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bdosborn

Colorado

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Posted: 01/30/21 07:34pm Link  |  Quote  |  Print  |  Notify Moderator

Have you thought about building your own system? It's easy with a little research. LTO is an awkward cell to work with due to the nominal voltage of 2.4V. Setting up for a 12V nominal systems means a 12V or 14.4V pile. These are are weird voltages to charge and run appliances on, you'll need a programmable charger and probably a dc-dc converter. 24V nominal is workable but the easily sourced cell(Yinglang)is only 40 A-H. To get to 600a-h@24V, you'11 need a 10S16P pile, or 160 cells. At $43.5/cell bulk price on Aliexpress, that would be $6,960 for a roll-your-own system.

Assuming you originally wanted 600A-H@12v, you would have the same capacity with 300A-H@24V. Then the cost is $3,480.

The tough part is finding chargers and a BMS for the LTO cells. They're probably out there (never looked) but LiFePO4 equipment is so much easier to find.


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pianotuna

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Posted: 01/30/21 07:51pm Link  |  Quote  |  Print  |  Notify Moderator

bdosborn wrote:

Have you thought about building your own system? It's easy with a little research. LTO is an awkward cell to work with due to the nominal voltage of 2.4V. Setting up for a 12V nominal systems means a 12V or 14.4V pile. These are are weird voltages to charge and run appliances on, you'll need a programmable charger and probably a dc-dc converter. 24V nominal is workable but the easily sourced cell(Yinglang)is only 40 A-H. To get to 600a-h@24V, you'11 need a 10S16P pile, or 160 cells. At $43.5/cell bulk price on Aliexpress, that would be $6,960 for a roll-your-own system.

Assuming you originally wanted 600A-H@12v, you would have the same capacity with 300A-H@24V. Then the cost is $3,480.

The tough part is finding chargers and a BMS for the LTO cells. They're probably out there (never looked) but LiFePO4 equipment is so much easier to find.


The one I sourced was a drop in replacement with a BMS. Just extremely costly.


Regards, Don
My ride is a 28 foot Class C, 256 watts solar, soon to have SiO2 batteries, 3000 watt Magnum hybrid inverter, Sola Basic Autoformer, Microair Easy Start.

Gjac

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Posted: 01/31/21 12:06pm Link  |  Quote  |  Print  |  Notify Moderator

Lwiddis wrote:

We can always depend on Don to keep us current on RV batteries issues.
Yes we can. Don have you looked at Nickle Hydride batteries yet? I have them in my Hybrid car and they work best and have tere longest life from 20-80% SOC which sounds just right for dry camping. They never fully charge unless there is a long down hill, and are cheaper than LI batteries for cars, but don't know if they can be made into a 12v battery? Have you investigated these yet?

StirCrazy

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Posted: 01/31/21 05:53pm Link  |  Quote  |  Print  |  Notify Moderator

pianotuna wrote:



The one I sourced was a drop in replacement with a BMS. Just extremely costly.



really, the last article I had read said they were 5 to 10 years off from being good enough for mass production and use. neat.

Steve

I was flipping back and forth between a few types but now that LFP has dropped so low and with no offgasing whats so ever you can mount them inside the condistioned space, so temp isnt a concern at all anymore. buck/usable ah they are now the cheepest battery on the market and if you solve the cold charging issue by puting them inside the camper there is no downside to them.

Steve


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pianotuna

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Posted: 01/31/21 06:11pm Link  |  Quote  |  Print  |  Notify Moderator

Steve,

It is a concern if you store at -40. How do you get the "living space" warm without a usable battery bank?

the company I was writing to has a 100 amp-hour LiFeP04 with BMS drop in for $400 Canadian. Their store is at Lac La Biche Alberta

* This post was edited 02/01/21 12:45am by pianotuna *

3 tons

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Posted: 01/31/21 06:42pm Link  |  Quote  |  Print  |  Notify Moderator

I’ve never heard of them, so I looked it up:

https://en.wikipedia.org/wiki/Lithium-titanate_battery

I’ll be sticking with LiFePo4’s because (per expion) they charge about 3x faster than flooded wet cell batteries which seems to strike a good balance between safety, density and charge rate - JMO

3 tons

BFL13

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Posted: 01/31/21 07:38pm Link  |  Quote  |  Print  |  Notify Moderator

3 tons wrote:

I’ve never heard of them, so I looked it up:

https://en.wikipedia.org/wiki/Lithium-titanate_battery

I’ll be sticking with LiFePo4’s because (per expion) they charge about 3x faster than flooded wet cell batteries which seems to strike a good balance between safety, density and charge rate - JMO

3 tons


What does "3x faster mean"? 1/3 the time for restoring the same number of AH? 3 x the AH in the same time?

