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Old 05-23-2018, 07:07 PM
Mich48041 Mich48041 is offline
Join Date: Apr 2008
Location: Riley TWP MI
Posts: 2,801

I conducted an experiment today on my RV-12. Not wanting to ruin the PC680 aircraft battery, I disconnected it. In its place, I used the riding lawn mower battery connected with jumper cables. I thought that the lawn mower battery might have trouble cranking the Rotax 912ULS, but it cranked just fine. I left the ignition switches turned off so that the engine would not actually start. I turned on all electrical loads, including landing light, to run the battery down. I periodically cranked the engine as the battery slowly ran down. It took an hour and a half for that cheap $35 lawn mower battery to drop its voltage down to 11.5 volts. The engine still cranked, albeit noticeably slower. The fuel pump fuse never did blow. I was not able to duplicate the symptoms reported by others. Perhaps there is some magic voltage that causes the fuse to blow and I never happened to crank the engine at that particular voltage. In my airplane, the fuel pump is the only load on that 5 amp fuse.
Joe Gores
RV-12 Flying
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