My Timberleaf Pica teardrop came with three different battery charging posibilities.
(1) Solar, which is my #1 choice.
A panel coupled with a decent solar charger is a gentle, mostly hands off, and fully self-suporting option that 95% of the time keeps up with my needs with virtually no active input from me. (I might pay passing attention to sun-exposure when choosing a campsite but that's not my first priority especially since I can remove the panel and set it out in a sunnier spot.)
(2) A shore-power charger, commonly called a converter, and, as is mine, often built into the power-distribution center.
This option requires being hooked up to shore-power - obviously - so it's not a self-supporting system. And because of our irrational obsession with size it's actualy pretty harsh on the battery. Seriously! What is the point of having a 40 Amp charger hooked up to an 80 Ah battery?
It's not like I'm pulling in to an EV charging station and am itching to get back on the road again by the time I pee and grab a snack!
If I hook my teardrop up to shore-power I'm going to be there for at least 8 hours. A nice, small, lighter, less expensive, 15 Amp charger is more than enough to take care of my needs, but you can't buy a power distribution center/converter in this practical and functional size.
Which makes no sense because all batteries, even Li's, appreciate and thrive on gentle foreplay and just like any of us, being repeatedly slammed with a hard pounding wears them out and shortens thier life.
Fortunately my Timberleaf was wired with a dedicated breaker for the converter. I leave this turned off, only occasionally flipping it on for a few minutes to confirm that the converter is still working.
If I want to use shore-power charging, say if the battery is down to 20-30% and I'll be parked deep in the woods for a few more days, I'll flip the breaker on then keep an eye on the battery monitor and shut the charger back off at about 80% charge to minimize battery abuse.
(3) DC to DC charger.
This device takes the raw output from the vehicle's alternator - which might be as high as 16V -
coming into the trailer on pin 6 of the 7-way connector, and tames it down to the proper algorithm for charging Li batteries without damaging them. Handy for putting a charge into the house battery when the vehicle is running.
I had one of these on The Van but rarely used it, so when I discovered that the DC to DC charger on the teardrop wasn't working it wasn't that much of an operational issue because I was getting along without it just fine. But it was a brain issue! One of those things that gives a person, at least one like me, itchy-brain. So I decided to figure out what was going on, even though that meant standing on my head and contorting in ways no human, let alone an old-man human, was designed for. After all, even if I don't use it, that DC to DC charger is supposed to be working!
But! While wiring diagrams for the trailer running-gear, lights, brakes, etc., are easy to come by, for some damn reason it’s rare to find an RV manufacturer that makes wiring diagrams available for the house-systems of thier products. (This is why I should stick to building things myself! I know where every wire in the cargo trailer and both our barns goes because I put them there - and still have the wiring diagrams to fall back on when I start losing my mind! I know - I know. There's some that claim I've already lost it, but they don't understand that some things were never in there in the first place so they weren't mine to lose - - -)
It's not like they don't have them. The diagrams are there for workers building the units. It's just that they apparently don't give a damn about the poor smuck that buys their shit!
Admittedly, most of us can't decipher such a diagram, but what about the repair person you call in? They could certainly use it!
When you buy a washing machine it comes with a wiring diagram - or at least one you can download from the manufacture's site. It's not neccessarily for you, but for the repair person you will have to rely on one day.
But the mobile RV repair guy, which in my case is me, is shit-outa-luck!
So here we go!
Once I verified that the truck is delivering the charge voltage to the 7-way I knew the issue was within the trailer. More specificly, probably back there behind the fire extinguisher where all the electrical/electronic stuff is hidden.
So now it's time to start taking things apart and try to create my own wiring diagram so I can figure out how it's supposed to work and from there what the hell is wrong!
The cloth is covering the positive terminal of the battery to prevent mishaps. Though I have the disconnect switched off, killing power to pretty much everything, that terminal is still hot and chassis-grounds are all over the place inside this small space. Inadvertently connect the two with a dropped tool and - well, it wouldn't be good!
Speaking of dropped shit, a trick I use when working in small, crowded places like this is to put a small magnet on my driver bit, sockets, or wrench so they hang onto ferrous screws, nuts, and bolts rather than letting them fall into some inaccessible space.
Using eyeballs and my meter I chased the incoming charging voltage from the 7-way, down the length of the trailer, to this auto-resetting circuit-breaker where the incoming black, or hot, wire changes to two seperate red wires that spiral off, along with the accompanying white ground wire, into the spaghetti-maze of like-colored wires stuffed into this small space.
Another quick meter-check shows the breaker is passing the charge voltage on through.
Crap! That means I have to start chasing individual wires snuggly bundled together with a lot of other wires, through tight spaces to figure out where they go and what's gone wrong! (If only there was something like - oh I don't know - a friggin WIRING DIAGRAM!)
After a lot of contortion, cutting of cable ties, unscrewing of cable clamps, scraping of hands, and a few scathing words, sometimes muttered, sometimes enunciated very loudly, I still wasn't any the wiser (it didn't help that one or two of the wires changed colors at butt-splices buried inside cable-bundles!), so I went at it from the other end to see if things would be any easier to track down. (Spoiler alert- no!)
I knew that in the panel just above the electronics bay I was rooting around in was a switch to enable/disable the DC to DC charger. (And yes, long before embarking on this folly I tried the switch in both positions just in case it had been installed upside down!) So I figured I'd start chasing from that end instead.
Well that wasn't any easier!
Oh, it was easy enough to figure out that the black wire plugged into the back of the switch was ground and the green hot, so that orange wire must be the one turning the DC to DC charger on and off. Chase it down and it will lead me to whatever is actually doing the controlling.
OK, yeah. That didn't work out quite so well.
You see - that orange wire disapeared, along with a bunch of other wires, none of them orange, into a wire loom (think plastic conduit) that loops through the living compartment and into the back of the electronics compartment - only there's no orange wire coming out the other end!
I had to stand on my head in the living compartment and tear open the wire-loom to discover that, buried deep inside that loom the orange wire was butt-spliced to a - oh crap! - red wire. Do you know how many red wires there are coming out the other end of this loom?! Five! I counted!
Eventually I managed to track that orange-then-red wire to this relay buried about as deep as you could get in the back of the electronics compartment, just above the battery and squeezed between the power-distribution center and the shore-power inlet, as far away from the actual DC to DC charger as you can get in here.
While I was nursing an aching head and trying to figure out how I was going to get that relay out so I could test it without disassembling the whole damn compartment, I also got to wondering
why the hot wire for the switch in the panel above was being fed through the battery monitor instead of directly to the switch.
So, to postpone trying to extract that relay, I decided to try and figure out the whole battery monitor side-trip thing.
I've been using this model of battery monitor - this is my third - for many years, but this is the first time I've seen these terminals on the back being used.
So I did some poking around in the blue-tooth interface for the monitor and buried in the 'settings' I found another tab for 'relay'
And found that this relay is for controlling an inverter (which I've never had and still don't), making sure the inverter is shut down if the battery charge-level gets below a user-defined threshold.
But more importantly, notice that the relay is disabled!
As soon as I enabled that relay through the interface and turned the orange-wire switch on, the friggin DC to DC charger started working!
Why in the hell someone decided to wire a switch to a relay through another relay, I have no idea. And one day I'll get my tools back out and bypass that monitor-relay altogether since it is unneccessary and completely redundant as well as introducing complications and potential failure points!
Now- maybe I should start drawing my own wiring diagram for next time? - Nah, maybe later -
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