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Old 02-18-2011, 04:54 PM
andrewbutler andrewbutler is offline
 
Join Date: May 2006
Location: Meath, Ireland
Posts: 48
Default First Start ALT Woes

Hello,

I did a first start of my RV7 EI-EEO last weekend and the alternator did not come on line.

I have an L-60 and LR3 regulator from B&C and have followed the Aeroelectric wiring model.

On working through B&Cs LR3 troubleshooting all voltages looked good, then checked the Field connector. Connectors were pushed back. Great we found the problem. No joy. Then went through all the checks again. The ANL40 that I have installed was blown. We put a blade fuse holder with a 20Amp fuse in its place. Fired her up, switched on the Alt field (no electrics on expect for the EFIS) and the 20Amp fuse blew almost immediately.

What are the modes that could produce this behaviour? Would a 20AMP fuse always blow? I see now that the ANL40 should have been a 60ANL, but why would the ANL40, with such low loads. If the battery was low, would that be the reason.

I was hoping to do my final inspection and first flight tomorrow, but it looks like that is now off.

Two specific questions: PIN 4 of the regulator (the Field) was registering about 3 volts with the Master on Battery only, and about 1.2 volts below BUS voltage when the Master was on both. Is this correct behaviour i.e. is the 3 volts reading correct?

Is is correct that in this set-up the Shunt would register a current when the Starter is fired? If not, then what would this suggest as I was definitely reading a current when the starter was engaged. My shunt is connected to an Advanced Flight Systems EFIS.

Best regards,

Andrew Butler.
RV7 EI-EEO
Galway Ireland.


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  #2  
Old 02-19-2011, 03:42 AM
andrewbutler andrewbutler is offline
 
Join Date: May 2006
Location: Meath, Ireland
Posts: 48
Default Fixed it

I figure the drained battery was pulling more AMPs than the ANL40 and 20AMP fuse could handle. Connected up to 30Amp blade fuses in parallel on a fully charged battery and voila, 14.5 volts on the BUS. Now have to order a new ANL60.

Regards,

Andrew.
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  #3  
Old 02-19-2011, 05:13 AM
Walt's Avatar
Walt Walt is offline
 
Join Date: Aug 2005
Location: Dallas/Ft Worth, TX
Posts: 5,667
Default

A drained battery will result in the alternator putting out max current for charging, in this case that output could exceed 60 amps.

Good job on the "fix".
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