SiO2 Batteries and High Amp Draws

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

Lwiddis
Explorer II
May 20, 2022
Another interesting, educational report. TY.

Price seems high even in Canadian dollars.
wa8yxm
Explorer III
May 20, 2022
Just so you know... I always assumed PSW inverters were not as efficient as MSW at turning 12 into 120.

Finally I researched... Peak efficacy is 89-90% on one 90% on the other. Identical.
BFL13
Explorer II
May 20, 2022
wa8yxm wrote:
Just so you know... I always assumed PSW inverters were not as efficient as MSW at turning 12 into 120.

Finally I researched... Peak efficacy is 89-90% on one 90% on the other. Identical.

Still has the PSW draw more amps than the MSW same load. So it is about the time being shorter for the PSW to beat the MSW for AH

150 amps for 3 minutes (0.05 H) = 7.5 AH
125 amps for 4 minutes (0.067 H) = 8.4 AH

But if it is a spud for as long as it takes to get soft enough by poking it with a knife, IMO you can't tell the difference for it being ready to eat if you make it 7 minutes for each case--in which the MSW then wins for having fewer AH.

150A x 0.12H = 18 AH
125A x 0.12H = 15 AH
otrfun
Explorer II
May 20, 2022
BFL13, interesting info, thanks!

How low (of a SOC) can SiO2's be safely discharged on a regular basis?

Your max load appears to be ~90a. Maybe I missed it, but will the voltage on your 200ah bank of SiO2's stay above the inverter's low-voltage cut-off while under a 90a (.45c) load at its minimum recommended SOC?
BFL13
Explorer II
May 20, 2022
otrfun wrote:
BFL13, interesting info, thanks!

How low (of a SOC) can a SiO2's be safely discharged on a regular basis?

Your max load appears to be ~90a. Maybe I missed it, but will the voltage on your 200ah bank of SiO2's stay above the inverter's low-voltage cut-off while under a 90a (.45c) load at its minimum recommended SOC?

They say you can run them down to Zero SOC many times no problem, but I have seen ads for AGMs saying the same thing.

So you can run them down past what would trip the inverter to just run ordinary low amp RV loads ok

The voltage drop is also from wiring not just from the batteries, so if I had fatter wiring and all that, the inverter could go lower in battery SOC before tripping, so my result could be different from another guy's with the same battery

I count the "0.45C" as using the C at the time, not the rated C when at 100% SOC, so watch for that when reading my numbers. Eg the 90 amps when the 200AH bank is at 110AH is 90/110 = 82% draw the way I do it.

I only took it to the inverter alarm at 11v not to the cut off at 10.5v so I don't know how much farther down in SOC it would go to get to 10.5

They have a somewhat higher voltage per SOC than Flooded batts so that helps with going lower in SOC before tripping the inverter too.
pianotuna
Nomad III
May 21, 2022
Thanks for the research.
3_tons
Explorer III
May 21, 2022
I do view these findings very interesting and ‘demonstrable objective’ :), Many Thanks for posting this!! No doubt, a solid case can be made for SiO2’s, particularly regarding cycle life (per Azimuth), uber high discharge amps, no sulfating (no equalizations needed), and the ‘hands down’ cold weather king…At first glance, initial acquisition cost might put some folks off (as with a few LFP…) but in many ways superior to some other types, thus, (similar to LFP’s…) for some folks, likely can be well justified over the loooong haul…

Again, Great Post !!

3 tons
time2roll
Nomad
May 21, 2022
Seems to hold voltage about the same as my old set of four GC2.

Has charging performance been measured? Such as how fast does the SiO2 get charged and when does it start to taper the current?
What is the temperature compensation below freezing?
BFL13
Explorer II
May 21, 2022
I have not plotted a set of charge profiles for different charging rates. Spec limit is 27% and at that I saw tapering starts in the mid 80s, so a little faster than FLA but not in the 90s like LFP. Like an AGM. I will plot an ugly graph on that someday

There are some temp plots in the Azimuth info links don't know if answer to that is there

Yes to the four 6s comparison for high draws --not like two 6s that can only do it down to 75% SOC. You need 4 to do it at 50%.

I will get the Wonder Dog to do the ugly graph work. (Mex has camped here some years ago at Englishman River Falls park--if he is on here he might recognize it)
StirCrazy
Moderator
May 21, 2022
BFL13 wrote:

They say you can run them down to Zero SOC many times no problem, but I have seen ads for AGMs saying the same thing.

So you can run them down past what would trip the inverter to just run ordinary low amp RV loads ok

The voltage drop is also from wiring not just from the batteries, so if I had fatter wiring and all that, the inverter could go lower in battery SOC before tripping, so my result could be different from another guy's with the same battery

I count the "0.45C" as using the C at the time, not the rated C when at 100% SOC, so watch for that when reading my numbers. Eg the 90 amps when the 200AH bank is at 110AH is 90/110 = 82% draw the way I do it.

I only took it to the inverter alarm at 11v not to the cut off at 10.5v so I don't know how much farther down in SOC it would go to get to 10.5

They have a somewhat higher voltage per SOC than Flooded batts so that helps with going lower in SOC before tripping the inverter too.

ya they say you can ocasionaly run them down to 0, but for maximum life stay above 50%. I do like this as it is a saftey net for the average person that kills batteries by acadently letting them get down to 0.

but I have to be honest , I am not that impressed with the current draw you got on them. yes it is the same as the four, 6V I have in my 5th wheel, maybe a tiny bit better, but two 100amp LFP will handle the same voltage and stay above 12V to aproximatly 10% capacity so I don't see an advantage there against LFP, but ya it is definatly a step up from normal batteries.

there is a place for SiO2, but I think there price now puts them out of reach for most, aside for the people who actualy do need them like PT, but even there he has been saving for 3 years. I think they are now the most expensive per AH of the main battery types, last time I checked.

I guess the way I look at these, and yes I did look at them and weigh the pros and cons when PT first started advertising them. I looked at upgrading to them but the only advantage I would have got is the cold weather usability and a slightly higher amp draw capacity. at almost 700 bucks per 100 AH battery x 4 it was just way to far out of my price range. I thought about them again when I went to upgrade the camper so I would have paid 1400 buck for 200ah capacity and to get maximum life I could use 100AH of that capacity so no gain over the cheep GC2 i stuffed in there as a temp measure. I ended up going with 300AH of LFP with a 100Amp BMS. I didnt need anymore amp draw capacity , there was an option for a 125amp or a 150amp BMS. but in the camper I am also worried about weight and size so about 1000 bucks I did the new camper setup.

but like I said if weight , size are not a concern and you do really cold weather camping its a option.