3 electrical systems

[Blue~Go]

Yay, more pics!

Your DWV plumbing in the tire locker looks just like mine.

I don't see any way the shower stall could act as a bulkhead. It's not really attached in any meaningful way that I know of, plus it's sitting on a few pieces of wood on the floor, plus the rear wall is up against the Chinook wall (bulkheads go transversely, not parallel). However the shower/kitchen wall (which is plywood not MDF) does act as a bulkhead.

Not speaking to the upper shower wall specifically, I've always been somewhat agape at how many places more wall insulation could have been added. The "Arctic Foam" is more of a suggestion (too thin). Maybe it should be "southern California foam" But I imagine it helps to keep warm/moist air from condensing on the inside of the fiberglass shell, which is a very good thing.

OTOH, if they had added insulation back then, it would probably have been fiberglass, tossing nasty fibers into the air every time we drive over a bump. Now we can put in something like Thinsulate instead (that's what I have bought for adding where it will fit nicely). So there is a win in there.

[Blue~Go]

I just noticed something interesting when looking closely at the photo of your tire locker floor and then when re-looking at the main photo (with doggie looking out the door). The top layer of Chinook flooring looks like waferboard throughout. Both of my flooring layers are plywood. Maybe that explains some of the damage you have? I mean, not that you want water sitting on any floor, but it will withstand a LOT more moisture than wafer board without failing. Is the underneath layer also wafer board? Or is it plywood?

[Riste]

You are correct about the top layer being OSB. I thought that was standard.
The sub floor has proven to be plywood, foam, or in the case of the area aft of the shower - pine plank. There has been a coating on the very bottom of all of these.

[Blue~Go]

Maybe it was different in early 1997 (I say early since you have the 1996 engine/dashboard). In early 1999 (mine) it was two layers of plywood. I believe it stayed that way until they went to a composite floor in around 2002 (fiberglass/foam/fiberglass). My understanding is that the composite floor was developed as a result of the Destiny (24' Chevy chassis) being at just about max weight rating before it was even went out the door. Theoretically, it should be lighter (although later 21' Chinooks seem to be heavier - whether that is the result of a resin-rich composite floor, feature creep, or both is not known to me).

Anyway, perhaps there was a time when the waferboard floor was how they did it (I doubt anyone re-did your floor all the way around).

Anyone else with a 1997 or older who can confirm?

[Riste]

Almost all of the information you requested:
1) Amp draw of your starter motor.
I have not been able to find this number. Can we use your v10 for this?
2) Number of amps that will be traveling through for charging (toward the house bank).
A max of 140 amps.
3) Length of run.
~25 feet.
4) Are you using a negative wire to return or keeping the chassis grounds that I presume you have now.
Unless there is a good reason to run an additional wire I would use the chassis ground.
5) Short circuit current rating of your house batteries all added together (this will determine the AIC rating for the fuse holder on the house bank end of the combiner wiring).
The manufacturers support line (Interstate) tells me that a single 6 volt Golf Cart battery is rated at 2289 amps short circuit. I am not sure how the fact that I will be using 2 of them in series effects this (didn't think to ask him). He stated that a 2000 amp fuse would be "fine".

[Blue~Go]

Hey, great! Okay, let's see if we need anything else.

Almost all of the information you requested:
1) Amp draw of your starter motor.
I have not been able to find this number. Can we use your v10 for this?

Why don't we. Even if we are wrong it's not going to be double. Worst case you have to buy a different fuse. I think (getting ahead of myself here) you'll be able to use MRBF fuses on that end, and they are not super expensive.

2) Number of amps that will be traveling through for charging (toward the house bank).
A max of 140 amps.

Edited to add: You know, this is a point of confusion for me. Funny, but I've never had charging sources so large that I had to worry about it or figure it out! I have a 60 amp shore charger, obviously solar is no large source (say 40 amps max), and my alternator (150 amp) doesn't regularly show more than about 65 amps going to the batteries.

Now I'm trying to get my mind around the 140 amp scenario. Despite a huge acceptance rate (5c), my batteries don't take 100 amps from my alternator (or at least not long enough for me to see it). (Probably a good thing or it would be toast.) But why is that? I'm not sure to be honest. This is coming up because you'd have to run very large wire to accommodate 140 amps at decent voltage drop rate (say, keeping bulk over 13 volts). But is that much really going to flow through? My experience says no, but I can't really say why. (Also buddy's experience.) I hate to tell you to run massive wire if it's not necessary. Okay, back to my blathering, but I just want to be clear that I'm not completely sure on this point.


One other thing: We know the wire itself will pass 140 amps because your starter is going to draw much more than that. So what we are talking about here is sizing the wire for acceptable voltage drop in the normal charging current scenarios.

3) Length of run.
~25 feet.

Is that a for sure or an estimate? Reason I ask is that I think your start battery on the 460 is on the driver's side, then you are going nearly all the way to the back plus "across the hall" to the generator compartment, right? I don't mean to doubt you, I'm just remembering that mine is something like 16-18' and that is only to just under the front of the couch (my start battery is on the passenger side, so like you it has to cross over, plus the wire has to go down to frame level, then back up again). I'm just double checking, because at least for me, I have found that my estimates seem to "grow" when actually using large cable. Maybe you already have that sussed though.

