Lithium battery upgrade.

[Rick Scorey]

I know a lot has been written on topic of lithium battery upgrades. I am looking for specifics if anyone has them. I’m trying to keep this as simple as possible.

I have a 2023 25’ Globetrotter with the factory 300 watt solar panels. I plan to upgrade to 2 – 100AH lithium batteries, brand yet to be determined. I want to keep the batteries in the current front mounted battery box and everything as generic as possible. I am doing this mainly to extend the 12 volt refrigerator run time.

I am planning to use the current converter and solar charger system making only configuration changes to the solar system (I understand the converter will auto detect the lithium batteries). I want to add a Victron shunt and a Victron DC to DC charger.

My questions are as follows:
1) Can anyone provide the model numbers for the Shunt and DC to DC charger?
2) For the install of the Shunt, it looks like I need to do some re-wiring in the box. Currently, the left side of the trailer goes to the left positive terminal on the battery and the right side of the trailer goes to the right terminal on the battery. The grounds on the opposite corresponding negative terminals. I assume I have to put both sides together to the new shunt for the positive. Is this correct?
3) What is the best way to hook up the DC to DC charger? Where does the center lug of the 7 pin trailer to car connection terminate in the camper?
4) Will the modification fit inside the current battery box or do I need smaller batteries?

Thanks in advance,

Rick

[jeffb831]

For the shunt, I used the IP65 500A one and mounted it in my battery box.
For the DC/DC, I used the Victron Orion 12-12 18 Isolated.

For the shunt, you need to combine the negatives. There should only be 1 negative leaving the batteries connected to the shunt and all loads go on the output of the shunt. I was able to move all the positives wires to the opposite terminal on the batteries so all positives come from the opposite battery as the negatives/shunt connection. I was able to fit the shunt and BB GC2 batteries in the box.

The 7 pin terminates wherever the "rats nest" of wiring is - it's where the DC distribution panel, solar charger, inverter are. If you look under all your couch cushions, there should be an access port. I'd add the charger in there if there is room.

[Tyler2you]

See suggestions below. Unfortunately, some of this gets complex quickly.

Originally Posted by Rick Scorey

2) For the install of the Shunt, it looks like I need to do some re-wiring in the box. Currently, the left side of the trailer goes to the left positive terminal on the battery and the right side of the trailer goes to the right terminal on the battery. The grounds on the opposite corresponding negative terminals. I assume I have to put both sides together to the new shunt for the positive. Is this correct?

Best way to approach this is to buy a Negative Buss Bar. Remove all of the negative connections from the batteries and connect them to the buss bar. Then run a new cable from the bus bar to one side of the shunt and another cable from the other side of the shunt to the negative connection on one of the batteries. The only positive connection to the shunt is the 18 gauge wire that powers the bluetooth and electronics.

3) What is the best way to hook up the DC to DC charger? Where does the center lug of the 7 pin trailer to car connection terminate in the camper?

If you have a FBT model, the 7 pin connections terminate in the DC distribution box under the head of the curbside bed. Wiring and configuring the DC-DC is a complex topic that's going to take some research to figure out what's best for your combination of batteries and tow vehicle. Many folks choose to rely on solar alone and just disconnect the charging connection in the DC box or remove a fuse in the tow vehicle.


4) Will the modification fit inside the current battery box or do I need smaller batteries?

If you buy LifePO4 batteries that are the same dimension/group size as your current batteries, you can make it all fit. It won't be fun and you may have issues with bluetooth range if you put the shunt in the battery box. Most folks end up putting the shunt inside under the bed. You're also going to want to install a disconnect switch so you can completely isolate the batteries for storage.


