Battery and/or charger issues...

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M

Mook

...are driving me crazy! I bought a Merchant Marine 2-bank charger (model MM-12210) from a vendor on e-bay (mistake #1?) It stopped charging bank #2 a few minutes after I plugged it in. I sent it back to the vendor and he sent a replacement. I checked and re-checked the connections and my electrical system for bank #2, and re-installed it (mistake #2?). Guess what? Same issue happened again. I now believe that battery #2 is too far gone to salvage, since it only got it to about 8v before the bank stopped charging. Bank #1 is charging and working 4.0. Has anyone else had any experience with this brand of charger? Has anyone had similar experiences (i.e. bad battery possibly ruining a charger?) Could a battery "go bad" enough to ruin should be a fairly rugged charger? Short of getting another charger and battery or opening-up the existing unit, any troubleshooting tips? Thanks for the read and be safe out there!
 
Jun 6, 2006
6,990
currently boatless wishing Harrington Harbor North, MD
Thermal cut off

Most battery chargers have a thermal cut off. It is designed to protect the chargers circuits when it supplies more than the rated current and the components overheat. Try switching the charger's positive wires on the battery banks and see of the other side stops working. With a bad (8V) battery the charger is sensing that it needs to go to full current and the battery can accept it due to an internal short. I'd guess that the charger is OK and just reacting to the bad battery in the bank.
 
Feb 26, 2004
23,335
Catalina 34 224 Maple Bay, BC, Canada
Try a Truecharge 20 or 40

we've found it's pretty much the only one that's dependable over the course of the last eight years with over 700 boats in our association. Xantrex makes 'em now. Many may differ, please do so, love to learn something new.
 
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