sunset_over_ypsi1.jpg (389444 bytes)Northern Michigan Solar Cabin

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Xantrex C12 Charge Controller, 12A, 12V

Last week of March, 2007

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Latest Diary entry:

3-30-07

After rooting around on the web for a while, I've come across some sites that sell bits and pieces that off grid homeowners might be able to use. Yandina has some products that allow you to combine AGM and lead acid batteries, 12/24 volt automatic switches and other handy devices. For as long as this is active, here is an interesting discussion on exploding battery banks in industrial settings - we'd all do well to follow the advice here.

I don't care who you are, this little tool is interesting for locating your solar panels.

And finally the data you've been looking for, excerpts from the NREL redbook!

3-28-07

If you read the diary entries from last year, I had left the battery bank at the cabin hooked up to the 90 watts of solar panels I had up there. This worked great for weekly trips. However, on the occasion I wasn't able to get there for three weeks, the bank went flat (as in 11.8 volts per battery), which required long term cycles of charging and discharging to get them back to full capacity. This year I'm going to try something different. I don't know what that is yet, but I don't want to kill batteries needlessly.

Well, the diary entries are coming hot and heavy as the first trip to the cabin approaches. If you watched the first episode of "This Old Shack" you saw how to make cables for your battery bank. I'd been using store bought cables - they corroded in less than 6 months of use so I opted for copper connectors and thus I showed you how to make them and build a battery bank.

While checking over the type 31 batteries in the large bank (see here) I found one that was very low on water. That's bad. Somehow I missed it so I'm drawing up a regular maintenance schedule that's better than the old one.

I have also created a new scheme that's between an RV and a cabin set-up. We'll see how that works (I'm not holding my breath). The second episode of "This Old Shack" will be filmed this coming weekend so stay tuned for more explosions!

3-27-07

There has been an update to the first episode clarifying series battery bank connections. See the link at left. 

3-26-07

The first episode of "This Old Shack" is in the can, edited and now available for viewing! While filming, I was able to get some actual work done; I made new cables for the the small bank, connected a 12volt power outlet to it and ran a 12 hour test at 9 amps using the laptop.

It's starting to look a lot like springtime! The snow cover in northern Michigan is gone, the weather looks "good" for next weekend, soooooo. It may be time for the very first trip to the cabin of the year!

3-20-07

I started to do the first episode of "This Old Shack" but after stammering into the camera for a half hour I decided to wait for a more opportune time. 

If you remember from my last entry, I've labeled all the batteries and split them into two planned banks, Large and Small. The large one for inverter use, the small one for 12 volt power use.

From testing here at the house (our southern hacienda) I've discovered that I can get up to 12-16 hours from each small battery running a typical 12 volt load, or around 30 hours when running as a bank

After the first two tests where I place a constant 6 amp load on each battery individually, I discovered that the charge time for each one (S1, S2, S3) varied. By a lot. How I did this was by charging each unit from a 70% charge to full charge (according to the Schumacher Smartcharger) at a 2 amp rate (Note: yes, this isn't a real world example. While at the cabin, I charge at 30 amps

 in order to bring the batteries up to full charge with as little stress as possible. What I noticed is that battery S2 got to 90% and stayed there. A loooong time. At a charge rate of 8 amps, it came right up to a normal charge. What I've done is equalize the battery with my manual charger and will test it again tonight. The other two small bank batteries are performing nominally (note to self: gotta start using more NASA like terms - call it NITWIT: Nasa Infusion of Terms With Interesting Testing) and don't look like they're a problem, even the one that did in fact give me problems when it was new.