"Voltage Booster" for 31M AGM Battery

e60ral said:
[MENTION=153545]LOLSNOW[/MENTION] how hard would it be to make something that is adjustable? Or have 2 diodes and a switch for low/high?


Here is my issue, and it's something that anyone who has a 31m in very cold temps should be aware of:

The required voltage to properly charge your batter varies with temperature. For my battery is is 18mV per every 1.8 degree from 77 degrees, you subtract for temps above and add for temps below 77 degrees.

I just noticed that my resting voltage on my battery was getting kind of low, which surprised me because in the current temps we have my fridge really only runs if i'm driving long enough to heat up the cabin enough for it to kick on a little, and regardless my daily driving is usually plenty to recharge the battery even it was. i was really confused and worried that something was wrong until i remembered that temps effect the charging voltage and looked up the spec for my battery.

This morning it was 10-15 degrees here, which means that that charging voltage needs to be about .6V higher than normal. My battery normally requires 13.8V-14.6V for charging, so factoring for the low temps and I really need at least 14.4V. With the HKB booster I'm running about 14.3 (it varies between 13.9-14.4ish), that that means is that in these low temps I'm barely charging my battery!

If you have a 31m battery in low temps make sure you check your charging specs and keep an eye on your SOC, you may need supplemental charging if it's cold enough
Click to expand...


I've noticed in cold weather my SOC has been hovering at 12.6. In extreme cold the SOC will be a bit lower too.

Anywho I've been testing a Triple state voltage booster that uses a flip switch between these options:
  • Off - No boost. Alternator will deliver stock voltage
  • Boost - Boost of ~0.4V
  • Boost Plus - Boost of ~0.8V

I placed an order for these boosters and should have them available in 2 weeks. If anyone's interested you can shoot me a PM to reserve one.
 
TrkyMfns said:
About 1.5 years ago I did a lot of research into these vehicles charging systems and the similarities they share with other brands, suppliers etc and found that some GM's also utilize these alternators and have a higher charging voltage.

What I found was that those GM's, from the factory, include a diode fuse instead of the standard fuse we have on our alternator sense wire. It causes the alternator to see a voltage drop on the alternator sense wire, and so the alternator boosts the voltage to compensate.

I was the guinea pig on this one, and while it's obviously a small sample size, I have had 0 issues over 1.5 years and tens of thousands of miles in all types of weather, temperatures and distances. I have an Odyssey 34R-PC1500 and a 1000 watt aftermarket sound system with 0 issues.

Gm Diode Fuse - PN 12135037
Littelfuse 1 Amp Mini Diode - Oreily Link

Click to expand...

Since GMParts.com wanted me to pay shipping I ordered 5 of these things. They're up to about $5/ea there and at O'Reilly's, though none of my local O'Reilly's had them.
From what I can tell just revving up the truck and playing with accessories in the garage this does slightly increase the voltage. I have the DC Engineering 270A alternator already installed, but had always wondered why I never saw about 13.8v even at highway speed. I used a dremel to take away some of the plastic on the outside edges and dropped one of these in. Instead of the 13.1-13.4v I usually see the truck is now sitting ~13.8v at idle. Run it up to about 2000rpm and it's up to 14.0v and stays there. I head out cross country tomorrow for the holiday and will really be paying a little more attention to this on the trip. Hopefully my still OEM battery will be getting a better charge and last a little longer!

EDIT 24Nov2018: The entire 8 hour drive down to TN, and out another 4 hours running last night, I never saw the voltage drop below 13.8v. It only hit 13.8v when the engine was warm and had been running for an extended period of time, (maybe the battery was fully charged?). Most of the rest of the time it was holding 14.0-14.2v, even with all sorts of draw from the radio, dashcam, lights, lightbar, etcetera.
 
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Looks interesting, I think I will go for one.

LOLSNOW said:
I've noticed in cold weather my SOC has been hovering at 12.6. In extreme cold the SOC will be a bit lower too.

Anywho I've been testing a Triple state voltage booster that uses a flip switch between these options:
  • Off - No boost. Alternator will deliver stock voltage
  • Boost - Boost of ~0.4V
  • Boost Plus - Boost of ~0.8V

I placed an order for these boosters and should have them available in 2 weeks. If anyone's interested you can shoot me a PM to reserve one.
Click to expand...
 
O O O'Reiley had one diode in stock so I took the family out for a night drive, Maestro on the HU showed a consistant 13.2-3 V with a cool 49 degrees outside. The manager said alot of folks have been calling about that part, I guess I was lucky and got the last one. Got home did the grind, at idle I'm seeing 13.9V, pretty consistent to friggin idiot. I appreciate everyone's shared knowledge and experience on this thread.
 
I'll add myself to the test pool... still stock battery, but with a bit of luck will be adding a secondary AGM to the mix in the near future.

I ordered three of the GM diodes from Mouser Electronics (after shipping it came out to $5.xx/ea)
 
Got a new AGM last week, before voltage was usually 13.4/5-13.8/9 max.

Just got the GM diode and put it in.

14.3-14.5 now.

Thanks again for the useful info!
 
I made a Dallas day trip to pickup my TE front end. I saw a 13.9 cruising for 8 hours there and back. I only saw 14.4/5 V at initial morning start for the first time of the day. I may try the GM option, I would like to see above 14.2V cruising
 
Triple State Voltage Booster

qE2X4aRl.jpg

iOc49vxl.jpg

www.arclightleds.com

Finally got these in last week and they're ready to ship. The triple state voltage is truly special since it's the only booster that has 3 settings:
  • Off - Disables the voltage booster and ouputs voltage at OEM levels
  • Boost - Increases output voltage by ~0.5v from OEM levels
  • Over Boost - Increases output voltage an additional ~1 .0v from OEM levels (best for cold climates)

In most circumstances you'll likely switch between Boost and Overboost depending on how your AGM battery's resting voltage is at in relation to the weather. You may also find yourself disabling it as well if you ever go back to a standard battery temporarily. All in all it's good to have options :nod:
 
LOLSNOW said:
qE2X4aRl.jpg

iOc49vxl.jpg

www.arclightleds.com

Finally got these in last week and they're ready to ship. The triple state voltage is truly special since it's the only booster that has 3 settings:
  • Off - Disables the voltage booster and ouputs voltage at OEM levels
  • Boost - Increases output voltage by ~0.5v from OEM levels
  • Over Boost - Increases output voltage an additional ~1 .0v from OEM levels (best for cold climates)

In most circumstances you'll likely switch between Boost and Overboost depending on how your AGM battery's resting voltage is at in relation to the weather. You may also find yourself disabling it as well if you ever go back to a standard battery temporarily. All in all it's good to have options :nod:
Click to expand...

Ordered :thanks:
 
Alright installing amps soon, I ordered one. THANKS LOLSNOW. The kids love the red party mode cabin lights as well
 
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