LiFePo vs Lead Acid - Knowledge and myths

[CarlD]

Originally Posted by redbarron55

OK, OK I need the LiFePO4 batteries, but the $$$ and a wife!!!
And there is the selling the extra money vs benefits for the other (better) half.
So now to find a screwdriver...

For the wife:

1. The LFP is lighter and SHE can bring more stuff along when you go camping.
2. You will not have to spend any time doing maintenance on the battery so you can spend more time with her.
3. A Battleborn has nice colors and will look nice in the camper.
4. ?

[Jon in AZ]

Originally Posted by jwcolby123

I would be interested in that as well. Why don't you research that?

Touche...

I'm in the category of those for whom lead-acid is good enough, at least for now. I know that both the plastic cases and the lead plates get recycled, and the acid gets neutralized for non-toxic disposal. Hard to say how much of the plastic actually gets re-used, but I'm reasonably confident all the lead does. With a fairly low melting point it should be energy efficient to re-process. A big question is how much of the lead used in batteries comes from new mining and how much from recycling old batteries. One source indicated 97% percent of lead-acid batteries are recycled and most lead used in current manufacturing is recycled (but didn't quantify "most"). I think it's safe to say lead mining and processing pose environmental risks for local communities.

Your turn...

[CarlD]

I got 5 bucks on Jon

[Air Doug]

Nice thread with lots of thoughtful input.

A few observations:

A couple of folks mentioned the cost of DC/DC converters but their numbers are too high. The Victron 9amp isolated converter is only $65 today. (As an aside, I have a couple of them for two systems and they work great and reliably put out 9 amps to the LiFePO4 batteries from the TV when needed.)

I think Charlie has hit the sweet spot when using lead-acid batteries and has optimized the system for that technology. The capacity testing I have seen shows the the 6V batteries come closest to meeting rated capacity. So I would go with a setup like his if I chose to stay with lead-acid.

Several have mentioned peace of mind. Boondocking with solar in the past year took us over 100Ah used before we could charge again, so going from one 100Ah BattleBorn to two made the difference between sitting back and enjoying the view vs fretting over the current draw constantly. The 70Ah (35 usable Pb-acid that came with the trailer would have been hopeless.

There are cheap ways of converting to LiFePO4 compared to my installation. Several mentioned using a suitcase solar system to charge up the battery beyond what a Pb-acid rated charger can provide. That is a great idea and might be all you need to do, especially if you get the $65 DC/DC converter and charge while you drive. Another is to buy some of the cheap, new prismatic batteries (Chins was mentioned), which is what I would do if installing a system now.

Self-promoting plug here: I wrote up my installation in FiverglassRV in 2018, including some pics and a wiring diagram with wire size, fuses, circuit breakers etc. It now has ~13,000 views, which generated some great comments. If you are thinking of converting to LiFePO4, there might be some good info there for you. Pricing is now obsolete, though. It is significantly cheaper to do today.
https://www.fiberglassrv.com/forums/...ozy-85205.html

[CHICO DAN]

The $50 AiLi Battery Monitor with Shunt worked excellent for my Solar upgrade.
Easy to install and use....never fails.
Why spend all that money on expensive BMS !

[CarlD]

Originally Posted by CHICO DAN

The $50 AiLi Battery Monitor with Shunt worked excellent for my Solar upgrade.
Easy to install and use....never fails.
Why spend all that money on expensive BMS !

Dan, A BMS monitors and protects the battery from over/under voltage, over/under temperature and over discharge overcurrent. It is a different function than the Aili battery monitor. You really need one with LFP or you will go nuts monitoring the battery all the time. What fun would that be!

[CHICO DAN]

AIMS and RV battery replacement LiFePO4 batteries have internal BMS

[CarlD]

Originally Posted by CHICO DAN

AIMS and RV battery replacement LiFePO4 batteries have internal BMS

True. All packaged LFP batteries come with a built in BMS. Some folks in this thread are talking about building their own battery from individual cells. They will have to add their own BMS.

[J.D.]

Thanks to all! I do follow Will Prowse and read up at Battery University.


My "solution" was to splurge / invest in a Jackery 1000 and 300 watts of solar. It will be easy to transfer to a new rig too. Thus far it has been great. Plug the shore power cord into the Jackery to keep house lead acid charged. Run 'fridge on propane. Downside is it is not enough for A/C.


When I will be in hot climates and NEED A/C, I bring a gas generator.


Works for me

[ThomasC]

Originally Posted by CarlD

True. All packaged LFP batteries come with a built in BMS. Some folks in this thread are talking about building their own battery from individual cells. They will have to add their own BMS.

Victron has 2 battery lines, with and without BMS's. Of course they offer external BMS's. Their batteries are pricey but they have a 200 amp model that is more cost effective. They also have 24 volt units that can be handy in some situations.

[parmm]

Originally Posted by J.D.

My "solution" was to splurge / invest in a Jackery 1000 and 300 watts of solar. It will be easy to transfer to a new rig too.

At 75 years young, I'm not going to worry about that. My newly acquired 2006 Scamp 19 will likely be my last rig!

[jwcolby123]

The large Bluetti makes a great all-in-one with a large battery, and it is LiFePo4. Not all of these things use that chemistry. It is a very cool solution, particularly for an old rig which is a PITA to rewire etc. Plus some of them now allow just plugging in another battery to extend the internal battery if that is useful.

