Friday, December 21, 2012

Working the demand side

Well it is rainy and dark on the solstice, but I'm doing OK on electricity.

I climbed up on the roof, and it looks like my connections are all plenty solid. Unfortunately I got caught in the rain and had to redo the work once it dried off a few days later. But all is well up there. I see way less amp-hours of charging coming from it because.... it's winter, in the far reaches of the Northern Hemisphere, is why. Even in the heat of summer I'll never get full power from these unless I drive to Mexico or something.

The simple fact is that I don't have enough electricity to run even a 1A @12V notebook in winter, no matter what I do! So worked the demand side. I got one of these Android tablets with a keyboard. It's slow, and I really hate not having a real computer, but I've got it set up so that I can at least read, and surf the internet, watch videos, and even do some work (slowly). The advantage of the tablet? It's ARM-based and uses about 200mA @ 12V. That's right: about 1/4 the consumption of an Intel-based notebook. This one has a spare battery in the keyboard, and gets 9+ hours of use without even having to plug it in to my house batteries! Perfect for winter.

A little side note is that the fast-recharge capability of the tablet is triggered by USB3.0 voltages: give it anything over 11V and it'll bulk recharge quickly. So I hacked up a cable that was female USB on one side, and my Andersons (12v house system) on the other. Cheap, and effective, I just have to remember never to plug any normal USB 2.0 devices into this little cable, or they'll shut off (circuit breaker) or get fried (fuse)-- USB 2.0 expects 5V.

I also found out that I have to bulk charge these batteries using my 75A converter every few days, for at least a half hour to 2.5 hours or so. That sucks; it means I have to find places to plug in. So I'll have to buy a gasoline or propane genset. I don't like dealing with either gas or propane, neither the pollution nor the noise, but gas is so easy to find, and gas generators can be found for reasonable prices. The one I want is the Honda EU2000i. I'd get the EU1000i but my converter will pull 1300W when the batts are really low, and so I need at least a 1500W genset, which in Honda land means I have to get the 2000W one.

My holiday is going well though, reading and studying mostly, and getting used to the tablet. This old dog does not want to learn the new tricks, so I'm basically setting up the tablet as much like a laptop as I can. So far so good.

Wow, the tablet is a Google Android, running Google Chrome, and it absolutely cannot cope with Google Blogger's web interface. Come on guys, get it together, will ya?

Thursday, December 6, 2012

Dark for the first time in over 3 years

Well the van went dark today with no electricity, for the first time since Friday, March 20th, 2009. That was apparently the date that I switched over from my old PWM controller to my new MPPT controller, and that's the date it had stored in memory as "the beginning of time". It was very strange to not have electricity! I'd forgotten what that felt like.

I did this because, after over 4 years, my Concord Lifeline GP4 batteries finally had enough abuse for one lifetime, and I replaced them. That's not a great duty cycle for these things, but I really did not treat them well-- deep cycling them a few times and not charging them back up promptly. It had gotten to the point where, last week, a couple days of rain and not enough hours of sunlight (only 9Ah of charge for the full day!!) had worn the batteries down to 12.1V by end of night. I've been studying the battery status for the last 3 months, since I've had the PC interface for the Sunsaver MPPT.

I use, on average, 20Ah-30Ah a day, depending on how much work I have. About 10Ah of that is my refrigerator, the rest of it is my computer. If I travel somewhere hot in the summer I might use much more, due to running the fan (4A at full speed, all day and night), but there's usually enough sun to recover.

So I swapped out the old batteries with two new, but smaller, Lifeline batteries, so now I have only 250Ah total capacity, instead of the 420Ah I used to have. A little math indicates that I can run behind on charge for only a few days now, then I have to charge them up, otherwise I'll be making the same mistake again. I have less margin now, but, better diagnostics too, and I own a converter, which I didn't have for years..

For wintertime, I'm thinking I should either get another solar panel to bump up my charging capacity, or maybe get a Honda generator. But both are costly. In the meantime, I've got a few places I can plug in to shore power to run my converter in the winter to charge up. Or, if I'm travelling, I can find an RV park with hookups and pay the $50 or whatever they want for that. Still cheaper than a generator or new panel.

I also could get one or two more batteries of the same make/model, and hook them up in parallel, to be able to go longer before recharges. Lots of options!

So the new batteries are in, and I had to change some of the wiring and hack up some different mounting in my battery box too. I took pictures too; maybe I'll post them in the Vandweller's list photo archives.

I also got rid of that insipid Cobra inverter, the one that made so much noise. I only really used it for my laser printer, and then it beeped and complained when the printer warmed up about the load being too high. I might just run that on shore power only, or with a generator if I pick one up. I have two smaller-- and silent!-- 150W inverters I could use for any small things I might need to run. But these batteries were expensive, and I'm going to make some of that back by selling off stuff I hardly ever use and could do without, like the inverter.