Replace 4D Batteries?

[Spfoster]

My 2004 28 TE came equipped with two 4D batteries that must be near the end of their reliable life span. I read somewhere that one should never replace a 4D or 8D battery with same because of their ungainly size and weight. One of mine is located where it is inaccessible for servicing without removing a deck support or the starboard hatch lifter arm. I am considering replacing the two 4D's with one group 31 starting battery and 2 group 31 deep cycle (house) batteries. This should save some space and make the batteries easier to handle. Does anyone see a problem with doing this? I also read that a true deep cycle battery does not specify a CCA of MCA rating, only the amp hour capacity. Is that correct - even though the battery is sold as a deep cycle battery?

[RobS]

There is no right or wrong answer here. It all depends on your specific needs: Do you spend time on the hook? What do you power and for how long? Do you pull the batteries in the off season or not? etc etc. The important ratings in researching deep cycles are reserve capacity and ampere hours.

[jleonard]

Say no to 4D and 8D batteries. They get heavier with age.
You can do the same with the smaller batteries.
And your back will thank you, however you chiropracter will be upset.

[mike66]

I actually used my mast/boom to load my 4D engine/bow thruster battery on board, then lowered it down into the engine room with another block hooked up the the overhead grab rails! I think 2 6V batteries sound alot better and easier to manage. Next time......

[DougSea]

I'm going to second Rob's post. It all depends on what you want to do, including usage, location, and any wiring effort involved with changing to a different configuration.

[Chris & Dale]

I too have a 4D AGM and Gp 31 AGM that are 7 years old and candidates for replacement. I'm lining up the AGM replacements (I'm horrible at replenishing water and access is always an issue) and yes, I'm replacing my 4D w/2 in-line Gp 31's.

I have a friend who's much more experienced at electronics & batteries than I and he's indicated that this will not be a problem. "I like group 31 size batteries; they have 110 amp-hr capacity, and are not too heavy. (70 #) Replace the 4D with 2 group 31's and get twice the starting amps and the same amp-hr capacity. Also, you have more redundancy, since either battery can perform the function. 1 group 31 AGM will start up to a 600 HP diesel under normal starting conditions." I'm also going to install the Yandina Combiner, which he also recommended, so the issue of the battery switch not being reset is not an issue....Chris proof!

As soon as I'm done I'll either post back here and start a new thread. Good Luck!

[johnmurray]

My 2004 A-30FC that I purchased new also came with two 4Ds. They are very heavy and difficult to service but they seem to still be fine...even after staying in the boat over each winter here in the frozen north. (I couldn't take them out even if I wanted to!) Should I replace them with something else based upon age alone or wait for some sign of a problem?

[Chris & Dale]

Do you know how old they are, and have you kept them on a good smart charger during the winter which would unto itself probably keep them from freezing? The only reason I'm changing mine is TIME - 7 years! Ever walked out to your car in the morning and the battery's dead? No clue the day before & no lights left on....it was just time. We're getting ready to fish the US Open King Mackerel Tournament and I don't want to be 25 miles off shore and find out one of my batteries has just given up the ghost. Kinda like my timing belt. No indication of any performance issues w/the motor and I'm not quite at 1200 hours....but it's 13 years old, so it's getting changed this week. Again, don't want to get caught off shore and have my motor seize up. Good Luck!