Replacing alternator with solar panel array on roof?

[Noel]

One thought is this...

I drive 37 Miles each way to work, and have the ability to charge both at home and at work. -As simple onboard smart 10amp smart charger to a deep cycle would work just fine. I recently aquired (free) 2 30ah AGM batteries that would work good to a 50% discharge per run.

1 Swich: Turn off Alternator Field, Discconects Primary Battery, and connects car load to Deep Cycles.

Monitor voltage, if it becomse too low, flip the switch back over, and run off your already full starting battery and alternator. And just wait until you get to the destination to charge the deep cycle from shore power.

A changeover relay could take care of this. -Just leave the starter connected to the starting battery, so you can get by with a 30amp relay.

Thinking of that, you could just leave the alternator hooked up, with no demand, it shouldn't be working hard.

Could also be done with 2 relays, a Normally open, and a normally closed. Flip it one way, and you could if desired, charge both, or Jumpstart yourself. Just like RV's do between Starting and House batteries.

Not that starting is an issue with a manual

Originally Posted by MetroMPG

I haven't. EPA says up to 2% decrease for an extra 100 lbs. (Tips to improve your Gas Mileage )

But there's no question that the weight penalty of carrying 130 lbs of golf cart batteries is far outweighed (pardon the pun) by the efficiency benefit of removing the alternator load from the engine.

[MetroMPG]

Noel - that's a creative idea keeping the starting battery "in reserve" in case you draw down the deep cycle batteries too much. I like it!

[Noel]

If you use a normally open relay for the starting battery, this means that if the relay fails, it's normal working is a connected battery to your car. A manual bypass switch wouldn't be a bad idea either.

I can get by without a starter, I can't get by without a fuel pump.

Another option is an actually switch inside the car, but that's a lot of heavy wire to run.

[Noel]

Simple one or ther other setup: SPDT Relay...

Pins


Not Energized


Energized


I would leave the starter and radio memory wire connected directly to battery. That would leave ALL other power drains, including headlights to be switchable.

One other thing to consider is the Fuel pump, although it is a drain, I'm not sure how well that motor reacts to less than normal 13.6ish volts, at say, 12.5v of a deepcycle under load, that's more amperage, and more heat for that little pump.


I'm starting to think my personal perferece for this mod would be instead of diverting everything, to divert the 2 biggest culprets, Lights, Blower and Electric Fan.

With anything else, there is give and take.

In the winter my commute is in the dark (and cold) both ways. Diverting those 2 loads could be a noticble difference in mileage, while not affecting mission critical devices.

[cfg83]

blackjackel -

Thanks for starting this thread. I had totally forgotten about this old solar panel.

Here is what it looks like on my dash :



I will be covering the light tan border in a darker color to avoid window reflections. Here it is showing almost 20 volts, but the volt meter knows it's way low in Amps :



What's nice is it has enough juice to run a fan :



If nothing else, I can use it for free poor man's A/C!!!!!!

Question: Do you think the heat in the car will hurt the panel when the car is parked?

CarloSW2

[MetroMPG]

The plastic frame on my 1A panel warped from leaving it on the dash. The glass even looks distorted. And then I knocked it over and cracked the glass. Amazingly, it still works.

[cfg83]

MetroMPG -

Originally Posted by MetroMPG

The plastic frame on my 1A panel warped from leaving it on the dash. The glass even looks distorted. And then I knocked it over and cracked the glass. Amazingly, it still works.

... Methinks I'll walk out to the parking lot right now to see if it's sagging in the heat.

CarloSW2

[MetroMPG]

I should have also said that I had it propped up in such a way that it wasn't evenly supported. And it seems to be about 50% longer than the one in your pic, so more prone to distort.

[cfg83]

MetroMPG -

Originally Posted by MetroMPG

I should have also said that I had it propped up in such a way that it wasn't evenly supported. And it seems to be about 50% longer than the one in your pic, so more prone to distort.

Yeah, I plan to build a support for it. The dashboard is deep so it fits just right. I will use the packing foam that comes in PC packing boxes. Hopefully, the foam won't degrade in the heat. I will also try to secure it properly for safety reasons (not that my dashboard isn't already a safety issue).

The panel has a thin clear plastic membrane/cover that I expect will peel off over time. As long as it's in the car, it's protected, so I don't care.

CarloSW2

[orange4boy]

Recycle your alternator!

I'm currently running alternator-less the simple way. Belt off, plug out, deep cycle battery, charge at home. I have 4 series 27 deep cycle batts for my auranthetics. I can fit two (if needed) in the front of my Toyota Previa for a total of 5.8 hours at 25 amps or 90 min at 75 amps. Just one battery (175 min at 25A.) gives me enough juice for 200 kms without daylights on and low elec. load.

Since I've been doing this for a while and It works, I'm happy without an alternator switch for the reduced complexity, belt friction and weight.


My first tank got me 17% better FE (mostly city)

My only issue is whether the lower voltage (12 vs 14.5) causes a cooler ignition spark and thus reduced FE improvement. Anyone know? To solve that the best set up would be two 8 volt golf cart batts.

Following info may be useful

Accessories approximately current draw:
- Air conditioner 12-20Amp
- Brake lamps 3-6 Amp
- Cigarette lighter 10-12 Amp
- CDI ignition 6-36 Amp
- Dome lamp 1 Amp
- Electrical fans 6-25 Amp
- Electrical clock 1 Amp
- Electric fuel pump 7-15 Amp
- Electric water pump 3-12 Amp
- ECU/EFI 10 Amp
- Headlights two low beam 8-9 Amp
- Headlights two high beam 13-15 Amp
- Horn power circuit 8 Amp
- Heat defroster 6-10 Amp
- HEI ignition 6-10 Amp
- Ignition coil 5 Amp
- Instrument panel 2-4 Amp
- Nitrous solenoid 5-15 Amp
- Power seats / Power windows 25-50 Amp
- Stereo HIFI normal 10 Amp
- Starter motor, normal cranking 125-250 Amp (fully loaded battery)
- Starter motor, initial engine turn over 500-800 Amp
- Throttle stop 5-15 Amp
- Trans brake 12-20 Amp
- Turn signals 5 Amp