On Friday, March 28, 2014 5:34:47 PM UTC-7, Wayne. B wrote:
On Fri, 28 Mar 2014 17:25:50 -0700 (PDT), Tim

wrote:



What I'd recommend is that if you have a 55a alternator, I'd go with an isolator capable of

at least a 70a. load. A 70a. alt- 100a. load etc. . Always go at least a step higher amp isolator

than what your alternator is rated for.



I have a 120a. alternator on my '77 Marquis, and I use a 150a. isolator.



===



What is the forward voltage drop across the diodes in the isolator?

That was always an issue with some of the older isolators unless you

had downstream voltage sensing for the alternator.

I know exactly what you're talking about Wayne, but in this simple case, the "Bat 1" (engine)is direct and interrupted from alt to battery so you have the "voltage sense" being used. The alt to "Bat2" Is rectified, and you lose about a half volt (give or take) to the charge the"house" battery. So 'house' isn't quite the same charge rate and 'engine' but, for what a typical person would do with it, it's pretty good because, theres no back draw....

?;^)