21EC batteries

[Pilotnavigator]

One more question on the batteries. Has anyone managed to squeeze 2 Group 27 batteries into the engine box? The one's i would like to get in are two Optima D27M's with a lenght of 12 inches (other measurements are fine). The factory centennial DC24MF is 11 inches. So I need only 1 more inch. Let me know if it is just the battery tray that would make the install not work, I could work around that issue. Boat is on order so I can't get m hands on it to see. But would like to plan ahead.
Thanks
John

 

[Ard]

John-

I've been actively pursuing this same thought process. On my R21 Classic I'm limited to 2 small group 24 batteries for house and starter with a footprint of 7"x10" max ea. On my boat I do have 17" of height. By playing Tetris I've concluded I can get 2 group 31 batteries either on end or stacked on their sides in that space. Obviously this eliminates flooded batteries as an option. You may be able to do the same if you have 13" of available height.

Take a look at the Lifeline GPL-31XT. These are rated at 125 amp hours and up to 1000 charge cycles ea. (the most I can find). You should also take a look at this excellent post by Howard: http://www.tugnuts.com/viewtopic.php?f=5&t=4100&p=30242&hilit=lithium#p30242 He has molded my thinking on the issue and explains why a 250 amp house bank is really more like 80 amps useable. He also touches on LiFePO4 technology, which interestingly enough, has evolved since his post. Check this out: http://store.starkpower.com/12V-100...ttery-LiFePO-Energy-Storage-Battery_p_24.html

This one battery, theoretically, will provide more reserve power than 2 of the Lifeline GPL-31XT and with a weight differential of 117 lbs (very significant consideration on the R21). And with theoretical charge cycles of 2000-3000, it should last several times as long as the AGM bank. The unanswered question is: will it start my engine? If it won't, maybe this will? http://store.starkpower.com/12V-Sta...-Ion-Emergency-Battery-Jump-Starter_p_68.html

I'll volunteer to be the guinea pig. We just need to get some crowd funding going here to raise some capital for the empirical testing. 😉

 

[Pilotnavigator]

some interesting ideas, so I might be able to put the batteries on their side and get two 27's to fit in the battery box and two extras in the stern. I already have one D27M Optima from the Sun Cat so I am tending to use them if I can put the one I have to good use. That is why the desire to get all 4 the same size in the boat. I agree that the total Ah is not really the usable capacity and I would really like to anchor for at least 48 hours without the engine running. We normally stay two days at each location then move 3-4 hours at 5knots so the batteries would get a reasonable charge then.
Guess we will see. More investigation.