Can you recommend a good battery tester for my 12v boat battery?

[a64pilot]

Originally Posted by Dave22q

Plug a voltmeter into your 12 v system and be aware of the readings. Amazon has very inexpensive ones designed for use in cars.

I have a Smart Gauge now, but truthfully I think you can determine a lot by doing the above, it's what I did with no issues before the Smart Gauge

[W3GAC]

I also keep aboard/ use the inexpensive Harbor Freight Tool battery checker. It has a 100a load switch that simulates the battery under load giving you a much better picture of the condition of the battery. You can/ and I recommend not just hooking it up the at battery terminals. If you go right to the starter terminal you'll get a whole circuit path test with your 100a load switch on. If the battery test ok, but this fails, you'll know that you have corrosion somewhere in your high current wiring/ usually a connector. I've seems these Harbor Frieght meters as low as $15, but usually abt $49. Worth every cent of either price! Batteries/ battery maintenance, troubleshooting battery issues quickly/ accurately is so important to us boaters, I consider it to be one of my most important tools aboard. And I keep one aboard... doesn't do you any good in the garage when you wake up on a cruise with battery issues!


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[LooseGoose]

Agree a Harbor Freight Load Tester is an inexpensive but very valuable addition to your tool assortment.

Always a great idea to have a spare battery at the ready, especially single engine, kids, away from help.

West Marine sells a great device called a battery combiner. It makes sure your primary battery is fully charged, and then aims the charging current to the second battery bank until it is in turn fully charged. Then it isolates the two. All automatically, once parameters are set up.

MAGNUM ENERGY Smart Battery Combiner | West Marine

[Photographer]

Thanks so much! Tons of very useful info!

[leftbrainstuff]

Multi meter and hydrometer. If you measure battery voltage while cranking you get voltage under load. You dont need a load tester unless you're testing lots of batteries that arent installed.

A hydrometer allows you to check individual cells in a flooded lead acid battery. A little slower and a little messier but the more precise means of determining state of charge. Only valid for a resting batterry.

We have a digital readout for each of our 3 x house and 2 x starting battery banks. In addition our battery management panel provides voltage of our house and starting bank. I glance at these readouts every time I traverse the passageway.

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[Photographer]

Awesome! Thanks so much!

[masonc]

On this subject, I'm a generator technician and we maintain residential and commercial emergency generators. My policy is that generators that don't start are useless, so I insist on changing the battery every two years on all the units we maintain. That eliminates 90% of our failures. If the owner waits for the battery to fail, that is a designed to fail system. A boater needs a 100% reliable starting engine, so change the battery regardless of status. In warm climates, starting batteries won't last much more than two years anyway. You can still use the battery for other purposes, just not for your boat (or generator).

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