Attention! Alternatorless modders. Get your voltage up

[The Atomic Ass]

Originally Posted by Daox

I'd be very interested in any info anyone has on how much power the ignition coil and fuel pump require. I suspect its not a tiny amount.

Not too terribly difficult to find out. Pop out the F/P relay, find the correct pins, and then using Multi-meter that handles at least as much current as the fuse, (mine will for 15 seconds), simply measure the current draw, and then check battery voltage. On any of the GM vehicles my parents have, as well as my bike, this can be done with the engine and ignition off. Same goes for the ignition coil.

Also, I'd be tempted to try this, except I can't really hook up for a charge anywhere convenient right now. (Apartment).

[Daox]

Yup, that is what I am planning on doing sometime this week hopefully.

[orange4boy]

My original claim on the the first post here seem to be bearing fruit: Gains from alternator deletion are much greater if voltage is kept above 14.5

Two tanks now under my belt with a big improvement in both most of this difference, I believe, is mostly due to the voltage increase. I did fix an intermittently dragging disk brake so I'm taking this with a grain of salt. On the other hand, I have removed the air dam and grille block I had set up.

Last three tanks averaged 24.15mpg
Previous 5 similar tanks averaged 21.7mpg
a difference of 2.45 mpg. A good 11% gain.

This is all alternator free by the way. This is on top of the gain from the original alternator delete.

I'm still looking for someone with a more consistent commute to bear this out.

[gascort]

Daox, thanks for the link to the 12V - 15V converter. I'm thinking about trying that out. I tried my route of connecting a 4V battery in series with the ECU and F/P and F/inj. relays, but that pushed voltage over 17V when fully charged and the relays clicked on and off rapidly. Plus that 4V would be a real pain to recharge relative to my big ol' 12V deep cycle.
On my car these relays are both powered by a "main" fusible link, at 100A. I couldn't isolate any smaller fuses that controlled power to them, strangely enough. They're all fused after the relays, so going by them, the injectors are on a 30A, the ECU on a 10A and the fuel pump is on a 30A. Surely they don't require that much, so it's time to see if my 10A multimeter can handle them. Maybe we can use one DC-DC up converter and a capacitor to power these, as the vicor converter is only:
12V-15VDC
75W

P/V = I, so 75W/15V = 5A

A fun little FYI, I was checking my math using google as a calculator, and if you put in the units, it gives your answer with units. amusing.

[Daox]

I just wanted to add to this thread for anyone searching in the future. Autospeed came up with a great and cheap DC to DC converter that we could use for this very application. I started a new thread about it here.

AutoSpeed - DC to DC converter solution for alt-less modders

[Daox]

I went ahead and bought two of those DC to DC converters. I believe that should be enough. I'll probably use one for the ignition system and maybe the ECU, and then one for the fuel pump.

[gascort]

Any luck with yours, Daox? I bought 4 of the Ebay ones and wired all four parallel to power(what I think are) the relays for my F/P and ECU. Drives fine, but decreased my FE according to my MPGuino. I suspect maybe a large capacitor may be required inline after these guys to provide plenty of current under peak demand.
Anyone else have ideas?
I'm getting pretty mad at this project; might just give up on the beltless and loop my power steering lines to delete it as much as I can, and use a lawn mower battery for my necessities and power all others from my Optima and the solar panels.
I should note that the decrease was not much; basically the same as what I registered when I tested going beltless with just the 12V battery - maybe 1-2 mpg highway lost vs. using the belt. Maybe this tells me I wasn't isolating all of the electricity sources for the computer and fuel pump, but when I disconnect these relays, neither works.

[Daox]

I haven't had a chance to hook mine up yet unfortunately.