Montana Owners Club - Keystone Montana 5th Wheel Forum - View Single Post

bsmeaton · 10-09-2006, 08:13 AM

Wow CAT - that must be a GMC exclusive and a nice feature.

There is a problem with keeping charge on the RV batteries from the vehicle. Essentially the TV alternator is regulated by voltage, such that around 14V the amperage output from the alternator is minimized to prevent overcharging. When the Monty is plugged in, this voltage is measure across all three batteries as one. It is common that your TV battery is freshly charged and overcompensates for your RV batteries causing the alternator to stop charging even though your RV batteries are not fully or deeply charged (they obtain a surface charge). My class A had a three battery isolator system that ensured each battery was measured independantly and recieved a full charge. I've often wondered why trailers didn't use something like that, or if it would help to add one. It sounds like your GMC has a feature to overcome that.

10-09-2006, 08:13 AM	#2
bsmeaton Montana Master Join Date: Aug 2006 Location: Lone Tree Posts: 5,615 M.O.C. #6109	Wow CAT - that must be a GMC exclusive and a nice feature. There is a problem with keeping charge on the RV batteries from the vehicle. Essentially the TV alternator is regulated by voltage, such that around 14V the amperage output from the alternator is minimized to prevent overcharging. When the Monty is plugged in, this voltage is measure across all three batteries as one. It is common that your TV battery is freshly charged and overcompensates for your RV batteries causing the alternator to stop charging even though your RV batteries are not fully or deeply charged (they obtain a surface charge). My class A had a three battery isolator system that ensured each battery was measured independantly and recieved a full charge. I've often wondered why trailers didn't use something like that, or if it would help to add one. It sounds like your GMC has a feature to overcome that.