Corrosion of Alde Convectors

Dutch061

@jimcenname

Jim, that is not the correct way to do a voltage drop test. Connect the negative lead of your meter to the battery negative, then use the positive lead on the outside of the Alde case. Make sure the Alde is powered on and operating. It is under these conditions that I observed close to .040 volts before adding the auxiliary ground.  After adding the auxiliary ground, my voltage drop was less than .002 like the rest of the camper. 

There are various "suggestions" as to what the maximum drop should be.

Anywhere from .3 volts to 5% of the supplied voltage, or in the case of 14 volts it would be .7 volts.

In my humble opinion, the lower the better. Especially in regard to this Alde corrosion situation. The better it can be grounded to the same "ground level" as the rest of the camper, the happier it will be in the long run.

Brad

P.S. I thought the Airstream bulletin was posted earlier in this thread which has now grown to 17 pages 

[Deleted User]

Can one of you brilliant minds speak with NuCamp regarding your findings.  Hopefully they will put out a service bulletin to let us know what we need to do. 

BrianZ

@Dutch061,
Thanks, Brad, for your interesting findings & comments.  For those of us with a T@B 320, like ours below, with the WFCO & nearby negative bus bar (arrow), can I assume you would advise connecting the auxiliary ground wire from the Alde cabinet to the silver bus bar?

The Alde is only about a foot away, behind the panel to the left, so even a smaller gauge wire than suggested should be fine I believe.
I'm wondering if the new ground would have any adverse effect on the sacrificial anode rod that I have installed in our glycol expansion tank, which is also wired to the Alde cabinet (for continuity with & protection of internal dissimilar metals that are also in contact with each other and the glycol); though I think it should be ok.  I still haven't run that extra main ground wire (or a pos) back to the battery.

Dutch061

I sent an email to NuCamp last week, I think Thursday afternoon. It may open some additional correspondence between us this week to come. I think they too are overwhelmed with everything that is going on.

@BrianZ

I would suggest doing a voltage drop test between the Bus Bar Ground, the Frame, and the 120 VAC Ground. Since your battery is outside upfront, I would really consider increasing the gauge of the ground wire to either a 6-gauge or adding a second 8-gauge wire.

I would also suggest doing a voltage drop test between the Bus Bar Ground and Negative Battery Terminal. It would be a great reference to have a before and after. Turn as many 12-volt things on as you can to load the ground.

Brad

bergger

Ok so dumb question but how do you know which wire coming from the convertor to the distribution bar is the ground wire?  Is there only one connecting the two or if there are multiple wires how do you know which is the ground?

Dutch061

@bergger

There are 5 wires total on the WFCO Converter, 3 on one end and 2 on the other. In the picture below, you clearly see the 12 VDC Output on the left indicated by the green arrow. The other end is the 120 VAC input.



In the photo below, you can see the connection points for the WFCO Converter, the Ground (White Wire) is on the top (in my case the empty terminal) and the Positive (Red Wire) connection on the bottom. This was also installed with the smaller gauge red wire. This smaller gauge wire is the 12 VDC input from the 7-pin connector after it passes through the junction block under the front of the camper.



Next is the Bus Bar Ground, the Green Arrow on the left is the 8-gauge Ground wire that goes to the batteries. The 8-gauge on the right is the other end of the white Ground Wire in the photo above.



Lastly, you can see the open cavity where the OEM WFCO used to live in my 400, I removed it and installed a Progressive Dynamics 9160ALV under the bed within 12 inches of the battery junction block. Again, this is why in my situation I am not concerned about upgrading the Ground Wire between the PDC and the Batteries. 



So, as you can see the WFCO Converter is easy to remove, it is held in place by 2 screws. Disconnect the 5 wires and slip it out. You could also swap this for a different WFCO (IE Lithium) if you so wished. 

