How to Bypass Alternator with a Switch DIY

[Mr. Previa]

Originally Posted by California98Civic

Can you put it inside on the rear deck? You would lose some power but you really don't want it in the wind. And maybe there would be enough power for most purposes even if it were inside. How much power does it produce? How many watts?

Hmm, not a bad idea. I don't know if I would like the back not viewable via my rear view mirror though. Maybe a camera?

The panel is 70 watts. It actually fully charged the battery from 11:30 to 3:30, and it was cloudy. It is a Mono-crystalline panel so it has better performance on cloudy days and indirect sunlight.

I thought about removing the rood rack and mounting the panel right on the top of the roof. But, I want to make all these mods removable. Though I love driving this junker van for some reason, maybe all the space in the cab, I would like to find a lighter vehicle like a GEO or the like.

This van is more or less a ginny pig for me. BUT... I LOVE proving people wrong!

[deathtrain]

what kind of charge controller you using?

[Mr. Previa]

Originally Posted by deathtrain

what kind of charge controller you using?

Green Energies LLC, 15 amp., 12/24volt.

[deathtrain]

another thing.. what battery monitor you using?

[toc]

What kind of MPG improvement can be associated with the alternator kill switch (considering you still need to charge the battery)..?

The voltage regulator should be stopping charging and thus no alternator load once the battery is charged, or have I got that wrong?

[California98Civic]

Originally Posted by Mr. Previa

Green Energies LLC, 15 amp., 12/24volt.

This one? Solar Charge Controller 12 Volts 15 Amps [SCC1215] - $12.95 : Green Energies E-store, Solar Products. That's a nice little inexpensive unit.

Originally Posted by toc

What kind of MPG improvement can be associated with the alternator kill switch (considering you still need to charge the battery)..?

Depends on your vehicle. MetroMPG saw something like 10% by unbelting the alternator on his Metro. I have seen less of a benefit, 3-5%, because my Civic has a "smart alternator" that modulates load according to needs anyway, so there is less to gain.

Originally Posted by toc

The voltage regulator should be stopping charging and thus no alternator load once the battery is charged, or have I got that wrong?

Yes, you have that right, if your car's system is "smart" in the way I described above. My understanding of older charging systems is that they run alternators constantly.

[oil pan 4]

A few years ago I found out I was able to unhook one of the 2 wires that plugs into the side of my alternator and kill alt out put on my car.
That alternator went bad and was rebuilt this year by a local alt and starter shop and I installed it in my suburban. Yesterday I started messing with the side wires trying to figure out which one I need to "cut" to do an alt disable, I started unplugging one wire or the other, then pulled both and nothing happens. It still kept putting out 14.4 volts.

I think the car had a diode in the battery charging lead.

[deathtrain]

you have a self excitation alternator. When you were able to disconnect one wire your alternator was actually "broken" for lack of terms. Since you got it rebuilt they fixed that and it says excited. This is common in older alt. before the smart charging came to be.

Start the car unplug it and put a light 12vdc light bulb on the output side of the alt. It will be bright and then dim down bleeding off the voltage. Once it goes out you should read 0vdc output. If it does read 0vdc then the above is correct.

[bheadrick]

so, what would be the minimum power rating you'd need for something like this? I see Mr Previa's panel is 70W and fully charged his battery in a matter of 4hrs on a cloudy day.
I've seen a 15W panel designed for charging a 12v battery that looks like it would fit nicely on top of a coupe trunk lid

[California98Civic]

Originally Posted by bheadrick

so, what would be the minimum power rating you'd need for something like this? I see Mr Previa's panel is 70W and fully charged his battery in a matter of 4hrs on a cloudy day.
I've seen a 15W panel designed for charging a 12v battery that looks like it would fit nicely on top of a coupe trunk lid

I would expect 15 watts to be insufficient. I'm planning for about 100 watts on the roof, using 2.5mm thick "flexible" monocrystaline.