"Voltage Booster" for 31M AGM Battery

[natkidder]

I bought a Projecta DC/DC/Solar.

I made a diode booster and it failed. I'm sure that was just a fluke. It should not have failed. No one else is reporting failed diodes. I was just running it on the main batt. though, just to check voltages. I still wasn't seeing numbers that would be ideal.

My HKB voltage boosting fuse/diode just failed so i thought I'd share the experience here for the benefit of others. It was this thread that led me to purchase it in the first place and I haven't heard of anybody describing what happens when one of these goes bad so...

I purchased the fuse Dec 17, 2017 and it worked as advertised until recently (Running a single X2 group 31 AGM, '13 Trail Edition, 105,000 miles)

First symptom was the stereo started intermittently cutting out and the nav display would show the Toyota emblem for a split-second before the music and audio screen would resume. Next, I had the same music cutting-out symptom along with my hard-wired radar detector restarting. At that point I knew it wasn't just the head unit dying and I was thinking rodent damage.

Then, I drove for a good 5-6 days with no symptoms, hoping it wouldn't do it again but knowing deep down that it would probably resurface.

This past weekend all of the above happened along with the headlights cutting out—again only for a for a split second. I was out of town, driving back from dinner to the hotel and was happy to get there with working headlights.

Saturday I figured I'd try to make it home and dig into the issue in my own garage and all was good for the first hour of the drive. Then the entire dash—speedo, tach, CEL's all stating blinking in and out with the nav doing the same. At that point the vehicle was still driving normally.

5-10 min later all the above was happening but now with the motor stuttering and the truck lurching (doing 55-60mph at this point). I could see the voltage display on my Scangauge fluctuating wildly, like dropping as low as 7v and spiking up above 15v so I got off the road and parked as fast as I could. Although I suspected it might be the HKB earlier on, seeing the voltage fluctuations made me pretty sure the fuse was the issue.

I pulled the HKB fuse and replaced it with the original 7.5a stock fuse and drove the final 3 hours home with the truck behaving normally and voltage now in the low-mid 13's as it used to read before the voltage boosting fuse/diode.

I fully realize that modifying stock vehicle systems always comes with risk but sure hope I didn't cause long-term damage to the electrical system.

 

[tb-av]

The diode I made also failed during my test period. That's why I decided to buy a DC/DC charge controller which also got me a Solar input.

Keeps my main batt. running at it's Toyota defined voltage. My AGM at it's desired voltage and offers me Solar.

$2 vs $250 but that's life.

 

[rayofsi]

wow these failures suck.
Putting in a DC Engineering Alternator soon, hopefully works fine with stock alt-s fuse. and giving me the voltage i need for my AGM battery.

 

[jhguth]

The diode I made also failed during my test period. That's why I decided to buy a DC/DC charge controller which also got me a Solar input.

Keeps my main batt. running at it's Toyota defined voltage. My AGM at it's desired voltage and offers me Solar.

$2 vs $250 but that's life.

DC-DC not an option for a single battery setup, an upgraded alternator is what you need

 

[03_4x4Runner]

Here is a related thread. http://www.toyota-4runner.org/5th-gen-t4rs/263285-agm-battery-charge-controller.html

 

[LOLSNOW]

Sorry to hear but I expected the HKB to fail which is why I designed my own since I doubted they were using the appropriate diode(s) for this application.

The diodes I use are more suited for this type of application nevertheless nothing is perfect and a failed diode can confuse the charging system so I built in a switch on mine to bypass the diode completely.

I've discontinued these, however, if there's interest I'd be happy to make another batch.

 

[SlickTRD]

Sorry to hear but I expected the HKB to fail which is why I designed my own since I doubted they were using the appropriate diode(s) for this application.

The diodes I use are more suited for this type of application nevertheless nothing is perfect and a failed diode can confuse the charging system so I built in a switch on mine to bypass the diode completely.

I've discontinued these, however, if there's interest I'd be happy to make another batch.

I bought one from you and I've been running it for 6 months with zero issues. I really like the flip switch, too.

 

[TrkyMfns]

I should have mentioned this a long time ago, but it slipped my mind. There is another reliable and MUCH cheaper way than all of the posted options to boost your voltage, and it's also OEM.

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.

The best part of this is, you can get one of these OEM diode fuses out of pretty much any 90's-2000 GM, Chevy, Pontiac for less than $1 out of your local junkyard. I bought 3-4 of them for about 2 bucks lol.

My voltage on a cold start is ~14.7 and ~14.2 when warm. In the summer I've seen it drop to around ~13.8 or so. Please note that these will not make your alternator to generate more amperage, just voltage. So if you are already pulling too much current from your alternator, boosting the voltage won't help you. This is for those of us that have AGM batteries and want to give them the recommended voltage.


More Information on the actual part.

Gm Diode Fuse - PN 12135037

Littelfuse 1 Amp Mini Diode - Oreily Link

 

[itr1275]

Snake oil confirmed.

AGM is still fundamentally a lead acid battery, and will charge the same.

Boosting the voltage won't (shouldn't) make a difference and can damage the battery if it's too high.

It sounds like it's a bad alternator or voltage regulator. Have you checked tested the Voltage Regulator? The output should be between 13.5 and 14.5 volts for recharging.

 

[jhguth]

did you just not read anything in this thread before posting?

edit:
or on this subject? or the owners manual/specifications for an AGM battery?

 

[J.F. Sebastian]

Are the DC Power 270A alternators really the only high-output, stock mount alternators for 4Runners in North America? Really? W. T. F?

 

[Jeffy]

I should have mentioned this a long time ago, but it slipped my mind. There is another reliable and MUCH cheaper way than all of the posted options to boost your voltage, and it's also OEM.

