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Boat Forum / Cruising / January 2005Starting batteries for 20 HP
Is there any reason to consider using dual purpose or a one starting, one deep cycle set up with a 20 hp Yanmar diesel? I would think the starting loads on the small engine are low enough that two deep cycle batteries would do fine.  SignatureRoger Long I suspect that you are correct. Our boat came equipped with 2 8D house batteries and a 4D starting battery. The starting battery was actually a deep cycle gel cell and worked perfectly well. (85 HP Perkins) I replaced it with a Group 30 starting battery for the savings in size. Unless your engine is hard to start and requires alot of cranking Incidently, the previous owner accidently started the engine in -20F temps using the deep cycle battery! Doug s/v CAllista Is there any reason to consider using dual purpose or a one starting, one deep cycle set up with a 20 hp Yanmar diesel? I would think the starting loads on the small engine are low enough that two deep cycle batteries would do fine. -- Roger Long I agree with Doug. i don't see any problems with it. > Is there any reason to consider using dual purpose or a one starting, > one deep cycle set up with a 20 hp Yanmar diesel? I would think the > starting loads on the small engine are low enough that two deep cycle > batteries would do fine. No problem - my Yanmar 2gm20's start almost instantly, and there's no pre-heater, so the load is modest (80 Amps?) and the total drain is minimal. However, I took the opportunity to replace my starter deep cycles with zero hassle AGM cranking batteries. Roger: Yes, two deep cycle batteries should easily start a two cylinder Yanmar. But don't you want to separate the batteries so you can't run them both down at the same time? I am pretty sure that one deep cycle Group 27 will also start your Yanmar easily. So set up two deep cycle batteries; each on one side of a 1, 2, all, off switch so you can always have one battery fully topped off after sailing all day after using the house loads. You can then alternate your "house" and "starting" batteries to keep them equally charged up. David Is there any reason to consider using dual purpose or a one starting, one deep cycle set up with a 20 hp Yanmar diesel? I would think the starting loads on the small engine are low enough that two deep cycle batteries would do fine. -- Roger Long That is exactly what I am going to do and the reason for my question. My experience is all with larger boats where there is usually a separate starting battery. It will be nice too to have an engine small enough to hand start although I hear the small alternator on this engine has a hard time bringing a battery back from the dead. SignatureRoger Long Roger: Yes, two deep cycle batteries should easily start a two cylinder Yanmar. But don't you want to separate the batteries so you can't run them both down at the same time? I am pretty sure that one deep cycle Group 27 will also start your Yanmar easily. So set up two deep cycle batteries; each on one side of a 1, 2, all, off switch so you can always have one battery fully topped off after sailing all day after using the house loads. You can then alternate your "house" and "starting" batteries to keep them equally charged up. David "Roger Long" <rwlong@maine.rr.com> wrote in message news:hZCEd.22915$Xs6.18158@twister.nyroc.rr.com... Is there any reason to consider using dual purpose or a one starting, one deep cycle set up with a 20 hp Yanmar diesel? I would think the starting loads on the small engine are low enough that two deep cycle batteries would do fine. -- Roger Long Yes, a deep cycle will start your Yanmar, but you are reducing the life of the battery by doing so. There's a reason, other than marketing, why batteries are labeled 'starting' or 'deep cycle' or 'dual purpose'. I believe the main difference is the thickness of the plates. Starter batts, are built for short duration, high loads. DC are for less load over a longer time period. DP are a compromise between the two. -- Scott Vernon Plowville Pa _/)__/)_/)_ Is there any reason to consider using dual purpose or a one starting, one deep cycle set up with a 20 hp Yanmar diesel? I would think the starting loads on the small engine are low enough that two deep cycle batteries would do fine. -- Roger Long I understand that but, is the load on a 20 hp diesel that you can start by hand high enough to significantly reduce the life of the battery? SignatureRoger Long > Yes, a deep cycle will start your Yanmar, but you are reducing the > life of the battery by doing so. [quoted text clipped - 20 