Battery Question

[kenkorona]

Hi,

I have a bunch of questions about batteries, invertors, charging, solar panels, etc. So I'll start off with batteries...

My TC came equipped with 2 Interstate Marine/RV Deep Cycle SRM-27 batteries. They are standard Flooded Lead Acid batteries with a cost of about $125 each. In the 10 weeks I've used my TC so far I never had an issue with adequate power, though to be fair I had little use for a microwave or A/C during that time. I also used the generator for a total of about 15 minutes during that 10 week period. And that was to run the A/C while I was stuck in the Walmart parking lot in Secaucus, NJ (please don't ask why I was there).

So I hear about people buying not just 2, but maybe 4 or more Lithium batteries at a cost of over $1000 each and I'm wondering why. I haven't done a thorough investigation, but from what I can tell the capacity of the Lithium batteries may be a bit better than a Lead Acid, but it seems hard to justify the wildly higher cost. Can someone explain?

Thanks
Ken

[Grit_dog]

FWC wrote:
Again, this is all a distraction from the point I was actually making.

The point in the very unlikely circumstance that you need to use your LiFePO4 camper battery in temperatures below -20C, the battery will work just fine, you will be able to fire up the furnace or battery heater and warm up the camper. At that point you can charge your battery, fill your water tank, and do what every you need to do.

Every time there is a discussion of LiFePO4 batteries, there are always a few who say that they are no good if you camp in cold weather (some are now even claiming 'cool weather'). My experience is exactly the opposite, they have worked just fine for me in cold weather. Yes there are limitations on charging, but these are generally easy to overcome, and are not nearly as restrictive as the limitations on your water system.

Ohmygosh, you’re actually correct. And you actually explained your position succinctly and completely compared to the passive aggressive, vague references when you were apparently trying to prove your point, and it is essentially what I was saying as well.
One needs to take more care and treat life’s differently to use in cold weather.

So even though pianotuna is sort of obsessed with batteries , he’s still correct, imo, in that most people throw their batteries in the battery compartment and that’s it and they would be real surprised when their batteries don’t charge.
One needs to make accommodations if you will for life’s.

Or to put it another way, they still don’t charge in the cold. Doesn’t matter if it’s -100 if you keep them warm. Then they’re not in the cold.

Thank you for finally using your words!

[mbloof]

FWC wrote:
Again, this is all a distraction from the point I was actually making.

The point in the very unlikely circumstance that you need to use your LiFePO4 camper battery in temperatures below -20C, the battery will work just fine, you will be able to fire up the furnace or battery heater and warm up the camper. At that point you can charge your battery, fill your water tank, and do what every you need to do.

Every time there is a discussion of LiFePO4 batteries, there are always a few who say that they are no good if you camp in cold weather (some are now even claiming 'cool weather'). My experience is exactly the opposite, they have worked just fine for me in cold weather. Yes there are limitations on charging, but these are generally easy to overcome, and are not nearly as restrictive as the limitations on your water system.

While it has always appeared that rv.net has more then its share of trolls and internet experts who seemingly always want to argue why something won't work, the reality for me is that for where I live and camp I'd rarely if ever run into temperatures that make charging my LiFePO4 a issue.

Obviously for others their MMV.



- Mark0.

[FWC]

Again, this is all a distraction from the point I was actually making.

The point in the very unlikely circumstance that you need to use your LiFePO4 camper battery in temperatures below -20C, the battery will work just fine, you will be able to fire up the furnace or battery heater and warm up the camper. At that point you can charge your battery, fill your water tank, and do what every you need to do.

Every time there is a discussion of LiFePO4 batteries, there are always a few who say that they are no good if you camp in cold weather (some are now even claiming 'cool weather'). My experience is exactly the opposite, they have worked just fine for me in cold weather. Yes there are limitations on charging, but these are generally easy to overcome, and are not nearly as restrictive as the limitations on your water system.

[Grit_dog]

@FWC.
Fair enough. I made some assumptions. Mostly because I figured what you were saying had at least “some” remote relevance to life ON earth which could somehow be at least loosely related to batteries in a camper….
So, sounds like a cool job, yet wholly unrelated to average or even extreme camper use.
Your replies are akin to the many other overtly literal responses and interpretations that somehow plague any sense of practical reason or application, on this forum…..

