battery question

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obenton

Veteran Member
Joined
Aug 7, 2016
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I recently purchased a 45ft Californian. The battery charger was original (1988)-Silicon Diode brand. The batteries were all low on water and I refilled them. The boat was then idle - getting engine work with little draw on the batteries except lights, Within 3 weeks the water levels dropped. Apparently there were three circuits hooked directly to the charger. The charger has been replaced and I am thinking of exchanging the 8Ds for 31 series. I know it will take about 3 31s per 8D. I think there is room for them and I'd rather not deal with the heavy 8Ds. The boat has three 8Ds and no battery dedicated to the generator ( which I would like). I'd like some advice - seems most the boaters I know are getting away form the 8Ds. Thanks
 
It's common to have some batteries that are deep cycle and designed to de discharged 30 to 40% and others that are designed only to start the engine or the generator. Generally speaking, deep cycles don't last as long when used as start batteries, and start batteries generally have short lives when significantly discharged. Were all the 8Ds hooked together or are some house batteries and one a start battery?

Ted
 
all were hooked together. Not really sure how they are arranged but I envision two starting banks and a house bank. My former boat had two starting batteries, two house and one for each thruster. All were 31 series and I understood the connections. The diesel mechanic agreed to load test everything this week. I'm hoping with a new charger and 24 to 48 hours of charging I will find the batteries functional for now, but I suspect i will need to replace them.
 
I have completely redone the DC system in both of the boat we have owned. The flat-out single best piece of advice you can take is KEEP IT SIMPLE!!

I would also suggest to replace those 8ds with proper flooded deep cycle golf cart batteries. Cheap, light(er) and they provide the most amp hours for the buck. You will likely need to buy or fabricate new boxes, but it will be fun for the whole family.

One big house bank fed by the alternators and the charger and one bank of dual-purpose batteries to start both engines and the generator charged by a Blue Seas ACR. Done! Easy to design, build, maintain, and understand. Moreover, far fewer points of failure.
 
I'm all in favor of avoiding 8D batteries. My back has never been the same since I tried to keep a little 4d from sliding off a hand truck.
 
We are very careful on our battery energy usage.

Our boat has 4 group 31 deep cycle, wet cell batts hooked up in parallel for house bank, and used as twin engine starters. Starboard engine alternator charges house bank. Separate group 27 starter batt for gen set. Isolated 27 starter batt in its own single batt box kept 100% charged... as emergency spare, just in case. House bank deep cells are eight years old and doing OK. When at anchor for days in a row we usually run gen set one hour in morning and one in eve for cooking, charging equipment, cooling down fridge and charging house bank. Gen set batt is solar charged as well as by gen set's alternator. Isolated emergency batt is trickle charged whenever 120 AC is on while gen set runs or boat is plugged into dock. I have a multi meter wired into house bank and in location where I can check house bank condition when desired. I like to keep battery circumstances simple and efficient and inexpensive.
 
thanks for the input.Have not been on the boat in a while. The original set up was 4 8Ds with one serving as generator starter and house battery, two as engine starters and a second house 8D. The inverter had 3 or 4 trojan batteries. . The 8 Ds looked good on load testing so I elected to keep them. The Trojans were fried- one of the cases was broken and leaking fluid. The set up now is a little overkill ,but I agreed to it. One 8D for each engine.. two for house , two group 31 batteries for the generator and 3 group 31s as inverter batteries. Had we not had the inverter/charger already I might have stuck with just the 8Ds. We do travel a bit and anchor out a lot. I prefer using battery power for the little stuff and not run the generator unless I need heat and air. I will replace the 8Ds as they play out. They are a pain to get in and out. Appreciate the comments.OB
 
obenton said:
....... One 8D for each engine.. two for house , two group 31 batteries for the generator and 3 group 31s as inverter batteries. .
Click to expand...

I would think an 8D battery for each engine would be a little much. My engine starts just fine on a group 31 AGM. I think the original battery was smaller than that.

