RichV6 is your man, but a battery can appear to have a good voltage and then drop massively while under load. Have you tried a jump start from another battery? That would determine if the battery is OK.
"Y mae dafad ddu ym mhob praidd"
1972 4/4, 1981 MGBGT, 1984 FLHT1340, 1980 XLH1000, 1990 ZX10
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