LiFEP04 Battery question

[PhotoMac]

Hey Everyone,
Welcome to camping season 2023! I hope everybody had a great winter!

So the battery we had for our 2021 Flagstaff 206LTD is dead. I brought it inside for the winter, checked it regularly and put it on the battery tender just now and it's saying NOPE. Probably didn't check it enough or top it off with the tender enough and that's on me.

*****SORRY if this is beating a dead horse, but I'm finding a ton of conflicts about it*******

The dead battery has given me the thought of getting a LiFeP04 battery to replace it since it weighs about half as much and will work for a good bit longer when running on batteries. I have no plans to leave the battery in the camper when we aren't using it (as much as I like the idea of losing a $300 battery lol)

Has anybody done this in their Pop-Up?
I've read a lot of conflicting information about doing this.
-Some say that they are drop in, except it wont charge to 100% with the stock setup. (Fine with me since I'm taking it out when not in use and we have solar if we needed it)
Some say you need a new Inverter, a Battery Isolation manager, and a DC-DC Converter to make all the thing work properly. Which goes totally against being drop in ready.
Some say you can NOT do this because it will damage the tow car's alternator by trying to draw too much power.
Some say it will NOT charge the tow cars alternator because the wires aren't big enough to send damaging voltage back and forth.

The list goes on and on of people (and the manufacturers) going back and forth about it.

We don't do a ton of camping not on power, but the added capacity and lighter tongue weight are both things of interest. I have a lithium capable battery tender and already have a wireless battery charge monitor so really I just need to get the battery and before I drop $300+ I thought I'd ask the experts.

What am I missing? Can I put a LiFeP04 battery in my Pop-Up AS-IS without any detriment? Or am I missing some majorly key component here?

Thanks in advance!

[nvs4602]

Yes you can do it. But why are you going to lifepo4 batteries? For most it's more battery capacity. And to not install it correctly so it can reach that full capacity, to me just doesn't make sense.

DC-DC charge controller on a motorhome is necessary to control the amount of current so 1 it doesn't overheat you alternator and 2 so you don't exceed the charge current of the battery. It's not un common for a 100ah lifepo4 to have a max charge current of 50amps. My 280ah battery has a max charge current of 75amps.


For your questions about charging from the 7 pin TV wire. I'm not up on that situation so I hope more will chime in.

[nvs4602]

For your current dead battery a trickle charger is not enough to bring it back. Either connect a bigger charger or connect it via jumper cables to your car. Make sure it has plenty of water and fill with distilled water as needed.

[TitanMike]

Originally Posted by nvs4602

Yes you can do it. But why are you going to lifepo4 batteries? For most it's more battery capacity. And to not install it correctly so it can reach that full capacity, to me just doesn't make sense.

One good reason to use a LiFePo4 battery even though a conventional converter will only charge it to 90% max makes a lot of sense. For example, a lead acid battery should only be discharged to 50% to prevent rapid degradation. A LiFePo4 battery can be discharged almost fully without similar damage. A 100 ah lead acid battery is practically limited to 50 ah and a 100 ah LiFePo4 battery only charged to 90% has almost the full 90 amps available.

Also, as the OP stated, he has Solar so it's within his ability to chargeva LiFePo4 battery to 100%

Lastly, when a lead acid battery is at end of life it's really at the end. Time to drain it, melt the lead plates, and make fishing sinkers[emoji16]


With a lifepo4 battery replacement is only recommened when they reach 80% of original capacity. That's still 30% more capacity than the usable capacity of a brand new lead acid. ( both 100 ah "size")
**********

For your questions about charging from the 7 pin TV wire. I'm not up on that situation so I hope more will chime in.

Charging from a 7-pin is not an issue as the factory wiring in the tow vehicle has enough resistance to keep current low enough to prevent damage.

Depending on the tow vehicle's voltage ( mine starts at 14.6 until starting battery is charged then drops to 13.8 ) the lifepo4 battery in trailer could be charged well into the 90% range.

