Shop connected DC-to-DC charger connected to fuse box instead of positive battery terminal - is it safe?

[Thomas_L]

I had a DC-to-DC charger ("Ecoflow alternator charger") installed, and the shop connected the positive terminal to the fuse box instead of directly to the positive terminal (see attached picture). It works, but I'm wondering if this is equally safe, especially given the amount of trouble that poorly done electrical work causes? I'm wondering if the high wattage is a concern (800W), and that it locates the actual fuse of that cable (which you can see on the very right of the picture in green) further away from the connection to the battery.
Also, the insulation of the cable got damaged when they put the cover back on the fuse box (you can see the gap in the black part, and further to the left the damage on the red part), so the wire is exposed. I guess I should replace that part of the cable (and at that occasion connect it to the positive terminal directly)? I hope it's safe to use the vehicle with the charger off?

 

[DaveInDenver]

That looks like a factory power distribution box. It might help to know your vehicle in case someone else has the same one and can give you first hand information or, even better, diagrams from service manuals.

If it's what it appears then it should have a nice, heavy cable supplying it. Taking a tap there may be electrically fine since that bolt is probably the other end of the cable feeding the box.

I'd bet that's what you'd find if you unwrapped that harness a few inches under your new red cable. It's typical the OEM will route a cable from under the box in a situation like this. Now there could be a large main fuse for the whole box. I don't see indication of that so this is probably just a common back to the battery.

Regardless if there's a main fuse or this is just a heavy common you can't go crazy just taking taps like this. GM sized the feeding cable only for the circuits they know about so adding ones like this could overload. I doubt what you've got is immediately unsafe from what I can see and could be more convenient and more solid than trying to stack lugs on side terminals on the battery. I'd do it this way as long as I verified the cable from the battery to this lug can handle the extra load.

Which brings up a question. If that's a distribution box why didn't they just use one of the circuits? Are they all used for something? That's where it would be nice to know if that's a fuse box for the truck harness or if it's an aux fuse box intended for accessories, like for hooking up winches or plows.

That 800W Delta 3 will peak at 76A from their specs. So any of the circuits other than the 60A would work, if that's an option.

In any case, the way they routed that new cable is obviously not good since the insulation was cut and the exit path is bending the cable too sharply. That should be repaired.

If you can verify that box and how it's supplied (e.g. a very large cable) is sufficient then I'd ask them to crimp a new lug on after they use a Dremel to clearance the box or lid. It would also be nice if they could fasten the new fuse holder down to something, too.

 

[Verkstad]

That's where it would be nice to know if that's a fuse box for the truck harness or if it's an aux fuse box intended for accessories, like for hooking up winches or plows.

Essentially its a distribution bussbar connected directly to battery.
That left end stud is where accessories may be connected.
Its pretty robust connection, I expect GM prints a max load spec for it. Maybe it's found in the owners manual.
Btw,
GM sells an add on fuseholder that connects directly to the battery. Its part of the kit to install their aux relay box.

 

[DaveInDenver]

Everything you say @Verkstad is what I would assume as well.

Not knowing GM products I just wasn't sure if all those circuits already lead to sub fuse boxes or what is show *is* the optional aux power box. The easiest solution would be just use the 80A branch if nothing's already on it.

That feed-side fuse tap looks slick, that'd be another good solution to all the issues. Much cleaner coming out the box.

 

[Thomas_L]

Thanks for the replies! It's a 2023 Colorado (I'll add it to my signature).
That makes sense it's a busbar or power distribution block. Unfortunately the manual doesn't have an engine diagram (except one without labels...), and I couldn't find one online either. Searched the manual and it doesn't mention either term.

I did find a few hits on the Colorado forums, though it's for the previous gen. But sounds like people are using this/a similar bar for winches etc, so should be fine.