Thanks in advance,

Rick

Here's another thread with some good info:

https://www.airforums.com/forums/f37...nt-239802.html

[JeffKim]

We have a 2023 GT 25FBT with 300W on the roof. Getting more refrigerator hours is good, but I think how far you want to go with upgrades depends on your style of camping. If it's a few days unplugged then two lithiums with the 300W and some TV charging should be adequate. I can work remotely and wanted to be able to work a week or so boondocking without a generator. So I ended up installing 400Ah of batteries and an extra solar controller for plug in panels (among other things). Depending on how far you want to go, it's a rather large rabbit hole and there many sophisticated and elegant solutions posted here in forums as you might have discovered.

With regard to the WFCO converter, a forewarning, I ran across this thread on the WFCO lithium autodetect before we picked up our GT and thought "this can't happen to me", but of course it did. It was a PIA to get it to switch over. Hopefully, yours will work but I ended up junking the WFCO for a Victron charger which plays well with all our other Victron equipment.

Another thought, the battery box size limits what will fit to Battle Born and a few others. Taking the plunge and moving the batteries inside there's a lot more battery brands to choose from and leaves room to add more juice later and also you don't have to cram everything into the battery box. I have average mechanical skills and I was able to do it without too much frustration and cursing. After a ton of research and consternation I put in bargain basement lithium and will see if I chose wisely but so far, so good after almost one season.

Last, I've posted this on a few other similar threads but while you're in the rat's nest and adding the DC/DC charger, I advocate swapping the standard issue Victron Blue MPPT 150|35 with a Victron MPPT Smart 100|30 which is more than adequate for the 300W panels. It's easy to do. The Smart has Bluetooth so you can follow solar charging on your phone and the existing wall display plugs into it. It also has VE.Networking so it optimizes with any other Victron equipment you might add later. I sold the 150|35 on eBay for about what I paid for the 100|30.

Charging wire terminates on the positive bus bar.

[1StreamDream]

Originally Posted by Rick Scorey

2) For the install of the Shunt, it looks like I need to do some re-wiring in the box. Currently, the left side of the trailer goes to the left positive terminal on the battery and the right side of the trailer goes to the right terminal on the battery. The grounds on the opposite corresponding negative terminals. I assume I have to put both sides together to the new shunt for the positive. Is this correct?

some good answers thus far, I will just add one point for consideration about the "split" wiring you see in your battery box. It is very likely that the "split" leads you have don't go left side/right side for powering your trailer, it is most likely true that one set of +/- wires goes to your main DC distribution area, and the other set of +/- wires goes directly from the battery box to your DC inverter (wherever it is in your particular trailer). The DC distro area is almost always up front, close to the battery box, the inverter can be elsewhere. Be very careful about how you combine wires, especially when you combine to a single negative wire for the victron shunt device. The size of that wire (everywhere in the relevant wiring path) MUST be large enough to carry the total maximum DC amps your trailer *could* draw, and if you are not comfortable with electrical wire gauge and amp rating tables, you need to consult with a knowledgeable electrician, this can get very dangerous if you undersize that wire. In my trailer, I upgraded that victron shunt path (and other similar paths) from a #6 AWG and a #4 AWG to single 2/0 AWG wire. Be careful in your combination plan.

[Tyler2you]

Originally Posted by 1StreamDream

In my trailer, I upgraded that victron shunt path (and other similar paths) from a #6 AWG and a #4 AWG to single 2/0 AWG wire. Be careful in your combination plan.

This is very good advice and something I should have mentioned in my response above. Upgrading the wires in/out of the shunt is something you need to take into account since you're directing all the current down one path vs. two.

[Rick Scorey]

Thank you for the great advise. Would it be advised to do the re-wiring first, install the cut off switches and install the shunt on the current AGM batteries. Then at a later date, simply replace the AGM with lithium and do the disconnect or add a DC to DC Charger?

[Tyler2you]

Originally Posted by Rick Scorey

Thank you for the great advise. Would it be advised to do the re-wiring first, install the cut off switches and install the shunt on the current AGM batteries. Then at a later date, simply replace the AGM with lithium and do the disconnect or add a DC to DC Charger?