And exactly to my previous point, that just because it “can” be done, doesn’t mean it’s the right solution for the application.

[FWC]

StirCrazy wrote:


interesting, at -30 they have more capacity available than SIO2 (80% Vs 60%) first time I have seen a chart that shows preformance below -20.
is there a corasponding chart that shows if there is a impact on cycle life when used at these temps or if the amprage (flow) is impared?

Nevermind, I just saw that was at a 9 amp discharge. more than enough to run a furnace.......

Steve

Those discharge curves are for a SAFT 44Ah cell, so a 0.2C discharge rate.

[FWC]

You are assuming an awful lot here. Notice I said polar and high altitude, the coldest place we deploy instruments is not the poles, it is the stratosphere. For those measurements, we charge the batteries in the lab, on the ground, same way you would in your camper, then use them at ambient temperatures down to a low of around -80C (-112F) but typically more like -70C. Of course we insulate everything, but internal temps still get down around -40C.

But thanks for calling me bud and telling me that the equipment I use doesn't work.

Back to the actual point here - there is no reason you cannot discharge a LiFePO4 battery below -20C.

Grit dog wrote:
^Ok, fair enough. So you are a researcher in Anarctica. (Because the Arctic never gets that cold and by never I mean at least since LiFePO4 batteries have been around)
And apparently you’re out with your instruments on the coldest days of the year or decade in Antarctica. They’re not going to work bud.
I’d like to hear how you operate in -94F temps and colder….I’m just a greenhorn I suppose because much below -50F, nothing runs. At -60 you virtually can’t keep heaters fired to to keep fuel heated enough to fire the heaters to have a place to warm your batteries.
Even in the Arctic you don’t really go outside much below -50F.

Not everyone here has worked or lived above the Arctic circle so your claims may sound impressive but until you can explain the process I’m not buying it.
Oh, you must be a freelancer, because I don’t know of any agency or r company that operates in the Arctic that doesn’t have strict cold weather protocols that shut down virtually everything between -35 and -50F for safety.
But maybe that’s changed since I worked on the Slope in the winter.

[StirCrazy]

FWC wrote:
There is no physical reason that LiFePO4 batteries can't be discharged below -20C. I don't pre-warm them in any way, just use them. They are generally rated for -20, because they only test to -20C because 99.9% of their customers don't care about performance below -20C. However, some manufacturers do test down to lower temperatures and while they loose capacity at low temperatures, it is not nearly as bad as many battery chemistries:

interesting, at -30 they have more capacity available than SIO2 (80% Vs 60%) first time I have seen a chart that shows preformance below -20.
is there a corasponding chart that shows if there is a impact on cycle life when used at these temps or if the amprage (flow) is impared?

Nevermind, I just saw that was at a 9 amp discharge. more than enough to run a furnace.......

Steve

[Grit_dog]

^Ok, fair enough. So you are a researcher in Anarctica. (Because the Arctic never gets that cold and by never I mean at least since LiFePO4 batteries have been around)
And apparently you’re out with your instruments on the coldest days of the year or decade in Antarctica. They’re not going to work bud.
I’d like to hear how you operate in -94F temps and colder….I’m just a greenhorn I suppose because much below -50F, nothing runs. At -60 you virtually can’t keep heaters fired to to keep fuel heated enough to fire the heaters to have a place to warm your batteries.
Even in the Arctic you don’t really go outside much below -50F.

Not everyone here has worked or lived above the Arctic circle so your claims may sound impressive but until you can explain the process I’m not buying it.
Oh, you must be a freelancer, because I don’t know of any agency or r company that operates in the Arctic that doesn’t have strict cold weather protocols that shut down virtually everything between -35 and -50F for safety.
But maybe that’s changed since I worked on the Slope in the winter.

[FWC]

I am not trying to be vague, I am pointing out that there really isn't a lower temperature limit to discharging LiFePO4 batteries, only to charging them.

This all arose because one user always brings up his specific scenario that he stores his camper at -37C and therefore LiFePO4 wouldn't work - my point is LiFePO4 could work, assuming he heats his camper, as he can use the LiFePO4 to power the furnace that he presumably uses to heat his camper to a livable temperature. This example is so out of the ordinary that it is really not a concern for 99.999% of RVers.

In most cases, if you use water in your camper, then you can use LiFePO4. The water system is much more sensitive to freezing than the batteries are.

