How do you know when to replace the batteries?

NiceBeny · Aug 10, 2014

There might be a way to test them but if it will make you trust your starting power then replace them, you will have peace of mind for a few years.

Stu Jackson · Aug 10, 2014

You might be interested in this:

AGM Battery Issues (from Maine Sail)
http://forums.sbo.sailboatowners.com/showthread.php?t=124973

Ralph Johnstone · Aug 10, 2014

cymeyer said:
They are AGM batteries and they work well.

My fear is one day they won't hold a charge and I won't be able to start the engine on the lake.

Somewhere in there, there should be a starter battery all by it's lonesome and disconnected from everything else on the boat, and waiting to ONLY start the engine.

When away and on the hook for several days, the starter battery should be treated as a holy shrine and bowed to four times a day. It should be regularly watered. It should be revered. But it should NOT be connected to anything else on the boat.

Maybe a little bit over the top, but you get the idea. The other batteries may be showing their age but the starter battery should be pristine. And it's the cheapest battery you've got

.

Stu Jackson · Aug 10, 2014

Have you read this?

http://forums.catalina.sailboatowners.com/showthread.php?t=124973

You could always take one of them in to a battery distributor or auto store and have them load test it, takes about 20 minutes.

Don S/V ILLusion · Aug 10, 2014

8 yr old batteries are pushing the limit on lifetime. Regardless of how you tezt them, i can pretty much anticipate the answer.

Stu Jackson · Aug 10, 2014

Don's right. Add to this the info in the link I gave you which states that AGMs fail without warning.

Your boat, your choice.

NiceBeny · Aug 10, 2014

Ralph Johnstone said:
Somewhere in there, there should be a starter battery all by it's lonesome and disconnected from everything else on the boat, and waiting to ONLY start the engine. When away and on the hook for several days, the starter battery should be treated as a holy shrine and bowed to four times a day. It should be regularly watered. It should be revered. But it should NOT be connected to anything else on the boat. Maybe a little bit over the top, but you get the idea. The other batteries may be showing their age but the starter battery should be pristine. And it's the cheapest battery you've got .

I agree and the cost of a new starting battery is much less then a towing service or in a emergency

Gunni · Aug 11, 2014

A battery monitor should be part of your install. They connect direct to the battery supply and give you voltage and amp-hour at the battery. If you had one you could turn on a number of DC items and place a load on the battery. Monitor the resting voltage and how long it takes to drop the voltage toward 12.0. That would give your the answer to your question AND help you to properly maintain your battery storage. A required piece of gear IMO.

FlorDLuna · Aug 11, 2014

I'll second that! Two winters ago I had new AGM batteries installed by a shop, and they recommended install a BM-1 battery monitor. This month it really came into its own when I sailed 3 days straight with full crew in the Around Long Island Regatta, and the device showed I still had 10 hours of battery power left at the rate I was using amps before I would need to turn over the engine. I would've been much more anxious about remaining 12 volt power if I hadn't had this device installed.

http://www.nasamarine.com/proddetail.php?prod=BMN-1_Battery