Also, two group 31 batteries or the generator is way overkill. Really, your two engines and the generator could be started with a single group 31 battery as long as you don't try to start all three at once.

As for the house and inverter, there's no need for separate batteries or banks. The inverter is just another house load. This is where I would be using the high capacity batteries.
 
WesK said:
I would think an 8D battery for each engine would be a little much. My engine starts just fine on a group 31 AGM. I think the original battery was smaller than that.

Also, two group 31 batteries or the generator is way overkill. Really, your two engines and the generator could be started with a single group 31 battery as long as you don't try to start all three at once.

As for the house and inverter, there's no need for separate batteries or banks. The inverter is just another house load. This is where I would be using the high capacity batteries.
Click to expand...

:thumb:

We don't know what your loads are, but if you have a residential fridge, you probably run it thru the inverter when not plugged into shore power. Otherwise, you could reduce your house batteries by about 1/2.
 
Agreed... it sounds very convoluted and far more complex than it should be. Take your time, do a lot of reading on battery systems and how other people approached similar problems. Boats like these should optimally have two systems (with the option of a small dedicated genset start battery). However, you need to design your system to how you will use your boat and not rely on the way the factory or previous owners did it. 8Ds are not deep cycle batteries and are overkill for starting... Group 31s are not deep cycle batteries either. Mixing and matching all of these means none of them get fully charged or pull down the entire bank.

But like I said, do your homework, take your time, and design the best system that works for you.
 
Engine manufactures usually will specify what battery to use under what conditions.
 
obenton said:
thanks for the input.Have not been on the boat in a while. The original set up was 4 8Ds with one serving as generator starter and house battery...
Click to expand...
Not a good idea. If the house drains the battery you can`t start the genset, and it`s your back up.
When I got my present boat someone had wired the 12v fridge direct to the genset batt, I couldn`t remove it fast enough and rewire it back into system Halvorsen designed it, via switch panel "Fridge" breaker switch.
 
Tom.B said:
Agreed... it sounds very convoluted and far more complex than it should be. Take your time, do a lot of reading on battery systems and how other people approached similar problems. Boats like these should optimally have two systems (with the option of a small dedicated genset start battery). However, you need to design your system to how you will use your boat and not rely on the way the factory or previous owners did it. 8Ds are not deep cycle batteries and are overkill for starting... Group 31s are not deep cycle batteries either. Mixing and matching all of these means none of them get fully charged or pull down the entire bank.

But like I said, do your homework, take your time, and design the best system that works for you.
Click to expand...

Tom - You mention... "Group 31s are not deep cycle batteries either." I question that. I have four 31 deep cycle wet cell batts in my house bank that I run down to 60 or 50 percent and recharge to 100%. Same bank is used for engine starters. About 8 yrs old now and still doing OK. Bought them at Batteries Plus. Manufactured by East Penn Battery and labeled as Deep Cycle.
 
WesK said:
I would think an 8D battery for each engine would be a little much. My engine starts just fine on a group 31 AGM. I think the original battery was smaller than that.

Also, two group 31 batteries or the generator is way overkill. Really, your two engines and the generator could be started with a single group 31 battery as long as you don't try to start all three at once.

As for the house and inverter, there's no need for separate batteries or banks. The inverter is just another house load. This is where I would be using the high capacity batteries.
Click to expand...

I am somewhat amazed at the amount of battery power that boaters feel they "need" to install for engine starting purposes.

Some of these boats have more battery in them than a big commercial truck that is expected to start in sub zero?

Few are going boating in temperatures below 50 degrees? 60 degrees?

Lots of battery compensating for poor charging and maintenance practices?

Beware the manufacturer, if they have added a fudge factor for the "typical boater abuse"... most of us on here are a fair bit better than those!!

As quoted, why would most of us REQUIRE anything more than a single Group 31 for starting?

$ave ca$h for other boat $tuff?