Rick--I don't see anything wrong with that approach. Recommend taking pictures of everything before you start disconnecting wires so you'll have a reference point. Also recommend that you wrap the ends of any hot wires you disconnect with electrical tape or something non-conductive until you get the batteries out of the way. Those stiff wires have a way of finding their way to ground just when you least expect it. It can create quite the spark fest or melt/damage things if you're unlucky. I also have a composite ratchet I use when working around batteries to avoid any mishaps.

[GOUSC]

Originally Posted by Rick Scorey

Thank you for the great advise. Would it be advised to do the re-wiring first, install the cut off switches and install the shunt on the current AGM batteries. Then at a later date, simply replace the AGM with lithium and do the disconnect or add a DC to DC Charger?

If you are placing the batteries inside your RV this should work. However, One problem I can potentially see is the size difference between AGM and lithium batteries if you place them in the battery box. I’ve seen AGM installs with the shunt and busbars placed higher in the battery box and the AGM height is low enough where it will work. If you use Battleborn GC2’s in the box they are higher and deeper. You can place the shunt up high but the buss bars will have to go lower.

[GOUSC]

FYI - attached are pics of a shunt install with lead acid batteries and Battleborn Lithium GC-2 batteries. This will give you an idea of the size difference. The person who did the lead acid installation did not have a waterproof shunt so he placed it outside the box in a waterproof container. The person who did the Lithium installation used the Victron IP65 waterproof shunt and placed it inside the battery compartment.

This will give you an idea of how you can place your shunt and pos / negative buss bars for a lithium install. If you do the install in the battery box using the lead acid set up in those pictures (and the IP65 shunt in the battery box) I think you would have to move your buss bars to a different location as they would be in the way of the GC2's.

[Rick Scorey]

Wow, you guys are great. Thanks again for all the good ideas. I plan to purchase lithium batteries that are the same size as the AGM batteries or go to a smaller output battery. I also will use a waterproof shunt so I can put it outside the battery box if necessary.

[utah bob]

Thanks a ton! I have exactly the same rig same year and all. The posts were very helpful. I’m planning on the same mods in the near future. Thank you.

[Rick Scorey]

I am finally getting ready to move ahead with my lithium battery upgrade. Here's what I am planning to do.

1. Purchase one 300 AH Eposh battery. This should fit in the battery box by trimming the handles if necessary.
2. I will add a Victron DC to DC 18 amp charger.
3. An on/off switch and fuse will also be added.
4. Hopefully my current charger will sense the lithium battery and not need to be replaced.

This all should fit in the battery box. Here's my question. The Eposh battery has a bluetooth battery monitor. I'm assuming that this will make the shunt unnecessary. Am I Correct? I also think the single battery makes the install easier and gives me more capacity than 2 100 AH batteries. If I need to replace the current charging system what would be recommended?

As a reminder, I am doing this mostly for the 12 volt Refrigerator. We use this trailer mostly for 2 week trips and are not trying to run the A/C or any large appliance. Is this a good solution? Am I missing anything?

[field & stream]

Two small points: if you remove the battery handles I suggest you wrap a sturdy strap or two around the battery for future removal, and adding a portable panel could help you get through shady times.

[JeffKim]

Originally Posted by Rick Scorey

I am finally getting ready to move ahead with my lithium battery upgrade. Here's what I am planning to do.

1. Purchase one 300 AH Eposh battery. This should fit in the battery box by trimming the handles if necessary.
2. I will add a Victron DC to DC 18 amp charger.
3. An on/off switch and fuse will also be added.
4. Hopefully my current charger will sense the lithium battery and not need to be replaced.

This all should fit in the battery box. Here's my question. The Eposh battery has a bluetooth battery monitor. I'm assuming that this will make the shunt unnecessary. Am I Correct? I also think the single battery makes the install easier and gives me more capacity than 2 100 AH batteries. If I need to replace the current charging system what would be recommended?

