Replacing AGM with lithium in 2021 tab320 BD

Yoshi_TAB · December 2023

Hi @rickpool

Yes agree with @Horigan . For your shunt to correctly read all the DC loads in the trailer, the shunt must be connected to the negative post of the battery so current from the all loads flow through it. If I did not use/have a shunt, the negative would go straight to the busbar like the positive.

The 225A fuse is very important (and only used) for the inverter circuit. Every circuit must be protected by a fuse. The 225A fuse protects the inverter circuit wiring. The inverter fuse is large because it protects a circuit with the potential of 2000W (inverter). To determine the size of a fuse for a circuit, Amps=Watts/Voltage. In this case you also assume the inverter is 90% efficent, so 2000W/0.9=2222 watts. So Amps= 2222/12=185 Amps. You generally add in a safety factor of say 20%, so that would be 222 amps, rounded to 225 amps for the common size fuse available. The 2/0 AWG wire is based on a 225 amp load. I used a class T fuse based on reading I did on inverter circuit protection. Class T fuses are considered the gold standard for interrupting a ton of current, making it great for use as a main battery fuse particularly for lithium batteries. The disadvantage of a Class T fuseis it's big and pricy. I added a switch to isolate power to the inverter. The capacitor in an inverter can hold a charge for a while. If you do not have a way to isolate it, if/when you connect the positive lead to the battery, you can get a large spark unless the capacitor has completley discharged. Here's the other part of my set up if you have not seen it. Just one way..there are others

Keep asking questions...happy to share what I learned.

Image: https://us.v-cdn.net/5021717/uploads/editor/m2/eqi9l8fdey7m.jpg

AnOldUR · December 2023

immanence said:

Why do people add shunts - is it to have something more accurate than the MPPT?

@immanence a shunt doesn't actually measure the level of charge. What it does is measures the current going in and out of your battery. The state of charge (SOC) is based on knowing the theoretical capacity of your battery. Over time slight inaccuracies can cause the reading to be off, but if properly set up it will re-calibrate itself to 100% SOC when topped off with a lithium compatible charger.

The Vitron app for the MPPT only reads voltage, not amperage. The voltage curve of a LiFePO4 is too flat to be an accurate way to determine your SOC.

Yoshi_TAB · December 2023

Hi @immanence

Just to add onto @AnOldUR a shunt can also track and allow you to see how much current (amps) each of your devices in your TAB are using. When you turn on a DC device such as the fridge, Alde, light, you can see the amount of current flowing or amps being used. So it allows you to manage the capacity of your battery when boondocking and estimate when you might run out of battery

as you use a device. You also can see when current flows into the battery from solar or chargers.

immanence · December 2023

Okay... I need a shunt haha... I am too much of a charge junkie not to have that accurate display!! I saw someone post one in another thread that was 40 bucks, so they don't seem expensive anyway.

I guess I am going to have to put off finishing this for a couple more days while I order a shunt... I keep adding components and delaying this project. Thankfully next camping trip isn't until December 31st! Haha!

And... This is a grounding bar, correct?

I was connecting battery negative to it and just thought: wait, why do I assume this is a ground? (Battery not actually attached yet.)

AnOldUR · December 2023

@immanence you might want to consider a Victron shunt. It's a bit more pricey, but will network with your Victron MPPT solar controller and other Victron devices for better efficiency.

https://www.amazon.com/gp/product/B0856PHNLX/ref=ppx_yo_dt_b_search_asin_title?ie=UTF8&th=1

Image: https://us.v-cdn.net/5021717/uploads/editor/z2/4ewscnh7721l.png

Yoshi_TAB · December 2023

Yes, that is the ground bar.

There a re a couple shunts..the victron requires the use of a bluetooth app to see the data or Renogy has one with an extenal display..personal preference and significant price difference. You'll get a "charge" using either of them

Amazon.com: Renogy 500A Battery Monitor with Shunt, High and Low Voltage Programmable Alarm, Range 10V-120V up to 500A, 20ft Shielded Cable, Compatible 12V Lithium Sealed, Gel, Flooded Batteries,Black : Automotive

https://www.amazon.com/Victron-SmartShunt-500AMP-Bluetooth-Battery/dp/B0856PHNLX/ref=sr_1_2?crid=3IN16KI6KVTNH&keywords=victron+dc+shunt&qid=1702601012&sprefix=victron+dc+shuntt,aps,45&sr=8-2

immanence · December 2023

@AnOldUR and @Yoshi_TAB thanks, I appreciate the recs! 500amp version looks like the one I want?

