SiO2 Batteries and High Amp Draws

[BFL13]

SiO2 is a specialty battery type that most folks would have no use for vs the usual RV battery types. They cost a lot too.( I had a special reason to get one)

Here is some info on them --I am not selling them!!! Just trying to show what they are

https://azimuthsolar.ca/product/12v-100ah-sio2-battery/

One big thing they are supposed to be good for is high amp draw loads for their size in AH. So here is what I found on that:

1. The 200AH bank (two 100s) with the 2000w MSW inverter and my wiring job has a voltage drop that stays about the same for the same load at any SOC above inverter shut-off voltage.

2. The MW draws about 55 amps and the kettle draws about 89 amps and the furnace in the TC draws about 3.5 amps.

So example using kettle to boil water for cup of instant coffee. (No advice needed on making coffee, you latte bunch, thanks anyway 🙂 )

A. Monitor before start--142AH, 12.7 volts, 71% SOC
After start- 88.7 amps draw, 11.7 volts, about five minutes kettle off
Monitor now--135AH, 12.5 volts (rising slowly), 68%

So that time 89/142 is a 63% draw.

B. Before-- 113AH, 12.3 volts, 57%
-11.5v at 88a
-11.2v at 90.5a
-11.1v at 90.6a
After= 106AH, 53% SOC

So that time 90/110 is an 82% draw.

(note how inverter amps go up as voltage goes down--"inverter creep" The inverter did not alarm at the 11.1 but would have at 11 but still run until shut off at 10 something. Both times cost about 7AH each

C. Another example kettle and furnace on 107AH and now 90.1 amp draw voltage 10.9 and inverter beeping

So that time 90/107 is an 84% draw.

I first got one SiO2 to run the MW (700w RCA) in the TC and did a quick test where ISTR it ran its 55 amp draw for over 30 minutes till SOC was about 20% afterwards. The battery discharge tables in their specs showed the discharge time was close to specs for that size draw.

The comical thing is I learned the MW can heat the water enough to make my coffee using fewer AH than the kettle in the TC.
-kettle 5 minutes at 89 amps --voltage drop 1.0 volt
-MW 3 minutes at 55 amps (MSW inverter. A PSW inverter would draw more amps but not take as long to heat the water, but still use more AH than the MSW depending on your version of hot enough)--voltage drop 0.8 volt.

Note the kettle also needs more water than needed for a cup to reach its minimum fill level marker, and it gets the water too hot. Yes I can use the propane stove with a pot of water and do it that way--if desperate!

However that is in the TC with the small MW and MSW. In the MH the MW is bigger and the inverter is PSW, so the kettle is a valid choice.

So that was pretty good IMO. For those kinds of high draws I would need four 6s at 50% SOC or 90/230 = 39% draw to stay above inverter alarm at 11 volts

[BFL13]

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?product=SKR%252d125AGM-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/uploads/2019/11/Azimuth-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. 😞 (and that is just as true for LFP ads on "faster charging" with no side by side charging profiles)

[pianotuna]

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.

[StirCrazy]

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

[StirCrazy]

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...

[3_tons]

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 🙂

3 tons

[pianotuna]

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.

[3_tons]

BFL13 wrote:
High draw per capacity ability and higher charging efficiency are different things
LFP has both; SiO2 has the first, not so much
of the other AFAIK but will know when I plot a charging profile

Ha! Well I suppose then by default that’ll soon make you RV.net’s own SiO2 ‘Resident Expert’!!…FWIW (now having expanded to 8 dang PV panels!!), solar has gotten cheap and adding more will greatly help overcome slower charge recovery - just saying…

3 tons

[BFL13]

High draw per capacity ability and higher charging efficiency are different things
LFP has both; SiO2 has the first, not so much
of the other AFAIK but will know when I plot a charging profile

[3_tons]

Unfortunately, I don’t possess that level of detail, mostly because (with level best honesty, pleased, since faster than my former GC’s) I’ve not felt any desire to develop such…But some others here (say, far more attentive than your’s truly - lol!) may be better able to inform…

Having said that (and from experience…), yes there is a gradual bit of voltage drop, but as I’ve previously posted (e.g. testing even at zero % SOC while at 125a Keurig brewing…), yet still no inverter or BMV 712 low voltage alarms - note, a single Aims LFP bench tested at 215 actual a/h…)…

FWIW, From all that I’d past researched (non-vendor sourced) and read here, I’m honestly not aware of any actual user disagreement concerning LFP’s quasi-faster charge recovery time (though I now lack the GC means to quantify such…), however this has just been my ‘seat if the pants’ but recurring experience (though not a ‘one off’!!)…Admittedly, I’ve given you a lot’s of ‘blow back’ in the past, yet with your most recent post, you’ve conveyed (at least in my view) a far better sense of where you’re coming from and which I can better relate to and appreciate- just saying…:)

3 tons

[BFL13]

Actually have almost no info on LFP charging profiles. To understand your data above, would also need the charging voltage and whether it reached that when tapering started.

Sometimes tapering starts "early" as was seen with PD some PD converters not holding constant amps in Bulk, and is not related to the classic Bulk/Absorption transition.

There is a need for some plotting and graph making to get the picture clear. 🙂

[3_tons]

I believe the 60 amp limitation is likely due to heat and the closeness of prismatic type cells - ain’t nothing wrong with that…Alternatively, cylindrical type cells have air spacing in between and often capable of 1c, (as with Aims and as I recall BB)…

Either way, know that using simultaneously my 100a ProSine 2.0 inverter-charger and the PD 9245 in boost, the highest combined amperage I’ve ever witnessed going into the two paralleled 200a/h LFP’s (say, starting out at about 30-35% SOC) is just over 70 amps (say 72a), but as you’re aware the current shortly thereafter begins to taper downwards - can’t recall exactly, but probably drops to mid or just over 60a within only about 15 min…

3 tons

[BFL13]

Yes they survived a year of floating ok.

With one I had to use the 20 amp setting on a Vector charger but with two I can use the 55 amp converter

I see that Alberta LFP says 60 amps limit so would need the 55 amper and not use my 75 amper. I guess it has the under-sized BMS you guys were talking about

[3_tons]

BFL13 wrote:
I got the SiO2s in late 2020

Seldom used since with covid reducing dog events. Took the TC out myself the other day to see that it all still works now things are starting up again

Heck BLF, they’re almost brand new then 🙂 !! So, with ‘lots to recommend’, and many years of what’ll surely be dependable service that awaits, ain’t no dang reason to be looking back!!

Just Enjoy!!

3 tons

[BFL13]

I got the SiO2s in late 2020

Seldom used since with covid reducing dog events. Took the TC out myself the other day to see that it all still works now things are starting up again

[3_tons]

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.”

Yet I don’t view this as some kinda ‘dire situation’ but rather just an alternative path to arrive at one’s own particular energy needs…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…

Cost is yet another another factor, and though prices more recently have appeared to drop, in the not too distant past (e.g. ‘conditions on the ground’ at the time…) LFP cost for our neighbors in the north seemed excruciatingly high ($$), likely making acquisition a relative rarity…Again, just my lay opinion only, but ultimately the BEST overall option might easily and logically have been to go forward using the very same battery type - No dreaded after thoughts required !!

3 tons