Suspected Converter Problem

[LipschitzWrath]

Hey guys, back again. Hoping to gain some insight into an ongoing problem we've had this summer.

RV is a 2004 Fleetwood Terry Quantum AX6 365FLTS.

The rv came with a factory installed WFCO 8855 converter. First things first. If you go to their website, you will see 8855's are 220v input. This may be the case now but certainly wasn't in 2004. Mine is 120v input and I have photographic proof. Let's please not waste time disputing this.

WFCO says the 9855 would be pretty much an equivalent now.

Anyways, onto the issue. I am wondering if there may be a problem with my converter. The reason I suspect it is because of generally poor performance. In the off season, I replaced the single group 24 battery the PO was kind of enough to leave me with a pair of Group 31 AGM batteries, 105Ah apiece.

It seems that this charger takes forever to charge these things. We're talking like if the wall panel shows 2/3 full, I need to run the generator for like 8 hours to charge them.

On a recent trip, the Batts showed 1/3 full and even after running the generator for seriously like 12 hours, they only showed 2/3. This seems slow. I know the indicator system probably isn't scientific level accuracy, but reading at the Batts with a multimeter seems to corroborate.

Other weird issues:

Sometimes at night with our 12v lights on in the camper (LED retrofits), I can see the lights flickering.

I get substantially different readings on the multimeter if I probe the output terminals of the converter versus the batt terminals. This despite the cables connecting the two being less than 4 feet long. For example, I forced the converter into boost mode. When probing the outputs, I got like 14.46v. At the batt terminals, I get like 12.43v. This seems especially odd to me considering any other time I probe battery terminals with a charger connected and charging, it seems like I'm reading the charger output voltage.

Lastly, I pulled the troubleshooting chart from WFCO and followed all steps. According to the chart (link below), my converter is fine. But it certainly doesn't behave like it's fine. I know PD advertises that when in boost mode, it takes 2-3 hours to bring the battery bank to 90%. Admittedly, this WFCO isn't as good as a PD, but 12 hours? Really?

http://wfcoelectronics.com/wp-content/uploads/2015/11/New-Flow-Chart-for-WF-9800-Series.pdf

I have my eye on a PD9260, but I don't want to spend the money if there's something else wrong.

This past weekend the batteries were completely dead and we brought them home to charge on a more "conventional" charger. It took a long time, but it worked.

Any ideas? Are my batteries just THAT big? Or is there something else going on?

Tell me what you guys think.

[LipschitzWrath]

BFL13 wrote:
You have the required 60a fuse/CB on the converter-battery path. But it seems there is no fuse/CB for when you are on shore power with the converter supplying the DC fuse panel. IMO that pos wire should be fused too.

The "return wire" if a second pos for converter- fuse panel needs a fuse too. You could put another fuse /breaker on the pos wire going from the converter to the fuse panel side of the 60a breaker there now. That would take care of both those wires going from the 60a breaker to the fuse panel if the supply were converter instead of battery. Right now, they only get protection if the supply is battery.

You could confirm that mystery "return" wire is doing what you think, by disconnecting the other wire and see if you still get supply to the fuse panel. Disconnect that and unless there is a third path, that should cut off 12v to the fuse panel. Now you know.

Your solar controller is supposed to have a fuse on its pos wire near the battery post. You can have that somewhere close to the pos junction at the inner end of the breaker instead, and let the 60a breaker do the rest of the way to the battery bank.

I agree with what you said. When supplied by the converter, the two wires feeding the DC panel are not protected and should be. However, like I said, it seems they never were (unless there is a hidden fuse/breaker somewhere).

For adding a breaker, what do you think an appropriate interrupt rating would be? I've been told best practice is to fuse for what the wire can handle. In this case, there are (I believe) two #8's feeding the DC panel. However, I don't think it would be wise to fuse them at 80A, since you can't guarantee that both wires would always be intact. If one of the wires worked loose at a connection, for example, you could potentially put 80A through one #8 wire before the breaker kicks.