RB
 
Tom - You mention... "Group 31s are not deep cycle batteries either." I question that. I have four 31 deep cycle wet cell batts in my house bank that I run down to 60 or 50 percent and recharge to 100%. Same bank is used for engine starters. About 8 yrs old now and still doing OK. Bought them at Batteries Plus. Manufactured by East Penn Battery and labeled as Deep Cycle.

stone beach said:
Group xx indicates the physical size of the battery. Not the type
Click to expand...

True - Group "XX" is size of battery. There are XX size wet cell batts that are built to withstand deep cycle use. East Penn is a renowned battery mfg and I believe one of the, if not the, largest. Batteries Plus chain of stores stocks East Penn's batteries, and sells them under differing brand names. What I know from experience is that the four group 31 [labeled "deep cycle"] batts I purchased at Batteries Plus Store in 2009 are still going strong being used in our Tolly's house bank and simultaneously as starter batts for our twin engines. :popcorn:

PS: Since around 2007 I began purchasing all batteries from Battery Plus. Have had great luck with battery quality as well as service. Prices are darn good too!
 
You can do the math for starting the engine based on stater amps....

But I would still use the manufacturers recommendation even if they added a fudge factor....does anyone have hard data that they do?

Any more than up sizing cabling or anything else to overcome typical less than perfect situations common on boats.

But often boats get batteries way oversized for engines because they are or supplement the house bank.
 
psneeld said:
You can do the math for starting the engine based on stater amps....

But I would still use the manufacturers recommendation even if they added a fudge factor....does anyone have hard data that they do?

Any more than up sizing cabling or anything else to overcome typical less than perfect situations common on boats.

But often boats get batteries way oversized for engines because they are or supplement the house bank.
Click to expand...

Having our four group 31 wet cell deep cycle batts hooked in parallel and used for house bank as well as engine starters I've experienced no problem for nearing a decade of use that way. I like to keep things on the side of KISS... with backups to go to if necessary.
 
Art said:
Having our four group 31 wet cell deep cycle batts hooked in parallel and used for house bank as well as engine starters I've experienced no problem for nearing a decade of use that way. I like to keep things on the side of KISS... with backups to go to if necessary.
Click to expand...

One can argue having that setup isn't KISS....and my point wasn't about total boat 12v setup...it was sizing a START battery....and that just saying that most boaters have batteries too large might be accurate...but a person still should outfit their own boat correctly.
 
When replacing 8D's hire a handyman or yard service person to do the moving. Also protect all the flooring. There will be dripping battery acid.
 
Pgitug said:
When replacing 8D's hire a handyman or yard service person to do the moving. Also protect all the flooring. There will be dripping battery acid.
Click to expand...



Off topic a bit, I know...

I mentioned years ago a 30something year old gentleman lives down the street and has lots of friends that hang out in his garage after work. They like to drink beer and work on misc projects in his garage and watch sports on the tv.

I started dropping 30 packs of Bud Light off monthly many years ago and started a long lasting relationship. Now that my body is riddled with arthritis among other things I find all I need do is ask and 2-6 volunteers gladly show up and do any heavy lifting I struggle with.

If there are similar folks near any of you I strongly recommend cultivating a relationship. If nothing else it pays to be considered the cool old dude down the street and strengthens your neighborhood bonds.
 
Roamer Blue said:
I am somewhat amazed at the amount of battery power that boaters feel they "need" to install for engine starting purposes.
...
As quoted, why would most of us REQUIRE anything more than a single Group 31 for starting?

$ave ca$h for other boat $tuff?

RB
Click to expand...

+1 for 8D is probably not a good starting battery - nor are they typical in offgrid deep cycle installations, either, meaning, (having two of them myself) I would question why you would ever need one.

You need 1000CCA or so (+/- 20%) for most starting applications.. and with twins.. (and a genny) you still really only need ONE.

Then size your house bank(s) for the most amp hours your wallet will afford in deep cycle, most typically going to be golf cart 6v's.. sam's club GCx, trojan t-105, interstate U2xxx etc.
 
The size and capacity of the starting battery should be whatever the engine manufacturer recommends. There's no real harm in making it a little more powerful but there's little to gain.