Unless there is a good reason to run an additional wire I would use the chassis ground.

Most just use the chassis; I was just checking. One thing is that you will need to change (or install anew) the two little negative "leaders" to be the same size as the positive wire (or larger). This is the one from the house bank negative to the frame, and the one from the Ford start battery to the frame (or frame like object they chose). For your sake, I hope the one on the 460 is easier to do! I still have the custom bent wrench (and a few new swear words) from when I did the one on my V10 start battery.

5) Short circuit current rating of your house batteries all added together (this will determine the AIC rating for the fuse holder on the house bank end of the combiner wiring).
The manufacturers support line (Interstate) tells me that a single 6 volt Golf Cart battery is rated at 2289 amps short circuit. I am not sure how the fact that I will be using 2 of them in series effects this (didn't think to ask him). He stated that a 2000 amp fuse would be "fine".

Okay, let's just have a little laugh about that last bit, and then move on along. In order for a 2000 amp fuse to be "fine" you would need wire approximately as big around as a tree trunk. Hee. Actually, that's just a guess. My chart only goes up to 4/0 and that is protected only with a fuse no larger than about 375 amps. What size wire would be good to 2,000 amps?! --- better get a bigger truck to haul it around!

Anyway, back to the short circuit rating. What that is is how many amps could *instantly* rush out of each battery if you, say, dropped a wrench across the terminals. Or had some other unforeseen short in the circuit (wires rub on frame or whatever). It's like all the stored power rushes out at once. The reason we need to know this is not to size the fuse (that is sized to protect the wire), but rather to size the TYPE of fuse. Some types of fuses would just melt or blow apart with that number of amps and then there goes your protection (and your Chinook). So we look for fuses/fuse bodies that are rated with an AIC (ampere interrupt capacity) of that much. But we still size the fuse for the wire.

On the 6 volt in series and how it affects short circuit rating. Good thought. Sometimes things aren't what they immediately seem with two batteries in series. But in this case, you do add the two figures together. So in other words, you will have 4,578 short circuit amps. (Amp hours don't double but the short circuit amps are about how much power the battery holds in bulk.) That is the house bank. The start battery we don't know, but if you use an MRBF (which is a convenient size and shape), they are good to 10,000 amps so you are covered. On the house bank would I use a fuse rated at 5,000 amps? That's kind of close so maybe not. If you have the height, I think I'd choose the MRBF because then your spares can do double duty (and it's rated at a very comfortable 10,000 amps AIC). But on the house bank you are also going to want to consider the form factor and how you are going to lay things out.

I don't mean to keep making you "do more work," but can you check on two things and then we'll get rolling?


1) Is the 25' length realistic once you run the actual wire, secure it, etc.
2) Remind me the size of your house bank (ah @12v) I know it's two 6-volt batteries but not sure the size.


Onward!

BG

PS: On the acceptance rate. Here are a couple of interesting notes. Remember I said that Lifelines have a 5C acceptance rate? Well that means that theoretically, my batteries could accept 1,875 amps of charging. And yet I don't regularly see more than around 65 amps flowing from my alternator into my house bank (if I'm combined). A friend with a V10 (same alternator - 150amps) and 500 amp hours of Lifelines thought he saw 90 once, but regularly saw around 60. So maybe it is just that the engine "takes" 90 amps to run? I don't really know the answer to this. Maybe it's because the batteries are not 100% empty, but I don't think it is that based on Lifelines charge time estimates at various C levels.

But maybe this means you don't really need to check on the acceptance rate of the batteries, because it's almost certainly going to be more than your alternator size. And if my 150amp alternator regularly puts 60 amps into the batteries (which soon tapers), then maybe you will get 100 amps maximum? How about we start there. Or we can size for whatever amperage you want to.

[Blue~Go]

So, I decided why not run a scenario based on what we have now.

So, we know the wire needs to be able to be fused to at least 200 amps, to account for the starter draw. Using 105ºC rated wire, and knowing that it will be partially in an engine compartment (heat), we see that 1/0 will be able to carry a properly sized fuse, with a little extra in case your starter draws more and you need to up the fuse size. It's possible to use "exceptions" to cut that back, but as you'll see below voltage drop means you won't be wanting to do that anyway. So 1/0 105ºC wire is rated to 242.3 amps in an engine compartment (this assumes it is not bundled but is traveling alone). 1AWG would be 208, but 1 is kind of an oddball size anyway.

So let's start by saying we're going to use 1/0 based on the jump starting draw/fusing, and then let's run that size by through our voltage drop calculator at the 25' one-way distance you mentioned above.

If we say that 140 amps will be traveling through that wire, then at 13 volts the wire would have about 6.5% voltage drop. That means that, say, 13.6 volts (which is about the minimum I see on my Scangauge) would be about 12.7 volts by the time it reached the house bank. That's not ideal. OTOH, sometimes I see 14 volts. At 14 volts your batteries would see 13.2 volts.