I believe there are two more prudent ways to do this. One, get a 40A breaker and hook both DC feed wires to that breaker's output. This would guarantee that even if one wire was compromised, you couldn't overload the other. Something tells me 40A would be more than enough supply to the DC panel, considering all the slideouts have there own battery feed via a separate breaker.

The other way I see to handle it would be to use 2x 40A breakers, one for each feed wire. This doubles the available supply to the DC panel and preserves circuit protection in all aspects. I'm just wondering if it is worth the added complexity.

I'm eager to hear your thoughts on that.

As for the solar controller, are you saying it needs its own breaker? I guess I was under the impression that by hooking it up to the "output" side of the battery breaker, it was protected because its current had to pass through said breaker to charge the battery. Maybe this is in error. I guess the question that needs answered is - what exactly am I trying to fuse/protect on the solar controller wiring? This will dictate where I place a breaker (and the rating of said breaker).

My vision now is to purchase a couple breakers as well as two buss bars - one for positive, one for negative.

The negative buss bar would mainly be for convenience to collect all the various ground wires. Through careful planning, I could also make future installation of a shunt very easy.

For the positive buss bar, I envision having the converter feed into the buss bar, and then feed the DC panel breaker(s) and battery breaker off the buss bar. This would provide protection in all directions for all wiring. The only case I can't reconcile is a dead short on the converter output. Would the reverse polarity fuses on the converter open in that instance?

Thanks for sticking with me through this!

[BFL13]

You have the required 60a fuse/CB on the converter-battery path. But it seems there is no fuse/CB for when you are on shore power with the converter supplying the DC fuse panel. IMO that pos wire should be fused too.

The "return wire" if a second pos for converter- fuse panel needs a fuse too. You could put another fuse /breaker on the pos wire going from the converter to the fuse panel side of the 60a breaker there now. That would take care of both those wires going from the 60a breaker to the fuse panel if the supply were converter instead of battery. Right now, they only get protection if the supply is battery.

You could confirm that mystery "return" wire is doing what you think, by disconnecting the other wire and see if you still get supply to the fuse panel. Disconnect that and unless there is a third path, that should cut off 12v to the fuse panel. Now you know.

Your solar controller is supposed to have a fuse on its pos wire near the battery post. You can have that somewhere close to the pos junction at the inner end of the breaker instead, and let the 60a breaker do the rest of the way to the battery bank.

[LipschitzWrath]

To add, my converter has set screw terminals on it where you insert the wire and tighten the Allen screw. #4 pretty much fills the entire thing, might be able to fit a #2. It would be very difficult to insert multiple wires into this terminal.

[LipschitzWrath]

BFL13 wrote:
Thanks for answering my questions! So the converter has a #8 to the neg junction as well as the #4? My question was how did you get both those from the converter if the converter has only one neg terminal?
You don't need that #8 there anyway, if that is how it is.

The chassis ground with an inverter is to reduce interference with television and radio, according to my Vector inverter's manual. I don't know what the similar chassis ground does for a converter set-up. I don't think it is "bonding" as with 120v set-ups, this being DC. (Pray now to the internet gods that nobody on here saw the word "bonding" and we get off on an endless debate about that! 😞 )

What amp size is that breaker on the positive side?

No, there is no #8 to the converter negative terminal anymore. There used to be, but I replaced that one with the #4. Once I did that, I then had a #8 wire sitting there that was connected to the frame ground on one end and nothing on the other (formerly the negative terminal on the converter). My point was that rather than remove that wire entirely by unbolting it from the frame, I landed the other end on the ground junction block to provide an additional ground path to the frame.

I did the exact same thing with the wire that formerly ran from the negative battery terminal to the frame. Left the frame side intact and landed the other end at the junction block.

These two wires supplement the new #4 I ran from the junction block to the frame.

My thought process was that the cable was already there and terminated at the frame, so it was minimal work to terminate it at the junction block and provide parallel paths for even lower resistance to ground.

Breaker is already (surprisingly) a 60A.

