Not for a while!
SteveW
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10 years ago
Call me wanker - again
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10 years ago
Probably this is because you're talking cars and I'm talking motorhomes, where the charge rate of the various batteries is of great interest.
No you don't. All you do is break the main battery feed after the starter solenoid and take cables to the ammeter shunt. If you like you can put the ammeter shunt right next to the take-off point and then run thin wires to the actual ammeter. It's a piece of piss. For anyone who takes an intelligent interest in the state of their batteries it's essential. But obviously it isn't necessary on yer little Ford Focus or whatever.
Bill
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10 years ago
I didn't know there's been a recent revision of the laws of physics.
How can you get a meaningful measurement across something that has to have the absolute minimum resistance? What two points would you measure across? What if the resistance of the path between those points altered due to corrosion? "Oh look! The battery is being charged at 2,000A! Or maybe there's a bit of corrosion on the earth strap terminal..."
Bill
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10 years ago
In my experience once there's a hard on the chances of failure are low.
Bill
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10 years ago
That's what they did with my hand.
Bill
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10 years ago
The case for the prosecution rests, m'lud.
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10 years ago
And we're back to the thread title.
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10 years ago
Mornington Glory?
Jim K
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10 years ago
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10 years ago
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10 years ago
Sounds like a viagra advert.
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10 years ago
You calibrate the device to show zero current flow when there is zero current flow. Far easier to do with electronics than to try and make a suitable shunt at home.
Maplin did a kit for just this about 20 years ago. You could either have it drive a bi-colour LED - red for discharge, green for charge, amber for balance, or a centre zero meter. The beauty of it is you don't need high current wiring to a conventional ammeter in the dash. And it can't be overloaded so can be in the same circuit as the starter motor.
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10 years ago
You've got a toe on your hand?
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10 years ago
You're just acting daft now. But I'll play ball. That resistance you mention. It's always extremely low. Normally it's a shunt. So if you're planning to (I quote) "measure the voltage drop across say the earth lead to the battery" the resistance of that lead and its connections are crucial to the measurement. The tiniest variation will affect the reading a lot. So you can't use something that might corrode or even flex a bit as a shunt.
Bill
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10 years ago
Yes. I knew that surgeon was an apprentice.
Bill
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10 years ago
Umm, yes, I s'pose we did live in ours solidly for 18 months, 22 countries and 40,000 miles...
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10 years ago
Define 'extremely low'.
As are those to the shunt within an ammeter.
Probably why you don't find ammeters on cars these days.
Try reading my last post. Carefully.