In the XL 601 & other low wing planes you use electric fuel pumps if your engine is not equipped with an engine driven pump. In this case do you normally provide a back up battery for one of the fuel pumps in case of an electric malfunction? What is the standard practice in this case?

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I have been flying with two inline fuel pumps for the past year and a half (and no mechanical pump). My electrical system includes an E-Bus that allows me to isolate the alternator (should it fail) and run my Fuel Pump #2 direct from the battery.

This however is not the perfect solution since a fault could occur with the regulator that could take my battery down (very rare, but still a possibility).

I DO have a low voltage alarm on my electrical system as well as a direct battery fault alarm on my EarthX battery.

However, I have always had it in mind to have a "total meltdown" solution. I recently bought, but haven't installed, a TCW Backup Battery and panel switch. The TCW will be wired directly to my Pump #2 with no connection to the rest of my electrical system.

I will now be able to, in a total electrical system failure, shut down my entire electrical system and flip the switch to directly power the fuel pump. The backup battery has about 1 hour and 20 minutes of run time on my 1.2 amp facet fuel pump. The TCW also includes (and I will install) a panel mounted low voltage light.

At the same time I also spent the stupid amount of money ($180 vs $20) for a B&C voltage regulator and will replace my Auto Parts Store special when I install the backup battery. The B&C regulator includes over-voltage protection, in addition to the solid state (vs mechanical) voltage regulation.

Is this over-kill? Probably. However, I will be able to say I have done everything possible to make my electrically dependent airplane as safe as possible, electrically. 


Gary, the 601 I purchased, completed and signed off has an L2C 0-235 with a mechanical engine driven fuel pump. The one I am building has the C-1B which has no fuel pump on it. Had I been flying the 0-235 C1B without some type of back up power for at least one  fuel pump I would have been making an emergency landing. As it were, I had a hand held Nav/Com in the cockpit and my Ipad running IFLY GPS so everything was just, wow, my battery is dead, but no big deal. 

I'm of the same thought as you. I want a completely different  power source to deliver my back up fuel! I have an over sized lithium battery pack to supply my ipad and cell phone which I also have Advare & IFLY gps on. I don't believe there is over kill when it comes to feeling safe in ones plane. I want to be able to say the same as you, I've done my best to make my plane as safe as possible. 

Like Gary, i have a totally electrical dependent airplane with 2 electric fuel pumps only (Viking). What I did was use dual LI-Po batteries and set them up so I can power the buss with either or both batteries.  I fly outbound on battery #1 and return on battery #2, so both are kept fully charged at all times. Both batteries are independent of each other and their access to the buss is totally controlled by individual switches and contactors for each. Alternator is also switched, so it can be shut down if needed.  I also run dual volt meters so I always know the state of each battery. Both batteries, contactors , wires, and switches come in at under 10 lbs., half the weight of a single wet cell battery.

sounds like a plan.


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