6 volt battery problem

Check the fluid level in the batteries. If they're quite low on water they won't take a charge. Also feel the sides of the cases to be sure they're not oveheating thus off-gassing. This would be the result of an internal short most likely. There is nothing about discharging them 70% that SHOULD cause them to fail completely though it's never a good idea to do this often. A good set of 6 volt batteries should easily recover from even a deep discharge. The REASON they were discharged when you picked up the RV was that it was likely not connected to 120 volt AC power while at the dealers. I've never had a dealer hook mine up while they have the trailer. I just disconnect the negative lead when I drop it off, put a note on the door telling them that the batteries are isolated and they hook them up if/when they need to. Otherwise they are returned nearly fully charged.

Give it time. You may be yelling "fire" before someone shows up with matches.

quote:
. If the batteries are very low to begin with, the charger will be putting out over 14 volts.
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Not true.
Very low batteries could start as low as 12.8 to 13.2, at maximum amperage.
As the voltage comes up, the amps taper down. You will not see 14+ volts till batts are 70-80% ??

30% of 12.6 volts is approximately 3.78 volts. Is this what you are measuring?

In any case, you're correct in assuming your on-board charger should have kept the batteries at a full charge or better...typically a float to absorb charge is 13.2 to 13.6. So, it seems either you have the batteries disconnected from the system, or your charger isn't working properly.

With the TT plugged into shore power, what is the voltage measurement on the batteries? If Charger is working, you will not measure less than 13.2 volts. If the batteries are very low to begin with, the charger will be putting out over 14 volts.

Make sure your battery disconnect switch is in the on position. Measure and let us know what you find.

Ron

What is the voltage at the converter output?

Hate to say it but from past experience of what others have reported it probably has done your batteries in. You may be able to get them back again but they will most likely not be at the same new performance before they was discharged below the 50% charge state.

I have never returned any of my trailers back for warranty work but if I did I would most definitely remove my large expensive battery bank and let them deal without a 12VDC battery source. I might connect up a Lawn Mower 12VDC battery to get me to the dealership and be legal with DOT safety regulations.

We have alot of money invested in our battery banks and you know the dealership is not going to replace them if they were discharged during the time the trailers set in their shop.

Just my thoughts here
Roy Ken

How are you measuring the 30%?