My first impression is to be skeptical of using a motorcycle battery to start a much higher compression diesel engine.
So these batteries claim 270 CCA of power and 18Ah of energy. So is this good enough? I think it is reasonable to assume that a starter will consume less than 270A of current during a start. At least I know that my Yanmar 3QM30 uses less than 300A since I have 300A MRBF fuse at the battery(And I am sure that 250A fuse would work fine too). To be generous, let’s assume that one cranks the starter for 10 seconds. This amounts to 270A * 10s / 3600 h/s which is 0.75Ah. Good for many starts without charging. This also implies that an 18Ah battery should turn the starter for about 18Ah*3600s/h/270A = 240 seconds or about 4 minutes (of course nobody should crank this long). Another concern are battery fires, but as I just read Lithium-Iron batteries are not Lithium-Ion batteries. Li-Fe are supposed to be safer. Wikipedia has a nice article on Lithium-Iron batteries: https://en.wikipedia.org/wiki/Lithium_iron_phosphate_battery. But still, just google “Lithium-Iron Powersports battery fire” and one of the first links is a YouTube video titled “Shorai battery fire”. Amazon has many good review, but one bad one titled “Do NOT order this battery” describes the battery catching fire and shows an image of a burnt up battery. Another Amazon review points out the misleading Ah ratings. Here is a quote from the review,” The stated Ah rating of 18Ah is only an "amp-hour pb equivalent" used to compare it to lead-acid batteries in terms of starting power. The actual rating is only 6Ah - which is on a little sticker on the bottom of the battery when it arrived, but stated nowhere online that I could find.” The manufacture claim that the Li-Fe battery should be charged with voltages between 13.1V and 15V with a maximum charging current of 10Amps. This seems like a nice match for a motorcycle but not for for a multi-bank battery system unless one rigs up a trickle charge system for the Li-Fe (maybe a Xantrex’s echo charge). So the bottomline is that it has 6Ah of energy rather than 18Ah (80 seconds of max start time), and while they claim to charge fast, manufacture specify that max charge voltage be no great than 15V and max charging current be no more than 10A. The later, may be an issue with typical +80Amp marine alternators. With only 6Ah for the price , I still remain skeptical, but see some future promise. It is rather bogus that manufactures are using “EqAh” ratings to fool people into thinking that the stored energy is greater than actual. - Paul E. 1981 C&C 38 Landfall S/V Johanna Rose Carrabelle, FL http://svjohannarose.blogspot.com/ > On Dec 1, 2015, at 10:22 AM, cnc-list-requ...@cnc-list.com wrote: > > > This was recommended for a 2gmf yanmar: > > > > "Shorai makes a nice, lightweight, Lithium-Iron motorcycle battery: > http://shoraipower.com/lfx18a1-bs12-p86 > <http://shoraipower.com/lfx18a1-bs12-p86> > It starts my Harley easily and weighs about 2 pounds. It?s also smaller than > most motorcycle batteries. That's a lot of power in a small package." > > My question: would this same battery work for a 3HMF, and would the charger > recommendation be the same? I like this idea a lot...! > > > Richard > 1985 C&C 37 CB; Ohio River, Mile 596
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