electrical confusion on 08 bus

You have a 08 Tiffin Bus.
1. The battery tender is for the chassis battery ONLY. It works as your chassis batteries were up and started the engine
2. Your 08 Bus has a Inverter/Charger which will keep the Coach batteries charged. Since your chassis battery tender was working, your bus had 120 power in storage. The Inverter/Charger is automatic, so either the coach batteries are BAD( probable since they are 6 years old if original) and boiled dry. Check the coach battery water. BUT, even if they are DEAD, the Inverter/Charger should have supplied 12 volt power. There is an exception to this. IF the batteries went dry or could not charge, then some model Inverter/Chargers will shut down and not charge until you put a good battery or surface charge to reset the Inverter/Charger. Also, on your Tiffin, there is a 250/300 amp fuse between the battery and the Inverter/Charger that may be blown. If the coach battery water is low or gone, REPLACE the batteries. Doug

One of the reasons I keep hammering on TRUE DEEP CYCLE like six volt Golf Car batteries over Marine/Deep cycle batteries is this.

In the 8.5 years I've had my Interstate U-2200s (A GC-2 size Golf Car battery) they have been run down to the point where lights won't give off noticable light a few times.. More times than I care to admit.

Still, they lasted eight and a half years.. They came back over and over again.

Alas, the last time (Shorted cell) They did not.

But I'd say tney have recovered at least 10 times.

Starting batteries run down that far... Generally do not recover, this includes Marine/Deep cycle.

SO, the moral of this post: Charge 'em back up and see what happens. Don't get out your checkbook before tomorrow at the earliest.

Most batteries don't do well if discharged to 0% charge state for any length of time. Watch your battery performance when you get them re-charged back up. Alot of folks usually has to replace them when this happens.

This is why alot of folks will get a complete battery disconnect method installed to switch out the coach systems from the batteries when stored.

Just something to watch out for...
Roy Ken

Your chassis batteries are for starting the coach. The house batteries are for everything else. While in storage, many parasitic draws attack the house batteries..propane detectors, carbon monoxide detectors, clocks in the dash radio etc. etc. Those are what run the batteries down. Our coach has a couple large solar panels on the roof to replenish what those draws take out. Your coach may be different. Often parasitic draws take place even if you turn the switch for the batteries off. The only way to ensure everything is disconnected is to disconnect the batteries at the post with a knife switch.

Regardless of the above, post the year, mfg, and model of your coach and someone with that model could tell you if yours is operating as it should. There are many variables as each mfg puts different options on every model, so what might be on mine may not be on yours. That said, you want to ensure everything is operational that should be on YOUR coach....Dennis

Without power in storage you'll need a solar panel to keep your house batteries charged if you do not disconnect them. Do you have a solar panel on the roof? Most engine batteries will stay charged as other than the radio memory there is not much else that stay on. Sounds like your"battery keeper" needs 120V power.

The battery keeper as I understand sends excess charge from the house batteries when they are being charged (when you are plugged in) to the chassis batteries to maintain them . Since you aren't plugged in , no charging is taking place so the keeper does nothing.
You have a drain on the house batteries co2 detector etc or something left on .

Battery keeper will probably only work if you are plugged into 120VAC. Dead house battery after five weeks? Sound about right. Parasitic power draw in the house can kill a single battery in a matter of days. If you cannot connect to shore power, consider adding a medium sized solar panel to the roof and have it connected to the house and chassis batteries. While it may not fully charge a depleted battery, it would more than make up for the low current draw items. Also consider turning off the battery disconnect switch when parked in storage.