lines] > > Roger Long >I understand that but, is the load on a 20 hp diesel that you can start by >hand high enough to significantly reduce the life of the battery? It depends on what you're using your boat for. If you're starting & stopping your engine frequently, then maybe a starter battery makes sense. But while cruising and using my 3GM30 (actually 27 hp) all I used were deep cycles and they worked fine. Another topic, one maybe you've thought about already, is how well the alternator on your Yanmar is charging your batteries. If your charging system isn't up to snuff, doesn't matter what batteries you're using, you'll never get full cranking amps out of your batteries. Paul Define 'significantly'. If you're starting only once in a while, as most sailboats do, I doubt that you'll notice the shortened life. Are you buying new batts, or are there 2 DC already in your boat? I had the separate start batt and a DC, When the DC went , I replaced with a DP (that's all the local Sears stocks anymore). When the starter batt goes away, I'll go with a second DP. I have a manual separator switch. -- Scott Vernon Plowville Pa _/)__/)_/)_ > I understand that but, is the load on a 20 hp diesel that you can > start by hand high enough to significantly reduce the life of the [quoted text clipped - 28 lines] > > > > Roger Long > I understand that but, is the load on a 20 hp diesel that you can > start by hand high enough to significantly reduce the life of the > battery? What's the voltage drop when starting? Starting batteries can see surges bring them down to as low as 8 volts and bounce back just fine. DC batteries don't like this. I'm not sure where the cut-off is, but if the starting load drops your voltage down below 10, or maybe 10.5 (assuming that you've got a good current path to starter & ground), then you might consider staying with a start battery. Fresh Breezes- Doug King I'll let you know when I get the boat:) My first two batteries are free, (and therefore probably minimum quality) when the boat is delivered. Since this boat will seldom, if ever, see shore power and often sail on and off its mooring, one of my first projects will be a complete upgrade of the whole power system. This will probably involve moving to sealed batteries in the bilge since these boats are stern heavy and a bit tender. I'll also probably put in a solar trickle system. SignatureRoger Long >> I understand that but, is the load on a 20 hp diesel that you can >> start by hand high enough to significantly reduce the life of the [quoted text clipped - 10 lines] > > Fresh Breezes- Doug King >I'll let you know when I get the boat:) > [quoted text clipped - 5 lines] >since these boats are stern heavy and a bit tender. I'll also probably >put in a solar trickle system. =========================================== With my last boat I used 6 volt golf cart batteries for both starting and a house bank driving a large inverter. The engines were 350 hp, 454 cubic inch V8s, and they never had a problem cranking, even in freezing weather. > Yes, a deep cycle will start your Yanmar, but you are reducing the > life of the battery by doing so. Not by enough that you would even notice it. A recreational boat starts so seldom and a load of 80A isn't enough to do any harm. > There's a reason, other than marketing, why batteries are labeled > 'starting' or 'deep cycle' or 'dual purpose'. > I believe the main difference is the thickness of the plates. Starter > batts, are built for short duration, high loads. DC are for less > load over a longer time period. DP are a compromise between the two. All true. Doug s/v CAllista > -- > Scott Vernon [quoted text clipped - 8 lines] > > Roger Long > > Yes, a deep cycle will start your Yanmar, but you are reducing the > > life of the battery by doing so. > > Not by enough that you would even notice it. A recreational boat > starts so seldom and a load of 80A isn't enough to do any harm. Right, I agree. But, being in the MD area, I've got to consider sometimes starting in cold weather and cranking more than usual. -- Scott Vernon Plowville Pa _/)__/)_/)_ >>>Yes, a deep cycle will start your Yanmar, but you are reducing the >>>life of the battery by doing so. [quoted text clipped - 4 lines] > Right, I agree. But, being in the MD area, I've got to consider > sometimes starting in cold weather and cranking more than usual. Actually, I think the bigger issue is the non-starter loads. If the boat has a fridge or other high house loads, you want to add house bank capacity, which then makes it hard to do the "swap 1 & 2" trick. Once you have dedicated banks it pays to use a proper starting battery. OTOH, my