Virtual alternator delete.
 

I should introduce myself better as a new member, but I have been a mental subscriber to Ecomodder for a decade, trying out most advise only short of a full belly pan and a Kammback, never caring about giving anything back to the community, sorry! However I've "invented" a new mod, not mentioned here I would like to share: I do a lot of city driving and noticed than when my alternator kicks in, my steady 35mph consumption goes up from 98mpg (2.4L/100km) to 70mpg (3L/100km) and my idle goes from 0.6L/h to 0.9L/h (I'm European, trying to mix empirical units with ISO units for this international audience), so an alternator delete is a logical next step, but I don't wan't to carry additional AH to make up for the missing charging, as the weight penalty will cost dearly in stop and go traffic, so here is my Hi-tech solution: Loosing the 40AH battery saves 16 pounds, replacing it with a 4S5P Li-ion pack, the size of a grown man's fist. The observant reader have noticed that this gives me a 16V car electrical system, but in reality it is a 15V system as I only charge each cell to 3.9V for a long cyclic life and safety as only float charging at 70% charged is safe with Li-ion. My car works perfectly on this, no fried coil or bulbs or any error codes. I did check with my workshop manual and 16V is within specs. Such a pack does not start my car so I added a super capacitor bank in parallel over a shunt resistor to take care of this. However, all this does not save me anything besides weight, so I've added a 50W solar panel and a 15V charger to keep my battery and capacitor above the 14.45 my alternator would like to push, so it shuts down. 50W solar on the dashboard is too puny for low beams, but they are only on at night where the sun doesn't shine anyway, so I got plenty for systems and DRL and my power windows are really fast!! This saves me guestimated 0.8L /tank idling and around 25% in city driving in the daytime, which both are substantial savings, that avoids the extra bettery weight and plug-in charging and does not require unbelting the alternator so quite unintrusive. It could even be build into a battery sized box with two wires going to the solar panel, and be a simple battery swap procedure to install and un-install.

Very good first post Luno. Our community would very much like to see A-B-A testing results of alternator off, on, and then off again to compare fuel consumption to get a good idea of actual % improvement in economy.

One thing I like about your system is that the battery can be charged in temperatures below freezing, which LiFePO4 cannot. I'll have to consider replicating a similar setup someday.

Looks interesting. I would second redpoint on the testing idea. Could you just run the scenarios you ran with the stock system again?

Also, you have saved some weight but you have spent a lot more upfront. How much do your solar panels and other components weigh?

I did consider LiFePo4 batteries, but Getting them to Europe is expensive, there is no European reseller of the sizes relevant here. Studying Li-Ion batteries, it dawned on me that undercharging them increase cycle life to 2000-4000 range and they become a safe as LiFePo4 batteries as you never drive them near the the electrode decomposition voltage, so in effect you have the benefit of LiFePo4 and a capacity/weight around LiFePo. What I did not mention is that I have a 10A LiFePo4 BMS on my pack as a secondary protection cutting off the pack if any cell goes above 3.9V or current draw is higher than 10A. I do know that this is an relative expensive system having a long payback time, but I had most of the stuff from an electric bike project. I've driven around for a week with this and it is totally reliable so far. What I also didn't mention is that when driving at night the battery lasts for 30 minutes until the voltage drops below the alternator cutout and it resumes normal operation, and there are no more savings to be had, but this is totally self managing. I have an MPGuino in my 98 Fiat, so my numbers are just the observed drop in the instant usage, during the last few days and I do understand that outrageous claims need matriculate proof, but I'm seeing the same numbers as other people un-belting and switching off stator current, The reason I have a large improvement in mileage is because this is a very mechanical efficient car (I can push the 990 pounds of it with my thumb to jogging speed in neutral on slick level asphalt) My real life city driving consumption is in the 47MPG range with traffic, but I need to run a few tanks to have a solid average, but the savings overall, including idling is around 25% city driving on the MPGuino so far.

What car do you drive?

I am unaware of any cars that weight as low as 990 lbs.

I am sure he meant kilos, which is almost 2200 lbs.

A few of us have done the same. Around 10% is the gain.

Weight doesn't cost much.

My Kangoo averaged 6.7 city (16mph average speed) and on a really bad day 9.7 with a 500kg+ trailer.

If you work that out that's 0.006l/100km per kg, including the aero and rolling drag of a trailer.

I can't imagine 50W of solar in Denmark does much. I've got 340W in Australia and it's not enough to keep up with the injection and ECUs (diesel). My previous 100W panel barely made a dent in my Petrol Kangoo's electrical usage, but topped off the battery nicely when parked.

