Alternator v. no alternator - 10% gain @ 70 km/h

[JanGeo]

I thought the fuel pump in a diesel is mechanical driven on the engine (injector pump) and it draws the fuel from the tank. Thus no power required except for the control of the injectors via a ECU?

It sounds like the best solution is still solar panels on the roof to lighten the alternator load when driving in bright sunlight and then the cost of the solar panels comes into play but at lease they will last the life of the vehicle and not require additional expendature. Plus on a bright day you can crank up the radio and use the excess energy!

[MetroMPG]

Note: split the discussion of weight into its own thread, because there's some good info in the weight thread deserving its own spotlight:

"Effect of weight on FE: estimates from online sources"
http://www.gassavers.org/showthread.php?t=2003

Note: I'm not saying the effect of extra batteries in a no-alternator set-up is inconsequential. But the weight discussion can affect everyone, not just the alternator experimenters.

[MetroMPG]

Originally Posted by JanGeo

It sounds like the best solution is still solar panels on the roof to lighten the alternator load when driving in bright sunlight and then the cost of the solar panels comes into play but at lease they will last the life of the vehicle and not require additional expendature. Plus on a bright day you can crank up the radio and use the excess energy!

It's a good point. 7 or 8 amps worth of solar would cost me roughly $700 though

[JanGeo]

You are getting the wrong cells - raw cells with 5.5 amp output crate of 50 for $450 last time I checked was over a year ago. 22% efficiency!!! 22 in series and 2 sets in parallel would give you about 14.5 volts at 11 amps and cover the hood in area 125mm square cells jet black no markings on them back side is an aluminum plate and contacts. As far as I know theses are the best cells on the market that anyone can buy.

OOPS!

http://www.sunpowercorp.com/solarcells/

[GasSavers_Brock]

In my case my car already weighs in at 3200 lbs. Throwing an additional 120lbs in the back is nothing to the car itself. It's like another person in the back seat. My typical commute is 11 miles to and from work, 1 stop sign each way so the added weight likely wouldn't affect me the way it would in normal stop and go city driving where weight really kills mileage.

For cost if it were all new
2 golf cart batteries - $150
1 Xantrex 1500w inverter - $100
1 Iota DLS-55 charger - $150
#4 wire from the back to the starter battery - $25
$425 total. I already had the heavy wire run for the inverter in the back, I just run the power back the other way in this case. I had the used batteries so I don't care if I run them in to the ground. The charger is one of two I use to charge my home battery bank in a power outage from a generator. So it was really just my time to set it up. I would not recommend this to “save” money. I highly doubt it would every pay for itself.

With solar I would need at least 2 KC120's to offset my load, at least $1200 and if I spend that much on solar panels I want to get the most out of them, that is to have them have them aimed correctly at the sun and use all the power they make. Oh and the wind drag from the solar panels would likely cause me to use more diesel then I am saving with the alternator disconnected. Maybe if you bought laminar (flexible) solar cells at twice the cost of regular flat panels cells, but that would be at least $2400.

Again my car once warm draws about 100w or 8 amps with nothing on, no radio, no DRL's, no fan or AC. That all just adds to the base 100w load.

And yes the fuel pump is mechanical driven off the engine. I am not sure what the car is doing with the 100w, but it uses it for something.

[MetroMPG]

Originally Posted by JanGeo

You are getting the wrong cells - raw cells with 5.5 amp output crate of 50 for $450 last time I checked was over a year ago.

Linky?

[JanGeo]

You know if you tapped into the inverter and the charger you could increase the efficiency a lot - the inverter pumps up the 12 volts to about 120-180 VDC then chops it into a square wave - the charger takes the AC and rectifies it into 180 VDC and chops it back down to 14 volts. You should be able to jumper into the inverter internal high voltage DC and connect it directly to the caps in the charger and eliminate the fet switching and rectifier losses. Actually if you ran more about 18 volts and used a switching regulator power supply to drop it down to 14 for the vehicle it would be most efficient. And that could be done with a single FET or power transistor good for plenty of amps.

[zpiloto]

Metro you have a 10% gain with an unbelted alternator do you had any data if you just removed the load from the alternator and not the belt. Maybe install a kill switch to remove charging when not needed. Any thoughts on if that would give a noticeable increase in FE may 2-3%

[GasSavers_Brock]

JanGeo this is true, but I wasn't as worried about efficiency at first since I was really just seeing if it made a difference and if so how much. Probably the easiest thing to do would be to go with a 24v battery bank and a 12v charge controller and let it do it's thing, the trick is getting up to the 50 amp range, well that is easy, it's just how much it costs. For instance I use an Outback MX-60 charge controller and it will take any voltage up to 140vdc and charge either 12v, 24v or 48v battery banks and you can set bulk, absorb and float voltages and times. Very nice, but they run $550.

The thing I really like about the iota chargers is you can feed them anything from 90 volts to 180 volts, AC or DC and they put out a rock steady 13.4 or 14.4 volts DC. I didn't believe it at first but someone who dug in to the unit tried and now uses it on his electric truck to charge a 12v battery from his traction pack for all the old existing 12v items.

[MetroMPG]

Originally Posted by zpiloto

Metro you have a 10% gain with an unbelted alternator do you had any data if you just removed the load from the alternator and not the belt. Maybe install a kill switch to remove charging when not needed. Any thoughts on if that would give a noticeable increase in FE may 2-3%

I'd wager the belt doesn't represent *most* of the gains I measured. Maybe a couple per cent of the 10 total. But I wouldn't know unless I tested it.

I've been waffling between rigging an electric water pump (so I don't have to worry about any belts at all), and putting the full belt back on and rigging a switch.

We'll see what winter brings. I'll probably be a lot less likely to be tinkering (adding/removing the belt for long/short trips), which may encourage me to use the fuse/switch.