previous boat had a finicky Westerbeke, which has a pre-heater, and it never had a problem starting off a Surrette deep cycle. I also live in the MD area (actually I live in MD proper) , and "sometimes" isn't really a factor, and "cranking more than usual" isn't either as long as it isn't the norm. I can start my engine at freezing temps with maybe 5 revs rather than the normal 2. If your engine requires alot of revs to start then a dedicated starting battery is probably a good idea. But even so, 80A isn't a heavy load for a decent deep cycle battery. I draw 50A to run the refrigeration and 100A to run the microwave. Doug s/v Callista >> > Yes, a deep cycle will start your Yanmar, but you are reducing the >> > life of the battery by doing so. [quoted text clipped - 8 lines] > Scott Vernon > Plowville Pa _/)__/)_/)_ >Is there any reason to consider using dual purpose or a one starting, one deep cycle set up with a 20 hp Yanmar diesel? I would think the starting loads on the small engine are low enough that two deep cycle batteries would do fine. > > Are you asking the proper question? If you have deep discharge batteries for cruising power in lieu of engine, then you might need to consider being practiced at starting by hand lest you find yourself without adequate battery to run whatever including starting the engine. If you have a small engine, keep a small starting battery for the task... Many production boats in this area (Great Lakes) have the dual battery configuration successfully, and occasional white knuckles. Skip I thinking about rotating both the hotel loads and the rather modest starting loads between two deep cycle batteries so the get even service. I'm aware of the problem with leaving them both connected if there is an electrical leak or misjudgment about usage. This wouldn't be as serious anyway as it would on a boat with an engine too big to hand start. SignatureRoger Long >I thinking about rotating both the hotel loads and the rather modest >starting loads between two deep cycle batteries so the get even >service. I'm aware of the problem with leaving them both connected if >there is an electrical leak or misjudgment about usage. This wouldn't >be as serious anyway as it would on a boat with an engine too big to >hand start. Depends on how fast you need the engine started. Say there's a drunk in a cigarette boat (or a tanker) bearing down on you. Or the wind died and you have a 3 knot current pushing you on the rocks 50 yards away. It's not that you have to have a motor ready for instant use to go sailing. It's the situations you get into because you think you have a motor ready for instant use. That said, I sailed for more years than I'd care to remember using the "rhythm system" for batteries as you describe. I did flatline the system a couple of times by forgetting to switch from BOTH after charging but it never got me in any trouble I couldn't get out of. Regardless, I now have an idjit-proof system I'm much happier with. Oh, and don't forget, batteries run other things than starters. Bilge pumps, for example. ____________________________________________________________ Glen "Wiley" Wilson <usenet1 SPAMNIX at world wide wiley dot com> To reply, lose the capitals and do the obvious. Take a look at cpRepeater, my NMEA data integrator, repeater, and logger at http://www.worldwidewiley.com/ My outlook is probably effected somewhat by watching the motorcycle size battery in my plane start the 160 HP, high compression, engine briskly on even below zero days. BTW the 1,2 Both switch is an anachronism that I'll be ditching as soon as I can get the boat back to Maine and overhaul the whole system. There are very inexpensive battery management and charging systems now that charge the batteries while leaving them isolated from each other for normal loads. SignatureRoger Long >>I thinking about rotating both the hotel loads and the rather modest >>starting loads between two deep cycle batteries so the get even [quoted text clipped - 29 lines] > Take a look at cpRepeater, my NMEA data integrator, repeater, and > logger at http://www.worldwidewiley.com/ >>snip< There are very inexpensive battery management and charging >systems now that charge the batteries while leaving them isolated from >each other for normal loads. > > It seems Glen and I have gone down similar paths... If I'm understanding him, both of us _suggest_ the same thing - keep engine starting energy available in a starting battery. It gives you both house batteries to draw down without hand starting. It's not only about the 1-B-2 switch. Go ahead , use one of those motorcycle size starting duty