Put a CHARGE into your Summer!

Hey, before you read this post, do me a favor go get two glasses of water and an eye-dropper before reading on about Marine Battery charging.

No, no. That’s okay. I’ll wait. Seriously...


First, choose one of your glasses and name it “My Marine Battery.” Now, drink half of the water out of that glass called your “Battery”.

The remaining water in your glass is just like the remaining capacity in your battery every time you get back from Lake Nocareintheworld and your Flooded Marine Deep Cycle Battery is now at 50% Depth of Discharge. Well, your flooded battery will lose a half to 1% of its remaining charge per day just sitting there until you put it on a charger before your next run back to the Lake.

“That’s okay,” you’ll say. “I’ll just hook it up to this handy Trickle Charger I bought at the discount store for $39.99.”

That’s what your eye dropper is for.

Using your eye-dropper, begin filling “Your Battery” with the other glass of water...I’ll wait.

How long do you think that will that take?

More importantly, how likely do you think it is that you’ll ever fill that “Battery” back up before you get thirsty and start drinking it? Want me to continue..? Oh, alright.

You see, The Battery Genius knows a thing or two about maintaining Marine Batteries and I’m here to say, unless you’re pumping at least 14.4 Volts into your Marine Battery – IT IS NEVER GOING BE FULLY CHARGED EVER AGAIN. 


Never never ever.

Battery manufacturers' specifications say that a standard 12 Volt Battery needs to be charged anywhere from 14.4 to 14.8 volts (14.7 specifically for some AGMs like Lifeline) and then maintained at that level for AT LEAST an hour, before it will be at 100% capacity again. What’s 100% capacity, you ask? 14.4 Volts. Heck, if you’re not hitting at LEAST 14 Volts, you should go to Vegas. It’s more fun gambling when you might win something.

Dead Battery + Dead in the water = NO FUN. I oughta know.

The MOST and I mean MOST you’ll get out of your INITIAL bulk charge from your $40 trickle charger is 13.6 Volts. What are you gonna do with 13.6 Volts? I’ll tell you – Your going to be repeatedly heading out onto the lake with a diminishing battery that will never last through the summer. Because next time you'll go at 90%... drain it. Charge it 85%... drain it. Charge it 70%. You see where this is going? Your Trickle Charger doesn't initiate at a high enough VOLTAGE to bring your battery back. What's worse - It'll just switch off when it gets itself reading "full" and never tell you HOW full your battery is. Or isn't as this case would be.

The BEST way to charge your marine battery is to use an On Board Charger. This is a permanently installed charger that you plug into shore power whenever you aren’t using your boat to maintain your batteries. Unless you are on the water ALL THE time, it may be a little out of your price range.

Associated Equipment makes a terrific bench-top charger  - The Intellimatic - great for Lead Acid Batteries of all kinds (deep Cycle or Starting).  They are available in three different models (Flooded Batteries, AGM & GEL) and all are made in the USA by Associated Equipment.

To get the very best advice on charging, maintaining, or buying Marine Batteries, call the folks at Powerstride Battery. They love talking about this stuff. Plus – its FREE for you: Toll Free (877)576-9379.


Most “smart chargers” are extremely stupid when it comes to determining what “Fully Charged” is and shut off at 13.4 Volts. Fully charged is 14.4. Period. Got it? Now go get some sun. You look horribly pale.

Apr 19th 2012 The Battery Genius

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