DiploStrat
Expedition Leader
May be time for a new thread on the eternal question of charging auxiliary battery banks. The equation is rather simple if you have two batteries of the same size and the same construction (i.e., FLA, AGM, Gel) connected by a short cable of adequate size - slap a solenoid between them and be happy. (And avoid most diode based systems.)
But most of us want a system with some of these characteristics:
-- Starter battery optimized for vehicle start - lots of cranking amps for a short time.
-- Camper battery optimized for long term discharge - relatively low amperage discharge for a long time, a so called "deep cycle" battery.
-- For various reasons, vibration, ease of mounting, etc., most of us are using AGM batteries for the deep cycle camper side.
So now we have a problem:
-- Modern vehicles seem to be moving to calcium/FLA batteries with charging circuits that commonly run as high as 15.5v (E.g. 2013 Chevrolet 3500HD)
-- Common AGM batteries are limited to a charging voltage of 14.4v.
Feeding a voltage over 14.4v to an AGM battery will dry it out quickly and, as they cannot be topped up, kill them. (Lifeline sent me a sharp warning!)
The 15.5v, confirmed by a voltage meter and a review of the GM manual has caused me to toss my solution out the window. The controller that I was going to use took one look at the 15.5v, declared an over voltage, and shut down. Bummer as I was getting a nice 190Ah at the camper batteries. ;-(
Soooooo,
-- Any one dealt with this problem?
-- And if you are simply using a solenoid: 1.) What voltage are you seeing at the AGM batteries, and 2.) What amperage are you seeing?
But most of us want a system with some of these characteristics:
-- Starter battery optimized for vehicle start - lots of cranking amps for a short time.
-- Camper battery optimized for long term discharge - relatively low amperage discharge for a long time, a so called "deep cycle" battery.
-- For various reasons, vibration, ease of mounting, etc., most of us are using AGM batteries for the deep cycle camper side.
So now we have a problem:
-- Modern vehicles seem to be moving to calcium/FLA batteries with charging circuits that commonly run as high as 15.5v (E.g. 2013 Chevrolet 3500HD)
-- Common AGM batteries are limited to a charging voltage of 14.4v.
Feeding a voltage over 14.4v to an AGM battery will dry it out quickly and, as they cannot be topped up, kill them. (Lifeline sent me a sharp warning!)
The 15.5v, confirmed by a voltage meter and a review of the GM manual has caused me to toss my solution out the window. The controller that I was going to use took one look at the 15.5v, declared an over voltage, and shut down. Bummer as I was getting a nice 190Ah at the camper batteries. ;-(
Soooooo,
-- Any one dealt with this problem?
-- And if you are simply using a solenoid: 1.) What voltage are you seeing at the AGM batteries, and 2.) What amperage are you seeing?
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