Brad

P.S. And yes, my OCD is going to force me to put ferrules on the ends of all the stranded wires to make sure thy have a solid connection. I just haven't gotten that done yet. 

bergger

Thanks Brad.  I'll probably open it up and take a look at things but honestly do not know if I want to mess with that stuff at this point.  I'm more likely to screw something up than help out.  The converter in the 2021 is half the distance to the batteries than in the 2020 being that it is in the middle of the kitchen just under the center cabinets.  Hopefully the existing 8 gauge wires will be fine.  But I'm definitely going to add a 12 or 14 ga additional ground between the Alde and the junction block.

And I just want to ensure I am correct from reading your posts.  The 14 gauge ground you attached to the Alde was then attached to the junction block near your batteries and not attached to the silver bus bar near the converter?  The silver bus bar is where the converter is grounded and where the battery is grounded to.  That is completely different than the additional ground coming from the Alde.  

Dutch061

Again, referencing the Airstream bulletin I believe it is imperative to put a larger ground wire 6-gauge or add a second 8-gauge between the batteries and the PDC. The exception would be if you are not using the OEM WFCO to charge the batteries. 

Yes, my auxiliary ground wire is connected from the Alde to the negative terminal of the battery junction block for a couple of reasons.

1. The battery junction block is adjacent to the Alde, probably 2 ft.
 
2. I do not desire to be ambitious enough to run the wire to the very front corner of our camper. The PDC is under the dinette seat on the door side in 2020. Running wiring from back to the front is not a fun job, I ran the network cable from the BMV-712 shunt to the panel adjacent to the door when I finally cut the hole to install the display. NOT a good time.

Brad

Dutch061

In an effort to help guide others, I have assembled a document that helps to apply the Airstream bulletin (specifically the "Adding Grounds to the 30' Classic) instructions to NuCamp. 

As mentioned on the opening page of this document, I make no guarantee that this information is accurate, true or otherwise useful.

However, I hope you will find it helpful as you address the corrosion issues.

Brad 

bergger

Thanks for the write up!  I decided to open some things up today in our 2021 400 to see where things are and hopefully add the auxiliary ground to the Alde.  Unfortunately the wire I already had made up and laying around was not long enough, only 3 feet and I'll need 4-5 feet.  Off to the store later.  Anyway I wanted to share a few photos of where the distribution block is in our trailer.  I was hoping I would have to just pull the bed panel under the television but after doing so I found it is hidden/protected in a bulkhead between the battery compartment and the outdoor storage compartment.  One extra step is needed to remove the wall of the bulkhead so you have access to it.  

Here is what it looks like after I opened it all up.  The distribution block is under that bulkhead wall on the left that has the 40amp fuse mounted to it. 


Before removal


After removal


After the distribution box cover is removed.  



A couple of questions.  So the terminal on the right with all the negative wires is where the auxiliary Alde ground is attached after the other end is attached to the Alde case?  

And I'm not sure if I'm testing things correctly with my multimeter.  I'm not too up on those things!  I set it to 12v and tested my battery, red on + black on - and I got a good reading of 13.87v.  I then turned on the Alde on 120v, trailer is plugged into shore power, using 1KW setting.  It turned on and I let it run for a few minutes.  I then put the neg lead on the neg battery terminal and used the pos lead to touch all over the Alde case and mounting bracket.  I got a reading of 0.  Not knowing if I was doing it correct I turned the multimeter to 120v and did the same thing and got 0.  I assume it needs to be set to 12v to test but since I got 0 volts I was not sure.  Does that mean I have a good ground already or do I have the meter set incorrectly?  Still plan on running the auxiliary ground but just want to know if I did that correctly.  

Denny16

Yes, an Alde ground wire could be connected to the ground (right side shown with black and white wires connected) connection terminal in your photo.
 Cheers 

bergger

I got an email back from NuCamp today, Creed.  I emailed him with details on our trailer and asked about wiring.  He said there is a 4 gauge ground between the batteries and the distribution block and an 8 gauge between the convertor and distribution block.  The battery ground seems solid, now I just need to see if I want to upgrade the ground from the converter.  The converter looks intimidating to me.  

Dutch061

@bergger

As far as the ground between the converter and the PDC, it is fine. I mentioned in my write up that NuCamp is using a WFCO PDC with a built-in converter. Airstream is using a PDC without a converter built in which is why they want it to be replaced with 6-gauge wiring.

