battery charger

Do all the normal checks on connections, water levels, clean the fan, etc. The fans sometime spin on their shafts and make a squealing noise, if so, change it.

On lead-acid batteries, as they get older or are cycled more often, a build of sulfate crystals cover the lead plates. Your charger may be reading this as low power and keep cutting in. 8D batteries have large plates and you can see the crystals when you take a top off and shine a flashlight in there. A battery conditioner will stop this happening. I've had success with Mobitronic wa-C conditioners.

The other thing to check is the volt sensitive relay in the charger which may be faulty and needs testing.

Hope this may help you in the right direction.

Are you sure the charger is cycling on/off or just the fan. When my freedom inverter is in charging mode the fan cycles frequently as required to remove the heat but the charge rate continues. You may need to just replace the noisey fan. Your battery volt meter or amp meter just be able to tell you if the charge is continuing. I had to replace two fans in my inverter before I got one that would work correctly.

Get them 'drop load' tested first. This is where a load/resistance is added gradually and will show up weak performance. A lot cheaper than 2 new 8Ds.

Some battery chargers/inverters have a battery condition or desulfication mode that will renew the life of a weak battery. If you have this capability I recommend you follow the instructions and recondition/desulfate your batteries before you run the load test.

4 years? They're done.

It depends. Do you have a multi stage, multi bank charger? Are the two banks isolated (from each other)? They should be, and if so, they have no connection to each other. One bank doesn't know the other bank exists.

Isolated Example:
Bank #1 is two 8D's in parallel (12V) for house and generator start only.
Bank #2 is two 8D's in parallel (12V) or in series (24V) for main engine start only.

Ariel: If the engines are not charging the batteries and the banks are tied together, then the old bank will drain the new bank of batteries. Even if the batteries are being charged I would recommend that the banks be isolated. If you have the ability to isolate the two banks then you can get some additional use out of the old bank providing they pass the load test.

Disconnect the two good batteries and test inverter.

Reconnect the two good batteries and then disconnect the two batteries in question and test inverter.

Notice any difference?

Dilemma solved?

I just reread your posts. thought at first you had a 32 volt bank. what volt system are you running on your boat with 16 vots worth of batteries?

Umm.. I suspect (per my earlier post above) your Viking is 12V house bank and 24V start bank which is common w/Detroit Diesels (do you have 6-71's?) ...don't start jumping across battery banks unless you know exactly what you're doing... unless you want to buy a lot of new 12V electronic components. Your engine starting batteries should remain isolated from all other service. The inverter should draw only from your house batteries. Ideally, the inverter should have its own bank of batteries.

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