Vulcanbike
Veteran Member
I'm thinking my 2 8D batteries on my '01 MS 390 are ready for replacement. Cummins 6bta 330 HP. Any suggestions on good quality replacements? Brand/model/price?
I'm thinking my 2 8D batteries on my '01 MS 390 are ready for replacement.
I'm the outlier here. My 8 Ds work quite fine and provide good ballast. This is a trawler forum where ballast is not a bad word.
I use three 8Ds, 2 for engine starts and 1 for genset. and am quite happy with them. There is an already setup space for each and every five years the local yard spends about an hour lifting the main engine starts in and out. The first genset went 8 years with no problem.
Get some prices, question the crowd advice and make your own decision. 8Ds can be very cheap. Sticking with what works has no downside unless you insist on being the strong back rather than using a young buck.
Here are the weights of the batteries discussed so far:
Group 31 57 lbs
4D 100 lbs
8D 127 lbs
GC 62 lbs
Any of the first three will start a Cummins 6BTA. Pick your poison.
And as foggysail notes above, two GC batteries weigh the same as one 8D and for house service are true deep cycle batteries, unlike most 8Ds.
David
My 3988 came with 3 8D batteries, 1ea. for starting the Cummins and 1 for house. I have since changed to group 31 for starting and GC for house but had problems with the Group 31 overcharging and using too much water vs. the GC. I now have 2 GC for each starting bank and 6 GC for house resulting in no more problems with charging using combiners. And I can lift them.
Good info here, David. Sunchaser, if you replace each 8D with 3 GCs, you'd increase your ballast and your AH capacity by almost 50%!
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NO! It only requires two GCs for one 8D. Remember, you have to connect the GCs in series 6v + 6v = 12v. Of course you could connect two GCs in parallel and series those two with another pair in parallel to have 12v at 460 amp hours.
I probably didn't explain that well. Take 2 8Ds out of the boxes and replace each 8D with 3 GCs. Now connect them in series-parallel and you've got 50% more weight and AH capacity. I did this with my 3 pairs of GCs and went from ~440 to 660AH.
I probably didn't explain that well. Take 2 8Ds out of the boxes and replace each 8D with 3 GCs. Now connect them in series-parallel and you've got 50% more weight and AH capacity. I did this with my 3 pairs of GCs and went from ~440 to 660AH.
I wired 6 GC into a 660 AH bank via series-parallel. These 6 batteries fit in the boxes formerly used by 2 8Ds. This makes up my house bank. The third 8D box that formerly held an 8D start battery now only holds a single G31 start battery.
The 6 GCs form a single house bank of 660 AH. Each series pair of GCs provide me 12V-220AH. I have 3 of these pairs combined in parallel to form a single bank of 6 GCs providing 12V and 660 AH. I'm not wasting any power and my battery bank is working well.
Imagine this bank shown below with TWO MORE GCs in series-parallel. 3 GCs occupy one 8D box and the other 3 GCs occupy another 8D box. That's my HOUSE bank.
My start battery is a single G31.
The 6 GCs form a single house bank of 660 AH. Each series pair of GCs provide me 12V-220AH. I have 3 of these pairs combined in parallel to form a single bank of 6 GCs providing 12V and 660 AH. I'm not wasting any power and my battery bank is working well.
Imagine this bank shown below with TWO MORE GCs in series-parallel. 3 GCs occupy one 8D box and the other 3 GCs occupy another 8D box. That's my HOUSE bank.
My start battery is a single G31.
Two starting batteries plus generator battery plus house bank does not make sense to me. .
Here are the weights of the batteries discussed so far:
Group 31 57 lbs
Hmmm.... Our G31s weigh 77.8 lbs.
And I felt every pound of each when I replaced the first bank myself.
-Chris