Renogy 50amp DCDC w/ MPPT - Chassis Ground?

[LandLocked93]

Yes, and tailshaft and bearings to axle etc. The point is that ground is via engine and body. Frame/chassis may have indirect grounding, but is not used as a ground path.

So agreed. Engine, body, and frame are the same contiguous ground; regardless of OE intention.
As I thought, we're on the same page.

I've got a pretty good grasp of ground loops - my EE work ensures I understand that along with circuit design and board layouts.

Respectfully, and I bet you would agree, the average EE has never touched a DVM, DOM, or (these days) a vehicle aged 1995 or older.

Fusing is what it is. Agree that it's right or it's not, implementer irrelevant.

Happy to share my wiring schema if you have any questions.

 

[george_tlc]

Sorry, but no. The frame is not a ground path. It may connect to the ground system via bearings, springs etc, but it is NOT intended to carry current. Again, there is no point where Toyota uses the frame to carry current. Current is carried from the battery to the block for high current and to the body for low current. You could remove the vehicle body/engine etc from the frame and the electrical system would run just fine.

I'm not your idea of an average EE

I have an 1980 diesel (from new) in Australia that I rewired from 24V to 12V (replacing all 24V 'stuff' with 12V. I've got a bit of a clue... The oz patrol (nissan) also has no OEM ground connection to the frame for grounding reasons. It too is only indirectly grounded via springs and tail shaft, bearings etc.

It's becoming nit picking, but my point is that you wrote about connecting and using the frame as a ground and I am simply stating that is incorrect and putting facts straight in this thread.

cheers,
george.

 

[LandLocked93]

Bruh...
A parallel path to ground equals ground.
A series path to ground equals ground.
A series-parallel path to ground equals ground.

Don't need an EE degree to understand comprehend continuity.
And that's all we're talking about in your scenario.

As far as YOU stating that I SAID (not true) "the chassis is the only path to ground", I simply paraphrased/recommended that, "a short(to ground), body to frame" in the cargo area for a device in the cargo area that needed a ground "was sufficient". (a redundant ground iow)
It is sufficient btw.

You admitted that THAT is happening in a TOYOTA 80 SERIES from factory anyway, so...not sure why the push back on your part.

 

[ntsqd]

When you put high current into something not designed as a conductor the whole circuit suffers for it. I suspect that this has to do with the current crossing welds within that frame structure, but that's an experiential guess at best. I've been around hot-rods & race cars with trunk mounted batteries for many decades. Every single last one of them that grounded to the chassis at the rear suffered hard hot starts. As soon as we delete that short ground cable and run a run cable of appropriate size up to the block those hard hot starts stop occurring.

Can ground low current circuits to the rear of the chassis and they work fine to just OK depending on just how much current is involved. If the load is voltage sensitive then a chassis ground at the rear will cause problems because it won't be truly at zero potential.
For instance, charging a rear mounted battery with a chassis ground will cause just enough voltage drop to not bring that battery to 100% SoC. You can get to 90%, maybe 95% and maybe that's good enough, but you'll never get to 100% SoC because there is too much voltage drop in the charging circuit. BT, DT, and didn't understand it for a long time. Can think of this as being a rough parallel to using a diode isolator. eeeuuuwwwww!

 

[LandLocked93]

When you put high current into something not designed as a conductor the whole circuit suffers for it.

I can see what you're saying IF one were using the unintended ground path (chassis) as the only ground for that circuit.

But my case, the same case recommended to OP, ground travels thru both body and frame.
If the body is - from factory - the only intended and least resistive ground path back to battery negative then that's how current will flow regardless.
I simply added the chassis ground for good measure.

I've been around hot-rods & race cars with trunk mounted batteries for many decades. Every single last one of them that grounded to the chassis at the rear suffered hard hot starts. As soon as we delete that short ground cable and run a run cable of appropriate size up to the block those hard hot starts stop occurring.

