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Old 10-13-2020, 03:50 PM   #1
Winnie-Wise
 
Join Date: Jul 2019
Location: Rochester, MN
Posts: 434
2108DS Lithium install: installing the batteries

See also my previous post on replacing the WFCO charger with a PD4655LIV.


Now that my charger in my 2108DS is ready for lithium batteries, it was time to put them in. These are GC2 100AH 12v batteries. I went with the GC2 form factor over group 24 as they looked like they'd fit better.




I'll post more about the actual install in a bit, but for now I thought I'd show possible orientations. Lithium batteries are sensitive to cold, and since I live in Minnesota I decided these better live inside the storage bay. Besides, they are mighty expensive and I don't want them out in the open. I opted for the driver's (street) side storage bay which is in the front of the TT.


The GC2 batteries fit perfectly in this space as you can see here. Of course the terminals are mighty tight so would be very difficult to inspect, but it could go this way:



Here are both batteries in place, but turned around so the terminals are toward the inside. You can see the batteries are now encroaching on the opening space of the storage bay.



Another possibility is tipping the batteries on their sides as they don't care about orientation:



They also can go on their backs and stacked like this:



There isn't enough room, though, to stack one on top of the other in their normal orientation. They stack to 22 inches high, and the space is only 21.5 inches high. Certainly a mod could be made to the bedside closet above, but I didn't want to get that deep into this project.

In the end I went with the last orientation shown, except I flipped the batteries over. This made the battery logo show up correctly, which was a nice benefit, but I was really looking for easy access to see and clean the terminals if necessary.
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Old 10-14-2020, 07:52 AM   #2
Winnie-Wise
 
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Ok, finally got the photos uploaded so here's the install.


Under the street side storage bay in the trailer frame is an electrical junction box (all 12v). This is another reason I wanted the batteries on this side of the trailer as this is where the connections are made. Here's what the box looks like pulled open. I have shore power and the battery disconnected.



Right in the center of that box you can see a lug where a bunch of wires are secured. You can't see the color of the big fat wire at the bottom as it tucks under the blob of wiring going out the right side, but that's a big red AWG 6 battery + wire heading toward the front (right from this point-of-view) of the trailer. You can see this wire going off the right side of the photo. I haven't tracked where the other wires go.

I temporarily unhooked this battery cable from the lug, pulling it out of the box, and routed it out the left side through a new 3/8" NM clamp in the middle knockout. Because this cable's connector was so fat, I had to first pull out the red/orange wires and also a ground (white) wire. This extra work was more frustrating than difficult.

Here's a view of the re-routed wire. You can see the new NM clamp in the middle left side of the junction box. I routed both battery cables to the storage bay as you can see between the junction box and the spray foam. The white battery - cable remains tied to the frame on the right side of the junction box (not in the photo). I did loosen that connection so I could turn the cable to point the right direction and routed the white cable over the junction box as you can see. To locate the hole for these wires I observed the existing pair of red wires (and gob of spray foam) that goes straight up to the battery disconnect switch. I decided an excellent location for these re-routed cables was to send them into the murphy bed space just behind the battery disconnect switch. With a small diameter (but long) drill bit, I drilled down from the murphy bed space and found the drill popping out through the insulation below. I had moved inland about 3 inches because the junction box is on an angled brace of the frame and I didn't want to get too close. It ended up just where I was hoping it would land.



Once I knew the hole was in the right place, I drilled it out bigger with a 3/4" spade bit. I didn't bother going into the insulation as I figured it would only wind up onto the bit. I then poked coat hanger wire down from the top, hooked on a cable, pulled it up, and repeated for the other cable.


I came up with a good solution for clamping the wire. I found a "hub" for a household breaker box that worked perfectly as a flange for another 3/4" NM cable clamp. It worked very well as you can see in these next photos.





You may have noticed in that second photo that I had 3 wires going through the clamp. This third wire is a new wire I was making up for the jack, but I had a doh! moment and realized I don't need to run the jack wire all the way up to the battery. Instead, I routed the original jack wire into the junction box you saw earlier and connected to that same +12v stud. The original wire was long enough to reach. Nice. Remember this stud connects to the battery. So in the final photo we are back to the original two battery wires. So, why wasn't the jack installed this way in the first place? My guess is the dealer installed the jack aftermarket and didn't want to get dirty crawling on the ground. Just a guess.


Next, I shored up the murphy bed side panels by gluing on some some 1/2" plywood to the inside. This helped make things more stable for holding the batteries and cables, as well as giving a more firm surface for screwing in the murphy bed access panel since the batteries will cover up the left side screw hole. Note that I used an electric staple/clamp to hold the cables to the panel so there's no chance the wires can get into the murphy mechanism.






