Friday, November 20, 2015


Yes. I might have to lie down in a darkened room for a few weeks. I went shopping and it was expensive! My 10-2 electric cable was double what the price of 12-2 cable would have been. Still, I now have a cable suitable for outdoor use and capable of carrying 30 Amps.

While I was out I picked up some plastic tubing and connectors. Not so much as to keep the cable dry underground but more to protect it from an errant shovel.

Next on the list was bolts to make an electromagnet but while I was in the store, I picked up some "super strong" magnets instead that I thought I'd try with the existing Chinese electromagnets. And of course a sledgehammer.

Needless to say, when I tested the super strong magnets against each other, they repelled nicely. Putting them on the electro magnets did nothing. Whether the current was forward or reverse, the electro magnet did not repel the super strong magnet. It's all really rather odd and seemingly defies the laws of physics.

Needless to say, when the total topped $100 I needed to go for a lie down! The electric cable was the most expensive part. Thinking about it though, with the way my motorhome is set up, I could get away with just 20 or even 15 amps. I could have put a 20A outlet in the yard and saved the $30 on cable but had to spend $20 on a lower rated breaker for the bus. Given the saving would have only been overall $10 I went with the bigger cable.

I had a look at solar panels and lithium batteries online. Then I sat and did some calculations. My maths for my microwave is wrong. I'd been reckoning on needing to use it 3 times a day and to cook a plate full of food from frozen which takes 15 minutes. As there will be only a cooler in the bus and not a freezer, nothing will be frozen. Thus, it will likely take only 5 minutes per plate.

5 minutes per plate is around 8 amp hours. Given the microwave will pull less than 100A then a smaller lithium battery should do. They can put out 100A continuously without breaking a sweat. Still, even a 30A lion battery is ludicrously expensive at around $200-$300. The low weight is very tempting as is the long life.

Thinking about power, I really don't need much. The cooler can be kept cool overnight using freezer blocks and powered straight from solar panels as can ventilation. It's only cooking that needs battery power. That and charging cellphone batteries. I could probably be very happy with 40AH.

Looking at solar panels, it seems an expensive way of doing things. It seems to be $2 per watt for solar. Given that a 40Ah battery would contain 480 watt hours and that would be about what is used in a day, I'd need to generate about 500wh. That means two or possibly 3 solar panels to be able to use the microwave three times daily. That's an expenditure of $600 on solar panels plus $300+ on batteries. Add in other stuff such as charge controllers and inverters and the cost would top $1,000!

Going back to minimal power usage, if the cooler was powered solely from solar panels then a smaller lead acid deep cycle battery would do all my cellphone etc charging. Thus, I could potentially get away with just a 20ah battery. Cooking would have to be done with gas and there'd have to be a battery powered extraction fan to eliminate the steam.

Again, solar power looks like being way too costly. I'm wondering again about wind power. Now that I have a welder, it shouldn't be hard to put together a wind turbine, even if it only runs a bicycle dynamo. That should still provide ample power to charge such small batteries.

Thinking more about the microwave, since a $3,500 lithium battery would hold 300ah, that would probably keep my minimal 30-40ah daily going for at least a week. Plugging in once a week would eliminate the need for solar panels.

Now, given 5 hours of half sun per day, the power needed to fill a 300ah battery would be 3,600Wh which would be 1,500 Watts of solar panel or 15 panels at a cost of $3,000. Basically, the perfect electrical system would be around $7,000. Now you can appreciate why I put a plugin for the microwave! Look at the prices of lithium batteries.

So, to recap, I'm probably not going to use much in the way of battery power since batteries and generation are expensive. I'll probably get more solar panels but rig them to hang inside the cockpit where they'll be protected and will afford added privacy.

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