I would like a display, but I also really like the idea of staying in the ecosystem. Either way, is the old gauge with the water monitor no longer useful?

And from reading, I will just wire this between the negative terminal on the battery and the ground bar? Any other considerations there?

Thanks to you both again!!

immanence · December 2023

Also with the Victron shunt, some reviews are saying they needed more Victron components to make it work well, but does it do okay if just interface with the MPPT?

pthomas745 · December 2023

I have a Victron shunt and that is the only Victron device in my trailer. The Solar controller can provide a readout of "current" , in amps, going into or out of the battery. It is fairly simple to work out how much power each device uses with just a little time and addition/subtraction. The main attraction of the shunt is it is a "counter" of amps into and out of the battery. For example, if your trailer has used 16 amp hours from a battery...it will tell you that. As the battery recharges, the "counter" will start "counting up".

Multimeters and the Solar controller readouts are still very useful for battery monitoring, they simply take a bit more "practice" and experience to understand what you are seeing.

immanence · December 2023

@pthomas745 are you using a multimeter to monitor the draw or individual devices? If so, what are the common monitoring points for you? Seems like most would require getting into under the benches.

Thanks for the heads up on the Victron. I think I am going to go with that. The review I noted sort of feels like an anomaly.

pthomas745 · December 2023

I installed a shunt a couple of years ago. It is a great upgrade, but learning how to use a meter was great training and experience for me. On my 2017, if I wanted to use a meter on the battery, I would have to open the battery box in front of the trailer. But: I also have a "solar port" on the trailer, and it is connected directly to the battery. I can simply use the meter at the port. ( I still would turn the battery switch off).

An owner on the FB page a few weeks ago moved the battery inside the trailer, and the person who installed it for her installed some battery terminals inside the tub in case a separate charger needed to be used, or other devices attached to the battery (an inverter, for example). Very creative idea. The terminals could also be used to monitor with a meter.

Recently, I bought a 50 AH lithium battery (139 dollars on Prime Day!) and then purchased the "40 dollar shunt" from AiLi through Amazon. It does all the things that the Victron does, but..it doesn't have bluetooth.

SLJ · December 2023

immanence said:

Why do people add shunts - is it to have something more accurate than the MPPT?

The shunt allows me to just glance at the monitor on the wall. Accurate and no phone needed. Don't have to get to the battery. Don't need batteries with Bluetooth. Or if you want to use your phone you can get a Bluetooth shunt/monitor.
I still have a Victron battery monitor that cuts my solar controller and smart charger if the batteries drop below freezing but that's the only thing I use it for. Can still see the Victron solar controller and smart charger on my phone but rarely look at them.

Image: https://us.v-cdn.net/5021717/uploads/editor/6w/qowusyxam27a.jpg

Yoshi_TAB · December 2023

Hi @immanence.

That is correct. The shunt goes between the negative battery and ground wire. It's mounted to something so its solid. Many connect them as close to the battery as possible. There is also a small positive wire to power the shunt that needs to be wired to the positive side of the battery. One thing to look out for is on the victron shunt, the bolts used to connect the negative wires to the shunt are someone large in diameter. You can look them up on line to make sure you get the correct ring size to crimp to your wires.

I also have the Victron. Again a personal choice, but I like less displays/lights inside my TAB. It also has some nice trend features on the app. which is sort of geeky to look at and sometimes helpful to see what's going on and troubleshoot.

Yes, the battery monitor on the Nucamp panel (i.e water gauge) is no longer accurate with a lithium battery becuase the full state of charge (SOC) for lithium is slightly different than for a lead acid battery and that scale range can not be changed. You can get the battery voltage from the solar app, but having it in the shunt app. is a bit more convenient to see the current at the same time. You tube a few shunt videos and you can see how to use them. As @pthomas745 always says, that monitor is not accurate even for lead acid batteries.

AnOldUR · December 2023

Yoshi_TAB said:

... but I like less displays/lights inside my TAB. It also has some nice trend features on the app. which is sort of geeky to look at and sometimes helpful to see what's going on and troubleshoot.