In the last photo above you can see I've installed a Victron shunt which doubles as a mounting stud for the negative side of the battery. The positive side is temporarily bolted together. I have a covered positive stud on order and boot covers for all the cables. I'll post an update when I get those in place. For the time being I taped up that positive connection with red electrical tape (shown in later photos).

Another comment on that last photo: I hadn't yet clamped the wires on the backside of the murphy panel, but more important I hadn't yet re-routed the positive battery cable out the left side of the junction box. Yes, I got this far before I decided I had to do that re-routing. You can see I was very short of wire by having the cable come out of the original side of the junction box. It would have worked, but was tight.

At this point the batteries are connected and the rig has power. In the next post I'll show how I covered up the space to hold the batteries in place and protect from junk that's in the storage bay.
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Old 10-14-2020, 08:28 AM   #3
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#6 gauge wire is very, very small wire for 200AH of battery. Unless you are just going to power some lights, a TV, computers, gas furnace, etc with a 300watt to 500watt inverter. Also just a small charger of say 20amp max charging power.

Also how long is the wire run from the batteries to the inverter and/or charger.
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Old 10-14-2020, 10:32 AM   #4
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Quote:
Originally Posted by al1florida View Post
#6 gauge wire is very, very small wire for 200AH of battery.
Thanks for raising this topic as I totally forgot to comment on it! I'll estimate I have about 3ft of 6 gauge wire down to that junction box, and perhaps another run of 15ft to the charger. However, the charger has 30A fuses that limit this circuit.

I assume the other wires that are direct connected also have their own fuses. I know the jack has a 30A inline fuse right along the inside of the trailer frame below the propane tanks. I haven't traced the other wires yet. Recall the original deep cycle battery setup was 100AH which is also too much for 6 gauge wire (it claims over 300 cold cranking amps for what it's worth). One thing that makes me feel even better is that the battery's management system will shut off power on a short.

It's a little disappointing that all I get is 30A. Certainly that's plenty for output from the batteries, but I was hoping to ram in power a bit faster. I talked to Battle Born about this and it sounds like available chargers may not fit my unit (without serious mods), and there's the icky issue of replacing that 6 gauge cable. He did remind me that solar could be direct connected to the battery and could add to the 30A, but it certainly won't add 70 more amps :(
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Old 10-14-2020, 10:43 AM   #5
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I should also point out I have no inverter installed. Not sure if I'm going there or not. If I do, it'll need to be small, or I'll need to re-do the whole charger setup I think.
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Old 10-14-2020, 11:28 AM   #6
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I think you will be marginal with #6 wire for the dimensions you quote if it is serving a circuit that is limited with a 30A fuse. There are two considerations to wire sizing: ampacity of the wire and voltage drop and you are marginal on voltage drop.

A 21' run of #6 carrying 30 amps results in a 1/2 volt drop which is a bit too much. The ampacity (maximum current carrying capability) of #6 wire is 120A which is fine.

The reason why 1/2 volt drop is too much is that the charger sees the voltage at its output terminals and adjusts its charging accordingly. But what really counts is the voltage at the battery terminals. You want to keep the voltage drop down to about 0.2V for best charging performance which requires #2 wire.

I realize that very few if any RVs coming from the factory use that size wire, but I would.

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Old 10-14-2020, 12:30 PM   #7
Winnie-Wise
 
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It seems I should be planning for a wire upgrade in the future. For giggles I found a calculator here, without knowing if I can trust it (yet): https://www.calculator.net/voltage-d...s=30&x=21&y=28 I believe all that goop in the URL will give the right settings: 13.3v DC, 20ft of AWG 6. It's showing a drop of 0.24v which is close to target. If my wires are actually a few feet shorter, I'm good. But note that my estimate of distance is a wild guess right now.

I'm looking at what I'd need to do if I wanted to move up to a charger with, say, 75A. If this calculator is any good, it looks like I'd need AWG 1 wire. That's big stuff. Considering the work involved, I'd probably go a step bigger. No plan to do this soon, but good to know about. Also, note that Battle Born has already told me I can pump 100A into this pair of batteries (50A each) without any measurable added wear. This is NOT true for other types of batteries.
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Old 10-14-2020, 01:36 PM   #8
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You are calculating for TWO AWG 6 wires in parallel instead of one. Your voltage drop will actually be double your result. Also, you should only be worried about CHARGING current for calculation purposes, and really only when in bulk or boost charge mode. I would assume you would install an inverter in your pass through storage with the batteries, where you won't need huge wires. The 12V loads in your camper should be pretty small, and not sensitive to a little voltage drop.