[BFL13]

Thanks for answering my questions! So the converter has a #8 to the neg junction as well as the #4? My question was how did you get both those from the converter if the converter has only one neg terminal?
You don't need that #8 there anyway, if that is how it is.

The chassis ground with an inverter is to reduce interference with television and radio, according to my Vector inverter's manual. I don't know what the similar chassis ground does for a converter set-up. I don't think it is "bonding" as with 120v set-ups, this being DC. (Pray now to the internet gods that nobody on here saw the word "bonding" and we get off on an endless debate about that! 😞 )

What amp size is that breaker on the positive side?

[LipschitzWrath]

BFL13 wrote:
So the two #4 wires going from neg junction to the batteries are equal in length for Method 3? (There was an issue before where the downstream battery --one above the other in racks) meant you had to go longer on either pos or neg to do Method 2)

I see where the confusion might be here. To answer your question, YES, the two #4 wires going from the neg jct to each battery are equal in length. I cut the first one, held it against the spool and cut the 2nd one to be the exact same length.

The issue before was that there was only one pair of wires entering the back of the battery compartment. There is a shelf dividing the upper and lower batteries. The two wires entered through the back of the compartment into the TOP battery compartment. They would thus hook to the TOP battery. Then, two cables would have to be hooked from the top battery to the bottom battery to parallel them together. This had to be done from the front of the compartment, so the cables were against the door of the battery compartment when closed.

What I did was add a second entrance point into the BOTTOM battery compartment. Through this entrance point, a newly added #4 power and ground cable enter to hook directly to the BOTTOM battery. An identical set of #4 wires enter through the existing entrance point in the TOP compartment and hook directly to the TOP battery. The other ends of these wires are joined at the ground junction block in the case of the negatives and at the breaker for the positives. Thus, the batteries are truly parallel'ed.

BFL13 wrote:
Was the #8 converter to frame wire for its output before, or was it a "chassis ground"? With a deck mount converter, they say to have a chassis ground, whereas a "lower portion" converter doesn't need one, being in the metal framework of the frame-grounded power centre.

Again, I see your confusion. The #8 converter-frame cable was the cable hooked to the negative output terminal of the converter and ran straight to the frame ground. I believe you're asking about the bare copper wire hooked to a separate terminal on the case of the converter. This wire does exist on my converter. It runs to a separate frame grounding point with dedicated terminal. These two fram grounding points are within a couple of inches of each other.

My electrical background would suggest this is a "bonding wire", as it bonds the metal case of the converter to ground so that a human body cannot serve as the path to ground if an internal short causes the converter case to become energized.

BFL13 wrote:
You added the #4 as converter output to junction stud, so unless there are more output terminals I am wondering if the #8 is a chassis ground. If so, you don't want that in with the negs on the neg junction stud. It should go to the frame independently. If it is output, you don't need it in parallel with the #4 to do 55 amps.

See above.

The new #4 converter neg output wire runs to the ground junction block. Before, the #8 ran straight to the frame ground. I utilized the junction block because this allowed me to connect the battery and converter neg cables all in one spot, then run one additional #4 from the junction block to frame ground. Otherwise, I would have had a #4 neg running straight from converter to frame and then 2 more #4's running from each battery to frame ground.

In essence, I did it to simplify the wiring arrangement.

BFL13 wrote:
What happened to the parallel link wires between the two batteries? You don't need them with Method 3.

Because I now have a separate pos and neg running to each battery, the two jumper wires that ran from the top to bottom battery compartments were no longer necessary. They are sitting in the 5er's "junk drawer" for emergency use.

I hope this clarifies some things. What I really need to do is sketch up a before and after diagram. I'm sure that would answer a lot of these questions.

[MEXICOWANDERER]

https://www.ebay.com/itm/Marine-RV-Brass-6-Gang-Terminal-Block-Connector-Common-Buss-Bar-100Amp-12V-...

It says 100-amp, but common sense tells me 50-amp maximum.

