Hi,
Sometimes it is possible to damage a alternator by not having the battery charged when you hook up to it. Read a warning sticker on all replacement alternators and it will say "Warranty void if battery is not charged prior to installing".
DOn't know if you damaged the alternator or not. You can also damage your alternator when jumpstarting a friend's car too. It has to do with connecting to the 10 volt battery, and having your car alternator put out the maximum amperage for say 5 minutes while jump starting the other vehicle. It is much better to do what you did, and use a jump start portable battery pack.
When I jump start a friend's car, I hook up the cables with my car running for about 5 minutes, then shut mine off just before telling them to start their car. Then the battery will get about a 10% to 15% charge over that 5 minutes, then use both batteries to get the amperage to start the car.
Plug in the RV to 120 volt power, you will need to charge both the coach battery (that runs things while camping) and the engine battery. You might be able to use both of them again, if you can charge them for say 24 hours on a 10 amp portable charger (the coach battery will charge fine on the built in charger).
If the battery will not hold a charge, then replace it. Consider it like a tank of gas, something you have to replace every once in a while, and more often if you let it sit long enough to discharge the battery all the way. You do not replace the battery each time it discharged all the way, but it only takes about 10 - 20 times discharging the battery all the way to destroy a otherwise should have been good battery.
Keep the RV plugged in if you can, or install a 100 watt + solar system, so that the battery will stay full. The RV will consume about 35 amp hours daily to run the CO meter, propane leak detector, and refrigerator. Most CO meters have two inputs, and are connected to both the RV coach battery and chassis battery. It can discharge both batteries.
So manufactures started installing 'master shut off switch' to disconnect all power from the battery to the RV. If they are off, then that should protect the battery - even if unplugged for say a month or so. Any longer, and you will still need to charge the engine and coach batteries.
Many recommend starting the RV once a month for say 10 minutes, to both recharge the batteries and lubricate everything. Keeps the seals from drying out and leaking.
Good luck,
Fred.
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