[thingstodo]

I switched out the lawn tractor battery to an older and less useful small car battery that floats at about 7V. It should take a bit more current.

Well, actually it takes a lot more current. The DC/AC converter trips on low input voltage. The clampon shows somewhere over 12A just before the inverter shuts down on low input voltage. That's a bit higher than I wanted to go.

So one 12V battery gives me 0.3A. Another gives me 14A. I'd like somewhere between, at about 4A.

After searching through my junk pile a bit more, thinking about what I could use to limit the current to charge the batteries, I decided to try an old toaster.

I plugged it into an outlet first and heated it up. Then, after it popped, check the resistance with a meter. It's about 16.4 ohms when I get the meter on it. I'm sure it was hotter before that. When I connect that in series with the NiCd batteries to limit the current, instead of the 12V battery, it appears to work.

The current is 26A into the inverter, and about 2.1A out of the DC of the inverter. The output voltage is only 138.1V. The battery string measures 101V. So the difference, 37V at 2.1A, calculates to around 17.5 ohms in the toaster heating element.

I'd like more charging current, so I boost the 12V into the DC to AC inverter. The output voltage climbs to 144.5V and the current rises to 2.4A. I forgot to check the battery voltage, but they are a large load so it's pretty safe to assume they are still 101V. 43.5V at 2.4A gives 18.1 ohms. That seems odd.

Going back and thinking about this, the toaster - with 120VAC across the resistor, allows about 12A. That works out to 10 ohms when the toaster gets really hot. So as current rises, the resistance goes down, but only to a point. The resistance should not have risen to 18.1 ohms fro 17.5 when the current went up. I'll have to think about that one.