Boosting voltage for alternatorless ecomodders

[Daox]

Alright, this is an oldie, but I'm finally going to try it. Tonight I was on my way home from a meeting and it was pouring. The poor Metro's lights are noticeably dim when running at 12V (vs 13.5-14.5 with the alternator hooked up) so much so that I usually just run around with my brights on to see on country roads.





So when I got home, I dug up this little dc to dc converter I got a while back for some random project. It takes 11-14V input and boosts it to 15-24V. I'm going to install this on at least the ignition circuit to boost the voltage back up to more normal operating voltages.

Why do this? Well, first off headlights are annoying DIM at around 12V as mentioned already. Second, there are other efficiency penalties associated with running lower than nominal voltages. Orange4boy noted this a few years back.

Thankfully, the alternatorless benefit overshadows the penalties, but why not have the best of both worlds? This solution I actually posted about in 2009. I'm sure a few people have run with the idea, but I don't recall anyone specifically documenting it.

I'm going to start by boosting the ignition coil voltage from 12V to ~15V. As mentioned, normal operating voltage is 13.5-14.5V. By running at 12V, the ignition coil is putting out 11-17% lower voltage to the spark plugs. A quick google says that most ignition coils run around 40,000V output. That means I'm loosing 4400 to 6800 volts by running lower voltages.






So, lets get on with it! Above you can see the dc-dc converter. Its a cheap Chinese piece I got off ebay. They're about $10 if you search for laptop car adapter or something like that. There are actually cheaper ones now for about $5 shipped that handle more power.





I cut the connectors off of it and crimped on some blade connectors. It'll be all be taped up to protect from any water. This also allows easy removal for testing and/or if it fails in the future.






This is the connection point. Its right before the ignition coil, so the install is quite simple. Snip the wires, crimp on connectors and plug in the dc to dc converter.

More to come...

[BabyDiesel]

Subbed! I have not made myself go alternatorless (yet...), but this idea seems to be quite the simple-ish life hack for this mod.

I'm also interested in the idea of boosting stock ignition power levels to help with my lean burn and push my spark plug gap closer to 0.1"

[Daox]

I'll also mention that I have had some misfire / hesitation issues with the Metro off and on. I've never really been able to fully pin point the problem. I'm sure some of it has to do with my malfunctioning kill switch (since replaced) and worn ignition components (distributor cap & rotor, not replaced), but I'm not entirely sure that this is 100% of the problem. On the only other car I've had an alt delete done on, my 97 Paseo, I had zero ignition issues with the alt delete and no voltage boosting done. Of course it had coil on plug, so it was probably innately less fussy.

[MetroMPG]

Related thread:

http://ecomodder.com/forum/showthrea...ery-20008.html

[ksa8907]

I realize its an added expense and all but why not get/build a 14-16 volt battery?

[Daox]

If you can find one for me for a reasonable price, and then find me an onboard smart charger for a reasonable price I'll consider it. Until then, dc to dc converter.

Seriously, I looked a while back and the prices I found were outrageous. If I were to spend that much, I'd just switch to lithium.

Its really not THAT much on the car that requires the higher voltage. I'm considering the ignition system and headlights. Thats about $25 in parts including connectors that make the headlight converters plug and play.

[redpoint5]

If the only issue was dim headlights, I'd just convert to HIDs which have a built in regulator to ensure a consistent output.

I'm not sure what the lower voltages are doing to your ignition/fuel economy though.

Running lower voltages will draw less power from the battery and help stretch the capacity.

[Daox]

For the fuel economy side of things, I don't see the lower voltage hurting anything besides the ignition system. The sensor voltages on the car are already regulated by the ECU. The fuel pump isn't going to be able to pump quite as much fuel at lower voltages, but I'm not winding the engine up so thats no big deal. The injectors will react slower, but the o2 sensor should automatically adjust for that. If I'm missing something, someone let me know.

I'm not really interested in converting to HIDs at this point in time, but that sounds like a good alternative. I've driven the car for nearly a year with the lights the way they are. I'm really more so doing this for the ignition system right now. The headlights are probably a big deal if you do more country driving which I don't do with this car. I'm not even sure I'll boost their voltage up yet. It was just a bit annoying late last night as I just wanted to get home, this happens a few times a year and I should probably just finish the alt delete mod and get my switch working so I can turn the alt back on.

[UFO]

Sounds like HID headlights are a good option for those of us not doing alternator deletes. I EOC my truck, and with the engine off, the lights dim considerably. I'd like to keep my headlights bright, not just to see, but to mask my driving behavior as rolling around with the engine off is not always acceptable to LEOs.

[oil pan 4]

I presented my solution to boosting voltage a few years ago:
Take a 6 and a 8 volt deep cycle battery of the same make and size and wire them in series.

A 7 cell battery should have a 14.9 volt open current resting voltage, should be considered "dead" at 12.2v. Under load I would expect a 7 cell battery to have about a 14.4v, +/- 0.2v under load.
Only problem I see is you would need to devise a special 17 volt charger to charge them up. Or attach each one to its respective 6 and 8 volt chargers.

Or go with a LiFePO4 battery. Normal volts for 4 cells is 13.2 and 12.7 is considered "dead".

For voltage dips causing dimming head lights use LED.
My LED head lights are full brightness down to about 11 volts and draw 7 less amps in low beam.