As a reminder, I am doing this mostly for the 12 volt Refrigerator. We use this trailer mostly for 2 week trips and are not trying to run the A/C or any large appliance. Is this a good solution? Am I missing anything?

We have a shunt, but I think a lot of people with Bluetooth batteries use the monitor and are happy with it. The Epoch 300Ah battery looks like a good choice if you can fit it in, as you point out it's a lot more than two measly 100Ah batteries. Hopefully there's enough slack in the inverter cable (or positive bus cable) to reroute it to the positive terminal.

Our stock AGM batteries came with a 100A MRBF on the positive terminal (those square block things). I know that a lot of people prefer the Class T fuse which is less likely to arc-over if it's blown. Lithium batteries can discharge very quickly so it's a concern. I did some research and kept the MRBF fuse, but it's a consideration. It might be hard to fit a Class T block in the battery box however especially with the On/Off switch.

Yes, hopefully the autodetect works for you. I didn't like that when I finally got the WFCO working, it was putting out something like 18A, so I replaced it anyways and basically didn't trust it to reset to lead-acid.

Don't forget to set your solar controller to lithium (#7 on the dial). But like I said I much prefer replacing it with the Bluetooth version. Adding a solar cutoff switch is a good idea as well.

I'm not sure what you mean by two-week trips. Are you trying to boondock for two weeks? Or just going between hookups? We have 4x100Ah and 300W on the roof and 400W external panels (no generator) and can go about a week with good sunlight before the batteries start getting low (with Starlink, computers, in addition to the frig).

[Rick Scorey]

I have already upgraded the Victron Solar controller to Bluetooth. We normally boondock but I also have a small 200 watt Honda generator that runs on propane. When replacing the WFCO, what unit did you replace it with?

Thanks again.

[JeffKim]

Originally Posted by Rick Scorey

I have already upgraded the Victron Solar controller to Bluetooth. We normally boondock but I also have a small 200 watt Honda generator that runs on propane. When replacing the WFCO, what unit did you replace it with?

Thanks again.

I replaced it with a Victron Phoenix IP43 12/50A. I really like it since it plays with all the Victron equipment and provides an optimal charge at the battery if you have the Victron shunt. It also doesn't have a fan, but it's also fairly expensive ($483). A cheaper option a lot of people have replaced the WFCO is the Progressive Dynamics 9100 lithium charger ($300 or so). It comes in 45A and 60A models. Also there's Boondocker*. Also, there's the Victron IP22 30A ($180) which I think others tout but I'm a little skeptical it's heavy-duty enough especially if you have a 300Ah battery. However, it will fit in the same slot as the WFCO charger, with the others it requires mounting it in the vicinity of the converter wiring it in (picture). It took me about an hour.

*I've heard Best Converter is a good resource and they probably know a lot more than I do.

[Tabawhatt]

Originally Posted by Rick Scorey

I am finally getting ready to move ahead with my lithium battery upgrade. Here's what I am planning to do.

1. Purchase one 300 AH Eposh battery. This should fit in the battery box by trimming the handles if necessary.
2. I will add a Victron DC to DC 18 amp charger.
3. An on/off switch and fuse will also be added.
4. Hopefully my current charger will sense the lithium battery and not need to be replaced.

This all should fit in the battery box. Here's my question. The Eposh battery has a bluetooth battery monitor. I'm assuming that this will make the shunt unnecessary. Am I Correct? I also think the single battery makes the install easier and gives me more capacity than 2 100 AH batteries. If I need to replace the current charging system what would be recommended?

As a reminder, I am doing this mostly for the 12 volt Refrigerator. We use this trailer mostly for 2 week trips and are not trying to run the A/C or any large appliance. Is this a good solution? Am I missing anything?

Just wanted to follow up... Did you end up installing the 300 AH? I'm looking at Lithium as well and thinking of a similar approach.