However, the 8-gauge between the PDC and the battery junction block is not sufficient (based again on what Airstream is doing).

Voltage Drop 101

For Ground Testing, connect the Negative Lead of the Multimeter to the Battery Negative Terminal. Use the Positive (red) lead to "probe" the things you wish to check.

For Positive Testing, connect the Positive Lead of the Multimeter to the Positive Battery Terminal. Use the Negative (black) lead to "probe" the things you wish to check.

In either test (positive or ground) you will always see some voltage. What is acceptable, that is where things get somewhat blurred. You can find anything from values of .2 volts to 5% of the system voltage (.7 volts). 

My response which is "subjective" is the lower the better!

Brad 

bergger

Thanks Brad.  I got a 0 reading on the negative test but I'll have to do a positive test to see what it is.  I did have the Alde on shore power running on 1KW.  Does it matter if it is on 1KW or 2KW when doing the test? Just trying to figure out why I got a 0 reading when ground testing. 

Dutch061

I wouldn't be as concerned about the positive (in regard to the corrosion issues anyway). I would suggest checking it with the Alde on propane too, just to cover all the bases.

Regarding the zero reading, depending on the meter, accuracy and resolution it may not be able to display readings that are into 3 decimal places. Or if it not set on the correct voltage range, that can prevent you from seeing anything either. 

I need to check mine on AC also, I haven't done that. 

Brad

Dutch061

As I have battled through the voltage drop testing and further research, I came a across a pretty handy App for my phone called Electrical Calculations. With this App, you can create scenarios to see projected outcomes based on gauge of wire, length of run, temperature, voltage, and amperage draw.

For those nerds (myself included) that really want to have a better understanding of the Power loss that occurs, I have run several different scenarios based on 12 VDC, either a 10 Amp or 40 Amp draw, and either 22 feet (estimated length of ground wire in our 2020 400 BDL) or 50 feet (estimated length of ground and power feed wires combined). 

Please find that document attached for reference or a headache.

I will post this in the discussion titled "Let's get grounded" also.

Brad

Denny16

The average DC load in a TaB is around 10 amps or less (not including charging the battery).  The only device that could create a load of 30-40 amps is the inverter, and it is wired directly to the batteries with properly sized cables.  Whilst the TaB has a 40-amp breaker (max allows load) it is wired for a max 30-amp load.  That said, it doesn’t hurt to have an oversized ground wire, and is usually a good practice.

Cheers 

Dutch061

@Denny16, Actually the OEM installed WFCO Power Distribution Center on our 2020 400 BDL had a 55 Amp Converter in it, and it is imperative that you include the battery charging input for this calculation. It is due to the 8-gauge wire size and the resistance that the converter NEVER puts out 55 Amps. The resistance prevents it from going into the Bulk Charge Mode, or if it does it is it is only for a few seconds until it switches to Absorption. 

But (and this is the tickler) the addition of the current from the converter has a direct effect on how many Amps needs to be able to pass through the wiring on the camper within an acceptable Power Loss range. It is this same Power Loss (resistance) that can cause back feed issues through the other ground circuits and aggravate the corrosion.

All I can say for certain is this, Airstream decided it was enough of an issue to create a bulletin for adding the auxiliary ground and replacing the 8-gauge ground wiring with 6-gauge. Which means to me that they have people who have investigated this and came up with the procedure on how they (Airstream) wish for it to be fixed or prevented. For me, I am all for prevention rather than fix which is why I have spent as much time as I have not only in testing but also in documentation to share with others.

You are correct, the inverter is wired directly to the battery junction block on our 2020, but it draws way more than 30 to 40 amps for anything I have used it for; typically, between 80 and 90 Amps. 

As mentioned, what I provided is to be used as a reference, to be used or not is up to each individual. 

So, take it for what it is worth.

Brad

Denny16

@Dutch061, I am not disagreeing with you.  Yes the inverter draws more than 40 amps, and that is why it’s wired directly to the battery.  I was just pointing out the inverter is not part of the trailer’s DC circuits going through the WaCo.  I also agree on the charging system, the Watco to battery connection needs to have the correct size wire for charging the battery.  I was just pointing out, the normal DC current draw on the TaB was way less than 30 amps., inverter and battery charging excluded.  

