Charging from truck charging system
Have a 2014 W&P and for the most part have had very few issues until this week. 1. When going down road the battery will not stay charged by truck Alt. 270 amp. Alt can handle this. The refe...
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Mex ..... I don't EXACTLY see happening in our Winnebago+Ford E450 motorhome what you're describing.
On the cab dash I have two four-place digital voltmeters and one three-place digital ammeter. As we travel, with these instruments I can see what the alternator does to both the engine battery and coach batteries. I see the voltage on the engine battery terminals, the voltage of the 12V system in the coach (slightly lower than the actually voltage on the coach batteries' terminals because of small loads on the 12V system dropping the voltage at the point where the digital voltmeter taps into the coach's 12V system), and positive or negative current flow into or out of the coach batteries. After 3-5 hours of driving, our 230 AH AGM coach battery bank always gets fully charged from the alternator when starting out from our campsite with the coach battery bank reading 12.0 to 12.1 volts.
When we start traveling down the road with the coach batteries being discharged, the alternator will indeed hold 14.XX volts on the 12V system in the coach (thus the actual voltage on the coach batteries' terminals being even higher) for quite some time while the ammeter shows a continuing decline in the current flowing into the coach batteries as they charge up. It takes warm weather for the voltmeters to begin indicating less than 14 volts right too soon. I don't know how Ford's alternator, or Ford's sensors, or Fords' ECU, or something in Winnebago's design/equipment does this ... but eveything seems to play together well for all three batteries at various states of beginning charge and at various underhood and/or outside air temperatures.
It seems to me that the problem of a modern towing vehicle not properly treating a towable's batteries boils down to one thing -> the cable size between the engine system and the batteries not being large enough. A long, heavy cable cable going back from the engine alternator's output to the TT's or 5'er's battery(ies) does not have to be overly expensive. Just start fabrication using the super long big rig battery jumper cables like you can find on the Internet or at truck stops - these are much cheaper (and very flexible, too) than buying large size flexible/limp cabling from an electrical supply source.
By the way, a truck camper should be set up the same way ... with large size cabling between the truck's alternator system and the camper shell's battery bank.
On the cab dash I have two four-place digital voltmeters and one three-place digital ammeter. As we travel, with these instruments I can see what the alternator does to both the engine battery and coach batteries. I see the voltage on the engine battery terminals, the voltage of the 12V system in the coach (slightly lower than the actually voltage on the coach batteries' terminals because of small loads on the 12V system dropping the voltage at the point where the digital voltmeter taps into the coach's 12V system), and positive or negative current flow into or out of the coach batteries. After 3-5 hours of driving, our 230 AH AGM coach battery bank always gets fully charged from the alternator when starting out from our campsite with the coach battery bank reading 12.0 to 12.1 volts.
When we start traveling down the road with the coach batteries being discharged, the alternator will indeed hold 14.XX volts on the 12V system in the coach (thus the actual voltage on the coach batteries' terminals being even higher) for quite some time while the ammeter shows a continuing decline in the current flowing into the coach batteries as they charge up. It takes warm weather for the voltmeters to begin indicating less than 14 volts right too soon. I don't know how Ford's alternator, or Ford's sensors, or Fords' ECU, or something in Winnebago's design/equipment does this ... but eveything seems to play together well for all three batteries at various states of beginning charge and at various underhood and/or outside air temperatures.
It seems to me that the problem of a modern towing vehicle not properly treating a towable's batteries boils down to one thing -> the cable size between the engine system and the batteries not being large enough. A long, heavy cable cable going back from the engine alternator's output to the TT's or 5'er's battery(ies) does not have to be overly expensive. Just start fabrication using the super long big rig battery jumper cables like you can find on the Internet or at truck stops - these are much cheaper (and very flexible, too) than buying large size flexible/limp cabling from an electrical supply source.
By the way, a truck camper should be set up the same way ... with large size cabling between the truck's alternator system and the camper shell's battery bank.