I don't doubt your experience.
But I'm speaking to an overland-built offroad rig owner who uses their current storage far differently.

For instance, charging a rear mounted battery with a chassis ground will cause just enough voltage drop to not bring that battery to 100% SoC.

A BCDC removes the issue to which you refer.
A diode isolator is a passive device with no "electronic awareness" to say the least. Much less any sort of voltage drop compensation.
It is not a peer to a charge-profile BCDC.

 

[ntsqd]

If self jump-starting is on the menu then the current usage isn't any different.

You talk about not having ground loops and then you suggest using both the body and the frame as parallel ground paths. That's a ground loop in my experience. It may or may not behave as one, but parallel paths to ground are never a good idea. Grounds should be branched, like a tree, and never in parallel.

You're pretty good at selective snipping to destroy the original intent of the sentence.

I think we're done here.

 

[george_tlc]

^ Agreed, misinformation in a thread that people will refer to is not a good thing.

Landlocked93 clearly doesn't understand the distinction between a poor ground path and an ENGINEERED one by Toyota etc. He doesent understand how the body mounts to the frame and at what places there's a possibility of an electrical path from the frame to the body.

Ok...
...at the very least consider brake lines with metal terminations - OEM or stainless braid- which connect the body to the frame in a metallic fashion. (OEM may be rubber on the outside but there is metal belting inside the rubber)
Beyond that, consider the springs which simultaneously contact the body and the axles.

Or perhaps the driveline itself...from engine to axle...yes there are rubber bushings on all the moving parts but the metal collars inside the bushings through which the bolts are positioned enable a ground between the engine and the frame via the frame/axle ears, again through which the bolts connect.

Ground loops impact more than just audio. One just can't hear it, is all.

So, there's some gems here. I haven't cut a toyota oem brake hose, but rubber brake hoses are made of layers of rubber and various fibers, I've not seen metal belting. He also seems to think that the brake lines electrically couple the frame to the body - if that was actually the case, then I'd hate to rely on that path to carry 10's of amps! The brake lines make physical contact between the brake pipes (the hardlines) and the ABS/Brake cylinder assembly and some of that touches the body on the firewall. There's no body/frame connection to brake lines at the axle ends.

Regardless, the next gems are due to not understanding the chassis/body mounting system.

The 80 springs (coils) do NOT make simultaneous contact to the body - the spring mounts at the bottom are on the axles, the spring mounts on the top are to the frame , NOT the body.

"... the moving parts have rubber but metal collars inside that bolts are positioned enable a ground..." Huh??? There is NO electrical contact from the metal bushing in the rubber control arm bushings to the links. The bolts touch the metal inner sleeves and the chassis end and axle end. There is no electrical path through the rubber. Body mounts are designed the same. Engine/transmission/transfer box mounts are all metal bonded to rubber bonded to metal, same with exhaust mounts. There is no electrical path through them.

The whole point (clearly missed) is that the body (and engine/transmission etc) are mounted on rubber with no electrical path through those mounts.

I'm pretty sure that the only electrical path from the chassis to the engine block AND body is via the tailshaft bearings and any damaged bushings. Maybe the handbrake cable too. The axles may make electrical contact (very poor contact given they are also coated when new) to the frame via the coils. Shocks (OEM) have rubber bushings and are electrically isolated. On the rear the top coils have rubber 'pads' to provide some NVH isolation, so the path is even worse.


There is a good reason to not do as landlocked93 has recommended.

1) if the body is a great ground path (and it is) and you now have grounded your device to a bolt. Is that a through a hole that has been drilled or a Toyota captive (welded) nut to the body? If a Toyota captive nut as described, then you have an excellent ground path and your job is done.

2) Now if it was a drilled hole with a bolt and you put a ground strap/cable connection from the other end of the bolt (that you drilled a hole) to the frame. Consider now having a poor contact through the drilled body, you now have a ground path that mostly only goes to the frame. As per above, the frame to body ground path (and we're really talking frame to block) is very poor and mostly through the bearings in the tailshafts. Not a good idea eh?