You are correct, nüCamp has undersized some of the DC wiring between the charger and battery, and a larger wire between the ground buss and battery.  For installations on the boats I have worked on, the main ground buss cable is rated for the total amp draw of all the sub DC circuits, even though they are not all used at once.  I think nüCamp should do the same, and I plan to upgrade the ground buss cable on our TaB400 to a 30-amp rating.
 Cheers 

BrianZ

Interesting analysis @Dutch061& thanks Brad, for sharing.  I like to use a similar calculator tool to compare voltage drops, which seems more intuitive to me, though looking at watts of power gives more complete info.  Here's another convenient one..
https://www.calculator.net/voltage-drop-calculator.html

I'm wondering under what circumstances would the DC circuit in a T@B 320S ever be carrying close to 30A, even though our WFCO 8735 model is rated at that for charging?  I'm also thinking that there would be substantially less than 50ft of cable in ours, maybe half that including pos & neg, so much less voltage drop/power loss.  Would charging really be an issue or a risk, or are we still focusing on the Alde corrosion issue here? 

The highest charging current I can recall actually seeing was 11A, but that was a combination of solar plus from the tow vehicle.  We mainly only use the converter for keeping our single 150AH battery topped off.  I also periodically charge it directly with a NOCO genius 7200 charger plugged into shore power (only 7 amps) if the battery is somewhat depleted, like after boondocking without solar.  I would still like to add that extra ground line, just don't see any urgent need right now.  I still wonder how many amps the WFCO will put out in bulk charging mode.  

Dutch061

@BrianZ,

I can't speak directly to the 320 (I suspect 35 amps), but in a 400 the Bulk Mode can deliver (per WFCO specs) 55 Amps. I know for certain (aka past experience) that is never going to happen with the OEM 8-gauge wiring. The primary focus is for the corrosion issue, but the added benefit if both the power wire and the ground wire were upgraded to a larger wire that you would get a converter that works properly. Which means instead of spending 24 to 36 hours to fully charge the batteries, you could do it in a fraction of the time. For those who are using a generator to charge, this is huge! The charging benefit is of no value for those who are always connected to shore power, we rarely camp in those types of places, which of course is the reason I have 400 Ah of lithium.

In my case the real-world results are a fraction of what the Power loss calculator predicts, but again it is a planning tool that easily allows comparisons to guide you to proper choices.

Using the higher voltage of lithium and 16.2 Amps (everything turned on) measuring from the battery negative to the Bus Bar Ground, my actual power loss is less than 1 Watt, while the calculation shows 6.952 Watts.

Really, the bottom line is to prevent corrosion and if Airstream felt it is necessary to use heavier ground wires, that those of us using the Alde system in NuCamp need to carefully investigate this too. Again, each owner needs to determine the necessity based on their use, but at the cost of replacing a bunch of parts, I can certainly spend some time and possibly money on stuff to prevent it.

Again, the wire gauge issue, 24 to 36 hours to charge, and others are not limited to NuCamp or Airstream. I believe that it is industry wide, or at least for the most part on campers with smaller electrical systems.

Brad 

Dutch061

One final comment from my additional testing last week.

I purchased a magnesium anode to install into the glycol reservoir and connect to ground. The thought being that the magnesium is "less noble" (will sacrifice itself easier) than the aluminum in the convectors. This all sounds really great, in theory.

1. After installing the anode with the glycol hot, I was able to measure a voltage drop to ground form the anode of 1.12 VDC, which indicates the anode was working. 

2. Measuring the voltage drop of the convector under the shower with the glycol hot, there was a 256 MV drop to ground.

3. Ground the anode and the same voltage drop becomes 750 MV (or about triple). 

Based on the voltage drop increase, it would appear that adding an anode is the wrong thing to do, this is based on my testing on my camper. If you were to test this, your results may vary, but based on this, I removed the anode and wiring. 