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.

The best part of this is, you can get one of these OEM diode fuses out of pretty much any 90's-2000 GM, Chevy, Pontiac for less than $1 out of your local junkyard. I bought 3-4 of them for about 2 bucks lol.

My voltage on a cold start is ~14.7 and ~14.2 when warm. In the summer I've seen it drop to around ~13.8 or so. Please note that these will not make your alternator to generate more amperage, just voltage. So if you are already pulling too much current from your alternator, boosting the voltage won't help you. This is for those of us that have AGM batteries and want to give them the recommended voltage.


More Information on the actual part.

Gm Diode Fuse - PN 12135037

Littelfuse 1 Amp Mini Diode - Oreily Link

Very interested in this, but concerned with that 1 amp rating. Also, the link you posted to the O'Reilly site lists the diode/ fuse rated for 32 volts and I'd like to confirm that's the max voltage rating, and it's putting out the proper 14 ish volts under operation?

 

[themuffinman619]

Sorry to hear but I expected the HKB to fail which is why I designed my own since I doubted they were using the appropriate diode(s) for this application.

The diodes I use are more suited for this type of application nevertheless nothing is perfect and a failed diode can confuse the charging system so I built in a switch on mine to bypass the diode completely.

I've discontinued these, however, if there's interest I'd be happy to make another batch.

I’d be interested in one.

 

[TrkyMfns]

Very interested in this, but concerned with that 1 amp rating. Also, the link you posted to the O'Reilly site lists the diode/ fuse rated for 32 volts and I'd like to confirm that's the max voltage rating, and it's putting out the proper 14 ish volts under operation?

Here is the data sheet on the O'Reily Auto Parts version. I can't say with 100% certainty that the OEM GM part and the parts store version are exactly the same, as I'm sure suppliers customize specs to fit OEM specifications when necessary. I am using one of the ones I pulled from a GM vehicle. YMMV.


https://www.mouser.com/datasheet/2/240/eafusespecialproducts-532167.pdf

 

[jhguth]

Very interested in this, but concerned with that 1 amp rating. Also, the link you posted to the O'Reilly site lists the diode/ fuse rated for 32 volts and I'd like to confirm that's the max voltage rating, and it's putting out the proper 14 ish volts under operation?

32V is the normal ratings for fuses

 

[heisenbise]

Wish I had seen this GM diode before I ordered the HKB one. Substantially cheaper and easier/quicker to obtain.

My guess is that the current 7.5A fuse is oversized. Smaller low profile fuses seem to be less common to come by. I was looking for a ~2A one for an add-a-fuse and couldn't find anything smaller than 7.5A locally.

 

[Jeffy]

32V is the normal ratings for fuses

Ok that's what I thought, that just threw my tired mind for a loop and I wanted to verify it.

Wish I had seen this GM diode before I ordered the HKB one. Substantially cheaper and easier/quicker to obtain.

My guess is that the current 7.5A fuse is oversized. Smaller low profile fuses seem to be less common to come by. I was looking for a ~2A one for an add-a-fuse and couldn't find anything smaller than 7.5A locally.

I'm fairly confident that circuit is only providing a voltage readout to the ECU and no real current, so 1amp should be plenty. Seems like worst case scenario would be you just blow the fuse, so I'm not too worried about the 1amp rating. And since the fuses are pretty cheap, it's worth a shot. I ordered 4 from a GM parts supplier for 20 bucks shipped, I'll see what happens.

 

[raptore]

I was inquiring about this in my email recently to you.


Definitely interested in another batch being made. A few friends are interested also.

Richie

Sorry to hear but I expected the HKB to fail which is why I designed my own since I doubted they were using the appropriate diode(s) for this application.

The diodes I use are more suited for this type of application nevertheless nothing is perfect and a failed diode can confuse the charging system so I built in a switch on mine to bypass the diode completely.

I've discontinued these, however, if there's interest I'd be happy to make another batch.

 

[jrandom]

[MENTION=153545]LOLSNOW[/MENTION] I would probably try one of those custom switch jobs if it weren't too expensive (I'm absolutely curious if it had a tad more resistance than the others)

I have been running a HKB for a while now, 24+ months or so, no issues.

I was curious and bought one of the GM diode fuses mentioned here a few post back. Like $7 on the big A. I plugged it in today, it does have a nub that prevents is from fully seating and tested it out. Getting the exact same numbers as the HKB. Works well, great price. Nice to have a cheap extra for the glove box.

 

[Jeffy]

[MENTION=153545]LOLSNOW[/MENTION] I would probably try one of those custom switch jobs if it weren't too expensive (I'm absolutely curious if it had a tad more resistance than the others)

I have been running a HKB for a while now, 24+ months or so, no issues.

I was curious and bought one of the GM diode fuses mentioned here a few post back. Like $7 on the big A. I plugged it in today, it does have a nub that prevents is from fully seating and tested it out. Getting the exact same numbers as the HKB. Works well, great price. Nice to have a cheap extra for the glove box.

I threw the GM one in this morning and shaved that nub down a tad so that it seats properly. Engine turned right over and immediately started reading 14.5 volts whereas before I would be between 13.5-13.7.

Just drove it for about 20 minutes on the freeway. Started off with 14.5 volts, which dropped to 13.9 volts after about 5 minutes of cruising at 65mph/ 1800 rpms. It bounced between 13.8 and 13.9 the whole way until in the last minute or so I got off the freeway and it dropped to 13.6 at a stoplight. Once moving again it was 13.8 until I parked. Previously, I hardly ever saw it go above 13.6 no matter what, and now that seems to be my new low point. I'm very happy with that, especially for the 5 dollar price tag.