See e.g.:

https://www.coloradofans.com/threads/power-distribution-at-battery.268826/

Battery Distribution

Hey Everyone I have a 2022 Canyon and Im currently trying to figure out how to connect a switch panel to the truck however the terminal bolt has a lock thread, and can get the bolt off, I havent found anywhere where the 4 100 amp wire cables too thats where i tapped in power. the switch panel...

www.coloradofans.com

 

[DaveInDenver]

I found the 2023 Colorado upfitter guide.

https://www.gmupfitter.com/wp-content/uploads/2023/01/23Colorado_Electrical_Body_Builder.pdf

This is what that fuse box is doing. It's the main distribution for power in the truck.

 

[DaveInDenver]

The aux relay box @Verkstad mentions is this:

2024 Colorado | Accessory Power Distribution | Fuse Box | Relay Center | Under Hood

Upgrade your Colorado accessory power distribution with this Under Hood Accessory Power Distribution Box from Chevrolet. This Genuine Chevrolet Accessory Power Distribution Box provides an add-on module that mounts under the hood and allows you to conveniently control up to four external...

www.shopchevyparts.com

It looks like it includes a fuse tap and 60A fuse.

So electrically what you've got is fine, they sized the feed to that box with at least 60A of margin apparently.

I probably wouldn't use it for a winch unless GM says that's OK. Even though there's a 400A path for the starter and 225A/300A for the generator it doesn't mean it's OK for a winch. Might be fine. I'd just confirm before assuming. Using it for a winch could see the combination of the alternator and battery sources going out to the winch, which could be as much as around 500A and could be significantly longer duty cycle than they expect. The battery cable would normally see no more than 300A sustained (assumed max charging, which is itself unlikely) or 400A intermittent (duration of starting). So it might be necessary to bump the cable from the battery to the box in size when you use it for a winch. Your worst case is dead engine and a sustained draw just using the battery. Does GM offer a factory winch?

In your case you're just in need of a solution that is mechanically better.



Looks like GM is using the Littelfuse Z-Case for this. The holder might be custom for the application but you may be able to find something similar from Littelfuse.

https://www.littelfuse.com/products/fuses-overcurrent-protection/fuses/automotive-fuses/bolt-down-fuses/zcase

The only custom aspect would be how it turns down and fits under the lid. It might be something you can buy separate from the relay box, which is $600 from the dealer... This box is a factory option it seems so I bet a good dealer parts guy could find just the holder.

 

[Thomas_L]

Thanks for the additional details! Good to know to be careful about adding the winch. GM does offer a winch, so planning to get that one (once I have saved up for it...)

 

[DaveInDenver]

FWIW, found the GM document showing how to install the factory Comeup winch.

https://comeupusa.com/userfiles/files/download/D00INFZL030.pdf

Looks like they use a special MEGA type fuse harness that sits on top of the battery aside the hold down bracket to get power to the winch and connects directly to the battery terminal.

That by itself doesn't say *not* to use the distribution box. This choice may only be due to them wanting to add a fused circuit. It's just a data point.

But at the same time this may be a clean way to get power and I'd at least see if you can find a parts person to find out if it's possible to get this bracket without the winch.

It also looks like I was incorrect in thinking you had a side terminal battery. This document also mentions the aux power box, which I think may reference that thing I linked earlier.

 

[Thomas_L]

Good find, thanks! To clarify, what would be the downside of just connecting the cable to the positive terminal directly? I know it would get crowded/untidy if adding more things (like a winch down the line), but it looks to me like that single cable would fit easily onto the bolt on the positive terminal...

 

[DaveInDenver]

Going straight to the battery post is fine. As you point out space is the limitation. As you build up more accessories you usually end up with a tiered approach. A few heavy cables on the battery that feed distribution bars or fuse blocks. It's easier to plan for it up front instead of having to redo work later. It's a personal opinion but I try to avoid ever connecting small single circuits straight to a battery, that's how you end up with a mess. I shoot for just 3 cables on the positive: the factory, my added aux fuseblock(s) and the winch.

 

[Thomas_L]

Makes sense, thanks for clarifying!