It takes about 2 1/2 hrs (150 min) to restore 184 AH doing a 50-90 on four 6s of 460AH with a 75 amp charger set to 14.8v, run from a 2200w gen (maxing out the gen for VA)--BTDT.

So if it means you can do that in 1/3 the time with LFP, that means in 150/3 = 50 minutes to do 184AH. So you would be charging at 221 amps for that 50 minutes. How can you do that in an RV?

At 1C, that would mean 221AH worth of LFP in the bank. At .5C that would be with 442AH of LFP.

You can carry the batteries, but howinheck can you charge at 221 amps with what size generator to run a 221 amp charger?

So what value to an RVer is the claim of "3 times faster" charging? How would you set up your RV to be able to charge "3 times faster"? I can't understand it.


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3 tons

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Posted: 01/31/21 09:39pm Link  |  Quote  |  Print  |  Notify Moderator

As I pointed out, Expion claims 3 x faster.. I have no desire whatsoever to conduct my own empirical timed test to challenge their claim as I’m quite happy to leave that level of parsing to someone who’s doggedly interested - lol... it’s plenty enough for me just to have optimized solar harvest recover times to much faster than with my former equivalent capacity GC’s - from ‘back-to-back’ experience Expion’s claim of 3 x faster recovery than with FWC seems at least somewhat realistic to me (+ or -), thus not really worth disputing Expion’s claim...JMHO,

3 tons

BFL13

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Posted: 01/31/21 10:29pm Link  |  Quote  |  Print  |  Notify Moderator

3 tons wrote:

As I pointed out, Expion claims 3 x faster.. I have no desire whatsoever to conduct my own empirical timed test to challenge their claim as I’m quite happy to leave that level of parsing to someone who’s doggedly interested - lol... it’s plenty enough for me just to have optimized solar harvest recover times to much faster than with my former equivalent capacity GC’s - from ‘back-to-back’ experience Expion’s claim of 3 x faster recovery than with FWC seems at least somewhat realistic to me (+ or -), thus not really worth disputing Expion’s claim...JMHO,

3 tons


IMO all they are doing is saying you can charge the LFP at 1C but the FLA's at only 0.3C so that to them means "3 x faster"--which is total hogwash when you define "faster" in terms of AH restoration over time unless you can provide the scenario in detail, for an RV set-up.

You did however do an empirical timed test to prove that somehow your solar charging is "much faster" with LFP than with your previous GCs.

It would be interesting to see your figures that show that, and with that, what you mean by "faster".

pianotuna

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Posted: 02/01/21 01:31am Link  |  Quote  |  Print  |  Notify Moderator

3 tons,

The issue with solar charging seems to be the capacity of the charge controllers. An 80 amp is $600 to $800 smackers. There are a few 100 amp controllers, but at least one of them is a "swindle" as it can't do 100 amps at 12 volts. So even a single LiFePo4 is going to exceed what solar can produce.

Suppose we take 14.6 as the "bulk" voltage. 80 x 14.6 = 1168 watts.

The same sort of limit happens with converters and inverter/chargers. Assuming 200 amp-hours of Li the power factor corrected Magnum maxes out at 127 amps. 127 x 14.6 = 1874 watts--so it would exceed what a 15 amp circuit could handle. So, I would have to scale back the voltage to 14.1. Or if I wanted the 14.6 volts, I would have to limit the Magnum to 123 amps.

So faster charging is not really going to be that much faster, especially with a large bank.

I would not think any serious boondocker would have less than 2 to 3 hundred amp-hours.

So the only "real" chemical advantage of the LI is that they don't sulphate.

The "physical" advantage is that they weigh a lot less than flooded batteries.

I want 600 amp-hours of SiO2. They would charge at .25 C or 150 amps. I have no way to provide them with 150 amps.

I know that BFL13 noted tapering on SiO2--but I do not know if he was charging at 14.6 volts. They, too, do not suffer from sulphation. Their ability to be used at -40 is needful for me--and I won't have to jump through hoops to prevent alternator damage, nor use dc to DC charge devices (though that would be a benefit, given my business use where I might well drive for 5 hours in a day).

I just today found out that SiO2 are lighter than flooded batteries of similar capacity. They are a bit cheaper than LiFePo4 from places such as Battleborn or Lion.

If you "roll your own" LiFePo4 then we get to about $368 USD. The folks at Lac La Biche quoted $313 (usd) for a drop in 12 volt 100 amp-hour with BMS.

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