Anyhow, hopefully there's enough rebutal to his recommendation that folk reading this thread will have a better understanding why the frame is not an appropriate ground path. What he has done on his vehicle works because the body is providing the ground path. Adding a connection to the frame provides no benefits when the body path is perfect and provides intermittent (or worse) problems when it isn't.


He also stated grounds are all the same, series, parallel etc. Wrong in so many ways, that it's not worth discussing.

Finally, Toyota does NOT use the frame as an electrical ground path. Their EE folk didn't miss the frame being made of steel, they understood perfectly well to use the body as the ground path for all non-engine ground connections because the frame is mostly electrically isolated from the body/block/etc.

cheers,
george.

 

[e9999]

Folks, let's make sure this all remains civil.

Added: cleaned up. Leave the personal stuff out please.

 

[spressomon]

Different ways to slice a pie...but for my applications and peace of mind, running a wire back to battery negative terminal neutralizes (pun intended ) all the potential confusion, consternation & discord about all things grounding.

Hopefully, I didn't open up another 'can o'worms'

 

[LandLocked93]

Folks, let's make sure this all remains civil.

Added: cleaned up. Leave the personal stuff out please.

 

[LandLocked93]

Hopefully, I didn't open up another 'can o'worms'

Just when...

 

[LandLocked93]

^ Agreed, misinformation in a thread that people will refer to is not a good thing.

Landlocked93 clearly doesn't understand the distinction between a poor ground path and an ENGINEERED one by Toyota etc. He doesent understand how the body mounts to the frame and at what places there's a possibility of an electrical path from the frame to the body.



So, there's some gems here. I haven't cut a toyota oem brake hose, but rubber brake hoses are made of layers of rubber and various fibers, I've not seen metal belting. He also seems to think that the brake lines electrically couple the frame to the body - if that was actually the case, then I'd hate to rely on that path to carry 10's of amps! The brake lines make physical contact between the brake pipes (the hardlines) and the ABS/Brake cylinder assembly and some of that touches the body on the firewall. There's no body/frame connection to brake lines at the axle ends.

Regardless, the next gems are due to not understanding the chassis/body mounting system.

The 80 springs (coils) do NOT make simultaneous contact to the body - the spring mounts at the bottom are on the axles, the spring mounts on the top are to the frame , NOT the body.

"... the moving parts have rubber but metal collars inside that bolts are positioned enable a ground..." Huh??? There is NO electrical contact from the metal bushing in the rubber control arm bushings to the links. The bolts touch the metal inner sleeves and the chassis end and axle end. There is no electrical path through the rubber. Body mounts are designed the same. Engine/transmission/transfer box mounts are all metal bonded to rubber bonded to metal, same with exhaust mounts. There is no electrical path through them.

The whole point (clearly missed) is that the body (and engine/transmission etc) are mounted on rubber with no electrical path through those mounts.

I'm pretty sure that the only electrical path from the chassis to the engine block AND body is via the tailshaft bearings and any damaged bushings. Maybe the handbrake cable too. The axles may make electrical contact (very poor contact given they are also coated when new) to the frame via the coils. Shocks (OEM) have rubber bushings and are electrically isolated. On the rear the top coils have rubber 'pads' to provide some NVH isolation, so the path is even worse.


There is a good reason to not do as landlocked93 has recommended.

1) if the body is a great ground path (and it is) and you now have grounded your device to a bolt. Is that a through a hole that has been drilled or a Toyota captive (welded) nut to the body? If a Toyota captive nut as described, then you have an excellent ground path and your job is done.

2) Now if it was a drilled hole with a bolt and you put a ground strap/cable connection from the other end of the bolt (that you drilled a hole) to the frame. Consider now having a poor contact through the drilled body, you now have a ground path that mostly only goes to the frame. As per above, the frame to body ground path (and we're really talking frame to block) is very poor and mostly through the bearings in the tailshafts. Not a good idea eh?

