Converter Replacement

[connie garcy]

We have a 1999 Sundancer 370DA and we have replaced the batteries many times over the years since 2006. The batteries keep boiling out, we turn off the battery switch before we leave and leave the converter on. Last year we changed out the battery isolator thinking that was bad being that it was the original. Could it be the charger has gone bad seeing it is the original.:huh:

 

[ttmott]

Assuming you keep having to change batteries then assuredly the charger (converter) or engine alternators are the issue. The converter is not isolated from the batteries by the battery switches FYI; at least that is how the 400DA is configured. So turning the battery switches off will not isolate the converter from the battery banks.
A failed isolator will either permanently combine the battery banks or have a leak to ground and tend to drain the banks. An isolator that is failed to ground will cause the converter to work harder but if in good shape should not be detrimental to the converter. A failed isolator will be warm or hot to the touch.
The engine's alternators can have a leak to ground or worse one of the diodes failed and pump alternating current to the battery bank which will greatly shorten the life of the batteries. A simple test for alternating current is to put a digital volt meter set to "AC" between a ground and the alternator's B+ terminal when engine is running and see if any voltage is detected. If above a couple of tenths of a volt you probably have an alternator issue. The voltage regulator in the alternators can also fail and overcharge the batteries; you can determine if this is happening by monitoring the helm gauges and verifying they are not indicating over 14.1 volt when running the engines.
But, most likely your AC powered charger is not sensing between bulk charge and maintenance charge and is overcharging the batteries and boiling them out.
You should consider completely getting rid of the old style isolators and moving to ACR's; your batteries will like you even more.

 

[Mike Blake]

Do you own a volt meter? If so check the voltage with the charger on and see what's going on. Should be in the 13.8-14.2 range. I had the same problem before I got my smart charger and new Optima blue tops.

 

[Lazy Daze]

First... if it's still the original charger, then yeah, chances are it's seen better days. But I don't like to condemn things "just because" they're old. There's specific tests you can do to see if the charger is outputing... not only the correct voltage, but also that it's dropping down after the correct amount of time. I had a ProMariner in my '99 and I called PM and they walked me through the steps to check it. Found out one of the charging leads was putting out the correct voltage, but it wasn't dropping off. I would suggest giving the manufacturer a call (it may be in a manual, as well) and asking them for the test procedure. That was you'll get a definitive answer.