Twin 914'2 w dual batteries

My friends, problems with current rectifier and my battery is 65 Amh, even so it didn't work, that's when I realized that there was an electrical panel and the electric pumps stop working or the engine will stop with the panel dry. Based on a lot of parallel circuit with an installation of a mechanical pump and one-way valves in the circuit; a single restriction is that the original mechanical pump holds at a maximum speed of 4500 rpm, but will not lead to a dry panel accident. As my plane has a retractable landing gear, autopilot, electric flaps, gps, G5, electric compensators and everything is now supported with a 45 Amh battery, lighter than the previous one.

Solution, installation of a mechanical pump running in parallel to the electric pumps

Solution, installation of a mechanical pump running in parallel to the electric pumps

I don't know how the twin engine Aircam is wired, but we do know that each engine needs a functioning electrical fuel pump. Because the engine is dependent upon an electrical fuel pump, it also follows that there should be dual fuel pumps for each engine, and dual power inputs for each  fuel pump group. That would indicate four fuel pumps, two generators and two batteries.

I guess one could wire it so that a single battery served as the alternate power supply for all four fuel pumps (as well as start battery for both engines) but that does not seem prudent to me. To me what makes sense is to use two LiFePO batteries, which are very light and small. And of course, the batteries should be properly maintained and tested and replaced before their capacity falls below the required level.

Yes, it is Intended  to be a safety of flight issue.

You have dual independent engines.  And the manufacturer would like to keep it that way.

The 12volt batteries are required to keep the Fuel pumps running in the event of a Generator failure.

Once the battery becomes depleted, the Fuel Pumps will stop and so will the engine.

The batteries are not sized for starting the engine, they are sized to run the Fuel pumps for at least 30 minutes without the assist of a generator.

So in the highly unlikely event of a dual generator failure, you would need a battery large enough to power the fuel pumps of BOTH engines for 30 minutes it might take for you to get on the ground.  

One battery could be used to power both engines and in the event of one engine failing the other engines generator would keep it going.

That single battery would probably need to be twice the Capacity of the current batteries to maintain your 30-minute reserve.

Connecting BOTH generators to a single battery is DOABLE.

Whether it is ADVISABLE is up to you.

If it is EXPERIMENTALLY Certified, it is your call.

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Everyone trying to redesign his fuel system needs to remember...

These are 914 TURBO Engines.

Each has 2 electric fuel pumps and Zero Mechanical pumps.

The fuel pressure needs to be 5 psi ABOVE the 5psi (40" Boost) pressure. 

The Fuel pumps need to be able to deliver 10psi on takeoff.

The Fuel pumps, as installed, deliver 15psi and are regulated down to 5-10 as required.

15-20 psi mechanical pumps that fit the 914 engine are going to be hard to come by.