I think I’ll stick with my Midtronics conductive tester; good, accurate results on the health of my golf-cart and start batteries, it only takes a minute, and no chance of starting things on fire… :^)
Fred Street -- Minneapolis S/V Oceanis (1979 C&C Landfall 38) -- on the hard in Bayfield, WI :^( > On Feb 7, 2017, at 4:52 PM, Josh Muckley via CnC-List <cnc-list@cnc-list.com> > wrote: > > There is no need to go full discharge. The voltage and capacity properties > of a lead-acid battery have a near linear relationship so a 50% discharge is > fine for testing. That should be 11.6v. All of this is just a comparison. > A brand new battery might show +/- 10% of the labeled rating. That doesn't > mean that you got a good or bad battery. It's just an indication of how > difficult it is to accurately measure the capacity. Typically batteries are > only considered at their end of life until they only test at 50% of original > labeled capacity. Capacity tests really are most powerful as a trending and > comparison measurement rather than a go/no-go. I've successfully used 100Ah > batteries that measured at only 7Ah. I know they are junk but keep them > around for various workbench projects. I've even used them to successfully > start my spare marine diesel sitting in the garage. > > Josh Muckley > S/V Sea Hawk > 1989 C&C 37+ > Solomons, MD
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