Lithium LFP 100amp 12 volt Upgrade from 6 volt Lead Acid - 40 amp "reverse battery protection" fuse

TerryLee · October 18

Hello everyone. I am learning all about a Lithium Battery Upgrade to 12V 100 amp LFP from 6V Lead Acid for my 2022 Tab 320s Boondock with 105 volt solar panel. (No inverter). I am using Grok AI for assistance. The AI mentions that the 40amp overall protective fuse located as the last fuse in the fuse panel, for battery protection may not be enough to cover the voltage from the upgrade 100amp Lithium LFP battery. It suggests adding a ANL 100 amp Blade fuse. Has anyone done this before and if so, adding this to the wiring for the battery in the front tub.. is that what you've done? is there any other alternative to protect? Thank you everyone in advance.

Sharon_is_SAM · October 18

What converter do you have? WFCO lithium compatible converter should have a 40 Amp Reverse battery protection fuse and a 30 Amp battery charger fuse. The wiring in the tub is for the battery and the fuse is 30 Amp.

TerryLee · October 18

It is a WF 8735/8740 AD which has the automatic lithium detection. The AI seems to think the Battery Protection fuse is not adequate enough for a Lithium LFP 100 amp upgrade, and that a protective ANL fuse be installed between the battery and the inside power panel, putting that fuse in the tub.. but there is no Inverter.

mjwaldner · October 18

Keep in mind that the fuses in the system protect the wire. So you should select a fuse that is appropriate for the gauge of wire. Wire gauge needs to be selected based on the current draw of the system. And yes you should have a fuse or breaker at the battery. Do you not already have that from the factory?

TerryLee · October 18

I believe the circled fuses are the inline fuses attached to the battery cables. So, these would need to be upgraded to handle the Lithium 100 amp LFP upgrade?

mjwaldner · October 18

You don’t want to change the fuses without changing the wire. One of the green fuses would be your solar. How many wires are coming off the + side of the battery? It looks like just the 2 but hard to see.

mjwaldner · October 18

If you’re not planning on adding an inverter to the system you should be fine not changing the wiring as you have not introduced any new loads. The new battery will be able to source much more current than you need and this is fine as your system will not need it. Is the converter charger in your camper able to charge lithium?

TerryLee · October 18

So, there are 2 wires coming off the current interstate Lead Acid battery. There is no inverter, and I wish to upgrade to a lithium LFP 100 amp battery. The 40 amp battery protection fuse is just fine and I do not need to add that 100 amp ANL fuse, is that correct? No.. I do not want to add any more load to the entire system I simply want to boondock more days is all, and I have a Bluetti AC200L for the AC needs! My model year of the Tab has the Lithium auto detect in the converter. Please confirm I won't overload my 2022 Tab 320S Boondock with 105 watt solar panel by simply upgrading the battery to 100amp lithium LFP! Thank you so much! Well for safety sake I should install that ANL fuse on the positive battery wire.

mjwaldner · October 18

The worst thing you could do is upgrade to the ANL 100 fuse without upgrading your wiring as that would be a fire hazard.

Unless there’s something unusual about your system that I’m unaware of, you should be fine. The only change is the overall storage capacity. In the worst-case scenario, the 40a fuse would blow to protect your system. If that happens, you’d just need to track down what’s drawing that much current.
With that said i'm not sure if there are any problems with moisture having the battery in the tung box. Maybe other 320 owners can chime in on that.

Also, make sure you’re aware of the limitations of charging in cold weather.

AnOldUR · October 18

Don't confuse amp hours with amps. One is the amount of power available over a period of time. The other is the the actual current being drawn from the battery at any given moment. Some LiFePO4's will allow you to pull 100 amps from the battery, but there's nothing in your system that will draw that much. The existing wire and fusing will offer all the protection that you need.

If you do install an inverter with a potential for larger demand, it would be wired directly to the battery and use a dedicated ANL fuse and wires size appropriate for size of the inverter.

pthomas745 · October 18

On your battery wiring, there are two sets of cables. One set is for the battery power to the trailer, and the other set goes to the solar port on the side of the tub. Both the positive cables are equipped with 30 amp fuses.

Many owners have installed lithium batteries in the 320's with no changes to the fuses at the battery or the fuses inside the converter.

In the trailers with the larger battery banks, inverters, etc, there are larger "battery protection" circuit breakers, but these setups are usually twice the size/amp hour rating of your 100 amp hour battery. Many 320 owners installed multiple batteries (lead acid or lithium) and made no fuse changes.

Sharon_is_SAM · October 18

TerryLee said:

So, there are 2 wires coming off the current interstate Lead Acid battery. There is no inverter, and I wish to upgrade to a lithium LFP 100 amp battery. The 40 amp battery protection fuse is just fine and I do not need to add that 100 amp ANL fuse, is that correct? YES - do not change the fuse size. No.. I do not want to add any more load to the entire system I simply want to boondock more days is all, and I have a Bluetti AC200L for the AC needs! My model year of the Tab has the Lithium auto detect in the converter. Please confirm I won't overload my 2022 Tab 320S Boondock with 105 watt solar panel by simply upgrading the battery to 100amp lithium LFP! Thank you so much! Well for safety sake I should install that ANL fuse on the positive battery wire.

You will not overload your 100 Ahr battery with a 105 watt panel. We had a 140 Ahr lithium battery and used 200 watts of panels and a 30 A battery fuse. Please don’t listen to AI. It is frequently wrong. In addition, the WFCO Lithium 8735 AD needs a jumper to permanently set it to lithium. Have you tested the charging system to confirm that it remains at lithium charging? You should see a blue light.

TerryLee · October 19

Ok. I will follow your guidance! SO in the end, I need to simply swap the 6v lead acid battery with the 100 amp Lithium LFP battery I bought. No change to any wiring, or fuses either connected to the battery, or inside on the fuse panel. I've confirmed with NuCamp that my 2022 tab 320s model has the charge controller that will auto adjust to the lithium battery, but, I will make sure through the Victron app that it does do that. I do heed the warning about AI, because by the time you keep asking questions more and more items seem to be needed and thus more money spent. Thank you so much for all of your help.

Sharon_is_SAM · October 19

@TerryLee - I think you mean the “converter” that auto adjusts to the lithium battery. The charge controller works with your solar, but you can monitor the effect of the solar and the converter on your battery via the VictronConnect Connect app.

TerryLee · October 19

Yes, I am very much a newbie here!

SLJ · October 19

Asking Grok AI electrical questions? No. Unless upgrading to an inverter to run AC or microwave (which a single 100ah barttery really won't do) do not change the value of any fuses. If you are adding an inverter follow the inverters installation instructions.

ckjs · October 19

FYI: if you were to install an inverter, you’d run new beefy cables directly from it to the battery posts. The exact size depends on the oomph of the inverter, but #2 gauge is about the thinnest needed. Our 2kW inverter uses 5 feet of 2/0 cable.

Marceline · October 19

SLJ said:

Asking Grok AI electrical questions? No. Unless upgrading to an inverter to run AC or microwave (which a single 100ah barttery really won't do) do not change the value of any fuses. If you are adding an inverter follow the inverters installation instructions.

I just came here to say this. I'm a professional translator and I've been using LLM's for a decade and I cannot emphasize enough that they should not be trusted - especially for something as critical as electrical wiring. People need to understand that AI isn't "intelligent" at all. It doesn't think. It just spits out a statistically probable set of words.

Don't burn down your trailer (or house) with this nonsense.

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Lithium LFP 100amp 12 volt Upgrade from 6 volt Lead Acid - 40 amp "reverse battery protection" fuse

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