Well that makes two of uskyidletime wrote:When you say "batteries" as in what my converter/charger is charging, you're referring to my house battery(s), not my start battery, right? I guess that's another dumb question, but it's early and I'm not fully awake yet.
I should have said "house battery" each time, but I may have slipped. I'm so used to two or more that maybe I said batteries. At any rate, the converter/charger charges your house batteries. That said, if you have a bi-directional separator (and I believe the Surepower 1315 in the '97+ Chinooks and also the Blue Sea 7622 are bi-directional), then some of that charge could be shared with the start battery, presuming conditions are correct for the separator to combine the two banks (which they likely would be).
kyidletime wrote:FYI I took a look at my converter/charger and although it is a 45 amp Magnatek, it is a 6345 model rather than 7445. I suppose that mine is just an older version of the same thing. My panel board CTL is a type 1, rating 30 amps, 120 vac.
I just took a look at one of those, and I see it's the same brown box, generally the same layout, etc. as the one I had. A couple of the pages I looked at are linked below, which show things pretty well:
http://www.ourelkhorn.itgo.com/convert.htm
http://home.earthlink.net/~whemme/
I would still encourage you to run a new/larger wire from the battery to the charger (the same wire likely also handles your DC loads; it did in my original setup). I know how it can sound overwhelming when you start thinking of everything at once, but maybe once you have the other things done you will reconsider it?
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Okay, anyone not really interested can just stop right now and move on to other topics. Fair warning
Just as an example, based on what my era Chinook has, and extrapolating it to where your house battery is under the hood on the passenger side...
Let's say 45 amps are running along the wire...
And let's say it's #8 wire (as in my era Chinook, but you can easily see by checking the red wire that comes in to the brown box as the supply - mine was in upper right over the DC fuse block).
And let's say the wire runs like mine does, but plus then continues on since your house battery is in a different place (now maybe they route the wire differently, but it's a long way no matter how you slice it). So, from the charger over to the wall = 3'
Over to behind the shower = 1'
Up to the wiring chase that runs above the window = 6'
Forward along the wiring chase to the forward overhead = 9'
Down the pillar to the floor and through a hole to the underside of the coach = 6'
Over to the driver's side frame rail = 2'
Forward along the frame rail, then up near the steering column to the engine compartment = 6'
(well ignore the solenoids for now)
Across the firewall to the passenger side = 5'
Then to the battery terminal = 2'
Total positive wire run = 40'
Then for the negative. Now usually, DC circuits are counted "both ways." Meaning the positive and negative run are added together (current has to flow through the whole circle). However, Chinook uses a chassis ground for much of the negative, so that is like a huge wire. So we can give a little credit. But there are still leads to get to the chassis, so we'll put those in:
From the charger to the chassis ground lug that is under the shower area = 7'
From the house battery to the frame = 2'
Total negative wire run is 9'
The chassis isn't infinitely huge, so I'm not sure what to "assign" that, but to be favorable, we'll just not count it at all. So of the wire we are "counting," we have 49'. Let's call it 50' which is 25' "one way."
So I go to voltage drop calculator and plug in the numbers, and get a voltage drop of 12.5% I have let the chassis part slide, but I would assume it has some voltage drop, tho maybe not much, as it is a "huge wire." (Is good to clean those contacts periodically, as they are outside under the rig.)
So the charger is putting out 14.4 amps, which is likely about what you want at 77º (just taking average flooded cell battery here). Now put in 12.5% voltage drop, and the battery actually gets 12.6 volts. Ugh!
Let's say you ran a new wire on a shorter route, under the couch by the wall.
So, from the charger over to the wall = 3'
Forward along the floor-to-wall joint under the couch and behind the water tank, then through the hole to the underside of the coach = 10'
Over to the driver's side frame rail = 2'
Forward along the frame rail, then up near the steering column to the engine compartment = 6'
Across the firewall to the passenger side = 5'
Then to the battery terminal = 2'
So this is now 28'
We'll keep the same lengths for the chassis ground leads, but also consider enlarging them so that you could go to a fuse size with a bit more headroom (optional).