However if your setup turns out to be like mine and my buddy's, and you only see say 80 amps (that's my 65 amps plus a little extra for your bigger alternator), then that would be cut down considerably. The figure at 13 volts would only be about 3.8% voltage drop (you can do the math).

If you went up to 2/0 wire, then at 13 volts you'd have 3% voltage drop. Obviously much better. I ran 1/0 wire but I only have around 16'-18' (I forget which now). That's because my house bank is under the couch so it's closer to the engine compartment by a good bit. I have no problem getting my batteries up to the absorption point, and even a little bit into it. Let's say I can get them 90% charged with enough driving. Solar easily handles the rest. I don't have any kind of voltage groomer on that wire, but I also have no need for the alternator to complete the charging cycle to 100%, and I didn't want to put the extra load on the alternator (I actually try not to combine at night, when I'm running the headlights, but that may be just unfounded conservatism - OTOH it's also no problem since I mostly drive the RV during the day anyway).

On top of all this, you are going to have your Ctek, so that's going to groom the power, presumably. Where will that be located? Close to which bank? Does it have a voltage sense wire (if so location won't matter as much).

[Blue~Go]

PS: On the fusing, as mentioned above, I'd probably choose to use MRBF on both ends, presuming you have the height on the house bank end (on the start end, at least with my passenger side Ford battery tray and the specified Group 65 battery, I have room for the MRBF).

If not, there are other ways to go (other form factors). I have an MRBF on the start battery, but then had to go to a Class T fuse on the house bank (but that's because my house bank has around 12,000 amps of short circuit power, so the MRBF has too small a rating at 10,000 amps). If you do only have two batteries with around 5,000 amps of short circuit potential as your house bank, then the MRBFs would be fine on both ends in terms of ratings.

[Riste]

As I review the numbers I am looking at the length (as you suggested Blue). Is it possible to run a 2/0 wire over the passenger door? The route going across the engine bay to the passenger side then through the firewall, then up and over the door, Then along the junction of the wall and ceiling inside to the refrigerator vent area.
The reasons I am thinking of putting the ctek in that area:
It would be close to the battery bank (in the old generator area)
I could bring in the solar in that area as well.
It would be easy to bring shore power to that area.
I need to do something to cover the exposed black fiberglass where the microwave used to live.

I'm having a problem attaching pics tonight.
How do you highlight other peoples words and bring them into your reply?

[Blue~Go]

Hi Riste,

Note: See next reply for illustration of the quote procedure.

I'll start with the easiest: To quote in reply, look up to the right and you will see a large "quotation mark." Hit that and everything will be quoted. Then you can pick and choose what you want. If you just want to remove some of the quoted material, just delete it. If you want to "interweave" quotes and responses, then you have to do a little finagling. What I do is highlight and "copy" the string at the beginning of the quote (it will have name and a bunch of numbers and brackets). In other words, the original "single" quoted block has some code at the beginning. This is a pain to type out, so copy that onto your clipboard. The code at the end is easy to type in each time (bracket slash quote bracket).

So to do interwoven quotes, I put the end code (manually type the bracket quote thing in) at the end of the phrase. Then I type in my words. Then for the next bit of quoted material I paste in that beginning code I copied, then at the end manually type in the bracket quote ending. And so on.

Next, on the wire. Maybe I'm not understanding but did you know you can fairly easily go through the "step well" area? If you take out a few screws and lift up that black plastic step surface, you will see a huge space (which probably already has some wires in it). Does that help or am I missing the point?

Lastly, I came back just now because I was re-reading about %C charge rates. As I mentioned earlier I have never had to pay much attention to these because I never have "large" charge sources to worry about. Anything I have is well within limits without really figuring it all out.

So I mentioned 5C. That's huge (500a for every 100ah of battery). Reading more closely (using Lifeline battery manual) that is the inrush current it can tolerate. But then they don't mention (that I have found yet) the maximum "regular" charging. They do mention they'd like to see at least .2C as a minimum.

The reason I was looking at this at all was to see if the batteries would even take your 140 amps from the alternator. As you have probably noticed, between your long run and high amp alternator, you would need very large/heavy/$$ wire. But what if the batteries either wouldn't accept that much charge, or the alternator wouldn't output that much to them? (Because it can be limited by either "push" or "pull.") Then there would be no sense in cabling for low voltage drop for that number of amps. (We're speaking of charging here, not jump starting which we know we have a handle on.)

I do know that my 150 amp alternator doesn't seem to regularly put more than about 65 amps into my house bank, even if it is down to about 50% SOC. With 375 amp hours of Lifelines, I think they *could* easily take more (even the MINIMUM .2c recommendation would be 75 amps). But they don't (or more isn't provided). My buddy with 500ah of Lifelines (same alternator/V10) said he thought he had seen 90 amps, but when we later checked that we never saw more than about 65 (same as me).

So why is that? And does that mean you will also see proportionately less from your 200 amp alternator? How much power does the Ford system take? I don't know the answer, and it's not something I have needed to figure out. But with a 25' (or longer) run, it's a good question.