Alternator Voltage Booster

[Pucker5]

So, I ordered one of these voltage boosters. The whole reason I fell into this rabbit hole was because my second agm battery in my electrical that powers my stereo was reading 12.5 volts at the terminals while at idle. My alternator is 250 ho so I’m pretty dialed in from and equipment garage point. I’m using 2/0 welding wire from battery to battery and I’m grounded on the frame so I’m not accepting that a 10ft distance between batteries is where Im losing voltage.

Now, for a fridge or winch I would have been fine with 12.5 as the end result is pulling yourself out of a pinch and keeping the baby’s milk cold. However for audio amps the difference in produced watts output between 12.5 and 14v+ matters.

I’m hoping this opens the gate a bit to allow my rear battery to keep at higher voltage. My next recourse is alternator bypass of ecu.

 

[Tapage]

@Pucker5 which booster you order .?

 

[Pucker5]

@Pucker5 which booster you order .?

Mk3

 

[Tapage]

Mk3

give you half V up I guess ..

 

[AimCOtaco]

Not sure if this offer it's still valid or will be extended to others MUD members but if not can you share where you got the fuse older you use .?

I don't think at this time that I'm going to make these for people I don't know real well due to the low reward ($) and high risk (fire) associated with this kind of a mod. I probably should have thought it through better before offering one to Craig but his would have come with a friendly "likely to burn and destroy everything you hold dear" disclaimer.

What I will do if I can hold myself down long enough is to try and better document a diy build up so everybody can confidently build their own. If I get that far I'll post it up for sure.

 

[SanDiegoCruiser]

I’ve had the one in the link above installed for over a year now. No issues. I really don’t drive my rig enough to notice any long term benefits, other than the fact that it appears my batteries are always getting at least 14v to them, even when at idle.

 

[CO_Hunter]

This is lacking some technical detail but appears to be the same thing (1 amp diode) minus fuse protection described in post 9. And by @AimCOtaco .

https://m.littelfuse.com/~/media/automotive/datasheets/fuses/passenger-car-and-commercial-vehicle/specialty-items/littelfuse_diodes_resistors_datasheet.pdf

Can be purchased at almost any auto supply store.

 

[Pucker5]

Which one in that link

 

[CO_Hunter]

02400113P, second from top. I would think any of the one amp diodes would be similar if they have same materials.

 

[CO_Hunter]

I ordered one from Oreily for a little over $4 total. I’ll bench test in few days.

 

[87warrior]

I made and installed the booster @AimCOtaco outlined on page 2. I have dual AGM batteries charging off the alternator and wanted to supply them with the voltage they need to stay healthy. Prior to this I had been 'topping them off' monthly with an AGM charger/maintainer.

I coated the diode leads with liquid electrical tape after they were soldered to to add-a-fuse kit.

It is a snug fit in the main fuse housing, but it fits.

The Cruiser is now charging at 0.5 volt more than I was before: 13.5-14.1 vs 14.0-14.6.

 

[gungriffin]

I made and installed the booster @AimCOtaco outlined on page 2. I have dual AGM batteries charging off the alternator and wanted to supply them with the voltage they need to stay healthy. Prior to this I had been 'topping them off' monthly with an AGM charger/maintainer.

I coated the diode leads with liquid electrical tape after they were soldered to to add-a-fuse kit.
View attachment 2191332

It is a snug fit in the main fuse housing, but it fits.
View attachment 2191333

The Cruiser is now charging at 0.5 volt more than I was before: 13.5-14.1 vs 14.0-14.6.

So the purpose of the resistor it to send a signal back to the alternator and trick it into upping the charge voltage by about .5 volts?

 

[87warrior]

@gungriffin that is exactly what happens

 

[bryson]

So the purpose of the resistor it to send a signal back to the alternator and trick it into upping the charge voltage by about .5 volts?

@gungriffin that is exactly what happens

Just realize that it is a diode, and not a resistor. A resistor will not have the same effect on charging that a diode does.

 

[nckwltn]

I ordered one from Oreily for a little over $4 total. I’ll bench test in few days.

@CO_Hunter what were the results of your tests?

Aren't diode's directional, is there an obvious way to know which direction it should go in? If not, I guess you would measure to see which side 12 volts were coming in on, and orientate appropriately?

 

[abuck99]

I have one of the HBKElectonic voltage booster fuses and it is directional- so assume the diode your working on is directional. If you plug in the fuse and the battery light doesn't turn off, turn the fuse around.

 

[nckwltn]

I found this fairly lengthy discussions over at tacoworld

AGM BATTERY CHARGING - ALTERNATOR VOLTAGE BOOSTER
and

The NorthStar AGM Battery + Voltage Booster Upgrade

The NorthStar AGM Battery + Voltage Booster Upgrade This thread covers upgrading to the best AGM battery available and modifying the voltage regulator...

www.tacomaworld.com

They dive into ECU voltage vs battery charging voltage, and if the ECU is seeing a lower voltage than the charging battery, and if that's the case the injectors are open a little longer due to the difference between the ECU and the charging voltage.

Someone also tested the Diode that GM/Ford have for this, and the diode basically melted before tripping (ie, no fuse protection)

Looks like a fuse + diode is the best way to go. which is what that $50 solution is (or the cheaper DIY solution)

 

[CO_Hunter]

@CO_Hunter what were the results of your tests?

Aren't diode's directional, is there an obvious way to know which direction it should go in? If not, I guess you would measure to see which side 12 volts were coming in on, and orientate appropriately?

The diode I mentioned above did work even though I went a little too deep trimming the edge so it would fit in the fuse slot. At start up it gave me about 14.9 v. I thought that was a bit too high and I liked the idea of still having a fuse so I built one off of an add a fuse as described above. Now the max I see is 14.8 and it settles in the mid 14s. It is the diode material properties that gives slightly different voltage drops. I don’t recall the actual charging voltage change from stock but I can say testing on an unloaded battery produced less voltage drop than what the charging system puts out as an increase. It is not 1-1, but doesn’t really matter much.

Yes you need to get the polarity right. With the fuse shaped diode it is not a big deal to rotate it. If your battery light comes on you know it is in backwards. If you build your own double check before soldering as you may not have room to rotate the larger assembly.

Yes, there are several good threads out there on this topic. People have been doing it for a long time.

 

[nckwltn]

@CO_Hunter, thanks for the feedback.

I bought the cheap diode option at advance auto, trimmed the tab and dropped it in (it's a little wider than the stock fuse, so it pushes some of the plastic around.

I was seeing 14.7 at start up, and 14.1 after warming up.

I'll still probably try to make something come together that uses a fuse and the diode, but right now I'm running diode only.


to figure out the polarity, I took a multi meter and checked to see which side of the female fuse socket was making 12 volts to ground and then put in the diode in the correct orientation

https://www.oreillyauto.com/detail/b/littelfuse-4149/lighting---electrical-16777/fuses-16615/fuse-blocks--universal--18449/b381070c3b6b/littelfuse-1-amp-mini-diode/02400113xp/4414229

 

[bryson]

You can always just use 2 diodes, one in each direction and then polarity won't matter (run the diodes parallel to each other, not in series), but you'll still get the voltage boost function. I'm sure that's how the actual booster fuses are run, because I know they are not polarity sensitive (unless you blow it in one direction, then you flip it around...)