Personally, I would run the batteries down and then see how the charging goes. Once you get some "real world" numbers from your shunt, and measure voltage at the converter and battery during bulk charging, you can call Battle Born to see how the voltage drop will impact charging.
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Old 10-14-2020, 02:26 PM   #9
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Quote:
Originally Posted by Old Navy View Post
You are calculating for TWO AWG 6 wires in parallel instead of one. Your voltage drop will actually be double your result. Also, you should only be worried about CHARGING current for calculation purposes, and really only when in bulk or boost charge mode. I would assume you would install an inverter in your pass through storage with the batteries, where you won't need huge wires. The 12V loads in your camper should be pretty small, and not sensitive to a little voltage drop.
Ah, dang, that explains it...thanks for pointing that out! The calculator does allow a choice for one conductor and I get 0.39v drop for 20ft.

I think if I want to charge faster I would put the charger right next to the batteries. I certainly have no plan to consume battery that fast, and if I do it would be via an inverter like you say. Then I could re-use the AWG 6 cable as the converter output over to my 12v fuse panel (with a 30A fuse).

My wife and I have been tent campers for years and years so we have habits (thankfully) that lend to not needing a lot of battery. For example, the TV is already gone, and the microwave will probably go too. I know many would think we are crazy...but that's how we are so far. So all that will be left on 120v would be the air conditioner (which has no plans for battery for me) and the electrical outlets. I don't plan to mod the outlets in any way, so I think for the small use of 120v AC I'd get a little portable inverter for running something like a laptop. But don't hold me to that! Just watch in a couple years I'll be adding that big inverter anyway!
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Old 10-15-2020, 06:14 PM   #10
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The batteries are all buttoned up, so I'll show how I did that. Nothing real exciting so this is mainly photos .

The inside of the storage bay has a curved front as that's how the front of the TT is formed. I fashioned a simple piece of 1/2" plywood with a spacer cleat along the top, and held it in place with a little plywood scrap as you see here. The plywood scrap also serves as a spacer to keep the batteries a bit away from the side panels of the murphy bed.


Here is what that back panel looked like when I was done. I added a cleat with a groove to stiffen it up as well as give a place for a side panel to slip into. I want this stuff to come apart fairly easily to access the batteries.


I picked up a 4-stud power distribution block from amazon (https://www.amazon.com/gp/product/B07C635FGR) that worked really well. It has a cover that needed a bit of tape to seal the unused openings. The 5/16" boots on the battery terminals are too small. I'm unsure if 3/8" would be big enough so I'll need to do more looking. But they are good enough for now.



Finally, I made an end cap that screws to the murphy bed panel (recall I added backer-board to that panel) as well as screws to the floor. A thin side panel closes it up.



All in all, I think it worked out well, and I think I'll be able to inspect the terminals easily without pulling it all apart.
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Old 10-19-2020, 06:08 AM   #11
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I put mine in the compartment where the head of the bed is stored when in the up position. With a slight framing bump out into the pass through compartment. This area is conditioned space, the passthrough is not.
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Old 10-19-2020, 06:59 AM   #12
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You noted you live in Minnesota, and your concerns then of the cold issues with lithium's and charging. I'm sure you know the magic line is 32 degrees and below for damage while charging them. I also doubt you want to camp in those temperatures all that much; but I'd expect your chosen compartment will easily fall to 20 degrees - in short order, if it's that cold outside. Not an issue for current discharge, but how to make sure it's warm enough when charging is your challenge. Nobody wants to inadvertently destroy such a pricy battery.
Temporary placement of an indoor/outdoor thermometer sensor in there might give you a feel for the compartment temperature versus ambient air temperatures. Best to you in your camping adventures.
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Old 10-19-2020, 07:06 AM   #13
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If I lived in MN and had Battleborn LiPo batteries I think I would remove the batteries in winter months and store them fully charge at my home in a space that doesn’t see freezing temps.
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Old 10-19-2020, 07:21 AM   #14
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I believe the storage specs for LiFePO4 batteries is to be between 50% & 70% charged, and for lead acid to be 100% charged.
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Old 10-19-2020, 07:50 AM   #15
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Yeah, I think I'll be bringing them in when I'm sure we are done for the season. We are thinking about sneaking in one more excursion .

The storage space of the 2108DS is pretty much "interior space" as much of it is divided from the real interior space by only 1/8" panel. The insulation is in the exterior walls. If we do this next trip it'll be freezing overnight so I'll put my SensorPush thermometer down there. It saves a log of data so I can see how it goes...though this will most likely be high-20s outside air. I might do a future test when it's in storage (in my backyard) and we have temps closer to zero. I could do that on shore power with the batteries missing.

