Thread: Alternator Performance

Wrong thread

Originally Posted by Mundy

Do you know off hand what the internal resistance of an AGM battery is? I am guessing around 0.08 ohms but is it constant through the charging cycle?

Hi again Mundy and sorry mate, this is one thing you need to get from the manufacturer of your specific battery as, and I might be wrong here, but I think you will find it is something that varies from one type of AGM to another and from one size ( Ah capacity ) to another.

On DC/DC advertising, and one thing that really annoys me is the lack of “full discloser” with the way they sell these devices.

I have continually sort graphs of any form, that show the comparison of how an alternator, operating at a given voltage, charges a give sized battery from a decent discharged level, as compared with how a specific DC/DC device would do the same charge.

With such a graph, people like yourself, who spend the time to research these things, would get an honest idea of how well each device works and then you could make your own decisions as to what really works.

A company called Ranox ( not sure they are still around ) and Ctek in Europe, both had graphs but both started with batteries at 75% SoC. Had they started with batteries at 50% SoC, a common use discharge level, we could have had a real comparison.

The problem for both makers is that at just 70% Soc, it would be break even between an alternator and a DC/DC device and for an SoC of 50%, their graphs would show the alternator, even one running at as low as 13.8v, would be the clear winner.

So I suppose it speaks for itself why they don’t post up such real world details.