Lost Power

[Brian B-P]

Originally Posted by cpaharley2008

I guess it is a good practice to replace cables when you replace batteries, similar to new tire valves with new tires.

It shouldn't be necessary. Most of my vehicles have never needed a battery cable replaced, and I consider replacing any vehicle before a quarter million kilometres (barring collision damage) to be a failure of either vehicle quality or maintenance. An inspection of the cables would certainly be appropriate.

I did have to replace the negative cable's terminal on our van, and it continually suffers excessive corrosion, suggesting perhaps the type of battery leak which John described.

[Brian B-P]

Originally Posted by John in Santa Cruz

I wish I had a proper load tester.
...
I suppose I could build something with a 1 ohm dummy load...

For just the load resistor plus a simple analog meter (intended for basic load testing), a commercially made tester is cheap.
100 Amp 6/12V Battery Load Tester
I have something similar, but from a Canadian supplier.

[John in Santa Cruz]

Originally Posted by Brian B-P

For just the load resistor plus a simple analog meter (intended for basic load testing), a commercially made tester is cheap.
100 Amp 6/12V Battery Load Tester
I have something similar, but from a Canadian supplier.

those are for testing starter batteries, they give you a rough read on the CCA capacity. I want to measure the AH at a discharge rate of 10 or 20 amps.

ah, THIS is something like what I had in mind.

https://www.banggood.com/150W-Consta...p-1255707.html

[cpaharley2008]

Originally Posted by John in Santa Cruz

is that meant for 12VDC or 120VAC or what? 1 ohm at 12VDC is 144 watts. 1 ohm at 120VAC would be 14400 watts, way more than a typical house circuit can deliver.

John, is that number correct or is it 1440 watts?

[John in Santa Cruz]

Originally Posted by cpaharley2008

John, is that number correct or is it 1440 watts?

120 volts into 1 ohm is 120 amps.

120 vollts * 120 amps is 14400 watts

its Volts*Amps = Watts, and Volts/Ohms=Amps, so Volts*Volts/Ohms = Watts

[tdf-texas]

Originally Posted by John in Santa Cruz

those are for testing starter batteries, they give you a rough read on the CCA capacity. I want to measure the AH at a discharge rate of 10 or 20 amps.

ah, THIS is something like what I had in mind.

https://www.banggood.com/150W-Consta...p-1255707.html

That's a nice tester!

I'm cheap so I just turn on my inverter, plug an electric heater into a powered outlet and measure the amp draw on the Victron battery monitor. It works.

[alanmalk]

Originally Posted by John in Santa Cruz

is that meant for 12VDC or 120VAC or what? 1 ohm at 12VDC is 144 watts. 1 ohm at 120VAC would be 14400 watts, way more than a typical house circuit can deliver.

For the typical hot dog we would have to compromise. 144 Watts would warm it up after a while, but 14KW would turn it into toast in seconds. A couple of Escape 160-190 Watt panels should work...

[John in Santa Cruz]

Originally Posted by alanmalk

For the typical hot dog we would have to compromise. 144 Watts would warm it up after a while, but 14KW would turn it into toast in seconds. A couple of Escape 160-190 Watt panels should work...

I figger 14KW could make a radiant dog roaster that does a few 100 dogs/minute

[alanmalk]

Originally Posted by John in Santa Cruz

I want to measure the AH at a discharge rate of 10 or 20 amps.
...

How about a constant current load, as in a Current Mirror? These examples will require a $15 MOSFET, a $25 heat sink, a dozen power resistors (surplus) and a handful of small parts.

--
Alan

[John in Santa Cruz]

Originally Posted by alanmalk

How about a constant current load, as in a Current Mirror? These examples will require a $15 MOSFET, a $25 heat sink, a dozen power resistors (surplus) and a handful of small parts.

--
Alan

I think that's pretty much what the tester I linked from banggood.com does. combined with an embedded micro to do the integration and projection to AH

[alanmalk]

Originally Posted by John in Santa Cruz

I think that's pretty much what the tester I linked from banggood.com does. combined with an embedded micro to do the integration and projection to AH

Ahh, but why purchase when you can scrounge for parts, spend at least triple $, spend hours in a cold basement with a hot soldering iron wrecking your eyesight & lungs, and generally earn a reputation (perhaps deservedly?). I offer myself as the perfect example of misguided ambitions...
--
Alan

[John in Santa Cruz]

Originally Posted by alanmalk

Ahh, but why purchase when you can scrounge for parts, spend at least triple $, spend hours in a cold basement with a hot soldering iron wrecking your eyesight & lungs, and generally earn a reputation (perhaps deservedly?).

BTDT, and have the solder burns to prove it.