A better alternator delete

[Ecky]

Well, I believe what he means is, breaking the electrical system into separate partitions.

[redpoint5]

In that case, it mostly defeats the purpose, which was to get the alternator to turn off. I don't see the benefit of creating islands of power.

[Piotrsko]

I thought it was to eliminate the power rob the alternator produces under load and still drive the car under sub standard conditions

[Daox]

I got the lihium battery charging dc-dc converters over the weekend. I plugged them into a 12V power supply and tweaked the output to be 4V and 4A output. I initially had it set to 5A, but it seemed like it was getting a bit warm for my liking. Granted, I was pumping 5A through alligator clips haha. That might have had something to do with it. I'll revisit that later when things are more finalized.

I am hoping to get the AC to DC power supplies today, and then I can test the charging side of this thing.

[Daox]

I got the ac-dc power supplies tonight. They're larger than I thought they'd be at about 5.25" long. However they are very light weight. I'm thinking I may take them out of the cases when I get to putting everything together. It will be better for cooling and size.





Here is the specs on it. It actually puts out about 12.3V which is fine for this purpose.





So, I hooked up one of the power supplies to the dc-dc converter. Then, I hooked the dc-dc converter up to the multimeter set to measure amperage and let it run for a while.





I wanted to see how hot the dc-dc converter would get just running at 4A for a while. It turns out, it runs pretty darn hot. I'm definitely sure I don't want to run it at 5A. The diode (the thing just to the right of the inductor coil) gets very hot. I measured the best I could with my IR temp gun and the highest reading I got was 216F after a few minutes running. The chip says SK54 on it, so I googled that. The first data sheet I found says max junction temperature is 300F. The capacitors were also pretty darn warm at ~145. A quick google search says electrolytic capacitors are good to about 180F. So, I guess I'm okay? Electronics guys feel free to jump in with some feedback.

[oldtamiyaphile]

I've been running a set up like this for a couple of years on a three of my cars. On my 'best' set up, solar panels charge my OEM battery to 100% float every morning. The alternator sees the full battery and doesn't charge other than regen.

For the first ~6 miles the alternator just sits at 11.7 volts (no charge). After that (and several engine restarts) the ECU sees the battery as getting slightly low and starts to put a slight charge in at 12.4v. It then cycles lightly depending on how much power the solar panels produce. On a sunny day in the open it's possible to almost drive entirely alt. less.

In two years I've saved ~140k alternator Wh. That's around 11 gallons over ~12k miles (around 3%). However you trick the alt into not charging should give similar results (assuming your method has enough capacity to reduce your alternator duty cycle to around 20%). All the same, the difference is too small to pick up in tank-to-tank fill ups. 1.5% gains would likely be more typical if you can't charge at your destination.

At it's simplest, I just keep my Fiat battery on a garage mounted solar charger, that keeps the alternator off for the first few miles just the same, but I don't have kWh numbers for that one. Sure is a simple 'mod' though

[teoman]

Check if the output GND is connected directly to the input GND.

If so you cannot connect the drivers in series to charge your cells without shorting them.

[UFO]

Originally Posted by Daox

I got the ac-dc power supplies tonight. They're larger than I thought they'd be at about 5.25" long. However they are very light weight. I'm thinking I may take them out of the cases when I get to putting everything together. It will be better for cooling and size.





Here is the specs on it. It actually puts out about 12.3V which is fine for this purpose.





So, I hooked up one of the power supplies to the dc-dc converter. Then, I hooked the dc-dc converter up to the multimeter set to measure amperage and let it run for a while.





I wanted to see how hot the dc-dc converter would get just running at 4A for a while. It turns out, it runs pretty darn hot. I'm definitely sure I don't want to run it at 5A. The diode (the thing just to the right of the inductor coil) gets very hot. I measured the best I could with my IR temp gun and the highest reading I got was 216F after a few minutes running. The chip says SK54 on it, so I googled that. The first data sheet I found says max junction temperature is 300F. The capacitors were also pretty darn warm at ~145. A quick google search says electrolytic capacitors are good to about 180F. So, I guess I'm okay? Electronics guys feel free to jump in with some feedback.

The cooler you keep the components the longer they will last. Especially the capacitors, they must be pretty crappy to get as hot as you measured.

[Daox]

Yay, Battery Hookup had a deal on 18650 cells. So, I got a case of 120. That will be more than enough for this project. I was thinking I would use 40 cells for this pack.

The cells are in packs of three. I'll have to disassemble them and figure out how I want to reassemble them once they are here.

[mpg_numbers_guy]

Pretty good deal! Guessing this is for a higher voltage booster pack, 4S30P to charge a standard 12V?