AGM BATTERY CHARGING - ALTERNATOR VOLTAGE BOOSTER

Thanks. I understand that part but just want to build a fused pigtail.

 

Sounds good. Will do. What did you do with the prongs on the fused/open end? Thanks.

 

Hopefully these answer your question

 

@DesertRatliff In my ‘06, that fuse slot I used is not used by the truck, so that was an easy decision. I cut each wire to 3” and soldered them together for a total length of about 6”. The wire lays in there nice and neat. When I originally proposed sealing the unused add a fuse slots, I guess I was just going overkill to make sure somebody didn’t screw up in the future and install the fuse or diode in the wrong slot of the add a fuse.

Even though add a fuses don’t affect the host circuit, I prefer to not add them to circuits that are important to the engine running. I don’t remember what that slot I used does in newer trucks, but I’m pretty sure it doesn’t effect the running of the truck. I would suggest using that one and put that slots original fuse in the lower add a fuse slot.

 

I tried using that slot on my truck, but there was a pretty high resistance to the 12V line so i passed it in lieu of the spot i used. FWIW i have a 2014, which is same as what @DesertRatliff has. Bottom line, it's a good idea to check to make sure you're tapping into the right spot

 

Thanks so much fellas! All questions answered.

 

That seems odd. In this 2006 schematic, you can see that fuse slot feeds from very close to the Alt-s fuse, and then goes on to feed other things. I can’t see how they could make that circuit so it has low voltage and still makes other things work.

 

Yeah i used your posts as inspiration for this. I wonder if something changed about that spot sometime between '06 and '14. To be clear, i wasn't measuring to the battery terminal, i was measuring to the positive on the ALT-S spot, i wanted to make sure where i placed the fused end was the same potential as the ALT-S hot side (if that makes sense)

 

I can't find a "charging voltage" spec for my battery. It is an agm battery, just a somewhat generic autocraft one I got from carquest. Is the increased charging voltage common to ALL AGM batteries or only certain ones? I've been using this one with no voltage mods for a while but if there is benefit then I'd like to do the voltage mod.

 

Someone smarter than me needs to respond. I’m only good and melting thing and increasing their fire potential.

 

http://www.carquestprofessionals.com/batteries/maintenance.html#chart_charging

IMPORTANT! Always use an automatic temperature-sensing, voltage-regulated charger! Set charger at 13.8 - 14.1 volts @ 68 f for GEL, or 14.4 - 14.6 volts @ 68 f for AGM. Do not exceed 14.1 volts for GEL or 14.6 volts for AGM

So your answer is 14.4-14.6 volts, maybe set to the +0.4 on the booster, since mine with them set to +0.6 volts sets the output to about 14.7-14.8 volts

 

so i finally found this thread and ordered the fuse from AUS. after running it for a week, and charging around 14.5-14.7, my AGM battery instantly drops to 12.2... Looks like its time for me to buy another AGM battery. wish i saw this sooner. lol

 

Thanks for the fast response. I was going to use the Ford diode method with a diode I grabbed while at the pick and pull junkyard (fuses and relays are the junkyard equivalent of grapes at the grocery store, free to grab one or two if nobody's looking). I'll try dropping it in the charge fuse location alone first and if the voltages work I'll use the add a fuse trick to put the fuse back in the circuit.

Thanks y'all this forum is the best!

 

My junkyard diode works as expected. It raised the running voltage to about 14.4-14.5 maximum during charge after start, then drops slightly to about 14.2-14.3 while highway driving depending on whether I have the headlights on.

I have the add a fuses on order so I can put the fuse back in circuit. I have to admit I don't fully understand how that trick works or how to do it yet, but I'll figure it out.

 

You're basically telling the charging system that the battery is .5v lower than it expects it to be, so it dumps out another .5v to it. Easy trick.

 

No, I get how the diode works. For some reason I can't wrap my head around how connecting two add a fuses together, adding the fuse and diode, and connecting the other end to a blank slot in the fuse box puts that fuse back in the circuit.

I get the voltage manipulation thing but for some reason I don't understand the add a fuse thing. I probably will once I start to do it and think it through.

 

We're only using the add a fuse terminals that are on the opposite side of the black plastic from the red wire. (blue brackets in pic) We're not using the add a fuses the way they're designed to be used. If you're using a fuse box slot for 12V that is already used, put that fuse in the lower slot of the add a fuse to maintain original functionality of that circuit.

+12V{fuse}---------------------{diode}------------Alternator.

 

@vwbuggsy, keep in mind the orientation and connections of those Add-A-Fuses.

The red side is bussed, the green connects the fuse back in and the blue is the new tap.



@Muddinfun is using the top slots of both Add-A-Fuses and the slot he's picked has +12V available on the top but is unused otherwise. It's pretty friggin' clever.

 

Ahhhhhh, okay now I completely get it and yeah that's brilliant! Very elegant solution. Thanks folks.

 

Did you ever figure this out. I think you can do something like this but you need to plug the 2nd fuse tap into the first (only reversed).