From the charger to the chassis ground lug that is under the shower area = 7'
From the house battery to the frame = 2'
Total negative wire run is 9'
The chassis isn't infinitely huge, so I'm not sure what to "assign" that, but to be favorable, we'll just not count it at all. So of the wire we are "counting," we have 37'. Let's call it 38' which is 19' "one way."
Let's shoot for 2% voltage drop and see what size wire we come up with... I'd guess #2 would be a bare minimum size, but let's run the numbers. I'm using 14 volts since we're talking about the 14.4 volt output here.
#6 (6 AWG) gets it down to 6%, which turns the 14.4 volts into 13.5 volts. Still too much for my taste.
#4 gets it down to 3.8%, which turns 14.4 volts into 13.8 volts. Better.
#2 gets it down to 2.4%, which turns 14.4 volts into 14.05 volts. Much better
#1 is somewhat unusual, so we'll skip that.
1/0 gets it down to 1.5%, which is great but I already know there is no way you are running a 1/0 cable. It's tough when the charger is SO far from the house battery! If you were planning a more boondocking-heavy use, I'd be suggesting that you move the battery bank to under the couch, make it two batteries, and as a side benefit have a much shorter run, but since you are only planning the occasional night boondocking for now, and want to keep mods down to a dull roar, I'm not.
There is another option though....
You could go with a 40 amp "marine style" charger, and mount that under the couch. Say inboard of the water heater. Now your charging wire run is MUCH shorter, and you have a charger of which all the voltages can be adjusted specifically for your battery type (now and later), and you can either equalize automatically or manually or not at all. The output is temperature compensated, so when your house bank is at 90º or 42º the charger output will be automatically adjusted to "equal" the settings you put in for 77º F. It's more expensive, but I think you more than get what you pay for, plus you get a much shorter wiring run to the batteries. To me the temperature compensation is worth the whole thing, because why worry about voltage or voltage drop, if it's 40º out and you are charging at 14.4 volts (77º) but it should be 15.0 volts? (I don't have the manual for your battery, so used the Lifeline temperature change.)
The AC wiring being longer is not a worry because at 110 volts, voltage drop is not a concern.
So let's say you put it up by the water heater somewhere (either by wall, or between heater and front of couch).
Now you have a relatively short run from the charger to the fuse block ~12'
And from the charger to the house battery is ~18'
We'll count the negative leads to the frame at 6'
So that's 24' from charger to house battery "round trip", which for the calculator we halve to be ~12'
Now running the same voltage drop calcs:
#6 (6 AWG) gets it down to 3.8% , which turns the 14.4 volts into 13.8 volts. Still too much for my taste.
#4 gets it down to 2.4%, so 14.4 is 14.05 volts
#2 gets it down to 1.5%, which turns 14.4 volts into 14.18 volts. Not too bad.
#1 is somewhat unusual, so we'll skip that.
1/0 gets it down to .9% Hey, 14.4 volts is still 14.27 volts!
Then on the "other" side, we have the run to the fuse block. This is around 12', plus we'll say 6' for negative leads, so 18', divided by two, is 9' effective one way run. We can also drop the 45 amps down to, say, 30 amps (this is just a guess in that you probably won't be running more than 30 amps on a regular basis through the house fuses. The wire will still be safe for the full amount, but we're talking voltage drop here. We do have to lower the voltage from 14 volts (which I used to calculate the charger run) to 12 volts. Most loads are supposedly fine with 10% voltage drop, with more sensitive things wanting no more than 3%, so I like to shoot for 3% overall on the load side of things. This still realistically results in more voltage drop, because you still have the runs to the loads themselves. But I feel it is acceptable.
So if you re-used some of the #8 wire you just got rid of...
#8 (8AWG) results in 3.5% voltage drop using our figures.
#6 (6 AWG) gets it down to 2.2%, so really no need to go further.
You would then need to run an extension AC wire from the charger to the brown box.
I realize you may still prefer to go ahead with just the PD charger, but I figured I'd run some scenarios so you could see the numbers. Of course you already know I'd be putting a marine style 40 amp charger under the couch!
[Actually, I mounted the charger on the front side of the shower wall, under the back corner of the sink cabinet, BUT, I have the battery bank under the couch, so the run is not that long. I'm still going to be running large DC wire because every little bit counts with large DC amperages - I just wanted to use that otherwise wasted space, and I already have a bunch of stuff under the couch!]


