running one big battery

[cosmic]

Question...  I hooked up one big battery insted of 2.   It's out of a Mac dump truck so its 3 times the size of one of the originals.   Still 12 volts.  I could turn the 440 over for an hour - lol!   I would not want to change the starter next.  I put the 2 positives to the positive of the battery and the one neg to ther neg. of the battery or vice versa and got rid of the cable that joins the 2.  Now 800 kms and 5 weeks later my alternator is in getting rebuilt but, it was old.  Now I know i'm risking draining the battery and having a problem when it comes to starting, but i'm willing to take my chances. I'm only camping a few times this year and I'm plugged in at the sites.
will this cause any other problems?
? i??
cosmic
1975 brave d21 440

[weretrees]

If you have the starting battery hooked up to run the rv 12 volt system then you could be feeding the alternator with amps from the converter when hooked to 110. May need to isolate.

[cosmic]

So what would amps to the alternator do if the rv key is turned off. I thinking that if i started the motor and had the 110v pluged in then i would get a double wammy. Hm?
Any other thoughts on this? there must be a reason for the 2 batterys besides the chance you could strand your self if you were to run the lights and fans too long. i??

[DaveVA78Chieftain]

Two battery setup is due to each batery being made to support different puposes.  The chassis starting battery is designed to provide high current for short periods for starting.  It also can be recharged rather quickly.  This is due to the design of the lead plates inside.
The coach battery is intended to be used at much lower current drains over longer periods of time.  The plates inside are beefier and thicker.

Can one battery be used for both functions?  Yes, however because of the design differences, the battery may not last as long.

The diodes in the alternator will prevent any damage to it.

Dave