Anyhow, hopefully there's enough rebutal to his recommendation that folk reading this thread will have a better understanding why the frame is not an appropriate ground path. What he has done on his vehicle works because the body is providing the ground path. Adding a connection to the frame provides no benefits when the body path is perfect and provides intermittent (or worse) problems when it isn't.


He also stated grounds are all the same, series, parallel etc. Wrong in so many ways, that it's not worth discussing.

Finally, Toyota does NOT use the frame as an electrical ground path. Their EE folk didn't miss the frame being made of steel, they understood perfectly well to use the body as the ground path for all non-engine ground connections because the frame is mostly electrically isolated from the body/block/etc.

cheers,
george.

At no point do I focus on/encourage OP to "use a non-"engineered" ground path as THE ONLY ground path.
I simply answered OPs question. And should OP take my advice OP will experience no issues or risk damage to any property.

Furthermore, circuit potential current is the same from the source (battery) to first load and from last load on that same circuit to ground (back to battery, by path of least resistance, whether it be by frame/chassis, body, or otherwise).

I mentioned brake lines in case OP has SS lines. As I do.
No I dd not say specifically that rubber lines complete a circuit.
But, and, yes SS lines absolutely connect the frame/chassis to the body. And overall If it made a difference otherwise we'd know about it by now.
If OP does not have SS lines then there is no diff to ground relative to what I recommended to OP; both as generally accepted and harped upon in your response.

The springs as you say contact the frame. The frame is connected to the body in my scenario. So what?
Again, current will take the path of least resistance.

To your other "points", there are several paths of current flow between the engine block, intake, etc and body from OEM. They're called ground straps. And they enable a path to ground between the two. They quite literally connect the engine to the body.
Hell battery negative is connected to the body via a direct connection don'tchyaknow.

As far as the holes you mentioned, they are OEM bolts and welded nuts that I proposed to OP to use.
It is accepted, and common practice.

Yes, as you say there is now a path to ground between chassis, body, and frame. Yet you disagree with just one of them.
Ok. We can presume you have no experience with it.
Works fine for me. As it will for others.
Which is the only reason I shared it to begin with.

And what you don't even feel like discussing...lol fine. Never heard of branched or tierd grounding before battery negative.
Sounds pretty fringe and thoroughly mental. Curious how that works.

 

[RUSH55]

Interesting argument.
I’ve always been under the impression that the chassis becomes part of the total ground circuit via grounding cable(s) between the starter and frame, as well as ground straps between the body and frame. This doesn’t necessarily mean strictly Toyota, but industry wide as well as commercial trucking and industrial equipment. Very few things I’ve worked on (changing a starter for instance) that did NOT have a ground cable tying the starter (engine block) to the frame.

 

[george_tlc]

^ you have to look closely at say an 80 series (others are similar) and you will find there are NO ground straps to the chassis. It is not part of the ground circuit in any way.

The 80 (as the example) has a big ground connection from battery to block and that IS the path that the starter current and alternator current use for ground. There are straps from the block/engine to the BODY and also from Battery Ground to BODY. There are no ground straps to the chassis.

Do not use the chassis expecting it to be anything but a poor and intermittent ground.

The 80 is identical to my Patrol in Australia regarding this. I'd venture to say that with all our land cruisers and patrols that you will find no OEM grounding via or to the chassis.

cheers,
george.

 

[ntsqd]

Grounding the frame to the rest of the vehicle is different than using it as a ground path.

One example of using the frame as a ground path being a bad idea is that the only trailer lights grounding method that has proven to be consistently reliable over years has been to run a dedicated ground wire system. The trailer frame is grounded, but it is not the conductor, the ground wire system connects to the frame in one place only. Older wiring of trailers tends to use it's frame as the ground path. Sooner or later those will have trouble with their lights and it is almost always the grounding thru the trailer frame that is at fault.

