Agm battery charging..

There is a ~.2V drop across the diode to keep it open. The ECU sees the drop and increases the output of the alternator by the same amount.

 

An alternator produces current flowing through the spinning field coil (the rotor) which creates high frequency AC power in the stator (stationary) coils. This is rectified to DC by a series of diodes, which are mounted behind the regulator and cover. Control schemes vary, but all alternators regulate output voltage by varying current in the field coil, which is fed via 2 brushes and the slip rings. The current is varied to maintain a specific output voltage. On 12V systems this varies from 13.3-14.7 volts depending on vehicle type and temperature. The regulator the alternator compares the voltage between B+ (alternator output) and ground to its reference voltage. The current in the field is adjusted accordingly.

By adding a diode to the B+ side of the regulator, we fool the regulator into thinking the main bus (B+) voltage is lower than reality. The regulator will then adjust the output voltage so that it is equal to its internal setpoint +Vfwd (usually about 0.5V) of the diode.

Hope that explains it.

 

thanks for the replies, I understood the voltage looked lower because of the diode but didn't understand why. I did not understand why a diode would change voltage until now . thanks again!!

 

I used the diode for a couple of years without any issues but switched to the voltage booster pro for a little peace of mind.

https://voltageboosterpro.com/

 

That still use diodes but has an inline fuse.

 

Somebody is salty but yes it still has a diode.

 

Encrusted, I sweat a lot.

 

Looks cool, I like that it can be adjusted to two different settings and has a fuse!

 

I just cheat and have a 200w solar panel on my canopy roof. I can set the voltage where I want it with the solar charge controller…. Keeps them Odysseys super happy.

 

Do you have a build thread somewhere?

 

I do…

https://www.tundras.com/threads/solar-time.127557/

 

Camp without the electronics.

 

Has anyone used an add a fuse like this? I tried and didn’t see any change on my volts… charging at 13.6 volts when running. I’m also checking at my battery terminals, that’s how you’re supposed to right?

 

Wrong hole

 

Thank you for pointing that out. Bumped me up a whole .2-.3DCV lol may just ride this out till I’m willing to upgrade my alternator. Or go maybe go solar for that trickle charge idk all I know is that I have a lot of accessories that need lots of juice

 

What your charging voltage? My ‘02 is older tech and with hkb (I did add a fuse diode while waiting for the HKB) I charge at 14.3-14.7 ish.

 

Pretty sure, assuming I was testing it correctly I’m charging at 13.9 now, where as prior it was 13.6
My USBC charger has a voltage reading of 13.9 as well

 

K, that sounds low to me. I’m guessing 2.0 gen has more smarts than first gen does? I like my two old trucks for how dumb they are, easy to fool.

 

What’s the correct orientation of the fuse and diode in that assembly?

 

Bottom slot, wrong way should show a dash light.

 

Difference between charging voltage on cold start and trickle voltage after that. My truck will push 14.2v on cold start and drop to 13.7 or so after a few min of run time. I run an agm, but just top it off with an agm charger about once a month or so. If you test it first thing in the morning on a cold start you'll likely see a slightly higher voltage.

 

I got up to 14.1 when I was driving earlier and then as it darkened outside and I ran my lights, fogs, and light bar on in addition to my sound system running. It only dropped to 13.8. So I definitely got a jump with the diode, I guess I’ll find out with time if it’s enough.