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Old 06-14-2021, 11:02 AM   #1
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Plainfield , Indiana
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A few questions on lithium upgrade

I have tried to do research on the forum and have collected a lot of data, but there are still a few questions unanswered for me. Here is my plan.

I have a 2013 FC 25' twin FB.

I am removing the batteries from the usual box location and replacing with two 12v 105AH lithium ion batts. These will be located in the front storage compartment. I plan to tie these down so no movement going down the road.

I will be purchasing a batt monitor with shunt. A fuse block with a fuse (i think 50 amp is what I need). A shutoff of course.

I do not plan on adding solar or solar controller. Big question is, what size wire do run between each batt and then to the DC block that exists in the unit? Will 2/0 be ok?

I really appreciate the help on this.
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Old 06-14-2021, 11:11 AM   #2
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Hi

Do you have an inverter? I'm guessing not, but it would be an issue if you do.

You will need to upgrade your converter / charger to run lithiums. The stock AS lead acid chargers will not do the job.

Unless you have an unusual shunt, it will go in the negative lead off the batteries. You will run a cable from the batteries to the shut and then another cable from the shunt to the negative bus in the trailer. Both will be the same gauge wire.

If indeed you have no inverter and 50A will handle all your loads, 2/0 is overkill. No problem with using it, but you could get away with something smaller.

If you go with a big converter charger (say 80A) that would impact your 50A fuse.

Bob
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Old 06-14-2021, 11:38 AM   #3
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Bob, thanks for responding so quickly. I forgot to mention that I dont have an inverter and dont plan to. I purchased the PD upgrade for my converter from Bestconverter.com which had the ability to charge the batts. The shunt comes with the Renogy monitor i'm purchasing. 50amp should take care of all my needs. So what size wire would you suggest? I just want to be safe and not start a fire or anything.
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Old 06-14-2021, 11:40 AM   #4
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I should also mention that the new converter is rated for 55amps.
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Old 06-14-2021, 11:55 AM   #5
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Originally Posted by rfequity1 View Post
I should also mention that the new converter is rated for 55amps.
Hi

If the converter is rated for 55A *and* it puts out 55A, you would want a bigger fuse. Something in the 60A range.

As far as setting a fire, the normal "rubber" insulated wire ( > 100C insulation) would be ok for 60A if it's a piece of number 6. Number 4 would be a common choice to give some margin safety wise.

https://www.usawire-cable.com/pdf/nec-ampacities.pdf

If it's a short run, there will not be much drop in it. Your 2/0 is well into the overkill range.

The reason you see big chunks of wire on batteries is that inverters pull a big chunk of current when something starts up. The wires usually are pretty long. You want a very low drop during that startup surge. You don't have any of that in your setup ....

Bob
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Old 06-14-2021, 12:52 PM   #6
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Ok, so that is 4AWG copper welding cable, right?
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Old 06-14-2021, 01:21 PM   #7
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Originally Posted by rfequity1 View Post
Ok, so that is 4AWG copper welding cable, right?
Hi

A welding cable is going to have *very* fine strands of wire in it. That's great for flexibility, not so great for putting connectors on ( the strands break ). Very normal automotive cable is just fine unless you have some major twists and turns.

Copper is the only thing you want to use. Aluminum wire has no place in any of this ever.

Once they are done, they should look a lot like the ones in this picture:

https://www.amazon.com/Spartan-Power...NsaWNrPXRydWU=

( just a random picture of properly made cables, I know nothing about that seller or their performance )

Stepping back a little:

There is no difference between the cables for a lithium battery setup and a lead acid setup in terms of wire gauge. If the loads / chargers aren't changing, whatever was there can stay there.

You will need a "jumper" for the shunt. It's gauge should be the same as what's on the other side ....

Bob
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Old 06-15-2021, 09:28 AM   #8
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Hello RFEQUITY1 - first, please do not use Lithium-ion batteries it is important to use Lithium Iron Phosphate Batteries (also known as LiFePO4) lithium-ion have a tendency to catch fire. Last year we installed lithium batteries in our International 25 - you can read the journey on our Blog here - lithium-experiment-part-2/ This may answer a lot of your question. Also we did not spend thousands of dollars to achieve fantastic results.
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Old 06-15-2021, 09:49 AM   #9
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What batteries are you getting , make & model ?
Do you know what a BMS - Battery Management System - is ?

Some lithium batteries have then inside the battery case , some do not , --- if not make sure you install / have installed a BMS that matches your setup !

There are about 6 lithium chemistries , each having different strengths / weaknesses --- these are for different applications .
Generally speaking , using any of the chemistries do not catch fire --- without abuse / the lack of knowledge and using proper use & maintenance .

With a matching BMS - any regulated power supply / charger will work - the BMS will take care of high - low - voltage - charging & low voltage disconnect .
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Old 06-15-2021, 10:36 AM   #10
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Here is the link to the batts I am using.

https://lithiummarinebattery.com/sho...4-128v-nominal
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Old 06-15-2021, 10:51 AM   #11
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Hi

So a bit of a "dark horse" in the lithium battery race, but packaged batteries with a built in BMS.