When the circuit is a starter, alternator, winch, or a dual parallel battery system the fewer connections and conductors in the circuit the better. Heavy equipment and boats have ground cables directly to their alternator(s) as best practice.

 

[RUSH55]

^ you have to look closely at say an 80 series (others are similar) and you will find there are NO ground straps to the chassis. It is not part of the ground circuit in any way.

The 80 (as the example) has a big ground connection from battery to block and that IS the path that the starter current and alternator current use for ground. There are straps from the block/engine to the BODY and also from Battery Ground to BODY. There are no ground straps to the chassis.

Do not use the chassis expecting it to be anything but a poor and intermittent ground.

The 80 is identical to my Patrol in Australia regarding this. I'd venture to say that with all our land cruisers and patrols that you will find no OEM grounding via or to the chassis.

cheers,
george.

Grounding the frame to the rest of the vehicle is different than using it as a ground path.

One example of using the frame as a ground path being a bad idea is that the only trailer lights grounding method that has proven to be consistently reliable over years has been to run a dedicated ground wire system. The trailer frame is grounded, but it is not the conductor, the ground wire system connects to the frame in one place only. Older wiring of trailers tends to use it's frame as the ground path. Sooner or later those will have trouble with their lights and it is almost always the grounding thru the trailer frame that is at fault.

When the circuit is a starter, alternator, winch, or a dual parallel battery system the fewer connections and conductors in the circuit the better. Heavy equipment and boats have ground cables directly to their alternator(s) as best practice.

So basically unless the chassis is deliberately connected to the body and engine block, it is not a reliable ground, is what you are saying? If the manufacturer did not intend to use the chassis as any part of the ground, that makes sense.

 

[ntsqd]

Even if it is connected you have to look at the nuances of how it is connected and WHERE it is connected. Easy to think of the frame as one whole piece. Structurally that is true (better be!). Electrically it probably isn't. Steel isn't the greatest conductor, it just happens to work. Most of the time.

 

[RUSH55]

By that token, I would only have to conclude that the body would be even worse considering all the sheetmetal joints, with many of them consisting of a panel adhesive or spot welds and seam sealer.
Must be the reason American Autowire markets this “ground kit” that eliminates grounding to either.(?)

All Copper Grounding Kit

All Copper Grounding Kit

americanautowire.com

 

[ntsqd]

The body could be that indeed, but there are some things working to it's advantage. Nearly all of the grounding connections to the body are made out of the weather (unlike on my trailer example). The other thing that seems to keep getting lost is that when the circuit is only a couple of amps and voltage drop isn't a concern, that then using the body isn't the issue that it would be if the circuit were passing starting, battery charging, or winching current thru the body. Cumulatively there may some significant current going thru the body, but the points of origin are all different. It is only in the region right around the body to battery grounding connection where things might not be so ideal.

 

[LandLocked93]

Do not use the chassis expecting it to be anything but a poor and intermittent ground.

Agree IF said chassis ground (conductor of electrons) is NOT connected to a (body/chassis) conductor of electrons back to ground.

Or vice-verse if you follow electron theory.
Doesn't matter either way tho.

Even if it is connected you have to look at the nuances of how it is connected and WHERE it is connected. Easy to think of the frame as one whole piece. Structurally that is true (better be!). Electrically it probably isn't. Steel isn't the greatest conductor, it just happens to work. Most of the time.

The whole truck is nothing but steel, apart from the plastics and textiles/cowhide inside the cab by and large.
WHERE the ground is connected to the frame makes all of 2/10ths ohm diff front to rear, at most.
And if that diff actually makes a diff relative to current flow (which it doesn't), current will make the decision which path to follow.
Even at 50/50, all the current flows back to batt neg (or alternator neg if engine is running), wherein batt output is not affected regsdless.