Shore power but no battery power

[4Rajas]

Just took 2007 2720 out of garage storage where the batteries had been periodically charged using 2A charger. All running/signal lights were fine during brief tow around block and power jack is working fine. I have two batteries in parallel with one directly connected to power jack and the other with a simple isolator.

Problem i have is TM lights, radio, etc all work on shore power but not on battery power. I have checked fuse on tongue near batteries and fuses on distribution panel and they all look ok. No apparent corrosion on battery terminals either. Picture of battery setup is attached. Everything was fine last year before storage and i believe the wiring battery setup is correct.

Any ideas/suggestions to resolve would be appreciated! Have through the threads here but no luck so far...
Thx

[ShrimpBurrito]

Have you checked the water levels in the batteries? Since it was on a charger for so long, albeit at a low current, it is possible the water has evaporated and thus the batteries will not output any power. Also, if the batteries weren't charging for some reason, they may have frozen, possibly cracking the case. That would allow the acid to leak out, and thus quickly evaporate.

Dave

[B_and_D]

Have you checked the voltage at each battery? You'll probably have to disconnect them from each other to do so.

[4Rajas]

Checked voltage/continuity at isolator switch on battery and that apparently was the problem even though it looked brand new. Kinda obvious is hindsight i guess.

Replaced and the world is fine again before my first trip of the year next weekend.

Thanks all for replies.