[mmartin_tdc]

On my Ram with CTD, I get 4.5 amps to the battery from the 7 pin wire, truck running.
That is not much more than a trickle charge. I installed a DC-DC converter so I could really charge the battery on travel days. With that I get 40.8amps at the battery while driving. I have a 100AH LiFEPO4 battery with a max charge rate of 50amps. These are measured with a shunt meter on the negative battery post, so real world numbers.
Not sure if it is an option for you, but I moved my battery inside my trailer so it would a) stay warm for charging. b) extra level of security. And in your case c) less pin weight.

[ependydad]

Originally Posted by PhotoMac

(Fine with me since I'm taking it out when not in use and we have solar if we needed it)

...

What am I missing? Can I put a LiFeP04 battery in my Pop-Up AS-IS without any detriment? Or am I missing some majorly key component here?

Just drop it in. None of that other stuff is needed. Your stock converter will likely charge it to 80-90%. If your solar is lithium aware, then it'll get you that last 10%, if you care.

[Aussieguy]

what Titan said... good solar will charge it to 100%.

the higher voltage and amps (14v +) on a newer converter will do it faster
only takes less than an hour to top it off the last little bit.......
then the charger will stop charging

If you have older converter that has max 13.6v charging
it will still top it off but will take 5 hours or more ... not worth the effort.

depending on your power usage ... 200-400w of panels will be a good average to keep your battery/s topped off.

don't know what you can fit on your camper's roof..... maybe a190w?
plus another 190w as a ground panel?

[BehindBars]

Alright, so this all sounds good, but what should I expect to pay for a group 24 size LiFePO4 battery? I see Amazon pricing at around $750. Is that typical?

[Aussieguy]

https://www.youtube.com/@WillProwse .......... lots of battery reviews
https://diysolarforum.com/
https://www.mobile-solarpower.com/
https://www.youtube.com/@OffGridGarageAustralia ... some battery reviews



some of the higher priced batteries have features we don't need for house batteries
we just need the ability to store energy and discharge it at a fairly constant rate



I am assembling my own from the 3.2 cells

[TitanMike]

Originally Posted by BehindBars

Alright, so this all sounds good, but what should I expect to pay for a group 24 size LiFePO4 battery? I see Amazon pricing at around $750. Is that typical?

That would be typical for a group 24 size that also includes low temp protection and has a 75 ah capacity.

There are a lot of group 24 sizes for less that have "stripped down" BMS's" and only 50ah capacity. Pick one for ~$300 and take your chances. Most have names that look like someone just drew 6-12 letters out of a hat and called it a name. Also have Customer Service departments that you can only send a e-mail request to and then wait for a reply.

I personally would avoid any product that doesn't have US based phone CS.

Then again, I'm good in the battery department, by best estimate, for the next 10 years or so. Hopefully my body is too[emoji57]

[BehindBars]

Originally Posted by TitanMike

That would be typical for a group 24 size that also includes low temp protection and has a 75 ah capacity.

There are a lot of group 24 sizes for less that have "stripped down" BMS's" and only 50ah capacity. Pick one for ~$300 and take your chances. Most have names that look like someone just drew 6-12 letters out of a hat and called it a name. Also have Customer Service departments that you can only send a e-mail request to and then wait for a reply.

I personally would avoid any product that doesn't have US based phone CS.

Then again, I'm good in the battery department, by best estimate, for the next 10 years or so. Hopefully my body is too[emoji57]

Good info. Thank you.

[ependydad]

I've heard good things about Amperetime and Chins, but I know nothing about their BMS.

[PhotoMac]

Wow I wasn't expecting so many responses, thank you all for chiming in!

The big thing with going with the LiFeP04 battery for us is just taking some weight off of the hitch and larger usable capacity. If it takes solar to get it up to 100 over the 90 that's not end of the world for us. Flagstaff 206LTD doesn't have THAT many electronics so in theory the LiFeP04 should run it for a few days without trouble.

You've all confirmed what I was believing to be true, but I needed you all to say it for me to be really sure about it.

Thanks everyone!