Bob
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Old 06-17-2021, 03:25 PM   #12
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I highly recommend downloading the wiring diagrams from the owners manual for your unit. You already had 2 lead batteries which means you also had a charger/converter to charge them. In my 2017 the converter is built into the breaker / fuse panel. Factory run 4awg wire was run from the converter to the batteries most everything else is 6awg or 10awg. I am upgrading to LiFePo, from studying the wire diagrams and looking in the camper I now know where to put everything and how the factory battery disconnect switch is wired, what fuses it already has, etc etc. Instead of replacing my converter I bought a 30A victron and put a switch on my converter to only use when I am charging from a generator (in addition to the Victron) so I can charge fast and minimize duration the gen is running.
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Old 07-06-2021, 08:50 PM   #13
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I occasionally camp in cold weather, so I’m going to guess that the battery box is not going to work. So what is the favored way to route the wires from the batteries to the controller when the batteries are moved under the bed?

What is the best thread or resource for breaking down this process of SLA-to-LiFePO4 conversion? (I’ve baked my SLAs and am ready to take the plunge, but probably won’t install roof solar panels.).

Signed, Handy LiNewbie
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Old 07-07-2021, 07:50 AM   #14
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Originally Posted by HotCorner View Post
I occasionally camp in cold weather, so I’m going to guess that the battery box is not going to work. So what is the favored way to route the wires from the batteries to the controller when the batteries are moved under the bed?

What is the best thread or resource for breaking down this process of SLA-to-LiFePO4 conversion? (I’ve baked my SLAs and am ready to take the plunge, but probably won’t install roof solar panels.).

Signed, Handy LiNewbie
Hi

How cold is "cold weather"?

Most lithiums will discharge down to -4F or below. Most will charge at 30F. When charging, heater pads are your friend.....

There are roughly 2,000 threads on doing this. Another one starts up about every third day. Bottom line always goes back to exactly how your specific trailer is built.

Bob
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Old 07-07-2021, 10:54 AM   #15
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Unless you plan to regularly camp in very cold temps (well below freezing, like in the parking lot of a ski resort in January), I don’t think you must relocate the batteries. Battle Born now has internal heating elements in their batteries that will keep them up to temp for recharging. Some insulation in the battery box plus the internal heating element should eliminate much of the concern.

If you do relocate inside, run a line to the a-frame area and have a two post power source outside. You can reconnect your portable solar port, and run any other 12v from there (lights, power jack, air compressor).

https://battlebornbatteries.com/prod...d-battery-kit/
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Old 07-07-2021, 11:30 AM   #16
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Quote:
Originally Posted by Prettygood View Post
Unless you plan to regularly camp in very cold temps (well below freezing, like in the parking lot of a ski resort in January), I don’t think you must relocate the batteries. Battle Born now has internal heating elements in their batteries that will keep them up to temp for recharging. Some insulation in the battery box plus the internal heating element should eliminate much of the concern.

If you do relocate inside, run a line to the a-frame area and have a two post power source outside. You can reconnect your portable solar port, and run any other 12v from there (lights, power jack, air compressor).

https://battlebornbatteries.com/prod...d-battery-kit/
Thank you! We can find ourselves camping in the mid 20s at night.
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Old 07-07-2021, 11:35 AM   #17
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Thank you! We can find ourselves camping in the mid 20s at night.


Cool. At mid-20’s I would just line the bottom and sides with some Dynamat Extreme, use the batteries with internal heating element, and call it a day.

You will need to make sure your charger can provide a ~14.5v charge to get the lithium fully recharged. Lots of threads on that topic, or just add solar and an MPPT controller.
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Old 07-07-2021, 12:37 PM   #18
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Thank you! We can find ourselves camping in the mid 20s at night.
Hi

Running loads in the 20's is not an issue. Most places will warm up past 32 during the day. The BMS will then allow charging.

Since it's battery temperature and they are pretty massive, they aren't going to get to 27 degrees when the air drops to that point for an hour or two. You need to look at the average temperature over 4 to 6 hours in this case.

If this still worries you, you can get heating pads that will get you to 20F in terms of charge temp. Not a great thing on solar, but fine on a generator or shore power.

Bob
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Old 07-07-2021, 08:48 PM   #19
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Quote:
Originally Posted by uncle_bob View Post
Hi

How cold is "cold weather"?

Most lithiums will discharge down to -4F or below. Most will charge at 30F. When charging, heater pads are your friend.....

There are roughly 2,000 threads on doing this. Another one starts up about every third day. Bottom line always goes back to exactly how your specific trailer is built.

Bob
.

Thanks, Bob. Sorry to beat a dead horse. I must not be using the search engine properly while on the mobile device. Makes sense that there are a ton of threads. I stumbled upon this one while trying to educate myself.

No solar and don’t want to install an inverter.

I’m leaning toward heated batteries from BB with a charger and a monitor. I also need a protector for the alternator.
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Old 07-07-2021, 08:53 PM   #20
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Quote:
Originally Posted by uncle_bob View Post
Hi

Running loads in the 20's is not an issue. Most places will warm up past 32 during the day. The BMS will then allow charging.

Since it's battery temperature and they are pretty massive, they aren't going to get to 27 degrees when the air drops to that point for an hour or two. You need to look at the average temperature over 4 to 6 hours in this case.

If this still worries you, you can get heating pads that will get you to 20F in terms of charge temp. Not a great thing on solar, but fine on a generator or shore power.

Bob
Ok. I didn’t realize that the BMS stops the charging at 32deg. I was wondering how you would prevent charger from trying to charge below freezing.
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