batteries instead of another ball buster - you have the house batteries as backup for hard starting (a second level contingency) if you ever need it. Just get enough CCA for the job... It's like buying a little insurance... Three-way isolation is pretty straight forward - except for non-matching battery banks with accelerated (smart) charging. Or do what a large percentage of owners do - live with the dual-battery discharge rules you suggest (and the outcomes). As you know, you'll face lot's of compromise decisions as you finish her out to your satisfaction (not ours). You will probably live thru whatever decision you make as we all have up to this point. Skip >Or do what a large percentage of owners do - live with the dual-battery >discharge rules you suggest (and the outcomes). >As you know, you'll face lot's of compromise decisions as you finish her >out to your satisfaction (not ours). >You will probably live thru whatever decision you make as we all have up >to this point. Dual batteries are working fine for me on an Atomic 4 gas engine, and the system is simple, if not idiot proof. As insurance for those times I may be an idiot, I carry a "booster pack" which is a sealed battery complete with jumper cable style clamps and all the appropriate switching, available at automotive suppliers for around US$50. Light, cheap, simple and I can use it to boost my car in the winter. Ryk If your engine has a compression release, it can be started using a bunch of D-cells. >>Or do what a large percentage of owners do - live with the dual-battery >>discharge rules you suggest (and the outcomes). [quoted text clipped - 11 lines] > > Ryk >My outlook is probably effected somewhat by watching the motorcycle >size battery in my plane start the 160 HP, high compression, engine >briskly on even below zero days. Not quite what I meant. I'm talking about how long it takes to hand crank the engine if you manage to flatline both batteries, which you eventually will do following the protocol you mentioned. >BTW the 1,2 Both switch is an anachronism that I'll be ditching as >soon as I can get the boat back to Maine and overhaul the whole >system. Which was my point. ____________________________________________________________ Glen "Wiley" Wilson <usenet1 SPAMNIX at world wide wiley dot com> To reply, lose the capitals and do the obvious. Take a look at cpRepeater, my NMEA data integrator, repeater, and logger at http://www.worldwidewiley.com/ > My outlook is probably effected somewhat by watching the motorcycle size > battery in my plane start the 160 HP, high compression, engine briskly on > even below zero days. Most aircraft batteries (even if motorcycle size) are AGM or gel. High energy density for their size. Also, I assume that you preheat your engine on your aircraft prior to starting.. All aircraft I have piloted require preheat prior to starting to minimize excessive wear while the oil decides to be useful. So most aircraft engines are not actually started at zero temps. > BTW the 1,2 Both switch is an anachronism that I'll be ditching as soon as > I can get the boat back to Maine and overhaul the whole system. Agreed. An antiquated concept. > There are very inexpensive battery management and charging systems now > that charge the batteries while leaving them isolated from each other for > normal loads. Not exacty inexpensive but worth it. Doug s/v Callista > My outlook is probably effected somewhat by watching the motorcycle > size battery in my plane start the 160 HP, high compression, engine [quoted text clipped - 5 lines] > systems now that charge the batteries while leaving them isolated from > each other for normal loads. There is a BIG difference between a DIESEL engine and a Gasoline engine, when starting in cold weather. Comparing the two is "Apples and Oranges" A diesel has a higher Compression Ratio than a Gas engine. Gas volitilizes at a much lower temp than diesel fuel. Gas engines have Spark Plugs that ignite the fuel/air mixture, and provides the required heat of ignition. In a diesel with no glowplugs the only heat generated is the Heat of Compression, which takes a while to build in the cyl. That's why they invented Glow Plugs, and Intake Air Manifold Heaters, to heat the fuel/air past the ignition temp. Me Glowplugs, etc are a feature of indirect injected engines. Many smaller diesels are direct injected and do not require glowplugs. My Perkins 85HP will start almost instantly even with temps below freezing. Doug s/v CAllista >> My outlook is probably effected somewhat by watching the motorcycle >> size battery in my plane start the 160 HP, high compression, engine [quoted text