Additionally, @jimcenname and I had several conversations about corrosion, galvanic action, grounds, etc. Jim had reached out to Rhomar tech support and was told that Rhogard is designed to help resist the galvanic action and as long as the PH remains around 8 (service as recommended) and the glycol is not diluted (past the pre-mix of 50/50) that it will be fine.

Brad

P.S. I mention the glycol being hot because as the temperature goes up, the voltage drop follows.

BridgerSunset

@Dutch061,
Wonder if this could be what you are seeing:

The natural potential (voltage difference) between magnesium & mild steel (the ground) is sort of around that 1.12 volts.
The natural potential between aluminum (convector) and mild steel is sort of around that 0.256 volts.
Now if you ground the anode, aren't you essentially electrically coupling the aluminum to the magnesium, with the resulting net potential of 1.12 minus .256 = 0.86 ..... which is in the ballpark of your last reading?

The implication being that there will be a net potential between the aluminum and magnesium, and so yes, understanding direction of current flow (+ or -) is key.

BrianZ

@Dutch061,
Brad, you've got some more interesting results here, so thanks again for sharing.
That said, I'm not convinced you have disproven the "potential" value of the anode, if properly applied.  As described, I would not expect your anode to protect the convector without providing an electrical connection between the two, such as by wiring both to the Alde frame, for example.  With the anode wired to the Alde frame (or ground, if frame is grounded), then the anode should protect boiler parts also in contact with glycol; but, it can't be expected to protect convectors not wired in common with the anode wire.  However, based on your test results, I'm now going to consider adding ground wires between the convectors and Alde frame (as some others have done), in addition to a ground wire between the Alde cabinet and ground.

I also plan to share my voltage drop measurements that you suggested here soon.

BrianZ

@BridgerSunset
Your explanation makes perfect sense, as aluminum can also be used as an anode, but it does not generate as high a galvanic potential as does magnesium.  So, the net result if wired in parallel would be the difference in their potentials.
Further, since the aluminum is what you're trying to protect from corrosion, its lower potential is why you need magnesium (with a higher potential) to serve as the sacrificial anode. It's actually a good demonstration of why you need a sacrificial anode & how it works.

BridgerSunset

The only hangup I have about the anode installation is that I was always taught anodes only protect "what they can see".  That is, current doesn't really go around corners or swim downstream looking for bare metal everywhere.  Hanging an anode in a plastic jug or in any vessel, seems to me that wherever the first place a cathodic circuit can be completed is where all the current flow (and therefore the protection) will go.

Maybe that protection reach is limited by the driving potential between the 2 metals - I don't know.  Wish i fully understood the whole process

Dutch061

I agree @BridgerSunset that your comments are very interesting, and you are correct, my voltage reading between the anode and battery ground was right at 1.12 volts. Will adding the grounds to each convector along with a magnesium anode installed eliminate the corrosion (galvanic action) 100%? I am not able to answer that either. 

By no means am I "an expert" regarding the prevention of galvanic action, I do understand what causes it and using a "less noble" metal to prevent the movement of electrons from the items you desire to protect. With that being said, I do believe the following statements to be true.

1. There is always an anode (-) and a cathode (+)

2. The electron flow moves from the anode to the cathode (depending on which theory of electricity you subscribe to)

3. The anode is typically the "less noble" metal, meaning it is the one giving up electrons (creating the voltage and amperage measured). As it gives up these electrons, it also gives up parts of itself (corrosion).

4. There has to be a means of connection between the anode and cathode, (in this case the glycol). If this glycol PH drifts to the lower side (acidic) the galvanic action will increase.

5. The resistance in fresh Rhomar water is around 10 Mega ohms, which means it is a good insulator. Distilled water is around 1 Mega ohm for comparison.

With these thoughts in mind, take a look at today's typical automobile.

