Battery Charger has failed

Don S/V ILLusion · Oct 18, 2014

In the absence of any info indicating what size batteries, I.e., capacity, go with the largest. Undercharging batteries is the quickest way to kill them.

stollo770 · Oct 18, 2014

You can find a ton of automatic battery chargers online and in stores. My advice would be to get a charger thats 20 amps but has a tiny computer in it that can adjust the charging voltage based on your battery's charge level. I have a single bank of 3 deep cycle batteries and I keep them charged with a 20 amp unit that automatically steps down the voltage to a trickle/maintaining charge once it detects that the batteries are full. It knows based on voltages/amps what batteries I have, how many I have, and what their electrical needs are and automatically applies charging power to meet those needs. I have the charger integrated into my shore power system so as soon as I plug in the boat, the unit automatically turns on and starts doing its job. Its pretty sweet and super healthy for the batteries. I picked it up for under $30.

Also, you mentioned you have two battery banks, but only one charger. If you truly want to keep your banks separated you need two chargers. Any connection between the two banks, even through a charger, will allow current to flow between them.

The Rach · Oct 19, 2014

MLampner said:
He battery charger has failed, it appears to have been the original. I am set up with two banks a house bank with two deep cycle and a starting battery. The original unit is rated 15amp DC, I can find 12 amp and 20 amp. Thoughts on which way to go?

From the West Marine site comes sound advice:

What size charger do I need?

Deciding how big your charger needs to be is determined by the size and type of your batteries, and whether your boat has a continuous or intermittent source of AC power to run your charger. Boats that spend most of their week at a dock, constantly hooked up to shore power, require smaller chargers. You need enough capacity to run the continuous loads on your battery system, like DC refrigeration (frequently the biggest user of battery power) and lights, plus enough power to float-charge your batteries. A good rule is to have enough amperage to equal the sum of the DC loads plus 10 percent of the amp-hour capacity of the batteries.

If you’re cruising or anchored out, and aren’t plugged in except intermittently, you will want enough capacity to recharge in the time you have available, if possible. You need enough juice to replace the power consumed by all the DC loads, as above, plus an average charge rate equaling the amp hours required divided by the hours available. Maximum amperage that batteries can accept during the Bulk Phase of the charging cycle vary depending on battery chemistry: flooded batteries can accept a charge rate of up to 25 percent of C; gel batteries have a higher acceptance rate of as much as 30 percent; AGM batteries accept the highest charging amps, as much as 40 percent of C.

Not knowing your usage profile or battery configuration makes a good specific recommendation impossible.

Richard Bryer · Oct 19, 2014

Take a look in the "gear for sale" ads on this site- there is a Xantrex Truecharge 20 amp for sale at a reasonable price. I have had one for 8 0r 9 years works very well.

Stu Jackson · Oct 19, 2014

Wiring a new charger From Maine Sail: http://forums.catalina.sailboatowners.com/showthread.php?t=136765

Benny17441 · Oct 20, 2014

That happens mostly due to faults in the shorepower supply but also because of age. Years back we downsized from a 30A to a 20A that was smarter and it ended up doing a better job than the old clunker. Check the specs and under equal conditions get the larger one but do not confuse size with efficiency.

EasyGoing · Oct 21, 2014

Don S/V ILLusion said:
In the absence of any info indicating what size batteries, I.e., capacity, go with the largest. Undercharging batteries is the quickest way to kill them.

Yes, but if you have lead acid, get a NOCO Genius. I have a 3 Gen rated for 3 banks at 10 Amps per bank. It is a 30 Amp rated unit, with pure sine control and 8 stage charging. I have 3 group 24 batteries and lots of 10W lights and with my radio (and sometimes stereo) and two batteries charged in 2 hrs 15 minutes, then float maintained for 12 hrs to see if they took a good charge. They did, very, very happy with this charger, customer service is excellent.