This would act as a great sub-branch distribution point either positive or negative. Lose the fumble screws, buy #8 stainless screws 3/16" longer then use 6x32 KEPS NUTS...



to minimize the fumble-factor when assembling. Hooking a ring terminal over a screw/stud then screwing down a nut with attached washer is light years easier than lining up a screw and terminal ring.

On busses used for positive distribution set your fuse or circuit breaker coming off the buss bar.

[BFL13]

OP said:

".... I did complete the battery cable upgrade last night. I added a single stud-type junction block in the crawlspace to serve as a ground junction. From there, I ran a new 4ga ground cable from the converter to the junction block. I also ran separate 4ga grounds to each of the two batteries. I then ran a 4ga ground from said junction block to the frame ground. In addition, rather than removing the existing 8ga grounds running from frame-converter and frame-batteries, I also hooked them to the junction block, providing several additional redundant ground paths to the frame

So the two #4 wires going from neg junction to the batteries are equal in length for Method 3? (There was an issue before where the downstream battery --one above the other in racks) meant you had to go longer on either pos or neg to do Method 2)

Was the #8 converter to frame wire for its output before, or was it a "chassis ground"? With a deck mount converter, they say to have a chassis ground, whereas a "lower portion" converter doesn't need one, being in the metal framework of the frame-grounded power centre.

You added the #4 as converter output to junction stud, so unless there are more output terminals I am wondering if the #8 is a chassis ground. If so, you don't want that in with the negs on the neg junction stud. It should go to the frame independently. If it is output, you don't need it in parallel with the #4 to do 55 amps.

What happened to the parallel link wires between the two batteries? You don't need them with Method 3.

[DrewE]

BFL13 wrote:

What I don't get is now your pos and neg are not equal from their junctions to the converter. The two pos are equal and the two negs are equal but they are not equal to each other. I am unclear (to say the least) if they are supposed to be.

Generally, the pos and negs do not have to be the same since it is a circuit and it is the total R of pos and neg that counts. So it ought to be ok if the pos links are equal and the neg links are equal but the paths from pos and neg junctions to the converter are not the same. Or maybe it does matter. I have no clue.

....

So perhaps somebody who does have a clue about all this like PT does, can step in here and explain it all. 🙂

For balanced connections to the battery, the wiring impedance seen by each battery needs to be the same. It matters not one whit whether the impedance is on the positive or the negative side, nor whether the impedance on one side is equal to the other.

If you think about it, the standard way of paralleling two batteries (with diagonally opposite connections for positive and negative) does not lead to equal positive and negative impedances for the batteries, and in fact the extra impedance from the paralleling wires is on the positive side of one of the batteries and on the negative side of the other one. It works because the total impedance, and hence voltage drop, is identical for each battery.

When there are more than two batteries, it can get a bit more tricky as sometimes some wires around the batteries carry more current than others, and so the voltage drop is greater in them when their physical characteristics are otherwise the same...but that's of no importance in this particular case.

I'm a fan of keeping things simple and of not having too many connections on one stud/bolt. Bus bars do often accomplish this nicely. A short length of copper water pipe, squished flat in a vice, makes the guts of a very effective and inexpensive bus bar.

[Cydog15]

BFL13 wrote:

pianotuna wrote:
Cydog15,

Surely you can't be serious that BFL13 is being paid. Is it an attempt at humor???

PT, better to ignore all this. For here, just take his "info" as being garbled, and go with the two companies' websites--imperfect as they now are, but being worked on 😞 --- for specs etc.

I am more interested in how the OP is making out with his project!

I'm with you on that BFL help that guy first. The OEMs have told powermax they want 13.8 max. I suspect they don't care about battery charging tech and don't cater to us, just Joe public. We by a lot of boondockers for the fleet and want the higher voltage and it will be 14.7 for sure. I take back the comment that you work for them, it just seemed odd you cared that much. We have samples that have the manual adjust and that is great but in the multi stage mode, 13.8 is not enough. PD isn't sleeping either. I'd keep an eye on their new stuff too.

