/Le 10/09/2017 14:55, davidjoyce@doctors.org.uk a crit :
/
> //
>
> / The primary 914 (electric) fuel pump runs on despite the battery
> being sitched off (or removed for that matter), and the alternator
> switch also off. I suppose that you could envisage some scenario where
> an electrical major short or the like burns out all the wiring back to
> and including the alternator, but simply losing the battery doesn't
> stop the engine going./
>
David and all,
There is a case that may leave you with a dead 914 engine with such a
setup : a Rotax-Ducati regulator overvoltage failure with a Lithium battery.
In such a case the Lithium battery will protect itself by shutting down,
and the regulator will stop supplying the pump with power. The engine
will stop within seconds.
Considering service life records, the probability of the Rotax regulator
failing is not a remote one. In that case a Lead/acid battery will still
be there and will even mitigate the OV event..
Of course some may consider Lead/acid is the past and Lithium the
future, but on what basis ?
Some years ago we conducted and in-depth study of the Rotax
alternator/voltage regulator-rectifier assembly, and concluded that the
Rotax regulator combined with the Rotax suggestion for the wiring the
pumps was not the best option for our 914.
Changing from Lead/acid to LiFePo is not a trivial issue, especially
with an electrically dependent engine.
--
Best regards,
Gilles
http://contrails.free.fr
http://lapierre.skunkworks.free.fr
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