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Topic ClosedLithium Battery install ?
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offgrid View Drop Down
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    Posted: 27 Oct 2019 at 7:08pm
Just to clarify your flow chart, when you say you're going to go from the 7 pin connector to the junction at panel, you mean you're going to isolate that circuit from the distribution panel itself, right? Otherwise you would be providing a connection directly from the 7 pin connector to the Li battery, bypassing the b2b charger. 

I've never traced out the routing of the TV 12V circuit from the connector to the panel, but it doesn't really matter where between the trailer connector and the panel you place the b2b charger. as long as the charger is regulating the TV battery voltage before it gets to the Li battery. The shorter the conductors in that circuit are the less resistance losses you're going to have.   You could even locate the charger in the TV between the battery and the trailer connector if you wanted to.
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Posts: 1014 		Direct Link To This Post Posted: 28 Oct 2019 at 7:28am
Originally posted by offgrid

Just to clarify your flow chart, when you say you're going to go from the 7 pin connector to the junction at panel, you mean you're going to isolate that circuit from the distribution panel itself, right? Otherwise you would be providing a connection directly from the 7 pin connector to the Li battery, bypassing the b2b charger. 

I've never traced out the routing of the TV 12V circuit from the connector to the panel, but it doesn't really matter where between the trailer connector and the panel you place the b2b charger. as long as the charger is regulating the TV battery voltage before it gets to the Li battery. The shorter the conductors in that circuit are the less resistance losses you're going to have.   You could even locate the charger in the TV between the battery and the trailer connector if you wanted to.

Correct, the thought is I find the junction and splice in before the panel. I have to say I like the idea of putting it in the TV before the pin connector! Yet another reason I ask such things! Thank you
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JR View Drop Down
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Posts: 364 		Direct Link To This Post Posted: 28 Oct 2019 at 7:32am
If this helps when I installed solar on my 179 last fall and the 179 is a 2019, the TV charging wiring going through the 7 pin connector was wired directly to the + side of the 12v trailer's battery.  Hope this helps.  Depending on where the WFCO convert is located, mine was in the back of the 179 by the entry door, and the + lead from the convert to the battery was one direct wire but the - lead was wired to the frame by the passenger side trailer wheel and then taken from the frame near the battery box to the - side of the battery.  Just some more incidental information.

Have fun,
Jay
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Posts: 1014 		Direct Link To This Post Posted: 28 Oct 2019 at 9:20am
Originally posted by JR

If this helps when I installed solar on my 179 last fall and the 179 is a 2019, the TV charging wiring going through the 7 pin connector was wired directly to the + side of the 12v trailer's battery.  Hope this helps.  Depending on where the WFCO convert is located, mine was in the back of the 179 by the entry door, and the + lead from the convert to the battery was one direct wire but the - lead was wired to the frame by the passenger side trailer wheel and then taken from the frame near the battery box to the - side of the battery.  Just some more incidental information.

Have fun,
Jay

Interesting.. Mine has only the main battery cable & the Solar-on-the-side line. You have a third? I know there is a buss bar (of sorts) near the auto-fuse underneath the camper up front. My thought is this may be where the 7 pin wire goes. That auto fuse does go to the battery.. That's the first place I hope to trace.

Another wet day today, so won't get out there to trace lines today, even with the power dis-connected.. 
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Olddawgsrule View Drop Down
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Posts: 1014 		Direct Link To This Post Posted: 28 Oct 2019 at 10:38am
Found it! 7 pin leads/line splices right up front underneath the camper, 182g port side. Just follow the connection pigtail back to the camper and you'll see the splices and the auto-breaker.

This is where I tapped in the for the inverter I had in there before. I already have the hole/grommet to run the wires. I was hoping for this! This will place the Dc/Dc charger up by my water heater and right where I hoped to place the lithium battery. 

Rain has let up, so I'm taking advantage while I can. I'm updating as I print out the pin positions to ohm out the 12v line.
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Olddawgsrule View Drop Down
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Posts: 1014 		Direct Link To This Post Posted: 28 Oct 2019 at 11:35am
Okay, that was the easy part! The battery is not direct wired off the 7 pin.

This is the mess underneath with the splices and auto fuses.

Top and right top is the 7 pin line from the TV to the splices above.

This is the 12vdc line from the 7pin 

Here the same line heads back towards the panel. Those two Red lines above are returns.

The two return reds now connect to the auto fuse.

Out the other side of the auto fuse and onward to the battery.
.  

Now for the decision of where to tap in.. 

To keep in mind here.. I'm going to dis-connect the Converter/Charger, it will not longer be part of the system. With that said, I still believe I can tap into the 7 pin splice. If so, this could be very easy as I would only need to re-route the battery cables and connect up the lithium battery. 

Thoughts???
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Posts: 1014 		Direct Link To This Post Posted: 28 Oct 2019 at 11:48am

Flow Chart
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offgrid View Drop Down
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Posts: 5290 		Direct Link To This Post Posted: 28 Oct 2019 at 2:27pm
Looks like you're on a good track. 