Like @Yoshi_TAB, I didn't feel the need for another display inside our T@B. If my OCD is kicking in, the app is easy enough to use and has enough information to satisfy the urge. For a quick reference, I put a volt meter up front on the tub. It's wired with a short run directly to the battery. If you understand its shortcomings, it can provide useful information at a glance. If I see it below 13.2V, I know I need to open the app.

note that the cigarette lighter port can be used with any 12V device, but also as a place to plug in a lithium charger to top off the LiFePO4 batteries.

Image: https://us.v-cdn.net/5021717/uploads/editor/ia/eqult9hihlv1.jpg

immanence · December 2023

@Yoshi_TAB I went to go finish hooking up the Lithium battery because I got my shunt today, and I was going to remove the batteries from the front tub, but there is a lot more going on here than I expected.

A couple of these are the solar input, so I expected that, but there seems to be more going on. I've got three going out the back of the tub. One is to the switch, but the other two I don't know. I thought they'd go to the junction underneath the trailer, but if that the case shouldn't there only be one addition wire to the brakes?

I did but this trailer uses, and they added an extra 12v battery, but now I am wondering if something else is going on as well? Afraid to cut power if I'm accidentally losing something else.

pthomas745 · December 2023

@immanence , follow the black "wire looms" from the battery, those plastic spiral things. One will be for the trailer, and that set of cables will go to the junction box behind the tub. Another will be going to your solar controller, where ever that happens to be, but that set of wires should also go back into the trailer...but not through the junction box. Do you have a "solar port" in this model year? If so, that "might" be the third set of cables. Follow the wire looms!

immanence · December 2023

@pthomas745 my mistake, there are only two! It was hard to see until I removed the batteries.

It turns out what I thought was a third loom running out is a actually a totally separate loom just ziptied to the other looms. Probably connecting the brakes on the other side of the trailer.

I did confirm what you said about one loom going to the junction and one loom just going straight into the trailer. I think I just psyched myself out. Thank you!

The offending loom:

AnOldUR · December 2023

@immanence I may not be seeing the path of your wires correct,
but it looks to me like you're wired "the wrong way" ...

immanence · December 2023

@Yoshi_TAB @pthomas745 WE HAVE LIFTOFF!!!!

Going to do some cleanup and documenting, but everything appears to be working! Thanks again for all of your help!

bjn2 · December 2023

I chose to move our LiFePo battery into the trailer because that likely will mean I don't have to deal with adding a heater so the battery can accept a charge when the outside temperature is freezing or below. Note that NuCamp is putting lithium batteries inside the trailer in 2024. Also, inside mounting means better security for relatively expensive LiFePo batteries. Note also that for 2024, NuCamp is using a WFCO panel that doesn't include a converter - it's basically an AC/DC junction and fuse box. The converter/charger is now a separate component. Stay away from anything featuring WFCO's autodetect. In my experience it never detects our lithium battery.

Yoshi_TAB · December 2023

immanence said:

@Yoshi_TAB @pthomas745 WE HAVE LIFTOFF!!!!

Going to do some cleanup and documenting, but everything appears to be working! Thanks again for all of your help!

Excellant..lets see some pictures..always fun to see other set ups...

Yoshi_TAB · December 2023

immanence said:

Probably connecting the brakes on the other side of the trailer.

Hi @immanence

Just so your aware, the wire for the emergency electric brakes does not come from the battery compartment.

There is a junction box under the frame of your trailer. The electric brakes are wired to the junction box stud #6. The positive wire from your battery compartment also goes to the junction box stud #6 but after the switch (battery >switch>junction box> e- brakes). That is why the switch has to be on for their to be power to the E-brakes.

You still have power going out to the junction box ..correct? Just checking

The other wires are for your tow vehcile 7 pin connector.

Here's a photo from the files section of this forum.

Image: https://us.v-cdn.net/5021717/uploads/editor/tq/2gy3cim8j5sd.jpg

immanence · December 2023

I created a new thread with pictures here: https://tab-rv.vanillacommunity.com/discussion/17955/litime-230ah-lithium-battery-install-in-2021-tab-320bd#latest

Thanks again for all of your help!