The size and capacity of the house bank is a different story altogether. Obviously, install at least what you need but it's hard to have too much capacity in a house bank.
 
WesK said:
The size and capacity of the starting battery should be whatever the engine manufacturer recommends. There's no real harm in making it a little more powerful but there's little to gain.


The size and capacity of the house bank is a different story altogether. Obviously, install at least what you need but it's hard to have too much capacity in a house bank.
Click to expand...

As you say is true!

What I don't understand is why have separate battery for starting engines? When working off of a parallel wired house bank works just fine and long as house bank is not dead [or very near too dead] there is plenty of crank power available. Of course, just incase house bank were to die due to over use or short-out then having gen set with independent starter batt is good for running the batt charger to get HB charged enough to start engine. Also, having an isolated starter batt available and always kept at full charge is good idea too. Top quality long set of jumper cables should be aboard. I have all that's mentioned here, as well as solar panel that charges gen set battery. IMO - Available, DC (battery and solar power combo) redundancy is name of the game on boats that travel away from dock.
 
psneeld said:
Engine manufactures usually will specify what battery to use under what conditions.
Click to expand...



That may be true, but boat builders will build a system based on what battery they can get cheapest by the pallet load :)
 
Art said:
Tom - You mention... "Group 31s are not deep cycle batteries either." I question that. I have four 31 deep cycle wet cell batts in my house bank that I run down to 60 or 50 percent and recharge to 100%. Same bank is used for engine starters. About 8 yrs old now and still doing OK. Bought them at Batteries Plus. Manufactured by East Penn Battery and labeled as Deep Cycle.



True - Group "XX" is size of battery. There are XX size wet cell batts that are built to withstand deep cycle use. East Penn is a renowned battery mfg and I believe one of the, if not the, largest. Batteries Plus chain of stores stocks East Penn's batteries, and sells them under differing brand names. What I know from experience is that the four group 31 [labeled "deep cycle"] batts I purchased at Batteries Plus Store in 2009 are still going strong being used in our Tolly's house bank and simultaneously as starter batts for our twin engines. :popcorn:

PS: Since around 2007 I began purchasing all batteries from Battery Plus. Have had great luck with battery quality as well as service. Prices are darn good too!
Click to expand...



You are welcome to think that and I won't hold it against you. You may enjoy great success with your EP Group 31 batteries that are labeled deep cycle, however they cannot and are not true deep cycle batteries. They will never out perform batteries designed from the ground up to be true deep cycle batteries like golfcart or industrial floor scrubber batteries. East Penn is a reputable company for sure, but they will also slap a deep cycle sticker on a battery if paid to do so.
 
Art said:
As you say is true!

What I don't understand is why have separate battery for starting engines? .
Click to expand...

It's fairly easy to drain your house battery or bank running refrigerators, microwaves, inverters, etc. Having a separate engine starting battery insures that you can start the engine and continue on your way.
 
Tom.B said:
You are welcome to think that and I won't hold it against you. You may enjoy great success with your EP Group 31 batteries that are labeled deep cycle, however they cannot and are not true deep cycle batteries. They will never out perform batteries designed from the ground up to be true deep cycle batteries like golfcart or industrial floor scrubber batteries. East Penn is a reputable company for sure, but they will also slap a deep cycle sticker on a battery if paid to do so.
Click to expand...

Tom

I know that there are more powerful, seemingly more long-life resilient, higher tech design deep cycle batts than the la (serviceable) deep cycle batts I get from Batteries Plus. And... that a couple or more thousand dollar$$$ won't really get us too much better service.

But! With eight years service [so far] and cost under $500 for four group 31 deep cycle batts (discounts given when purchasing quantity), as well as batt size/weight that I can handle easily and that fits perfectly into my batt bank confine area... well... what more can I say!

Except this - https://www.batteriesplus.com/batte...31m/sli31mdc?gclid=CMj0-YKvxdECFQiSfgodkWUKow
 
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