Batteries - Electrickery!

Haven't had a lot to do with batteries for quite some time.
On the boat at the moment is a lead acid type battery which is in place for starting the stbd engine. A 135hp 6 354 Perkins.
There is also a new 34M PC 1500 Odyssey AGM battery on board and believe it was going to be used for the Port engine. Just didn't get installed. Both batteries are rated at 880 cold crank.
The older one is on it's way out. Buckled and does not hold a charge. I presume that is why the other is not in place.

My question is, is 880 CC approximate the right size for this size engine?

Also the AGM battery is about 2/3 the size of the other battery. Is that just the advancement in design of these batteries?

It says "dual purpose" so is it better suited to being used as a house battery?

I know these Odysseys are expensive and have a good reputation, but it just looks so small!!

Any info would be helpful.
Capstan
SPECIFICATIONSPulse (5-second) Hot Cranking Amps (PHCA)1500Cold Cranking Amps (CCA)85020Hr Nominal Capacity (Ah)68Reserve Capacity Minutes135Dimensions L x W x H (in)10.85 x 6.76 x 7.82Metric Dimensions L x W x H (mm)275.59 x 171.7 x 198.6Weight (lbs)49.5Weight (kg)22.4

Dual purpose, IMO, means that they are not good at either. Start batteries are for starting engines and deep cycle are for house batteries.

AGMs can supply the same amps with a smaller case size than a flooded cell battery. But for house use the smaller case means a lower amp hour capacity. There is little if any difference between starting and deep cycle batteries in the AGM type, but significant differences in the flooded cell type.

The 34M AGM will probably do the job and Odyssey is a good brand. I prefer a good quality Group 31 flooded cell battery. These typically are rated at about 1,000 CCAs. Wal Mart has them for about $130, Sams a bit cheaper.

Your buckled battery is definitely toast. It probably froze last winter due to being discharged.


David

Capstan said:

Haven't had a lot to do with batteries for quite some time.
On the boat at the moment is a lead acid type battery which is in place for starting the stbd engine. A 135hp 6 354 Perkins.

My question is, is 880 CC approximate the right size for this size engine?

Click to expand...

So much of battery choice centers around the way you use your boat and how it's setup. But it sounds like you have twin 6.354's and do I understand correctly you have two 880 CCA batteries total, for everything?

If that's the case, I would say you don't have enough battery power. You need more battery capacity than "just enough" to start the engines. Sometimes a Perkins can get cranky and be difficult to start. A little air in the fuel lines and you're in trouble. I would recommend a minimum of 1000 CCA batteries.

For example: I also have twin 6.354's and twin banks of two 4D lead acid batteries separated by a battery switch. I don't use the inverter, unless the engines are running. When the engines are off and we need 110V we run the 7.5 KW generator. The batteries last me on average 8 - 10 years.

But if your use involves living on your batteries with an inverter, then you cut your LA battery life in half, even if your careful. Or run those LA batteries down to 50% or less a couple of times and kiss them goodbye. You really need deep cycle batteries for that purpose. In any case, you need to choose the batteries size and type that works best for your life style and boat use.

"Sometimes a Perkins can get cranky and be difficult to start. A little air in the fuel lines and you're in trouble. I would recommend a minimum of 1000 CCA batteries."

A CCA rating tells how large a load can be spun during engine start , not how LONG the batts will do it.

The diesel needs to be spun rapidly to create the heat to ignite the fuel.

In winter a bog CCA is a benefit.

If the engine must be cranked to bleed it (a very poor operating choice) frequently the house deep cycle bats will motor it far longer than the start bank.

Our engine spec sheet includes minimum CCA/MCA requirements (happens to be 1250/1560), so perhaps there's a Perkins equivalent data source to that?


We use an Odyssey M34 to start our 8 kW genset, which uses a Yanmar 3-cyl. diesel. I think the M34 is a bit of overkill, but haven't checked that.


-Chris

Wear eye protection and be very careful removing the "buckled" battery as it is badly damaged and can short internally.

FF said:

CCA rating tells how large a load can be spun during engine start , not how LONG the batts will do it.

Click to expand...

Not quite. From Wikepedia:

Cold cranking amperes (CCA) is the amount of current a battery can provide at 0 °F (−18 °C). The rating is defined as the current a lead-acid battery at that temperature can deliver for 30 seconds and maintain at least 1.2 volts per cell (7.2 volts for a 12-volt battery).