I personally love Battle Born batteries, though they are too rich for my blood. They use the round cells instead of the Prismatic. That might make reliability a tad higher.

My take on this is that if any of these cells works for 90 days, they will work for 10 years, discounting maltreatment. The BMS makes maltreatment harder.

It is entirely likely they will last for 20 years. The rated degradation is to '80 % capacity' which means they still retain 80% of their charge after the rated cycles. Who knows what will really happen, but I am 101% confident mine will last longer than any of the PbA I have owned, likely by a factor of 3 or 4. I shudder to think of the $ I have recycled. I should own stock in a lead mine.

I bought a single 100w solar panel, just to dip my toes in the water. I'll likely end up around 400 watts solar. I intend to buy a cheapo low end generator as well that I can just plug the entire RV into, big enough to run a new 6K btu air conditioner if needed. Slowly build out my system to a huge battery, lots of solar and a genset for backup. But my endgame is to live off grid in my unit. Happily I have about 3 years to make it all work.

[jwcolby123]

Check this out.


https://batteryhookup.com/?mc_cid=a2...eid=522cdd1e98

[Motoboss]

All this is new to me and just wading in with solar. I have 150 watts of solar panels (1 100 and 1 50). Considering sufficient sun, question is, is this enough to recharge a LifePo4 battery from, say 50% in a reasonable amount of time (4 hrs or so)?

Reason being I would like to install a 12v dc fridge,

Power Draw @ 12V Amps Watts
Cooling 2.5-3.3A 30-40W
Idle(When Maintaining Temperatures) 2.9 35
Peak (During Testing) 6.6 80
Rated Max 20. 240

My other draw is very little, LED lights, water pump periodically, furnace fan in cold temps at night. The biggest draw is the fridge and would like to be able to run it, with no other draw during the day while solar recharges the battery during the day.

Essentially will 150 watts of solar run the fridge without depleting it in a 24 hour period?
I’m considering a LifePo4 as my next battery and would like to get away from a generator but if it won’t work then I will stay with my qroup 27 AMG deep cycle.
If this sounds confusing, it totally is to me

[gordon2]

Originally Posted by Motoboss

All this is new to me and just wading in with solar. I have 150 watts of solar panels (1 100 and 1 50). Considering sufficient sun question is, is this enough to recharge a LifePo4 battery from, say 50% in a reasonable amount of time (4 hrs or so)?

That totally depends on the size of your battery (assuming sufficient sun and 150 watts PV). For a 100 AH battery at 50% discharge the 150 watt panels might take 4-8 hours depending of the occasional clouds passing.

[Motoboss]

Originally Posted by gordon2

That totally depends on the size of your battery (assuming sufficient sun and 150 watts PV). For a 100 AH battery at 50% discharge the 150 watt panels might take 4-8 hours depending of the occasional clouds passing.

Sorry, should have added the batter would be a 100 AH battery. But it is doable? Thank you

[Defenestrator]

The rule of thumb is assume 5hrs of generation on a good sunny day. Your panels get you 750Wh, but your fridge looks like it will eat 840Wh. So, on a good day you'll run a 90Wh deficit out of your 1300Wh battery. I suspect those numbers are a tad pessimistic on fridge duty cycle, but you'd still barely break even most good days.

For boondocking with that size fridge, I think I'd basically want to add 100Ah of battery and 200W of solar for it specifically. Or 200Ah and 300W to hedge bets for multiple days of cloudy weather.

[Sparky0]

Home made option...
https://www.fiberglassrv.com/forums/...ack-89711.html

[jwcolby123]

As noted by others, 150 watts is a little light for a compressor fridge. The problem with the numbers you quote is that they don't discuss duty cycle and ambient temp. In the middle of winter with temps in the 60s inside the rv then the duty cycle might be 10% on 90% off. In the summer with high 70s or more, then maybe 40% on 60% off. Etc. Not to mention the fridge runs 24/7. Either way 150 watts is not enough me thinks.

Add at least another 100 watts. Don't even think staying with Lead Acid will solve the problem however, it will only make it worse. A lead Acid requires a full charge daily or you slowly (or rapidly) kill the battery. At least a lithium doesn't care if it is only partially charged sometimes.

Also the more battery the better. There will be days where the sun doesn't shine. One of those small cheap generators can help in those situations.

[jwcolby123]

Originally Posted by Sparky0

Home made option...
https://www.fiberglassrv.com/forums/...ack-89711.html

Very nice Job on that!!!


I notice yours was a few years ago. Look at this.

https://batteryhookup.com/products/n...w-bms-low-temp

$260 for 100ah with bms, ready to use (more or less). Buy two, drop it in your case, add an inverter:

https://www.amazon.com/BESTEK-Invert...82MDRC64&psc=1


and a couple of usb charger thingies,

https://www.amazon.com/Lastest%E3%80...K4F588G5R4594D

switches

https://www.amazon.com/dp/B081139P7K...xpY2s9dHJ1ZQ==


and fuse block.

https://www.amazon.com/Blue-Sea-Syst...01P6FTHC&psc=1


200 watts solar: https://richsolar.com/collections/40...ppt-controller

Voila, a home built power source. More or less. Still gonna cost around $1200 when it's all said and done. But this kind of thing is what I am slowly putting in my Scamp 19' 5th wheel.

I'll have a power pack on wheels! Rubber Tramp Rendezvous here I come.