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 > SiO2 Batteries and High Amp Draws

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3 tons

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Posted: 05/22/22 10:49pm Link  |  Print  |  Notify Moderator

PT, you posit some Interesting though somewhat speculative goals (IMO here only)…However (due to cost and such..), since folks are still somewhat early in the SiO2 discovery process, rather than a speculative approach, you might consider (before proceeding…) waiting to take advantage of BLF’s actual ‘hands-on’ test results - most likely a valuable resource for an objective evaluation…Per your previous (as I recall…) it seems as though time is still on your side, eh…Just an idea [emoticon]

3 tons

StirCrazy

Kamloops, BC, Canada

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Posted: 05/23/22 06:30am Link  |  Print  |  Notify Moderator

3 tons wrote:

StirCrazy said: “haha, weird that they are so expensive there for LFP. you had to order the Sio2 and just doing a quick search a drop in bought online from alberta lithium is 550ish this one

but ya it makes sence if you alreay had one to get another , after all what are you going to do, throw it out.”

…For PT, cold weather is of paramount concern, so it’s great for others to know that there’s a viable alternative that (admittedly here, just from my own perspective…) has excellent performance characteristics though (IMO…) seemingly more similar to other FLA’s (i.e. but higher currents, and no sulfating = longer life) than to the nearly flat voltage plateau of LFP’s…

3 tons


how did you turn this about PT lol. I think I even state that if you doing extreem cold weather camping then this is something to look atif your not set up to keep your batteries warm, and the original poster doesnt have that issue haha . but cost has definatly become a factor, I like everyone thought they would drop but they went on sale for a little bit and are right back up to the original price.. which is weird...


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StirCrazy

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Posted: 05/23/22 06:41am Link  |  Print  |  Notify Moderator

pianotuna wrote:

High draw on LiFePo4 is limited by the battery management system. It depends on what the maker sets it at. Anyone know what is most common? 100 amps (1c)???

Seeing as my goal is a battery bank of at least 400 and possibly 700 amp-hours, the speed of charging of Li is not useful to me--as my fastest charger maxes out at 127 amps @ nominal 12 volts.

Efficiency also does not concern me as I want to float the batteries between trips. SiO2 float nicely. Li, not so much.

For me, the most important factor is full charging not required on each cycle. My understanding is that both Li and SiO2 are quite happy, if they are fully recharged once every 30 days.


1C seams to be the most common set up on a 100Ah battery. in your 200ah single batteries yoyu se 100, 125, 150 depending on who makes it. the way to get around it is to build your setup like you would in a normal setup. if you want 400AH of storage use two 200AH batteries or four 100AH batteries . if you go the later you can have a 400Amp draw, the first anywhere from a 200 to a 300Amp draw. in the camper I did a single 300ah battery and I used a 125amp draw BMS but I have nothing tht takes anywhere near that, I think if I leave my water pump runing ll my lights on the furnace on and the fridge on 12V I might be drawing 18amps... but I did build it so I could add a microwave later if the wife wants one and a small one is about 80amps i believe. in the 5th wheel when I get that set up I will be building three of what I have in the camper so 900AH capacity which will give me a draw capability of 375Amps which is more than enough to handle my 2000 watt inverter. there are BMS that have capabilitied of 250amp draws and such but I felt that even using a 1C discharge rate was likda useless on any battery, like look I can do a big draw, but my battery is dead in one hour.... the draw with out the ability to sustain it to me is useless, but ya I can see where the capability for shirt bursts would be desiriable.

I also float mine and they seam to like it with no issues so far, but I do float at a voltage that would indicte a charge level of 90%, so I bring them up to 100 on a full charge voltage then the float kicks in and they taper to 90% it all depends on your gol. if you want to get the absolute most lige say 7-8000 cycles then ya you have to jump through some hoops but if you want to get just the advertised 3000 ish then there pretty good to go and easy to manage. the issue your going to have is cold weather and where the batteries are. it is easy to get the 700+ AH requirment but what level of discharge do you need? this will tell you how many different 4 cell batteries you need to build and what kinda BMS you need.

Steve

pianotuna

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Posted: 05/23/22 07:23am Link  |  Print  |  Notify Moderator

When I added solar, I deliberately turned on EVERY DC draw in the RV. The lights had not been converted to led. It was enough to cause the automatic circuit breaker between the battery bank and the power distribution center to trip.

Of course, with large inverters 2C from a 100 amp-hour battery is quite possible. My first inverter was 2500 watts (modified sine wave rated to run motors). The goal was to run the block heater for 3 hours in extreme cold. I did one test with the 875 amp-hour bank, and ran the roof air until it shut down--it took about 90 minutes.

In my opinion it is better to have high amperage batteries--so two 200 amp, or one 400 amp may offer superior service to four 100 amp jars.


Regards, Don
My ride is a 28 foot Class C, 256 watts solar, 556 amp-hours of Telcom jars, 3000 watt Magnum hybrid inverter, Sola Basic Autoformer, Microair Easy Start.

BFL13

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Posted: 05/23/22 07:28am Link  |  Print  |  Notify Moderator

IMO you don't need "hands on experience", but you do need some ability to "critical read". PT can do that same as the rest of us.

So far my experience with SiO2 shows they do the depth of discharge as claimed, but I have not confirmed much of the other data claims.