[MEXICOWANDERER]

Look at how a shunt is configured. Studs? You must be joking. Try 3/8" x 16 bolts. The professional way to wire is to have TWO BUSS BARS. One positive the other negative. Switch either polarity between the battery and the buss bar.

If your chargers need more than one connection, there are pretty little 100 amp brass busses that will work fine. I toss the #8x32x 3/8 screws and upgrade to stainless screws, nuts, and washers. One half inch long. Much easier to work with.

Wiring should be kept simple and intrinsic. The word means "intuitively understandable".

Think "original RV manufacturer wiring layout" then do the opposite. Hunt and peck to find wiring routes is a loser.

The more connections you expose to war-zone grade battery corrosion the more problems you will have, the larger the expense and the larger the headache.

[red31]

cuz the smartguage man says so!

Finally, if you only have 2 batteries, then simply linking them together and taking the main feeds from diagonally opposite corners cannot be improved upon.

common interconnects

[BFL13]

Ok, you can have two neg wires from shunt to the two- battery bank with those two wires being equal per Method 3. That end of the shunt is the junction for the neg fan per that Method 3 drawing. The two negs are also your parallel neg link between the two 12s.

What I don't get is now your pos and neg are not equal from their junctions to the converter. The two pos are equal and the two negs are equal but they are not equal to each other. I am unclear (to say the least) if they are supposed to be.

Generally, the pos and negs do not have to be the same since it is a circuit and it is the total R of pos and neg that counts. So it ought to be ok if the pos links are equal and the neg links are equal but the paths from pos and neg junctions to the converter are not the same. Or maybe it does matter. I have no clue.

So IMO go with Method 2 since you have two batts anyway. And as you say, if you change to a pair of 6s, you will need their series connection link and Method 3 makes for two parallel links you don't want with the 6s.

So perhaps somebody who does have a clue about all this like PT does, can step in here and explain it all. 🙂

[LipschitzWrath]

BFL13 wrote:
Exactly half is hard to achieve. You have no way to know if you are getting that or 1/4 and 3/4. You just ASSume half each except with Method 2 and two batts you are pretty safe there getting about half each.

Method 3 requires all links to be equal or it doesn't come out right. The shunt and its single wire (however long) to battery neg adds to the length of the neg linkage. Good luck figuring out how much to shorten the two negs to make it all come out even again!

No need to re- drill everything, just junction as now and use "adapter wires" with a 3/8 at one end for connecting to the shunt.

Longer bolts will hold more lugs but eg, Mex says to avoid stacking if possible and go with buss bars. Some stacking is going to happen. It is worse with big lugs that are uneven, not flat. Hard to stack those. Stacking also requires rotating the wires away from one line up so the lugs can touch down flat. With many wires in the stack, you end up with a windmill of wires and can't get one around there because something is in the way of it sideways.

When you collect several thinner wires on a buss, the next single wire out from there has to be fat enough to carry the total amps of all those thinner wires.

Why can only one wire come off the shunt? It doesn't say that in the manual. Why can't I have two negative wires attached to the shunt, one to each battery. Electrically, this is no different than method 2, so I don't get why it's not allowed.

[BFL13]

Exactly half is hard to achieve. You have no way to know if you are getting that or 1/4 and 3/4. You just ASSume half each except with Method 2 and two batts you are pretty safe there getting about half each.

Method 3 requires all links to be equal or it doesn't come out right. The shunt and its single wire (however long) to battery neg adds to the length of the neg linkage. Good luck figuring out how much to shorten the two negs to make it all come out even again!

No need to re- drill everything, just junction as now and use "adapter wires" with a 3/8 at one end for connecting to the shunt.

Longer bolts will hold more lugs but eg, Mex says to avoid stacking if possible and go with buss bars. Some stacking is going to happen. It is worse with big lugs that are uneven, not flat. Hard to stack those. Stacking also requires rotating the wires away from one line up so the lugs can touch down flat. With many wires in the stack, you end up with a windmill of wires and can't get one around there because something is in the way of it sideways.

When you collect several thinner wires on a buss, the next single wire out from there has to be fat enough to carry the total amps of all those thinner wires.