8D Battery Replacement options

I replaced my 8 8Ds for house and 2 8Ds for start, with L16 6v batteries - I can get three L16's in the space of two 8Ds. They provide more amp hours overall because the total amount of lead is more. The L16s are taller so they do not work for everyone. The individual batteries weigh less (about 125lbs each) so are not as hard to move around. The batteries are designed for industrial use - scrubber/sweepers and Lifeline sells them in AGM. If I did not use these, the Rolls were my next choice.

The specs for our engine recommended a 4D or equivalent. The local Ford Lehman guru suggested an 8D because of the colder ambient and water temperatures. We got a deal on 3 Optima Red Tops. Since we were rewiring the house bank, we had the wire and lugs so it was an easy job. The bank has it's own 3 stage voltage regulator and alternator so there's no conflict with the T-105's (house bank).

Larry M said:

The specs for our engine recommended a 4D or equivalent. The local Ford Lehman guru suggested an 8D because of the colder ambient and water temperatures. We got a deal on 3 Optima Red Tops. Since we were rewiring the house bank, we had the wire and lugs so it was an easy job. The bank has it's own 3 stage voltage regulator and alternator so there's no conflict with the T-105's (house bank).

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I bet those do the job!

Looks like a nice ship shape install.

ksanders said:

I'd rather see your windlass and crane running on your house bank though.
From my standpoint there should be zero loads on the start batteries other than starters.

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Why do you think this? Our boat did have the windlass powered by the house(4 golf cart) batteries and every time we ran the windlass our GPS would beep and go crazy. Move the windlass power supply to the start battery(8D) and have had no problem with electronics since. We always have the engine running while using the windlass............

I have two 8D for the motors (2 Cats 3208, 375hp), a house with 6 Troyans 6volts and another 8D for the crane, windlass and generator. Works well

When I called American Diesel...they basically told me a group 24/27 (depending on specs) for a Lehman 120.

I went up a notch in size.... and even in 20 degree weather it bangs right over with 850 or so CCA....physical size is around a group 27.

When I read the specs on Lehman starters...really a good group 24 should really handle it...but only in a perfect world.

Many of the big production guys like Sea Ray got away from 4Ds and 8Ds and went with group 31s in parallel to start and another as Batt 2 for backup...even to start their entire Cummins line in Rays up to 45 feet or so.

I`m not against 8Ds at all, but installing/disposing @ 53 kg is a challenge.
My genset start batt has 150ah dimensions, (would you call that a 6D), puts out 1150CCA, I bet its predecessors 30 years back did half that, so a 4D would probably suffice. But it is back up, just in case, for the mains.

rochepoint said:

Why do you think this? Our boat did have the windlass powered by the house(4 golf cart) batteries and every time we ran the windlass our GPS would beep and go crazy. Move the windlass power supply to the start battery(8D) and have had no problem with electronics since. We always have the engine running while using the windlass............

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Simply because I want nothing attached to the start batteries that could drain them.

I have both a crane and a large windlass. These are tied to the house bank, and I suffered the exact thing that you reported. When running the windlass the voltage would drop to the nav system causing it to reboot.

To solve this I simply start the generator when running the windlass. The battery charger keeps things up enough to not bother the electronics.

With caution the group of 31 can be fine, BUT the problem is they can never be asked to suffer deep discharges.
Or they will need rapid & frequent replacement.

Thats fine if a Sams club is the source , they check nothing , just hand you a new set 2x (the computer knows).

So the question then becomes what service use is the crane ?

5 -10 min of dink hoisting should not be a problem, an hour surely would be.

Discharge rate 50A? or 200A ?

Again a SOC meter would be a big help in understanding how hard you are hammering the set.

The spiral wound or AGM batts might be a better choice for long hard accessory use , and the charge back up quicker IF you spend the bucks to rapid recharge.

If you are not paying around $400 for an 8D, it's not a deep cycle. A $150 8D is a starting battery with thinner plates.

If you are not paying around $400 for an 8D, it's not a deep cycle. A $150 8D is a starting battery with thinner plates.

Possibly , but what you are paying for is the LEAD in the battery , the case and spacers are cheap 50c a pound plastic.

The yachty markup $400 for $150 worth of lead in a different plate thickness is partially caused by by the lower production of deep cycle batts , VS the huge number of 8D for Trucks, Coaches, Cranes, Ag & earth moving etc.

Since many of these commercial uses DO require more than just a thin plate start batt ,(like a 31) the 8D usually is a fair compromise , but certainly not for repeated real deep cycle work.

Many OTR trucks run lots of lights with an Espar cycling of and on for 12 hours , sometimes with a TV , and lap top , and bunk heater. No place for just a start batt , but the cheapo 8D seems fine with the service.

The 8D in this service are seldom deep discharged , and with a 10 hour charge time , even an imbecile 1 wire V regulator can bring them to 100% , so they live long and prosper (3-4 years).

Check the CCA as well as the 20 hour rate for your next batt endeavor , as simple and cheap can work for many.

IDEAL solutions are fine IF you fully use them , otherwise a waste of currency.

IMO - Singularly the most important factor for extending the life of deep cell batts is never allow discharge over 50% - Period.

I have a lit screen Digital Multimeter batt tester hooked directly to our house batt bank and placed easily viewed on shelf in master stateroom; observable from salon. Flip of its switch and I see %age charge, drain during equipment use, and rate of recoup thereafter... as well as rate of charge while charging. I also see how fast it releases “over charge” after charging is completed and how long it took batt bank to level off at 100% charge. I don't always leave it on... but I do check house bank often!

Starter batts are a different animal in that soon as engine is started alternator should quickly return them to full charge.

Separately I keep a Multimeter in engine compartment (where I often “play around” early morns). I sometimes hand check starter batts as well as our “emergency batt”.

I believe starter bats should not be in house bank; OK to use deep cell as starter. Also, I believe in and do keep a completely isolated never used "new" combo batt for emergency in its own box with a trickle charger continually attached that activates whenever AC is on. As we are not dock sitters and seldom use gen set more than couple hours a day the “Emergency Batt” arrangement works well; it maintains high charge.

As with any piece/item/function on a boat... general surveillance for maintaining acceptable status quo is the name of the game to avert occurrences of untoward conditions.

Happy Boating Daze! - Art

I decided to install a magnum battery monitor (SOC) on the inverter/house bank (900 AH). I moved the crane from the starting battery to the inverter/house bank so the windlass is the only other draw on one of the starting batteries and the other is only a starter (and can be combined if needed). I am having the marine service folks remove and install new 8Ds. This keeps it fairly simple and amply powered so I won't have to worry about engines not starting.

For those with a deeper interest in batts , this months HOME POWER mag is starting a 3 part series on bat maint , operation and cycling.