a timer and or logic from the Low Voltage Disconnect fire the charger system engine up and give the batteries a charge. Propane is a lot easier to deal with... and probably safer. Otherwise you can find TEG Thermal Electric Generators on the used market and they "in theory" have no moving parts. There are tricks you can use to discourage vandals, which can be talked about in direct Emails if you need that type of information. > (Apparently the snow drifts can get quite bad so we might > need to borrow a snowmobile for the last 400 yards or so.) A set of 10 gallon propane tanks are easier to haul than the equivalent gasoline tanks... less messy to use and safer. Propane engines tend to be self priming and that's a very nice feature. > We're thinking of putting the batteries in a chest freezer > disguised by thin plywood so it just looks like a box. We're > told by the site owner that a fridge looks way too much like > trailer trash so disguising it with wood should work. I'm > thinking we would put the charge controller in there for a > little heat and the dump load in winter Consider some of what I call non shinny diamond plate sheet metal cover plates shot onto the freezer box properly and strongly secured both to the ground and the box with safety screws and strong security head lag nuts. Put the wood over it if you like... but protect it first. Rare is the case where you'll have to dump generated energy unless your charging system is way overkill. Otherwise, use the load dump to heat the box or building. > Are we nutz? Have I asked some stupid questions? > Tony (history or the world...) It's spelled "nvts". Your questions are valid and Kris had some good ideas in his post. cheers, s.
