Battery Replacement Advice

[MOOSE]

Currently we are running two, dual purpose, flooded, Interstate SRM-24 batteries that are now two years old and have served us well.

First, how often do most of you folks change batteries?

And second, some years ago, Les Lampman told me he liked the Optima Blue Top 56AH dual purpose batteries; what do the rest of you think?

Al

[Da Nag]

We had a discussion on this not too long ago - here's a link.

Plenty of opinions to go around...some prefer a battery strategy of "cheap and replace often", others like the Optimas and other more advanced and expensive solutions.

I started with Optimas, and had a less than stellar experience with them. Most people seem satisfied with them, but I've migrated over to the "cheap" side for reasons listed in the thread above.

[CAVU]

Moose,
I have a 2002 w/twin Hondas. Mine came with the exact same batteries. I got four full seasons out of mine and was very happy with the Interstate brand. The only down side I found is that when I removed the batteries each winter for storage I always got a few holes in my shirt.

[MOOSE]

Thanks, guys. This was just what I was looking for.
Al

[JamesTXSD]

OK, battery-folks... another question. Our boat came with a grp 24 battery (house side); we had the factory folks install another battery. With the problems we've had with the Guest charger (more about that another time), when I checked in the battery compartment, I found that we have one grp 24 and one grp 27. With the RVs we've had, we always had matched batteries for the house. I can't get these things to hold a charge for more than overnight, without much load on them. 8 months old on the boat, btw. Checking with Interstate, I find that one battery is 17 months old, the other is 11 months old. Yeah, I'm less than enthralled with that situation, as well.

So, is there a problem with the 24 and 27 wired in parallel? The only big draw we have is the fridge, which would go several days with no problem when the boat was fresh out of the factory (8 months ago). We consistently see the battery go below 12.0v. With the automotive battery charger on, the batteries will read 13.4, but as soon as the charger is turned off, they show less than 1/2 capacity, and usually read 12.3 or 12.4. I've checked them with a multi-meter, so I know our little cig-lighter W-Mart readout is right on.

No telling how long the Guest has been non-functional, so that situation may have contributed to our current battery woes.

Thanks for any insight.

Best wishes,
Jim B.

[drjohn71a]

Jim, While I may have missed something, you really ought to have TWO house batteries if you're running a fridge.

Also, along with the warmer climate of South Texas and the Keys comes increased problems of keeping the water levels up. Not much time with low water can kill the exposed plates. Also, my motorhome charger is too aggressive, so I have to shut it off and use low amp battery "maintainers" to keep from boiling the water out.

I am guessing one or both of your batteries is suffering from damaged cells and thus limited charge holding capacity. There are alot more knowledgeable ppl than me on here, but what you're describing is a path I've been down on other boats and my motorhome. Overfilling and underfilling are both problems solved with the auto fill tubing pump sets. The ppl at my RV place said using the auto fills can make the 6 volt batteries last 7 years.

Just a shot at the problem... I am guessing it'd be best to get two new batteries or three (two house) and avoid over drawing, overcharging, and water level fluctuations.

John

[Not For Hire]

Al I had two Interstates and I replaced them after one year. Not that they failed or were ever lacking in any respect. I had those two batteries and two on-off-all switches on the boat.

But I went to a three battery system with vsr and multi switches. I decided to upgrade the batteries. I now have two "dual purpose" batteries as starting batteries, and a single "deep cycle" battery for the the house battery. All are very heavy, lead/acid, batteries. All will start the Hondas, all can act as house batteries. On a hot day I believe the deep cycle would start a V-8 although it is not designed as a starting battery.

I don't know how long I will keep them before I swap them out. I am fond of the dual purpose batteries in our dories and would recommend them as starting batteries anytime. Plenty of starting power yet can also act as deep cycle batteries so if they are also used as house batteries they don't wear out so fast. In my boat I use group 24s. In previous boat I had group 27s and they lasted five years when I swapped them out on general principles.

Regards,

Mark

[Not For Hire]

Jim, This chart has been posted before. I "borrowed" it from an RV site that had a good discussion of batteries. You can't get a true measure of battery state of charge until a couple of hours after the charger has been turned off. Ambient temperature also affects measured charge.

I don't believe there is a general problem with having a group 24 and 27 wired in parallel for the house. But if one battery is healthy and the other not the good battery can drain into the bad one, or at least have an adverse affect on the good battery. I presume you have a third battery for the starting battery? Is your charger wired to charge three banks (3 batteries) or two? Are your house batteries deep cycle or something else?

Disconnect the group 24 from the circuit and see if your performance doesn't go up using just the newer battery. I bet it does. If so I would replace that older battery and if you have the room go with a second 27 for your luxury yacht.

Regards,

Mark

[thataway]

To address Wild Blue's situation: I agree 100% with Dr John--one group 27 is way too small a battery for a refigerator. What has happened is that you have damaged the battery by drawing it down to too low a voltage. A common rule of thumb is not to draw a battery down below 50% discharge--that is 12.2 volts for flooded lead acid. AGM is about 0.1volt higher-- or 12.3 volts.

I don't know how much "deep cycle" capacity the batteries have, but I would be looking for at least two 110 amp hour batteries in parallel just for refigeration. I have generally used golf carts which are true deep cycle--many of the "marine dual purpose" are not really the best deep cycle batteries.

We have chosen to use two group 31 AGM batteris for the refigeration--and kept another house battery for the "house"--that is lights, TV etc. We keep monitering the batteries with a digital volt meter and never let them get below 12.2 volts.

As for batteries--sometimes if I am near replacement sources, I don't cycle batteries on a regularly basis. If we were going to cross an ocean we would replace batteries every four years. We have virtually never had a battery failure, with good voltage management.

As for "mismatching" batteries: Generally one should have both batteries on a charging circuit the same capacity and age. Ie two group 27 or two group 24. Also remember that there are a large range of capacities of group 24 batteries--from in the 50 amp hour to over 90 amp hours.