J/30 Class Association

best replacement batteries?

Posted By: nathankt79

best replacement batteries? - 03/08/19 01:49 PM

Good morning all,

At the end of the season last year, I came to the conclusion that it is time to replace the batteries in Conundrum. Can everyone chime in on what type or brand of battery they like the best? I'm not sure if I should go lighter, gel cell, some other direction, or just go with a tried and true sealed, lead acid battery. What are everyone's thoughts?


Posted By: Russ Atkinson

Re: best replacement batteries? - 03/08/19 04:35 PM

I have 2 conventional lead acid batteries. Both identical marine deep cycle form Interstate.
I do not have a battery charger on board other than the alternator on the engine.
I run off the front battery all season - only switch to the back battery on over night races and only after the instruments tell me battery power is low (they stop working)
I bring them home in the winter and charge them before putting them on a shelf. I charge them again before putting them back in the boat in the spring. Batteries last about 10 years
Posted By: Rhapsody #348

Re: best replacement batteries? - 03/08/19 11:00 PM

When I had Rhapsody I bought two Group 24 sealed Lead Acid batteries from Walmart for $70 each. I replaced them after 7 years, because I thought it was a good idea, not that there was a sign they were loosing capacity. I had a Xantrex smart charger (Dual 10 amp) that was connected on the dock. When I sailed the boat I used battery 1 on odd days and battery 2 on even days to get equal usage out of them. Similar to Russ when night sailing I swapped to the other battery and started the engine to charge (then battery switch placed on all).

I left the batteries on the boat in the winter but stopped by once a month to top them off with the battery charger. If the batteries discharge the electrolyte will freeze and crack the case.
Posted By: Rob Van Name

Re: best replacement batteries? - 03/11/19 09:55 PM

I bought two Duracell AGM group 24 batteries from Batteries+ for about $198 each. The Optima yellow top batteries lasted about 8 years. Life on a trickle charger is good.
Posted By: Chris623

Re: best replacement batteries? - 03/15/19 12:24 AM

My suggestion would be 2 AGM batteries, but at a minimum would stay away from batteries marketed as marine starting or even marine dual purpose as those batteries are really only needed with very large engines. (Ref: Pbase-MarineHowTo)

One of the best IMO is Odyssey Battery which used to be available as Sears DieHard Platinum. Odyssey states a 3-10 year service life. As I am on year 13 on the battery I use most often, I'll be sure to eventually replace it with the same.
Posted By: NaturalHigh

Re: best replacement batteries? - 10/17/19 05:09 PM

Convenient timing for a thread on batteries! I am looking at options to upgrade my battery capacity, but the custom battery tray is pretty limiting for putting in anything bigger than a group 24 (would love to fit a 27 or 31). Has anyone fitted anything different than two 24s?

If I was to change the whole bank out, I would consider a Group 31 AGM house battery, and the smallest size AGM starting battery with enough CCA to comfortably start the 2QM when cold (400ish CCA)
Unfortunately I have a perfectly good Optima Bluetop 24 that is too good to switch out at this point, but is too big to fit a larger house battery beside. My other option is to tie two G24 together in the tray and mount a small starting battery on the side of the tray or elsewhere.
Posted By: Twilight Zone

Re: best replacement batteries? - 10/25/19 04:45 PM

FYI - a group 24 plus a group 27 fit perfectly in the standard battery tray installed in my boat ( Hull #32 - 1979)
Posted By: NaturalHigh

Re: best replacement batteries? - 11/07/19 11:01 PM

Really, I wonder if my tray is slightly smaller. My smaller than standard G24 optima is like 1/2" too wide to fit a G27 beside it without cutting according to my measurements.
Posted By: MichaelRuzzi

Re: best replacement batteries? - 12/01/19 02:16 AM

One of the other options is to switch high-capacity house-battery type Group 24s on a separate circuit in the battery box and add a smaller starting-only AGM battery such as a Group 31 on a new circuit. The advantage of the AGMs is that they have very lax angle tolerances for mounting and can even be mounted sideways if need be. The Yanmar engines that J/30s use don't have terribly high cold-cranking amp needs and can definitely be started on a smaller battery. Another good option to consider is reducing your draw by converting all of the interior light fixtures to LED if you haven't already, that was some of the best money that I spent on Mondial. The insanely over-engineered spring-loaded bayonet-type halogens that come standard suck down power at something like 5-10 Amps apiece.
Posted By: #511

Re: best replacement batteries? - 12/16/19 04:11 PM

I saw a notice from the coast guard the LED lighting was producing radio interference..
Posted By: Rob Van Name

Re: best replacement batteries? - 12/29/19 06:08 PM

Originally Posted by Rob Van Name
I bought two Duracell AGM group 24 batteries from Batteries+ for about $198 each. The Optima yellow top batteries lasted about 8 years. Life on a trickle charger is good.

12/19 Update: one of the Duracell AGM group 24 batteries lost capacity after two years ( but not enough for warranty coverage ). The symptom was low voltage warning on chart plotter after two hour day sail. The batteries were actually one year old when I bought them. For reliability I replaced them with two Gel cell group 24 that were manufactured in November 2019.
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