It is time to replace two Group 27 Deep Cycle batteries and I could use some assistance. The batteries are used for the instruments, lights, and starting the Yanmar Y2QM15 diesel. Battery data is provided by Resereve Minutes, Amp hours, Cold Cranking Amps, and Marine Cranking Amp. Which numbers should be used in the analysis to determine the best fit?
Group 27 Deep Cycle Batteries
- Thread starter RickS
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no glow plugs
Yanmar does not use glow plugs. That's why they can be a little difficult to start in cold weather. For cold weather start, advance the throttle 3/4 and back off as sson as it catches fire.
Yanmar does not use glow plugs. That's why they can be a little difficult to start in cold weather. For cold weather start, advance the throttle 3/4 and back off as sson as it catches fire.
Another source of basic battery information is
West marine Advisors, either in the catalog or online.
West marine Advisors, either in the catalog or online.
Starting Diesel in cold weather
If it is really cold and your engine does not have glow plugs, use an electric hair drier to blow hot air into the air filter intake and the engine will start right up.
If it is really cold and your engine does not have glow plugs, use an electric hair drier to blow hot air into the air filter intake and the engine will start right up.
Group 27
The numbers you should compare is the Amp Hours (more is better). Amp hours is the amount of amps the battery can supply over a given time (usually given at 20 hours). Make sure that the AH rate is the same (some batteries use a different time) when comparing two different brands. A G27 deep cycle battery will have enough cranking amps to start your engine.
The numbers you should compare is the Amp Hours (more is better). Amp hours is the amount of amps the battery can supply over a given time (usually given at 20 hours). Make sure that the AH rate is the same (some batteries use a different time) when comparing two different brands. A G27 deep cycle battery will have enough cranking amps to start your engine.
All group 27's are about the same
Any group 27 (~100 AH) battery will start your engine. I was not aware that the numbers differed that much amoung the group 27 batteries. If you have a choice go for more AH.
Any group 27 (~100 AH) battery will start your engine. I was not aware that the numbers differed that much amoung the group 27 batteries. If you have a choice go for more AH.
Replace 27s with Golf Carts
Golf cart batteries are a little taller than 27s but as an option, if the height is available, you could also replace the 27s with a pair of golf carts. There are different AH golf carts starting around 220AH and I think the next stop is 245AH. Also, a little car battery will beat a big deep cycle batter for engine cranking. For example, you can test it yourself by taking the battery out of your wife's car (
) and seeing how it cranks - you'd probably be surprised.
Golf cart batteries are a little taller than 27s but as an option, if the height is available, you could also replace the 27s with a pair of golf carts. There are different AH golf carts starting around 220AH and I think the next stop is 245AH. Also, a little car battery will beat a big deep cycle batter for engine cranking. For example, you can test it yourself by taking the battery out of your wife's car (
) and seeing how it cranks - you'd probably be surprised.Starting
Your diesel requires quite about of power to get started...that's why diesel pickup have two batteries. Be sure they are wired together during the starting sequence.
Your diesel requires quite about of power to get started...that's why diesel pickup have two batteries. Be sure they are wired together during the starting sequence.
Remember ,It's only a 14 Hp. engine,
Couple good group 27's will last a long time, I like the AGM's for year round use, not sure if there's something better if you store on the hard part of the year.
Couple good group 27's will last a long time, I like the AGM's for year round use, not sure if there's something better if you store on the hard part of the year.
One 27
One 27 is plenty to start your little yanmar, I once started my 2GM20F with a half dead battery. But most boaters have 2 batteries on a 1-2 and both battery switch so run on one 27 and have the second as back up on a sail boat because you are not charging while sailing. Nick
One 27 is plenty to start your little yanmar, I once started my 2GM20F with a half dead battery. But most boaters have 2 batteries on a 1-2 and both battery switch so run on one 27 and have the second as back up on a sail boat because you are not charging while sailing. Nick
Rick any group 27 deep cycle battery will have
the cranking amps to comfortably start your diesel engine. The storage capacity in amps is mostly important in terms of your electrical consumption and recharging schedule, more so than as a comparison factor between batteries. I beg to differ with other sailors, but bigger is not always better. Bigger group batteries cost more, weigh more and occupy a larger space. If you have to lug a pair of 31's down the companionway and fit them into an impossible tight space you'll know what I'm talking about. You may conduct an electrical survey and determine your amp usage between your average recharge opportunities and that may give you an idea of how to size your batteries. Remember batteries shoould not be dicharged more than 50% of their rated capacity so a 100 Amp battery should only be discharged by 50 amps before recharging. To maintain a modest resrve capacity is prudent but to pay and lug around excessive reserve waiting for that one unlikely instance where you might need it is not smart. I also digress with sailors that recommend batteries be always combined. I alternate battery banks and try to always maintain them isolated with one acting solely as an emergency back up. To combine a spent battery with a fully charged one will only result in having two partially discharged batteries. This is not an absolute rule as long as you know what's happening and what you need to do.
the cranking amps to comfortably start your diesel engine. The storage capacity in amps is mostly important in terms of your electrical consumption and recharging schedule, more so than as a comparison factor between batteries. I beg to differ with other sailors, but bigger is not always better. Bigger group batteries cost more, weigh more and occupy a larger space. If you have to lug a pair of 31's down the companionway and fit them into an impossible tight space you'll know what I'm talking about. You may conduct an electrical survey and determine your amp usage between your average recharge opportunities and that may give you an idea of how to size your batteries. Remember batteries shoould not be dicharged more than 50% of their rated capacity so a 100 Amp battery should only be discharged by 50 amps before recharging. To maintain a modest resrve capacity is prudent but to pay and lug around excessive reserve waiting for that one unlikely instance where you might need it is not smart. I also digress with sailors that recommend batteries be always combined. I alternate battery banks and try to always maintain them isolated with one acting solely as an emergency back up. To combine a spent battery with a fully charged one will only result in having two partially discharged batteries. This is not an absolute rule as long as you know what's happening and what you need to do.