So this spec tells you how many amps the battery will supply after 30 seconds of cranking at zero F. Another spec used for marine purposes is MCA which is the same except the temperature is 32 deg F.


If a diesel won't start after 30 seconds of cranking, something is really wrong!

Yes, neither CCA or MCA tell how many amp hours a battery can supply, but that rating is meaningless for a starting battery.

Here is a table of approximate battery size and CCAs required for various size diesels. I just made it up ;-).

0-2 liter (small Yanmars, Westerbekes and most gensets), Group 24, 500 CCA
2-4 liter mid size trawler engines, Group 27, 650 CCA
4-6 liter 6 cyl Perkins, Lehman, Cummins, Group 31, 900+ CCA


David

I often wondered why my 8 kw Onan genset was equipped with a 4D battery. When the battery died, I replaced it with a group 24 and used the remaining space in the battery box to store my spare raw water pump for the big Cats. The group 24 is a sealed battery.

ranger42c said:

Our engine spec sheet includes minimum CCA/MCA requirements (happens to be 1250/1560), so perhaps there's a Perkins equivalent data source to that?
-Chris

Click to expand...

Good question Chris. I looked in both Perkins Marine shop manuals I have and couldn't find any comment about minimum battery size. Probably because 6.354's were used in everything from light trucks, fork lifts, generators, boats and no one battery size fits all uses. And battery size for a forklift would certainly not be sufficient for a boat. If it's in the manual, they buried it well.

However, Marshall Boat Co. the makers "Californian" in the 1970's, which is similar to the OP's boat, as a standard put two LA 8D batteries in all their twin 6-354, 38' - 42' trawlers. If you wanted something different, it became a dealer upgrade. The 8D's had a CCA around 1300 to 1400 and MCA 1750. If you ran your refrigeration while at anchor you could run through those two batteries fairly quickly. Depending on needs most owners overtime either switched to 4 - 4D's, which is about 4000 CCA total or converted one bank to deep cycle batteries for the house use.

-----------------------------------
hmason
I often wondered why my 8 kw Onan genset was equipped with a 4D battery. When the battery died, I replaced it with a group 24 and used the remaining space in the battery box to store my spare raw water pump for the big Cats. The group 24 is a sealed battery.
---------------------------------------
You're right a small car battery is plenty big enough. A 4D is over kill on a 8 KW generator. It could have been intended as a last resort backup battery for your main engines too. Did you find a set of jumper cables in the engine room?

Edelweiss said:

Good question Chris. I looked in both Perkins Marine shop manuals I have and couldn't find any comment about minimum battery size. Probably because 6.354's were used in everything from light trucks, fork lifts, generators, boats and no one battery size fits all uses. And battery size for a forklift would certainly not be sufficient for a boat. If it's in the manual, they buried it well.

Click to expand...

Too bad. Another data point might be from the label (if any) on your starters.

-Chris

ranger42c said:

Too bad. Another data point might be from the label (if any) on your starters.
-Chris

Click to expand...

And since you mentioned it, starters are another non-standard in 6-354's. My starters are Delco 35MT's with an external solenoid. But in my gillnet boat they were Bosch with a different flywheel tooth count and solenoid.

The Delco solenoid's mechanically force the starter gear drive into the flywheel, which causes a significant battery load. The voltage drop from a weak battery or poor electrical circuit results in solenoid contacts chattering and ruins the solenoid. So its important to have adequate battery capacity.

Jumper cables in engine room?

No, but I put a set in. With 2 LA 8ds and 2 AGM 8Ds plus the group 24, I doubt I'll need them anytime soon.

hmason said:

Jumper cables in engine room?

No, but I put a set in. With 2 LA 8ds and 2 AGM 8Ds plus the group 24, I doubt I'll need them anytime soon.

Click to expand...

:lol: Probably not!! But with batteries I'd rather have extra, than just enough . . . . But maybe you can jump your generator battery or do a little welding with those cables, if you run out of things to do??

Ha. Good idea.

Thanks everyone for the information. Lot's of helpful tips.
Spoke to a Perkins Rep/mechanic and he said that it comes down to the size of the starter (Good call Chris). That the starter for our 6-354's are large so require the extra CCA. 1,000 and up would usually be recommended, but, another factor is that we will not be in cold climate so we can get away with less.
However, as most people recommended, better to have a little more and not get caught out one day.
Thanks,
Capstan

"better to have a little more and not get caught out one day."

Batteries age and loose capacity in time