Just a couple of suggestions. 

If you place your solar charge controller in the same area then you'll have all your power electronics in one place. 

Overcurrent protection: I would add a fuse at the battery + terminal. That is where the high current is going to come from in the event of an electrical fault in the dc circuit. There should already be a 30A breaker on the conductor to the 7 pin connector at the TV battery so that line is protected. If you're running 10 gauge then use a 30A fuse, but its possible that might blow if you operate the slide while some other loads are on. 6 AWG would be better, with a 50A fuse. 

You can physically disconnect the 12V side of the WFCO, nothing wrong with that, but I'd suggest also turning and taping off its ac circuit breaker so it doesn't ever get energized. 

If you add a battery monitor that actually clocks amphours in and out you will have a way to monitor true battery state of charge on that expensive Li battery to replace the crappy lights that won't work for Li anyway. if you do, get one that uses an actual inline current shunt not a hall effect donut, those drift a lot. 
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Posts: 1014 		Direct Link To This Post Posted: 28 Oct 2019 at 4:16pm
Originally posted by offgrid

Looks like you're on a good track. 

Just a couple of suggestions. 

If you place your solar charge controller in the same area then you'll have all your power electronics in one place. 

That I will work on and think about. Now, the solar is a 'suitcase' kinda think I put together,

Overcurrent protection: I would add a fuse at the battery + terminal. That is where the high current is going to come from in the event of an electrical fault in the dc circuit. There should already be a 30A breaker on the conductor to the 7 pin connector at the TV battery so that line is protected. If you're running 10 gauge then use a 30A fuse, but its possible that might blow if you operate the slide while some other loads are on. 6 AWG would be better, with a 50A fuse. 

This is one of the reasons of tapping in where I hope to. I catch the 7 pin in and splice the DC/DC inline. All fusing is in place as it runs now. All I've done is change the charging from the WFCO to the DC/DC. It stills runs through all existing fuses... No?

You can physically disconnect the 12V side of the WFCO, nothing wrong with that, but I'd suggest also turning and taping off its ac circuit breaker so it doesn't ever get energized. 

To this the thought is dis-connect it. I would no longer require any of it's service. If correct on this.. the Shore-power is independent of the WFCO and will run when plugged in. Well AC side. DC side will be dependent on my battery only.

If you add a battery monitor that actually clocks amphours in and out you will have a way to monitor true battery state of charge on that expensive Li battery to replace the crappy lights that won't work for Li anyway. if you do, get one that uses an actual inline current shunt not a hall effect donut, those drift a lot. 

Oh, I have two of the already. When you run solar you need to know both incoming and outgoing. I do agree on a shunt being better... I've tried both and am a fan of ferrite in it's place.. just not in this situation.. Mine clocks watt hrs. 

Thank you for responding, I was awaiting you! 

As I sit right now, I've been able to recharge the PbA's (dual 6v's) and run the Frig (on battery) while driving. That tells me I have enough amps coming through to maintain. I no longer battery run the frig while driving. I find propane to be so efficient, inexpensive and easy. Now the system just has to re-charge the batt's. System is good and TV power is good (not all can state that).

Question becomes:What have I missed here? I'm not asking to draw anything greater than what I have already and use. 
Question is: Am I tapping in at the right spot?

I 'think' I am... 
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offgrid View Drop Down
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Posts: 5290 		Direct Link To This Post Posted: 29 Oct 2019 at 6:17am
Yes, true, if you connect the dc dc converter where you're suggesting you're not interfering with any existing overcurrent protection. The reason to add a battery fuse is because there should be one there, FR is remiss in not having one there already in my opinion. That is where the current is going to come from if you have a conductor or charge controller fault, and you're not protected now. Any halfway decent power circuit designer will tell you that is bad practice.

If you disconnect the dc side of the wfco it won't do any charging, but if you leave the ac side on it will remain energized when you're plugged in. Just turning the breaker off and taping it as a reminder will fix that. You could also go in there and disconnect the ac from the wfco but then you'd have to remove those conductors or otherwise protect them from shorting out. Shutting the breaker off accomplishes the same thing. 

Current transformer donuts ( CT's) work fine for ac circuits because their magnetic fields are continuously varying in a known way. But they can't measure the static magnetic fields in dc circuits. Hall effect sensors work on a different principle, are much more fussy, and are sensitive to external stray magnetic fields.  That's why a simple current shunt is much more reliable for dc measurements.

I don't think you've missed anything other than I suggest you get a good understanding of what the BMS in your Li battery does and doesn't do. It needs as a minimum to do cell balancing. Some also provide a backup max voltage cutoff, and some also have a thermal cutoff. If yours doesn't have those features, depending on your risk tolerance you might want to add them externally, Victron for one has a product that does that.  Consider that you will be sleeping on top of this battery which could catch fire if it ever gets seriously overcharged...unlikely but not impossible...


 
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