Optimistic Paranoid
Adventurist
OK. There's a thread going on over on RVnet about charging house batteries with the vehicle's alternator, and something came up over there that I haven't run into before. Wonder if any of the electrical gurus here know anything about this? Parts of two separate posts:
"I don't like causing a slow death to my alternators diodes which increases the AC voltage ripple thru the dc system. Which in turn can slowly destroy the ECM, PCM and other electronic circuitry. It can play havoc with sensors as well. Smaller wires to the batts from the truck will help slow the amperage demands that sometimes are too much for the trucks alternator and cause damage to the diodes.
Best to charge slow off the truck (not big wires) or use Solar collector and/ or a small Quiet Generator. My camper walls are thin and you can hardly hear the honda 1000 watt gen even when raining and underneath the camper its quiet.
I suggest that all truck/ car owners check for AC ripple occasionally to keep dc system healthy. Esp. after installing a rebuilt alternator. Even new has been tested with too high of AC noise in the system."
And:
"Checking for AC ripple in your charging system is as simple as taking your digital volt meter and setting it on the AC scale and touching the test leads to your batteries while the truck is running.
.05v is a about as much as you want to see, .1 is generally considered a “fail”.
Depending on the alternator it may take some searching but you can get new diodes for most. Those are what stops the AC ripple.
Having an alternator tested at most auto parts places won’t help, they don’t usually check AC ripple, just 12v output. An alternator that flunks an AC ripple test will still pass their 12v load test.
"I don't like causing a slow death to my alternators diodes which increases the AC voltage ripple thru the dc system. Which in turn can slowly destroy the ECM, PCM and other electronic circuitry. It can play havoc with sensors as well. Smaller wires to the batts from the truck will help slow the amperage demands that sometimes are too much for the trucks alternator and cause damage to the diodes.
Best to charge slow off the truck (not big wires) or use Solar collector and/ or a small Quiet Generator. My camper walls are thin and you can hardly hear the honda 1000 watt gen even when raining and underneath the camper its quiet.
I suggest that all truck/ car owners check for AC ripple occasionally to keep dc system healthy. Esp. after installing a rebuilt alternator. Even new has been tested with too high of AC noise in the system."
And:
"Checking for AC ripple in your charging system is as simple as taking your digital volt meter and setting it on the AC scale and touching the test leads to your batteries while the truck is running.
.05v is a about as much as you want to see, .1 is generally considered a “fail”.
Depending on the alternator it may take some searching but you can get new diodes for most. Those are what stops the AC ripple.
Having an alternator tested at most auto parts places won’t help, they don’t usually check AC ripple, just 12v output. An alternator that flunks an AC ripple test will still pass their 12v load test.