Battery mod not working out?

[California98Civic]

It is working quite well now. I installed a better battery maintainer yesterday and drove with it for the first full day today. It is 6amps (instead of 1.5) and designed for the deep cycle motorcycle battery I have adapted. Total weight for battery and maintainer is under 16lbs. I was able to run today without the alternator at all and still stay in good fully-charged down to about 60% capacity range. Current tank is likely a third straight new high MPG. It is at 64.4mpg this time (even though ambient temps are lower, nights are longer, and work has been requiring more early morning and after dark commuting). With the alternator totally off all the time now, I think this tank average may climb during the last 150 miles of my normal 600 mile range. I'll post a writeup of what I have done as soon as I can.

[oil pan 4]

You are spinning the alternator but have cut exciter power right to get your gains correct?
If you picked up about 4% with the alt spinning at no load, that is good.
I think I could pick up 2 or 3 times that with out spinning the alternator in my truck. I expect big gains from a mod like this since the coolant pump is is now electricly driven.
35mpg with a huge truck could be possible.

[California98Civic]

That's right. The belt is still hooked-up. The electricals are disconnected (easily reinstalled in under 1 minute on the roadside if needed). I have seen quite a bit of discussion here about where the biggest gains come from, unbelting or just disconnecting the field wiring. I was persuaded by the guys arguing that the major source of drag comes from powering the alt., and that it is basically freewheeling otherwise. The powering of the magnetic field to
generate electricity produces most of the drag on the engine, they say.

If you look in my trip log, at the "Aliso" run, beginning in the last few days you will see evidence of what this mod seems to be doing in a high load driving situation. If the log and my estimates are reliable--and it's not really scientific, though quite methodical--I appear to get at least 10% gains on this run.

I have begun to believe that the gain is greater where the engine load is higher: on the freeway and climbing. My "Aliso" run has significant climbing, from near sea level to maybe 500 feet in maybe 5 miles.

Originally Posted by oil pan 4

You are spinning the alternator but have cut exciter power right to get your gains correct?
If you picked up about 4% with the alt spinning at no load, that is good.
I think I could pick up 2 or 3 times that with out spinning the alternator in my truck. I expect big gains from a mod like this since the coolant pump is is now electricly driven.
35mpg with a huge truck could be possible.

[jakobnev]

Originally Posted by California98Civic

..how would I identify the feedback line (yes, that's how green I am...

There should be two wires from the alternator to the positive battery terminal. The thin one should be the feedback line.

[WD40]

Originally Posted by jakobnev

There should be two wires from the alternator to the positive battery terminal. The thin one should be the feedback line.

can you please elaborate on how to do this fake input, I too am a total noob with electronics
thanks for your input

[oil pan 4]

I have to try this for sure.
My salvaged float charger panels will go on first.
I have gotten word my trucks batteries I installed back in 2007 have likely bought it from sitting for the last 8 or 9 months. It could be time for optima deep cycle batteries.

[California98Civic]

Originally Posted by oil pan 4

I have to try this for sure.
My salvaged float charger panels will go on first.
I have gotten word my trucks batteries I installed back in 2007 have likely bought it from sitting for the last 8 or 9 months. It could be time for optima deep cycle batteries.

Problem!

Although I'm hovering between 66.5 and 67.5 mpg and hardly use the alternator in daylight, I wonder if the battery mod is damaging the fuel system. Three or four times I have run the voltage down to under 12. Most of the time the voltage is between 12.1 and 12.7. Now I seem to have fuel flow problems. The car hesitates and testing suggests the hesitancy is not not dependent on battery voltage, bump-start fuel pressure loss, throttle position, load, engine temp, or engine speed. I know the fuel pump is electrical. Have I damaged my fuel pump with my weird alternator optional set-up?

[deathtrain]

I dont think you have. the reason is that you control DC motors with voltage and you control AC motors with hertz. so with the car being DC the pump will just run slower. the best way to check is to hook up a fuel pressure gauge on the fuel line and start the car. then do it again with the alternator hooked up. you should not see that much of a drop. check manual for the min-max fuel pressure for your ride.

[oil pan 4]

They should be ok.
Most auto parts will operate with 8 or 9 volts DC.

You may need to change the fuel filter.

[ConnClark]

A loaded down DC motor is more likely to burn itself out running at a lower voltage. This is why electric motor systems have an undervolt alarm.