3 new batteries...rv not starting

[rvcruiser]

Bought 3 new Interstate batteries (1 start, 2 house). Connected all, turned key, engine started. Started gennie. Ran engine and gennie for a bit then shut all down. Plugged power cord back in. About two hours later tried to start engine. Totally dead but did start by using aux start switch....ran engine for about 20 minutes, shut off, turned key again... Nothing!
Dealer said batteries were "ready to go".
Any suggestions what to try next? Trying to get everything ready to head south and out of this freezing weather.

[rvcruiser]

Again...thanks to all who responded and sorry it took me so long to update!:o
It was the simplest fix....positive terminal on the new starter battery was just the slightest bit loose.

p.s. Cannot believe the quick start of the engine with the 1000 cranking amps. Now just counting the days to leave for the south.

[RJsfishin]

Maybe you din't need new batts. Maybe you just needed to fix the problem you're still having ??

[opnspaces]

I'm also with BFL, check your battery posts and terminals. It sounds like you have a loose connection.

[rvcruiser]

Thanks to everyone who took the time to respond. Will try all suggestions tomorrow in daylight (and warmer weather). I will let you all know the results.

[MEXICOWANDERER]

I agree with BFL

Stick volt meter probes to POST of chassis battery then try to crank. What do you see?

[BFL13]

Loose connection at a starting battery post? Worked once then not next time. Dead means no connection at all, not a low battery which would try to start it but fail.

[MNtundraRet]

If you went in, purchased the batteries, with no time to fully charge the batteries before taking them home, they were not fully charged. You would have needed to make sure the batteries were connected via "disconnect" switch and allowed to charge at least over night.

Did you check battery voltage with a multi-meter? Should have been 12.6+ volts. With the converter connected the voltage should have been 13.6 volts, or 14.4 volts for charging (13.2 volts if fully charged and maintaining).

I would suggest that the batteries were not charged, or you may connected the batteries wrong (missing ground or reversed battery(s).

[raygreg]

one of the batteries is hooked up backwards?

[Ranger_Smith]

Sounds almost like alternator is not charging start battery. Converter seems to be working as house batteries are getting charged and are starting coach when aux is pushed. Could also be bad ground on start battery. Get motorhome started and check for 13.6 to 14.2 volts on start battery when running

[John_Wayne]

Put a meter on the batteries and what type of reading are you getting? Are you sure your converter is working ,should be close to 13 volts if converter is working.