J/30 Class Association Forums J/30 Forum The Boat, Sails and Equipment Battery Charger

Hello all. I am brand new to J30s and learning the ropes on some of these repairs and hoping I could borrow some of your expertise.

I had the boat to shore power with a little space heater on to fight the freezing temps. When I came back, I switched to the battery and it seemed they had gone dead. I made sure the battery charging switch was up, unplugged the space heater, and plugged shore power back in and I thought the batteries were charging again, as evident by the voltage meter slowly rising on rechecks. I came back the next day and now the battery charging switch keeps turning itself off, almost like its tripping a circuit and the batteries are dead.

Could anyone explain to me whats going on with this? Did I blow something out with that space heater or is there a capacitor that I need to replace to get the batteries charging again?

Thanks for the advice everyone!

- Cameron

Cameron,

It appears if the battery charging switch is a circuit breaker that is being overloaded. Can you take pictures of the breaker and battery charger an post here? Look up the breaker rating and what the battery charger rating is too.

When in doubt shut off batteries and use portable charger...
The little question here is if the heater was 12 V?

soon as you say shore power we sort of anticipate the heater was 120. and should have nothing to do with the battery side.

Hi all,
Sorry for the delay, just had a chance to go look at everything again. Used a volt meter to isolate that power was getting to the charger but not beyond, and the internal output meter on the charger is stuck at zero. In fact, when I apply power to the charger the internal breaker blows.

My charger is a Readi Amp 8 (2 bank 12 volt VDC 8 amps). A quick google search mentions that this particular charger is a "battery killer". Does any one have any advice on if the charger can be serviced or what type of charger I should replace it with?

The last thing I can think to check is if the batteries are still good. I'm planning to charge them with a plug in trickle charger later, but is there anything else I should do to interrogate the batteries?

Thanks! Cameron

I've had this type of Xantrex charger on Rhapsody since 2007 and it works well. (pictures are links to products)


I think this is the new version of the Xantrex charger.



It is dual bank and microprocessor controlled with "smart" charging cycles. Never had a problem cooking batteries with this like you see with some chargers.

I agree with Bill,
I've had a Xantrex on Koesh for years and have had excellent luck with the charger. It's been gentle enough that my cheap automotive batteries have lasted me for eight years so far. Make sure that when you wire it in you use proper Marine grade, tinned wire for all circuits. My boat had some of the shore power wired with solid core that I'll be replacing with the new harness I'm making up over the next year.
Doug Marshall

Using a NOCO Genius GEN2 20 Amp 2-Bank Waterproof Smart On-Board Battery Charger since 2012 with EverStart Group Size 24 Marine batteries on the advice of Capt Vic. Occasionally on sale at Walmart for less than $100. At 7 lbs a bit heavier than the one above.

Awesome, thanks for the advice. I've heard good things about both of these battery chargers.

Another idea, after speaking with a friend at the dock and he suggested adding in an Automatic Charge Relay (like a Blue Sea m-ACR) which would help isolate battery discharge. Does anyone have experience with these on our boats?

The ACR is a nice add-on but not really needed. It's convenient in that you don't need to manually move the battery switch (1, 2, all, off) to have the engine charge both batteries. I had thought about it a while back but decided to stay with the proven battery switch. I also had a very complicated rule for the battery switch. If it was an odd day, we sailed using battery #1. If it was an even day, we sailed using battery #2. Both batteries were Walmart group 24 marine batteries that cost ~ $75 each. I changed them last May after 7 years... not because I was having problems but because I didn't feel comfortable cruising knowing that I had two batteries that were 7 years old.

If you have a dual bank battery charger like the Xantrex and are at a slip where it can be connected, your batteries will always be topped off whenever you go out. The charger has diodes that isolate the batteries from each other, but will charge both batteries no mater what the position of the battery switch. The diodes also prevent back flow currents to the charger when the charger is off so the batteries don't drain. The battery charger is always connected to the batteries, so it is just a matter of applying AC shore power to turn it on.

ps - here is the shore power / charger procedure I documented for Rhapsody. It was before I added the AC breaker with reverse polarity sensing and the new DC panel but has info you could easily use if you decide to wire in a charger.