You have to distinguish between data sheet stuff and dealer sales claims, which we all are able to do too.

Looking at Azimuth dealer claims trying to sell SiO2s, eg they push the cold weather operating range as -40C.

But Stark brand AGMs also claim -40C to 60C operating range, so what is so special about SiO2 in the cold? Beats me. Would have to do more research if I cared.

http://www.wegosolar.com/products.php?pr........-Stark-AGM-12V-Solar-Battery-Sealed-125A

Speaking of "sales" note that is really a 105AH batt at the 20 hr rate. Another trick is if they use the 10 hr rate like ISTR SiO2 does in some blurbs. Got to pay attention!

Claim is "faster charging" with SiO2. That is where I always want to see the actual charging profiles with times etc for a side by side comparison.

Usually you see that faster charging has to do with a lower internal resistance. Maybe. Sometimes they mean you can use a higher amp charging rate and that makes for less time. But if you use the same 55 amp charger it will do 55 amps and no more in each case.

So the SiO2 spec says IR is "under 6.8 mOhms". The Stark AGM says 5 mOhms. So how can the SiO2 be faster? But these IRs are at 77F. We don't know the IRs at different charging rates and where along in SOC the IRs are. Makes you wonder how the SiO2 could be "faster"

They both have charging limits of about 27% so you can't use a bigger amp charger to get a faster time like you could with LFP, eg.

So here is their claim for "faster charging"

https://azimuthsolar.ca/wp-content/uploa........zimuth-Silicon-Dioxide-4-Pager-min-1.pdf

2 x faster! 3 hrs vs 6 hrs . So how far down in SOC is the starting point where you can charge it up to what SOC ? "Regular" 100AH batts take a very long time to get from 90 to 100% SOC. On generator (their sales pitch for less gen time) you stop the charge at 90 anyway. So what is the comparison in time for doing 50-90s?

Seems like a bogus sales claim to me! It could turn on where along in SOC it goes from constant amps to tapering amps. That is why we need the charging profiles to compare them.

Anyway, I will check for that with my SiO2s and see how it goes.

I do think the data sheet stuff can be believed but you have to watch out for those "sales" guys. [emoticon] (and that is just as true for LFP ads on "faster charging" with no side by side charging profiles)

* This post was edited 05/23/22 07:40am by BFL13 *


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pianotuna

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Posted: 05/23/22 07:49am Link  |  Print  |  Notify Moderator

BFL13,

AGM taper later than flooded. I suspect SiO2 taper later than AGM. There are now Li batteries using SiO2 anodes--for greater capacity and faster charging.

I'm happy with low and slow. Only once every 30 days would I need to get to 100%. With dual banks that is easy with the current technology I have in place.

I'd be tempted to get a pair of the largest SiO2 (270 amp hours), instead of multiple 100 amp-hour units. I would have to charge "one at a time" on that monthly schedule. It is more expensive to do so as there is a discount on multiple 100 amp-hour jars.

I look forward to hearing the results of your testing.

3 tons

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Posted: 05/23/22 09:00am Link  |  Print  |  Notify Moderator

Per StirCrazy: “how did you turn this about PT lol.“

Not my intent, when I write I try to assume that the larger audience (who might have just tuned in…) may know little about the subject matter du jour - so I emphasized ‘the known’ cold weather virtues of SiO2 (else folks may get partial info) while adding that additional findings might still await. (e.g. just lessons I’m reminded of when communicating…).

3 tons

BFL13

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Posted: 05/23/22 03:47pm Link  |  Print  |  Notify Moderator

"2 x faster! 3 hrs vs 6 hrs . So how far down in SOC is the starting point where you can charge it up to what SOC ? "Regular" 100AH batts take a very long time to get from 90 to 100% SOC. On generator (their sales pitch for less gen time) you stop the charge at 90 anyway. So what is the comparison in time for doing 50-90s?

Seems like a bogus sales claim to me! It could turn on where along in SOC it goes from constant amps to tapering amps. That is why we need the charging profiles to compare them.

Anyway, I will check for that with my SiO2s and see how it goes"

Ok graph in the other thread, but 50-90 was 90 min vs 139 min sort of more or less almost, so that is 65% of the FLA time not half the time, but it is still a lot.

BTW you can't say "2 times faster" when discussing generator time. It is not like eg, 60 mph vs 30 mph. What is meant is "half the time". Sales babble.

StirCrazy

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Posted: 05/24/22 06:46am Link  |  Print  |  Notify Moderator

pianotuna wrote:



In my opinion it is better to have high amperage batteries--so two 200 amp, or one 400 amp may offer superior service to four 100 amp jars.


Im not sure if I agree or not, the % of draw would be the same so it might not make a difference if you were using all the same. when I am going convert my 5th wheel I will be going from four 208AH 6V to three or four 300Amp LFP (depends what my wallet will alow me to do haha.) so this senario doesnt apply as I am basicly going from [email protected] to [email protected] so the percentage of draw will be a lot less, hene the heat will be a lot less.


I wonder if it makes a difference just going from FLA, or what ever to LFP due to the lower internal resistance... that might make enough of a difference alone.

pianotuna

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Posted: 05/24/22 07:13am Link  |  Print  |  Notify Moderator

Every extra connection causes some additional resistance and a possible failure point.

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