Oh God, A Kangoo. Been there, Get over 85 kM/h and it drinks a lot. 6.2L/100kM highway was the best I could get going at lorry speed. Spare parts are extremely expensive and special tools for everything. I drive a Fiat Seicento 1.1 SPI from 1998 now. This car is not known for great mileage, mainly because of a very low gearing and slightly wider tires and I seriously believe that the Fiat test driver doing the test tried to drive very Italian. Luckily Fiat have struggled for decades to reduce consumption to pass increasing NEDEC driving cycle demands, and as parts are interchangeable between models I've managed to create quite the hypermiler: In 1999 they made the Seicento Suite model, that either came with a cloth roof or AC, both of which used more fuel, so they changed the gearbox for a 12% taller one. I got one of those. In 2000 they made the 4 injector MPI version of the Fiat Punto, which had a bigger engine so worse consumption than the previous SPI models, so they used a milder camshaft with less overlap. I got one of those too. I drive Ecopia B381 tires on 4.5" wide 14" rims which also increased the gearing by another 9%. Driving 50kM/h (or 35mph) in 5'th now happens at 1300 rpm. Interior is gutted, including rear cushion frame. Weight with me in it on a lorry scale was 690kg with spare tire and everything, that is 1521 pounds, without me that would be 1345. Factory nameplate dry weight stamped in the trunk is 610kg. Weight saving include 40 pounds saved on lightweight (6 kg each) rims and tires. 100 pounds interior and spare wheel. also some pounds on unused spot welded brackets and superfluous auxiliary systems around the car, like rear wiper with motor and more than one outside mirror, the whole heater blower motor and associated plastic and cardboard moulding (now using 4 server 80mm fans and ducting straight from the front grille, with pwm control), A cheap after-market 4A radiator fan connected with strips directly to the radiator instead of the original heavy metal frame thing made by Fiat and a 300g crap radio instead of the 90' Sony head unit that weighted 4 pounds. BTW, Passes MOT every time.

Oh, what is this, I thought this was a boasting thread but every other comment is from someone doubting by my claims? I can see one caveat with my measurements and that is that running 0.5V higher shortens the open time of the injector but also increases the hang time after power is cut and that not by an equal amount, but I have explained already that I have not run a full tank yet, so my figures might need correction once I've done a fill-up!

City driving is 1/3 - 1/2 power wasted on auxiliary systems from water pump and alternator. Weight is very important in stop and go. When piston heads claim that 5 pounds saved in their hotrod is the same as adding a HP it is also the same as saving a HP when accelerating to the same speed at the same rate.

We do use the same sun on the northern hemisphere and whatever sun height we have here is equivalent to whatever angle the sun hits you at down under. With the added benefit that in summer it stays up for longer. But you are right in that 50W is cutting it close. Having it behind a windshield cuts a 1/3 of power received, ad to that the elevated temperatures in a parked car in summer. So lets say the gets me 40 kWh yearly at my latitude (from the solar energy tables), that's 105 Wh a day on average. So this is not an all year system, and if I need to ad more panels in the fall or for longer trips (load is shared between solar panel and battery now most of the time unless I drive South around noon), so be it.

Idling with everything else off takes 2.5A for the ECU, coils, fuel pump and the single injector (1.1bar fuel pressure). If You have a diesel, maybe a very fancy one with an electric high pressure booster pump your base consumption is much higher, what you get is better atomization which improves fuel economy, but if it takes 350W of electrical power to do that in your car the benefit is eaten up in city driving where you only need 2-3 HP for driving at constant speed, so 1 HP mechanical to make 350W electrically is insignificant on the highway and but bad in city driving. So I agree, putting 350W of solar on your car saves you more than me putting 50W in mine, because your base consumption is higher to begin with. 10% to you saved by omitting the alternator is the same as 25% for me, it is because alternator drag is a much higher percentage to begin with on a small car. The stator coil alone uses 2A when turned on. So when I say that my savings are comparable to what others are getting, I mean in absolute HP savings. If this is only 10% on your car it does not mean that the mods is less beneficial for you as we both save the same amount of fuel by doing this. The reason this takes 350W for you is possibly also because of more electrical loads, electrical power steering? Urea catalyst? or heated oxygen sensor? (I know almost nothing about diesels).

Cheers!!

I'll better do a proper writeup on this with pictures of my clamp meter on every wire and videoed A-B-A tests between fill-ups for some of you to take this serious And I should, Irrefutable numbers are always the best arguments.

That actually sounds like a cool idea, hadn’t thought to boost battery voltage to where the alt would automatically not charge, but it seems logical...

It’s also a ridiculously light car, which is helping you in city driving... my car weighs around 1200kg, so it could use for some weight to come out lol