Anyone have advice how to cover the lugs in storage? Hmm...maybe those small boots will have a purpose for this.
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Old 10-19-2020, 11:24 AM   #16
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There was also Room in the bed storage area to install my inverter and this was super easy to run battery wires from the Junction Box under the frame. If I can figure out how to attach a picture I will.
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Old 10-19-2020, 01:13 PM   #17
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Don't overlook the fact that it is the interior temperature of the battery that needs to be above freezing to charge.

If you are living inside the RV the temp in the inside storage compartment is unlikely to be below freezing.

Additionally there is some heat generated when charging the batteries so that helps keep them from dropping below freezing as well.

Bottom line, I would think the temp in the storage compartment would have to drop to at least 25* for several hours before the battery will start to go below 32* far enough inside the battery to damage anything.

I think it was mentioned you will be putting a thermometer in the compartment to know what the temperature is, so that really helps as well.
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Old 10-19-2020, 02:52 PM   #18
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I commented in your other thread. Glad it worked out for you on a weekend trip. Definitely get solar and make accommodations for the tow vehicle to charge the batteries in a better fashion.

I have been using Battle Born (two 100 amp) batteries for 3 years in my 25' boat. There it runs a Victron 2000W/80Amp inverter charger. Use is cooking microwave/induction burner, plus running two chest freezer/refrigerators.

My concern is several fold. You should be fusing the cables off the batteries as close as you can to the terminals. I would also want a manual "on / Off" switch. to isolate the batteries---and this would turn off the Victron monitor (which I also have).

Best practices would suggest that the unsecured 12 V positive bus bar may be a hazard. If you have secured it in a fashion so that it could never possibly touch the negative terminals--that is perfect. I don't trust many "Amazon" products made in China. I had a 300 amp Chinese on/off switch fail (spectacularly) at about a 150 amp load--melted complete with arcing!! Stick us US made and rated products!

Also I would be concerned about the tangle of wires, with multiple methods of attachments in the metal conduit box: small terminal with multiple connectors not covered. Wire nuts, Push thru wire connectors. Proper connectors should have covers over each positive connection, buss bars are better than multiple to a single terminal, and a swaged and heat shrink but connector is far safer, than wire ties and push thru wire connectors. Yep, the factory did it that way--does not make it "correct".

It has been mentioned, but for clarity, when measuring the length of wiring in a DC circuit one takes the total distance of wire of the positive and the negative. In this case, 20 feet of positive and 20 feet of negative, is 40 feet.

For charging off the tow vehicle or an engine alternator, I use a Sterling 30 amp battery to battery charger that is profiled for the LiFePO4 battery. In my personal case, I have a cross over switch, so I can use the same Sterling charger for charging from the towing truck battery (F250 6.7 L diesel) or the boat engine's alternator.

Thank you for the great illustrations of your install. Incidentally the LiFePO4 battery is one of very few which can be installed upside down!
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Old 10-20-2020, 07:05 AM   #19
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Bob, thanks for the comments! Lots to digest here. I've found this project somewhat difficult because I don't know the terminology so finding parts has been a little challenging. My plan is to update my setup as I learn, and hopefully there will be little value in parts that end up tossed. Perhaps I should be looking at marine suppliers for parts?

For the fuses are you saying I should put 100A (or maybe 50A?) fuses on all four cables? Then I think I'd want to find a fuse holder with boltable lugs on each side. I'd also like to find a better way to cover all these lugs. The "boots" I have sort-of work, but so far I've only found 3/8" (barely larger) as well as the square type that are for more standard automotive battery terminals. But I probably just don't know what to search for.

That tangle of wires on the frame under the TT really bugs me. I believe step 1 for me is to decode it all and make a schematic. An effort has already been done to this effect on this forum and I believe that diagram is close if not exact. I just need to verify and adjust. I'm not sure where I'll go from there. It would be nice to find a better, more weather sealed, junction box than this one that seems to be more suitable for use in a barn.
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Old 10-20-2020, 09:58 AM   #20
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For the fuses are you saying I should put 100A (or maybe 50A?) fuses on all four cables?
I'm realizing you meant the positive cables should meet at a fuse, and then the fuse should feed my positive busbar. That would make sense. I'm thinking I should also put my disconnect in this path.

Today the battery disconnect does not disconnect the jack and slide. Can anyone think of why I shouldn't have it whack those as well? I'm thinking that 99 times out of 100 I'll be messing with levelers and wheel chocks and will have the access door open anyway. I actually like the idea of disabling the jack so nobody can mess with it when the TT is in storage.
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