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Home » Public Forums » GMCnet » Fitting high capacity AGM's (what to buy and how to install? )
Fitting high capacity AGM's [message #367705] Fri, 26 November 2021 12:03 Go to previous message
boybach is currently offline  boybach   
Messages: 566
Registered: December 2020
Location: Vancouver Island
Karma:
Senior Member
Hi all, I'm in line to get a pair of used (but well within service life) Lifeline 300AH AGM batteries. They are big marine deep-cycle units weighing 90lbs apiece and physically able to fit in the battery compartment (if I can manage to pick them up, that is Smile )

These batteries

https://lifelinebatteries.com/products/marine-batteries/gpl-6ct/https://lifelinebatteries.com/products/marine-batteries/gpl-6ct/

John Lebetski, Bruce Hislop, Billy Massey and I have discussed the implications of installing these beasts, i.e. the effect on the alternator if used as a "drop-in" replacement without any modifications.

I have to admit that I don't understand the science or math behind the problem, but I do get the point that the alternator would be overworked constantly trying to bring the battery bank up from a state of low charge, resulting in a cooked alternator. We don't want that.

Charging from the Onan/shore power via the converter would be ok as my converter has an AGP accessory port.

The solution suggested by Bruce was to install a DC-DC charger and wire it in parallel with the converter. I get that. I plan to get either the 40amp or maybe the 20amp Renogy unit as they seems fairly affordable compared to the others I saw out there.

https://www.amazon.ca/s?k=Renogy+40A+DC+to+DC&i=automotive&ref=nb_sb_nosshttps://www.amazon.ca/s?k=Renogy+40A+DC+to+DC&i=automotive&ref=nb_sb_noss

Even though hooking up the charger "in paralell" to the converter may seem like a fundamental job to an electrician, I'm afraid I find it a mite intimidating, both as far as the physical location and hookup goes. At first I thought I could locate it in the electrical compartment next to the converter but because these Renogy units don't have auto switching and require an "ignition on" connection to switch on, I started thinking maybe the best place would be up front on the firewall?

If that location on the firewall is a possibility, could I also connect the main terminals of the charger there?

Do I need to fit a Yandina combiner too?

As the batteries (chassis lead-acid)are different types, will the AGP's drain the chassis battery or vise-versa? OTOH, am I overthinking this whole thing? Confused

TIA for any input,

Larry







Larry - Victoria BC - 1977 ex-Palm Beach "Ol' Leaky" 40,000 miles, PO said everything working but forgot the word NOT. Atwood helium fridge, water heater & furnace. SS exhaust system, Onan, Iota Converter, R134A, New fuel lines & heat exchange hoses
 
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