Batteries Can be Confusing
Rick, It sounds like you have one bank of batteries for all your needs. You don't say what type of boat you have, I will assume it is sail. For the most part, the larger the bank the better. The caveats are cost, weight, ability to recharge. When comparing deepcycle batteries the best measure IMHO, is 20 hour amp rating. (How many amps can be drawn for 20 hours and reduce the battery to 10.5v, dead) The primary purpose of the deepcycle battery is to provide amp hrs for extended periods of time. The larger the bank for a given daily draw the longer (in cycles) the bank will last. All parts go into a cost equation to determine the best buy.
Rick, It sounds like you have one bank of batteries for all your needs. You don't say what type of boat you have, I will assume it is sail. For the most part, the larger the bank the better. The caveats are cost, weight, ability to recharge. When comparing deepcycle batteries the best measure IMHO, is 20 hour amp rating. (How many amps can be drawn for 20 hours and reduce the battery to 10.5v, dead) The primary purpose of the deepcycle battery is to provide amp hrs for extended periods of time. The larger the bank for a given daily draw the longer (in cycles) the bank will last. All parts go into a cost equation to determine the best buy.
a twin bank of 27's in more than adequate
i also have a 2qm15 with the typical house draw, lights, inst, etc but no refrigeration and I've never had any problems with my 24 starting battery and a 27 for house use. you do have one advantage over many others in that the 2qm can be hand started with the crank. I had to do that once when we were in perryville and had a great wind situation for weeks. we just started the motor and motored to the bridge and shut it down and sailed. we did this for weeks, then, lo and behold we realized one afternoon that we had run both batteries down. got out the old crank and it started right up. in cold weather a very short burst of starting fluid makes it a lot quicker to start the qm. now before everyone gets in an uproar about starting fluid ,I SAID A SHORT BURST< one second is all that's needed and it won't harm the engine in any way. my engine is 29 yrs old and its still doing just fine. s/v que pasa?
i also have a 2qm15 with the typical house draw, lights, inst, etc but no refrigeration and I've never had any problems with my 24 starting battery and a 27 for house use. you do have one advantage over many others in that the 2qm can be hand started with the crank. I had to do that once when we were in perryville and had a great wind situation for weeks. we just started the motor and motored to the bridge and shut it down and sailed. we did this for weeks, then, lo and behold we realized one afternoon that we had run both batteries down. got out the old crank and it started right up. in cold weather a very short burst of starting fluid makes it a lot quicker to start the qm. now before everyone gets in an uproar about starting fluid ,I SAID A SHORT BURST< one second is all that's needed and it won't harm the engine in any way. my engine is 29 yrs old and its still doing just fine. s/v que pasa?
Space limits
Due to boat space limits, we are pretty much limited to two Group 27 batteries. The sailboat is on the hard from October thru May. The Yanmar 2QM15 engine is a bear to start cold which may be due to the engine and the batteries being 4+ years old. Although we've tried, we've never been able to hand start the engine. When the engine is cold and we try to start the engine, the draw will reset the insruments. Starting a warm engine will have no affect. Since we sail in Lake Michigan, a cruise could be approx 8 hours.
Due to boat space limits, we are pretty much limited to two Group 27 batteries. The sailboat is on the hard from October thru May. The Yanmar 2QM15 engine is a bear to start cold which may be due to the engine and the batteries being 4+ years old. Although we've tried, we've never been able to hand start the engine. When the engine is cold and we try to start the engine, the draw will reset the insruments. Starting a warm engine will have no affect. Since we sail in Lake Michigan, a cruise could be approx 8 hours.
battery life
at 4+ yrs your getting close to or at about the typical life span of them. has your engine ever had any internal work done? that is an engine that is 28-30 yrs old. it may have low compression and need rings, pistons, valve job or all of the aforementioned. if it has low compression the starter fluid will definitely help. there is a trick to starting it with a crank. hold compression release open, then get engine spinning with hand crank, then close release while still attempting to crank. it may take a couple of trys. especially if there's been a cold spell. P.S. if your drawing down the voltage that much then it could be a couple of things. battery on last leg. check all your battery cable connection's they are ok then possibly remove starter and have it checked out at a shop where they can check it out. you just might have a weak starter. s/v Que Pasa?
at 4+ yrs your getting close to or at about the typical life span of them. has your engine ever had any internal work done? that is an engine that is 28-30 yrs old. it may have low compression and need rings, pistons, valve job or all of the aforementioned. if it has low compression the starter fluid will definitely help. there is a trick to starting it with a crank. hold compression release open, then get engine spinning with hand crank, then close release while still attempting to crank. it may take a couple of trys. especially if there's been a cold spell. P.S. if your drawing down the voltage that much then it could be a couple of things. battery on last leg. check all your battery cable connection's they are ok then possibly remove starter and have it checked out at a shop where they can check it out. you just might have a weak starter. s/v Que Pasa?
Go 6 volt
Two 12 volt group 27 will give you 160-200 amp hours. Two 6 volts wired in series will give you 245-260 amp hours in the same (roughly) space, although they will weigh more. The "golf cart" types can also be discharged a bit more than the 12 volt types. http://www.dynobattery.com/prod01.htm
Two 12 volt group 27 will give you 160-200 amp hours. Two 6 volts wired in series will give you 245-260 amp hours in the same (roughly) space, although they will weigh more. The "golf cart" types can also be discharged a bit more than the 12 volt types. http://www.dynobattery.com/prod01.htm
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