Replacing alternator with solar panel array on roof?

[Hankinator]

Originally Posted by MetroMPG

You may actually get worse gas mileage doing this than if you simply leave the alternator connected full-time.

Great point! I intended this to be a "precautionary" battery boost if you feared you would not make it to a place to charge your batter for your next start.

I wonder if anyone has done the math or measurements on this. Technically its the same amount of energy wether it be maintaining all the time or charging a portion of the time....a little alt. drag for the entire trip or a lot of drag for 1/4 the trip....interesting.

I will post my charger specs when as soon as I can get them.

Thanks,

Hankinator

[larryrose11]

Hello all,
I have given this a LOT of thought, but my wife said no-way.
My friend here at Ford added 2 panels to his HEV escape. The DC-DC converter on this model is bi-directional. He left it disabled (factory default) when parked so as to not damage the HEV battery from overcharging during the day.

Here was my findings / plan
Solar panel: Use one from UniSolar: they are thin (about 5mm), flexible, and light. Easly mounts smoothly to the roof.
United Solar Ovonic
you can get them on eBay. The framed 64W will work. The frame can be removed, and the metal backing can be carefully removed by dissolved the adhesive with a solvent.

Replace your 12V SLA battery with a high capacity deep cycle, 100+AH.
Install a relay on the field of your alternator, so you can disable it remotly,
Finally, adjust the I-line control pin on your ECU so the alternator's only maintains your battery at 12.5V. Otherwise when you turn the field back on, it will fill the entire battery, killing your FE.

The 64W panel can fit on my Honda civics roof. It will only delver 5A in the sun, not nearly enough to run the 12v system on a regular car.

Over the whole day, the US-64 panel I have at home will delver about 30 Ah in my experience. The rest should charged at home every night, like AndrewJ micro-PHEV setup. AndrewJ saw a 10% increase in FE from the micro-PHEV setup. The solar pannel would help top up the battery during the day after the morning drive in, but wouldnt provide much power when under way. The efficiency of non-space grade panels is pretty low (10% for thin film, 14% for crystalline), and the sun provides 1kW/m^2.

[Daox]

Has anyone just setup an ammeter to see how much juice they're pulling during normal driving?

[cfg83]

Daox -

Originally Posted by Daox

Has anyone just setup an ammeter to see how much juice they're pulling during normal driving?

No, but I was thinking about that too. I think my alternator is rated up to 95 Amps, but I have an ammeter (for something else) that goes to 60 Amps on the dial. I am (obviously) guessing that is too small. Also, I would think that the cables to/from the Ammeter would have to be rated to meet/exceed max amperage of the alternator (or the battery?!?!?).

For that matter, would you want to connect the ammeter to the battery or the alternator?

CarloSW2

[cfg83]

larryrose11 -

Originally Posted by larryrose11

...

Over the whole day, the US-64 panel I have at home will delver about 30 Ah in my experience. The rest should charged at home every night, like AndrewJ micro-PHEV setup. AndrewJ saw a 10% increase in FE from the micro-PHEV setup. The solar pannel would help top up the battery during the day after the morning drive in, but wouldnt provide much power when under way. The efficiency of non-space grade panels is pretty low (10% for thin film, 14% for crystalline), and the sun provides 1kW/m^2.

That's egg-zactly what I wanted to know.

CarloSW2

[Hankinator]

Originally Posted by cfg83

Hankinator -



Welcome to EM and thanks for the info. The "charge/maintain" mode is what I want to know about. What brand of charger are you using?

CarloSW2

My charger is a Shumacher Speed Charge WM-1200A. I think its a few revisions old by now. I got mine from my Dad...he likely got it at a yard sale........

Shumacher has a website.

[cfg83]

Hankinator -

Originally Posted by Hankinator

My charger is a Shumacher Speed Charge WM-1200A. I think its a few revisions old by now. I got mine from my Dad...he likely got it at a yard sale........

Shumacher has a website.

Thanks, this looks like it's the once-lost now-found grand-child :

SC-1200A - 12/8/2 Amp Charger/Maintainer/Tester


This gives me a "spec" a and a general price-point to work from. Schumachers are all over ebay, so I can be patient for what I want.

.... virtual time passes ....

This information also helped me to Google this :

Solar Charge Controller | Batterystuff.com

A 12V 7 Amp Charge Controller protects your lead acid batteries from overcharge. This charge controller is to be used with any of the P3 or Sunlinq 12 and 25 watt 12V product line and can handle up to 100 Watts of Solar Power. Controller ships with SAE type input/output trailer plugs allowing direct connection to the solar system. The controller is designed to plug and play with the 5 piece accessory set that ship with the solar panel.

Wow, here's another charger :

Sunsei Solar Charge Controller | Batterystuff.com

I have an old Unisolar flexible panel, with specs close to this current model :

UniSolar  Rated   Rated   Rated   Open     Short    Dimensions
Model     Power   Voltage Current Circuit  Circuit  (inches)
          (Watts) (Vmp)   (Imp)   Voltage  Current 
                                  (Voc)    (Isc)
USF-11    10.3     16.5   0.62    23.8     0.78     21.80x16.70

I am hoping that the "Sunlinq 12" mentioned above is a good match for my Unisolar :

Sunlinq 12Watt 12V Portable Power Pack

Sunlinq SL-12 :

Maximum current at STC* (mA)  = 800
Nominal Operating Voltage (V) = 12V
Typical Power (Watts) at STC* = 11
Maximum Power (Watts)         = 12

*Standard Test Conditions: 
Irradiance level 1000W/m2, 
spectrum AM 1.5 and cell temperature 25 ºC

CarloSW2

[MetroMPG]

Originally Posted by cfg83

No, but I was thinking about that too. I think my alternator is rated up to 95 Amps, but I have an ammeter (for something else) that goes to 60 Amps on the dial. I am (obviously) guessing that is too small.

That should be OK. The alt is rated to deliver way more current than you typically use. It has to be able to delivery a battery charging current while also running every electrical accessory in your car.

I guesstimated that my car takes 288 watts or 24 amps to run the engine, cruise control and parking lights. I don't have a DC ammeter (other than the 10A on my DMM) so I haven't actually confirmed this.

But you should be OK measuring current with a 60 amp limit.

[larryrose11]

CarloSW2,
In my experience, a charge controller is unnecessary for anything less than 100W while charging pB-A battery. You do loose power without a MMPT, but it is not necessary. The current is what charges the battery, and it will be delivered at whatever the battery voltage is instead of the nominal operating voltage. You could just put your panels in parallel and be done with it.

[blackjackel]

50w solar panel

http://www.rvfunproducts.com/50w-rv-...el-p-1832.html $266

BEEFY 50W 3Amp solar panel, I think this alone could keep your battery charged as long as you park it for a little while every day...