1. Dissimilar metals used - cast iron, aluminum, powdered graphite can be used in engine blocks or cylinder heads. Engine block is where the primary ground from the battery is attached (most vehicles)

2. Radiators are aluminum core with plastic tanks (without ground straps)

3. Heater cores are aluminum with plastic tanks, again without ground straps

4. Engine coolant is propylene glycol with a corrosion inhibitor package

5. As long as the coolant is maintained (most vehicles are now 5 years or 150K miles) there are no issues with galvanic action creating leaks or swelling issues. However, if it is not now you have compounded the problem by not only having a compromised corrosion inhibitor package (no longer provides corrosion protection) but you have a glycol solution that is acidic. With an acidic solution and 2 different metals immersed in it, you now have a battery and electrons flowing regardless of the presence of an outside power source.

Previous to Propylene Glycol, Ethylene Glycol was used along with copper-brass alloys for heater cores - tanks radiators - tanks, and there was a ground strap installed on the heater core most of the time. The heater core was installed into a composite housing (aka plastic case). Corrosion was a real issue, most likely caused by the thoughts that the "anti-freeze was permanent". 

Go back a little further in history, and methanol was used. In fact, before it was denatured, people were caught lying under vehicles drinking the coolant solution!

Which brings me to these closing thoughts (using the Airstream bulletin for guidance), "if adding an anode and grounding all of the convectors truly provide the 100% fix, why does Airstream not mention or recommend it"? I only say this because it is a safe bet that there are engineers at Truma-Alde and Airstream that are way more knowledgeable about galvanic action as it relates to the Alde system than I will ever be.

Again, I am not an expert and do not claim to be. I am trying to provide information that will allow each of you to make decisions on what is best for you.

Brad

BrianZ

@Dutch061
Thanks for your interesting contributions to the anode discussion, Brad.  You make some great points & questions too.  I'm no expert either, and have to remind myself that this is all still experimental, so we may very well end up with more questions than answers about this endeavor.  Maybe the Rhomar is the best answer and combined with timely servicing, corrosion will become a non-issue.  I was surprised that your Rhomar has a resistance of 10 M-ohms though.  I tested my 6 month old jug of green glycol and it was between 1-2 M-ohms, and neither of these seem to me like the ideal "electrolyte" to facilitate the galvanic anode protection; but I suppose that's how it should be to avoid corrosion in the first place.  So, maybe between that change, plus the adjusted pH to around 8 will give the needed protection.  Improved grounding can't hurt either.
By the way, regarding your first point #4, galvanic corrosion requires two connections between anode & cathode:  a metat-to-metal electrical connection, plus a connection through an electrolyte to complete the circuit.  This article shows ways that it does not occur..
https://www.ssina.com/education/corrosion/galvanic-corrosion/

BridgerSunset

Yeah, could be that internal corrosion just hasn't  been a common problem in our systems, and the Truma engineers haven't flagged it as a problem.  There's not a lot of metallics in it, on the whole.  The fear is if the Alde boiler itself corrodes - an expensive fix.  Hopefully the Rhomar pH helps.  I'm  surprised it's 10 megaohms.

The external corrosion at the convector stubs is what much of the discussion was based on (I think).  Internally placed anodes won't help external surfaces.  That's a different mechanism in play at the stub, though we don't  know exactly what.

Regarding anodes, odds are this:
If you hang a regular nail in the glycol bottle, it will rust (iron oxide flakes), worse near the fluid level where oxygen is present.  If you hang a mag anode, it will also "rust" (magnesium oxide crystals) similarly.  Same with an aluminum anode (aluminum oxide crystals).  There's not really any current flowing off the anode for protecting;  rather, it is just oxidizing & spending itself, on itself.

If the anode is hung in a vessel where there actually is a conductive medium, and a large exposed cathode nearby, and a return pathway, then I think the anode could be effective.  Be it the pex pipe separating components, or lack of a real ground, I suspect the path is flawed.  Would be nice to have a pro tell us definitively.

As a side note, for you awesome experimenters, I wonder what the number (and neg/pos) is if you put the red lead directly on a grounded magnesium anode and the negative lead on the aluminum convector.   My T@B is buried in snow..😮‍💨

ScottG

BridgerSunset said:
...

The external corrosion at the convector stubs is what much of the discussion was based on (I think).  Internally placed anodes won't help external surfaces.  That's a different mechanism in play at the stub, though we don't  know exactly what.
...

Agreed.