Replacing alternator with solar panel array on roof?
Has anyone thought about doing this? You could get all your electrical power from the sun isntead of your engine/gasoline...
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Lots of people have wondered about this. It's entirely doable, but: hugely expensive (roughly $1000-1500 in panel costs alone to supply ALL my car's electrical needs); potentially difficult to mount the panels without adversely affecting aerodynamics, and potentially not enough surface area to mount the panels, depending on the vehicle.
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MetroMPG -
Blackjackal and I were talking about this today. How about this scenario : 1 - Voltmeter to monitor battery charge. 2 - Switch to turn off/on the alternator at will (I know this is doable in a Saturn S-Series). 3 - Large solar panel that can be used to recharge the battery while at work. Panel would not be deployed unless you were at work. Assuming the above works (big assumption), then the scenario would be an alternator "recharger" that is deployed when you get to work. That way, there would be no aero penalty. Benefits: a - You could have a smaller solar panel that does the same as a "trickle charge". I am not talking about the 6"x12" panels or the VW panel. I am talking about a "marine battery application" style solar panel. b - The voltmeter could allow you to make an "intelligent choice" when it comes to activating the alternator. Problems: a - I don't know if you need special "in between" electronics to keep the battery from being damaged. Maybe you do, maybe you don't, maybe it depends on the panel?!?!?! CarloSW2 |
Solarbug Has Them...
This little car has solar panels on the roof to recharge it's batteries.
http://ecomodder.com/forum/member-ju...7-solarbug.jpg Free Drive EV - Solar Bug |
It would be fun to do, but you would have to undertake this with a mindset 'regardless of cost benefit'.
If you were skilled in bodywork, you could 'cut in' a solar panel or panels into you roof, much like an aftermarket sunroof. Safe with the trunk deck (if you have one) maybe the hood (but I'm not sure about the heat and solar panels). |
Hi all.. 1st post. Solar would be a great idea. A little off topic but if you couple the "alternator kill" switch idea with the use of a battery charger at home when your car is in the driveway..then you would not be using any alternator drag to recharge your battery. You still have to pay...its not free it just ends up on your electric bill...I have not done the calculations but I am sure the cost is minimal to charge your battery.
Depending on your work schedule you could put your solar array where you park at home for recharging purposes... I know without the use of the headlamps that I can go almost a week without an alternator (found out this out on accident when my alternator fried). If you monitor your batt voltage when you see it getting low you could flip the switch and engage your alt. again. I have also put in a request to have my place of buisness allow me to plug in my car every day (if necessary). I have a CPU controled battery charger that changes from charge mode to maintain mode automatically. I have heard charge and discharge of a standard car battery will decrease its life span....not sure. A deep cycle may be more suited for this. Also what about a solar array in the back window area inside the vehicle. Great ideas...keepem comin. Thanks, Hankinator |
Hankinator -
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CarloSW2 |
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But the most damage will come from simply discharging deeply. Batteries don't like that, and only have so many cycles in them. I'm in agreement with metromizer: a fun energy efficiency project, but not something to undertake if the goal is saving money. |
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Considering alternators are not very efficient to start with, you'd be throwing away gasoline in the conversion losses. The alternator would be working extra hard to simultaneously (1) provide the vehicle's power needs and (2) replace the energy in the battery. If you're going to run without an alternator to save fuel, it needs to be grid/solar charged, or carefully set up to deliver current when braking or in engine over run conditions. |
Hello, first post
I think it would be a far better idea to plug your car into a regular outlet (with a AC/DC power supply of course) and recharge the battery that way. It's cheaper and works anywhere at any time, unlike the solar array. |
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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 |
Solar altenator?
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. |
Has anyone just setup an ammeter to see how much juice they're pulling during normal driving?
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Daox -
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For that matter, would you want to connect the ammeter to the battery or the alternator? CarloSW2 |
larryrose11 -
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CarloSW2 |
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Shumacher has a website. |
Hankinator -
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SC-1200A - 12/8/2 Amp Charger/Maintainer/Tester http://us.st12.yimg.com/us.st.yimg.c...6_2010_4418676 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 http://www.batterystuff.com/images/p...troller_md.jpg Quote:
Sunsei Solar Charge Controller | Batterystuff.com I have an old Unisolar flexible panel, with specs close to this current model : Code:
UniSolar Rated Rated Rated Open Short Dimensions I am hoping that the "Sunlinq 12" mentioned above is a good match for my Unisolar : Sunlinq 12Watt 12V Portable Power Pack Code:
Sunlinq SL-12 : |
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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. |
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. |
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... |
I just had an idea... what if I could buy a tiny lightweight battery charger that I can keep inside my car under the hood and I Can rig some sort of windup power spring thing to where i can pull out the power plug and plug my car in to charge the battery every day... But its so confusing with all the different kinds of chargers and powers etc..
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so has your panel been enough to keep your battery charged or do you still need to plug it in sometimes?
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MetroMPG -
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Make Model Pmax Vpmax Ipmax Isc Voc Length Width Hrmmmm, this might be a good sign (depending on what they mean by higher temperatures) : (Page 100) http://www.collectionscanada.gc.ca/o...01/MQ31541.pdf Quote:
1 - With the engine off, take a battery voltage reading (I can do this using the cigarette lighter). 2 - Park it at work all day with the dashboard window facing south. 3 - With the engine off, take a battery voltage reading. If it works, it should always be better than when I park the car. If nothing else, it should keep my battery topped off (it's not a deep-cycle battery). CarloSW2 |
MetroMPG,
your right, I should have been more clear. I was under the assumption that we were talking about deep cycle battery of significant capacity, like your 6V, 225 AH (Trojan T-105's?) Something small like the 12v 7ah SLA's would gas in no time. Sla's can be sensitive too. CarloSW2, deep cycling a normal starter battery will kill it fast. because they can handle being discharged for very long. Put in 1 or 2 big deep cycle batteries, you do better. |
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CarloSW2 - I'm sure you can leave that panel directly connected to the battery. I have a similar slightly larger panel - 15 watt, 1 amp - and it's been supporting my near dead starting battery for more than a year, directly connected.
Why is it near death? Because I ruined it in 2006 with multiple deep discharges when I first started experimenting with a charge-depleting 12v approach! It has very little capacity now, and the panel is just delaying the inevitable. |
MetroMPG,,,, have you ever done a test to see the difference an extra 100lbs does to mpg?
That's one I would be really interested in. (I don't have a scanguage) |
I haven't. EPA says up to 2% decrease for an extra 100 lbs. (http://www.fueleconomy.gov/feg/driveHabits.shtml )
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. |
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 :) Quote:
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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!
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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. |
Simple one or ther other setup: SPDT Relay...
Pins http://www.the12volt.com/12voltimages/relaytextA.gif Not Energized http://www.the12volt.com/12voltimages/relaytext2.gif Energized http://www.the12volt.com/12voltimages/relaytext3.gif 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. |
blackjackel -
Thanks for starting this thread. I had totally forgotten about this old solar panel. Here is what it looks like on my dash : http://img239.imageshack.us/img239/9...c262jx5.th.jpg 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 : http://img221.imageshack.us/img221/6...e2pmfm7.th.jpg What's nice is it has enough juice to run a fan : http://img221.imageshack.us/img221/6...dfanlt0.th.jpg 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 |
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. :o
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MetroMPG -
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CarloSW2 |
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.
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MetroMPG -
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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 |
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 |
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