Location for electrical component on 24v BJ74? Need ideas!

[MyCruiserisaHogBeast]

Friends- I need some ideas. I’ve spent the last 3 hours pulling things apart and putting them back together trying to find a spot for this 24 to 12v step down converter. It’s the basis for my entire plans for an electrical subsystem. I’ve got all of the components ready to go, but I can’t find a place for this, I’m really frustrated. I figured it should be no problem finding a place for this under the hood, but the 13B-T factory 24v set up takes up every single bit of space. The only place it can fit is in front of the air intake, but it’s close to the headlight and on top of that I can even get a drill in there to pilot some holes to mount it.

Dimensions are 9.5x4.5x2.5”. It just doesn’t quite fit ANYWHERE. Ideally it would be located under the hood close to the batteries. Right now it’s looking like I’ll have to run some massive 0 or 2 ga cables behind the rear seat and back (I’ve got a kiddo and I don’t want her or her friends around it), which would require me relocating my amp to the other side, just complicating everything.... before I got investing in cables for this does anyone have any ideas? Thanks!

 

[jblueridge]

What Watts or amps is that?
I have a smaller one mounted above glovebox.

 

[MyCruiserisaHogBeast]

What Watts or amps is that?
I have a smaller one mounted above glovebox.

1200 watt, 100 amp. I know these things tend to not be super efficient so I’m hedging my bets. Won’t quite fit behind the glovebox looks like it’s going on the wheel well behind the interior panel unless someone can give me another idea. Just wasn’t planning on running it that far back need to get some big cables...

 

[roscoFJ73]

We have 24volt forum attached to the diesel forum

 

[MyCruiserisaHogBeast]

We have 24volt forum attached to the diesel forum

I know. I was looking more for tips on where to put it.

 

[Felde]

I did same to my BJ73 the other week.
Have a 240W (12V 20A) thing that is very much smaller than yours. Fits between battery and wall.
Mounting this in the engine bay only works if its water tight and heat resistant.
I question that 1200W /100A is a good idea. That is 50A atbthe 24V inlet still. Wth that amount of power you will need more space for thick cables, power distribution, switches and fuses anyway.
Without a separate 3rd battery it will drain your starter batteries quite fast.
If you however plan a 3rd battery, the question is where that might go.. No way to squeeze it anywhere under the hood. Will need to go inside. (I have same issue though).
What about having the power center in the lower compartment of the cubby box?

Regards Ralf

 

[MyCruiserisaHogBeast]

I did same to my BJ73 the other week.
Have a 240W (12V 20A) thing that is very much smaller than yours. Fits between battery and wall.
Mounting this in the engine bay only works if its water tight and heat resistant.
I question that 1200W /100A is a good idea. That is 50A atbthe 24V inlet still. Wth that amount of power you will need more space for thick cables, power distribution, switches and fuses anyway.
Without a separate 3rd battery it will drain your starter batteries quite fast.
If you however plan a 3rd battery, the question is where that might go.. No way to squeeze it anywhere under the hood. Will need to go inside. (I have same issue though).
What about having the power center in the lower compartment of the cubby box?

Regards Ralf

Hey Ralf,

I am stashing in on top of the back wheel well. Running a length of 2ga from the battery to the converter with a 900 watt fuse, it actually doesn't end up being that long. From there it runs to an amplifier and a 12v fuse box. The amp is a 750 watt unit with RMS significantly lower than peak of course, the whole idea with this thing is to give me headroom.

I spoke in length with a friend do mine who is an EV engineer, we went over the plan and he told me to just send it and see what happens. If it powers my gear without blowing up, awesome, if not it wasn't a huge investment, and then I'll just upgrade to a battery equalizer. Space and simplicity have been the problem. I thought about a 3rd battery on a 12v subsystem, but like all things inside this truck, nowhere to put it all. This is the most straightforward and cost effective way. I'll post it in my build thread when I get there.

 

[Felde]

Understand. I have the same issue and no good solution yet, too.
I would like a setup with starter and consumer battery split. But a dual battery setup with 24V/12V and charger connection is difficult / expensive. And no place to put the extra battery.
I just didn't dare to put heavy consumers on the starter batteries. At least not without assuring the engine runs when consuming.

 

[MyCruiserisaHogBeast]

Understand. I have the same issue and no good solution yet, too.
I would like a setup with starter and consumer battery split. But a dual battery setup with 24V/12V and charger connection is difficult / expensive. And no place to put the extra battery.
I just didn't dare to put heavy consumers on the starter batteries. At least not without assuring the engine runs when consuming.

I don't think you'll have any issues, just make sure stuff like amplifiers and high draw stuff powers on and off with the key. Shouldn't draw much if there isn't gear on the output side pulling power, I'm going to wire in a breaker to the converter so I can disconnect it when I know the truck will sit for a while.

Basically a 12v option with a 3rd battery is next to impossible. On by BJ74 there is barely enough room for the factory vehicle under the hood, let alone another amplifier and additional battery. The converter seems to be a good way to go, it's cheap and has enough headroom to push pretty much anything I want through it. If it fails, a battery equalizer the the classy way to go. It basically ensures that your batteries charge equally, allowing you to pull power from one battery (to create 12v) while not ruining your batteries. My only question is amperage, they only seem to go up to about 40 amps, I'd need to make sure whatever I'm powering doesn't overcome that threshold.

This has been an interesting project. I like this stuff, I'll like it a lot more if it actually works as intended. We'll see...

 

[Felde]

Agree. Good concept.
I strongly disencourage using the equilizer to compensate for 12V power taken from one battery. The 24-12-stepdown converter is the right solution to this.
The Equilizer is designed for compensating differences in charging amperage caused by different resistances in wirering and internal battery resistance.
When pulling 12V from one battery, the drawn amperage passes not only the equilizer but also the one battery, causing inbalance and unnecessary wear.
I just had to replace my batteries due to the PO took 12V from one, which killed it.
That's why I also installed 24-12-stepdown and equilizer two weeks ago.