@Yoshi_TAB yes power still going out to junction. I need to do a brake check test just to be 100% sure though.

rickpool · December 2023

@Yoshi_TAB and @immanence - I am trying to understand whether I need a negative bus bar (as I believe Yoshi_TAB user) or can I simply tie all negatives into the grounding bar (as I believe immanence did)? Thanks as always for my continuing education!

immanence · December 2023

@rickpool there are only a two (if I recall correctly) free slots on the grounding bar already in the trailer. I am guessing that Yoshi's build with the inverter, etc just needed more grounds, but I'd wait for them to chime in. I just needed one for the battery and one for the diagnostic LED I put in.

Yoshi_TAB · December 2023

Hi @rickpool

A bus bar is used to keep the wiring "cleaner" such as less connections on a single battery terminal or if you have no open spaces on the OEM busbar , etc. As mentioned, I also used it because of the larger 2/0 AWG wire used for the inverter part of my install which is too large to tie into the OEM bus bar (sized for 10 AWG wire).

If you have open slots on the OEM bus bar, it can be used and a new busbar is not necessary.

rickpool · December 2023

Thank you both! I understand.

rickpool · December 2023

I am trying to simplify the charging of my new LiFePO4 battery without swapping out my older WFCO in my 2021 320. Is there a preferred way to “permanently” install a separate 20a LiFePO4 Battery Charger? 1. Is “permanent” a bad idea? 2. Can I connect it to the battery terminals directly or should I connect it to the Bus Bars? 3. Can I leave it plugged into the 110 circuit that feeds the Air8 (and manually swap the plugs if ever I need the Air8)? 4. Can I leave the WFCO unit switched on (to battery) when charging the battery (note I do not have an inverter)? 5. Do I need to isolate anything else (like the TV 7-pin)?

Thanks!

Marceline · December 2023

rickpool said:

I am trying to simplify the charging of my new LiFePO4 battery without swapping out my older WFCO in my 2021 320. Is there a preferred way to “permanently” install a separate 20a LiFePO4 Battery Charger? 1. Is “permanent” a bad idea? 2. Can I connect it to the battery terminals directly or should I connect it to the Bus Bars? 3. Can I leave it plugged into the 110 circuit that feeds the Air8 (and manually swap the plugs if ever I need the Air8)? 4. Can I leave the WFCO unit switched on (to battery) when charging the battery (note I do not have an inverter)? 5. Do I need to isolate anything else (like the TV 7-pin)?

Thanks!

I have an old (2013) T@B. I've had a lithium battery since Jan 2020.

Here's my philosophy on charging:

First of all, I don't think it's worth it to install lithium unless you do a lot of camping off the grid.

If you mostly camp off the grid, you will mostly be charging from solar or maybe a generator. So the converter is moot. I'll swap out my old converter when it dies.

I know that people use their campers in all sorts of ways, and of course it's fun to add all sorts of bells and whistles, but what's the "use case" for quick-charging (20a) from shore power? I would think that adding a DC-DC charger would be more useful.

Yoshi_TAB · December 2023

Hi @rickpool

I'll answer your questions...but maybe others can also chime in.

1. Permanent is ok if it's properly installed. By that I mean secured in place so it does not move around while bouncing down the road and fuse protected on both the DC and AC side. If it's plugged into an AC outlet, the breaker will offer protection on the AC side. I've seen some chargers have their own DC fuse, but some may not. Also a way to disconnect power to the battery like a switch between the battery and charger would be advised (IMO)

2. This is where a busbar comes into play. IMO, a busbar is best so you do not have multiple/stacked connections on your battery terminals. Having stacked connections can lead to loose wires at the connection points, poor contact points all leading to points of failure or weak connections. Or worse yet, a place where loose connections can spark.

3. Yes that would be fine. As an option, the WFCO has room for 5 AC circuits, and only 4 are most likely being used. So you can add a new dedicated AC circuit. (I believe you have a newer 320?). The circuit breaker can also be used to cut power to chrger when not needed.

4. I'm not certain if having two (WFCO & standalone) chargers on is an issue, if that is what you mean. If your standalone charger is plugged into an outlet in the TAB, power would need to remain on. As an option it's easy enough to disconnect the WFCO charger. It's two wires that are spliced into circuit #1. I don't have pictures, but I removed the wires when I insalled my transfer switch so the charger would not work when powering the WFCO on battery power. Here's a link where someone used a relay. Lithium Charging voltage low in Bulk mode (vanillacommunity.com)

5. Nothing occurs to me.

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Replacing AGM with lithium in 2021 tab320 BD

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