clipped - 17 lines] > > Me > There is a BIG difference between a DIESEL engine and a Gasoline > engine, > when starting in cold weather. I don't plan on starting my sailboat engine in weather as cold as I fly my plane in. That's for sure! SignatureRoger Long I assume you have to preheat your aircraft engine in cold temps. I had to preheat mine in anything below 40F. I've never seen a diesel engine in a plane either. Doug s/v Callista >> There is a BIG difference between a DIESEL engine and a Gasoline engine, >> when starting in cold weather. > > I don't plan on starting my sailboat engine in weather as cold as I fly my > plane in. That's for sure! > I assume you have to preheat your aircraft engine in cold temps. I had to > preheat mine in anything below 40F. I've never seen a diesel engine in > a plane either. They are available, at least in Europe. The advantage is that they run on turbine fuel rather than avgas which is often hard to find. SignatureMy real address is crn (at) netunix (dot) com WARNING all messages containing attachments or html will be silently deleted. Send only plain text. > I assume you have to preheat your aircraft engine in cold temps. I had to > preheat mine in anything below 40F. I've never seen a diesel engine in > a plane either. Most of the dirigibles had diesel engines, and the German air force had diesel powered planes including at least one fighter. http://www.csd.uwo.ca/~pettypi/elevon/baugher_other/ju86.html Modern developments in metallurgy and turborcharging may bring the diesel back into aero prominence http://www.deltahawkengines.com/diesel00.htm Just poking around finding interesting stuff on the wwweb. Beats working! DSK > Is there any reason to consider using dual purpose or a one starting, one > deep cycle set up with a 20 hp Yanmar diesel? I would think the starting > loads on the small engine are low enough that two deep cycle batteries would > do fine. Just about everything I've seen in the thread is correct, but I have a couple of odd thoughts for you to consider. We currently have 2 group 31s, about 230 total AH. Our 2GM20F will start off a half-discharged group 27, so starting isn't a serious issue. Major consumption is lights -- many, many lights -- as we're addicted to reading and night sailing. Our main problem has been that we motor too little. Usually, we've been lucky to have even 50% charge. ---- Our last charter, the starting battery connected directly to the alternator. The house battery was tied in via a simple on-off switch: On to charge, off otherwise. That's not the best way to charge and it's possible to drain all the batteries, but you can't fry the regulator. ----- Last spring, we got a 12 watt solar charger which changed our habits significantly. When we weekend, we're charged to 100% as we start out. On our annual 3 week cruise around the Chesapeake, that little charger satisfied our needs completely as long as we motored into a harbor every few days. One morning, the battery was dead. A few hours of sun later, we had enough charge to start. I'll probably combine the two ideas next time I have to replace a battery. Remaining 31 goes next to the engine, short leads. House bank gets beefier, panel goes directly to it. Battery switch is almost always off. SignatureJere Lull Xan-a-Deux ('73 Tanzer 28 #4 out of Tolchester, MD) Xan's Pages: http://members.dca.net/jerelull/X-Main.html Our BVI FAQs (290+ pics) http://homepage.mac.com/jerelull/BVI/ > > Is there any reason to consider using dual purpose or a one starting, one > > deep cycle set up with a 20 hp Yanmar diesel? I would think the starting [quoted text clipped - 32 lines] > gets beefier, panel goes directly to it. Battery switch is almost always > off. Ahoy Jere! Have you moved or am I mistaken? I thought you were in the SanD area. If you're the same guy, I was seeking information about finding moorage a couple of years ago around the south bay etc. Never made it to SD though, but am now in middle Tennessee. Boy the sailing is sure different here! Rico > Ahoy Jere! > Have you moved or am I mistaken? I thought you were in the SanD area. If > you're the same guy, I was seeking information about finding moorage a > couple of years ago around the south bay etc. Never made it to SD though, > but am now in middle Tennessee. Boy the sailing is sure different here! No, have only sailed the Right coast, mostly Chesapeake Bay. SignatureJere Lull Xan-a-Deux ('73 Tanzer 28 #4 out of Tolchester, MD) Xan's Pages: http://members.dca.net/jerelull/X-Main.html Our BVI FAQs (290+ pics) http://homepage.mac.com/jerelull/BVI/ |
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