Which battery to buy?

[sailsail]

Would like some recommendations......

going to replace my old 'mismatched' batteries and not sure what size, make to buy.
The boat is just used weekends, no refrigeration, no hot water heater, etc. Basically just to start the engine, run the lights, and the water pump and bilge pump.
The boat is an old 31 foot, yanmar 3GM30 engine.
Any suggestions?

 

[higgs]

Are you at a dock with shore power?

 

[kloudie1]

Two size 29 deep cycle 12V .. Sams Club has a great deal on 'em
http://www.samsclub.com/sams/search...marine battery&fromHome=yes&_requestid=126628

 

[Joe]

Higgs question on shore power is important.... how do you plan to charge your new batteries? If you have shore power you can invest in a hardwired smart charger ... a ten amp size is plenty....that will make battery maintenance a breeze.

Kloudie recommends the group 29, wet cells from Sams.... which I think is an excellent choice for your needs.. and budget.

 

[sailsail]

We have shore power....but we haven't used it for charging the batteries. We had an old (it came with the boat old) solar panel which kept the batteries charged, but it finally gave up the ghost this winter.
We plan to buy another one....30 watt.

 

[Anonymous 121765]

S,

Down here in Florida, wet cell non-sealed batteries tend to have evaporation problems. Make sure to get sealed batteries deep cycle.

I use AGM batteries as they are a big improvement over wet cell. The newest type batteries coming out now are dry cell batteries.

I checked a year ago, but not all sizes were available then. They claim to hold a charge for 7 years. But for me, the jury is still out.

I've had the AGM's for five years now, and they keep running strong.
I have a digital 2-10amp charger and use a weekly house timer set to float every other day for an hour. This has worked great for me. The AGMs will cost about twice of the wet cells, but I cannot complain.

Careful when buying batteries though, make sure the date stamp is current. If it's a year or more old, don't buy them. They can sit on the shelf a long time with less than a full charge and the memory index may be weak.

CR

 

[mitiempo]

Only buy sealed batteries if they are agm or gel. All batteries outgas and if they are sealed flooded you cannot add water.

If the batteries use a lot of water it is not evaporation but probably overcharging.

Flooded batteries do require a few minutes maintenance per month but are by far the best value.

 

[Ron20324]

Two size 29 deep cycle 12V .. Sams Club has a great deal on 'em.

Tax return came Saturday, so I'm off to Sam's Tuesday for two or three 29's. I think they are still $85?

 

[kloudie1]

Ron.. that is the current price in Baton Rouge.. dunno what they are up there.. may be a couple bucks more -or-less than here..

 

[Benny17441]

The standard setup for a boat to be used as a weend sailer with small to moderate power usage is two deep cycle batteries with a 1-2-Both-Off switch. Wet cell batteries are the most afordable and perhaps forgiving and can be found in Group 24 (85A), group 27 (100A) and group 29 (115A). Their price may range according to size from around $75-$125. The kicker is than in order to maintain a reliable power backup for engine starting you may be forced to alternate the batteries usage and rely on one battery at a time for your week end power needs. I would say your usage is going to be under 20 a/h for a 24 hour period so you may need 40a/h for a two day weekend and 60a/h for a long one. Since it is recommended that a battery not be drawn more than 50% of its capacity to preserve its useful life then the group 29 should be your best choice as a single battery at 50% discharge will provide some 58 a/h. If you recharge batteries underway or at anchor by running the engine you could surely use Group 27s. Dipping over the recommended 50% discharge ocassionaly and briefly will not significantly shorten their total useful life so in an emergency you could bring them down to 35%-40% of charge and live to sail another day. You also have the option to carry a starter power pack which could serve as your reserve power backup which could mean that you could combine the two batteries and have available twice the amp capacity. In that case two group 24s would serve you right. Since good warranties for marine batteries have fallen by the wayside it may be best to invest in a good quality battery to start with as they are likely to last longer. I happen to have had good experience with Interstate batteries. Try to purchase fresh batteries and test them for holding maximum charge after a few cycles.

 

[sailsail]

Thanks, that was helpful.

 

[Scott T-Bird]

It sounds like your usage is pretty light ... we have group 27's (lighter and less space required than 29's) because the space is limited and 29's are a just a little too difficult to get in place. The wet cell 27's are more than adequate. If you don't have access to shore power and don't want all the solar and wind generator gismos, just be sure to do plenty of motoring. The alternator doesn't charge them the best, but it'll get you by if your battery usage is that light. I've had the same batts for about 5 years now without ever a discharge that wouldn't start the engine.