As for my non-camper use - in my professional work I use LiFePO4 (and Li-Ion) batteries to power instruments for polar and high altitude research. Ambient temperatures regularly go below -70C.

[Grit_dog]

^ FWC, why do I feel like you’re being intentionally vague just for the sake of argument?
You use lifes at -30 while camping but not in your camper. So what other possible applications are there and what are you using them for. Snomachines? Jumpstart pack? Headlamps? Off grid cabin battery bank?
How do you warm them to charge them? At -30 I’ll go on a limb and say that the discharge isn’t going to warm them enough to charge, or even if it does, charging won’t maintain them at 60deg warmer than ambient unless you’re heating them externally somehow.
If I’m wrong, please explain, as I’m always interested in learning something new.
And OP, I’ll apologize for all of us for the thread jack…

[FWC]

There is no physical reason that LiFePO4 batteries can't be discharged below -20C. I don't pre-warm them in any way, just use them. They are generally rated for -20, because they only test to -20C because 99.9% of their customers don't care about performance below -20C. However, some manufacturers do test down to lower temperatures and while they loose capacity at low temperatures, it is not nearly as bad as many battery chemistries:

[StirCrazy]

FWC wrote:

Grit dog wrote:

Or more accurately, even though "you" personally want your rig "camp-able" at -30 deg and colder, LiFe's still have issues below freezing and you can't just "turn on he furnace" as one person suggested, although they will still "work" to discharge, IE provide power down to well below freezing (Not -30, someone can look it up though ). It's charging when the batteries themselves are around or below freezing.

Bottom line, they are a great option for lightweight, and duty cycle for warm weather campers. Not worth fiddling with if one is winter camping.
Although it appears some folks (on rvnet here anyway) really enjoy engineering and maintaining "off grid" solutions. I wonder if the "maintenance free" aspect of LiFe's is lost on the added $ and effort to make them work though.

Why would you not be able to turn on the furnace at -30?

PS, I winter camp extensively with my LiFePO4 batteries and have used LiFePO4 batteries well below -30 (just not in my camper).

because there only rated for discharge to -20C. but if you had a way to warm the battery up first you would have no problem. but thats interesting how are you prewarming your bateries or are you?

Steve

[Grit_dog]

^No doubt. And if I wanted/needed a large (reserve) and/or lightweight battery bank, I believe build your own Li is currently the setup to beat….inmost conditions.
While it would be slightly more convenient I actually would never get my money’s worth out of expensive batteries in our current scenario of camping like twice a year.
My point to FWC was, liFePO4s in cold weather are like that hot chick at the bar. Fun in the sack, nice to show off, high energy, but high maintenance.
Temperate weather or enough time and effort to keep her happy, they are great.
SiO2 are pretty intriguing as well.
And by the time we camp enough for our batteries to matter, technology will be better than it is currently. In the meantime, anything will work because I have generator(s).

[pianotuna]

Grit dog,

Further in the thread I do suggest that Li banks can be excellent--and if you roll your own, not an impossible price.

[Grit_dog]

FWC wrote:

Why would you not be able to turn on the furnace at -30?

PS, I winter camp extensively with my LiFePO4 batteries and have used LiFePO4 batteries well below -30 (just not in my camper).

Rather confusing response. I suppose a LiFePO4 could/will provide enough power to run a furnace fan at extreme low temps.
The challenge is in charging them unless the battery temperature is high enough.
So batteries inside camper, camper furnace keeps them warm, your power source charges them.

Not sure what you mean you use yours extensively at -30 but not in your camper. That is what we're talking aboot here, isn't it?

I use and charge a LiFePO4 battery in well under freezing ambient temps as well, but the battery receives heat from my engine (sno-bike). If it was exposed to open air and snow it wouldn't charge, while riding.

So your position is LIFePO4's are good for extreme cold camping?

I'll leave this quote from Battleborn, the "gold standard"

"At 25° F, a Battle Born battery will no longer accept a charge. This is to preserve the cells in the battery, and the internal BMS will allow a recharge when the temperature is above 32° F. Every single battery that we assemble has this intelligent internal BMS."

Sounds like it's possible to nurse your LiFe's through the cold, but that was my point, why fiddle around with it for "extensive" cold weather use?

Maybe you could expound on your processes to keep your LiFe's able to charge when your using them at -30.