SiO2 Battery -UPDATE 5 (Two Batts)

[BFL13]

Updates 22 Oct, 8 Nov, 10 Nov (photo), 14 Nov, 15 Dec

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

Mostly PT has given info on these over several posts in several threads, but I have lost track where.

What are the main pros and cons for this battery again? I might actually have a use for one! What amps draw can a single 100 stand for how long--5 minutes of MW at 100 amps? Left in a hard to access place and no worries? Can float voltage be too high or too low?

(AGMs do not stand up for what I am wanting to do--BTDT 😞 )

Thanks

[BFL13]

I got the second one so have 200AH under the closet floor hard to get at, but close to the inverter so that all works out. Also am able to use the 55 amp converter and be close enough to the 25 amp per 100AH charging rate "limit". The thing is, these are modified AGMs and you need to get them to full every so often, same as regular AGMs.

Only way to do that is charge them at 14.6ish till amps get right down. I found that to be around 0.5a/100AH same as my old regular AGMs. BUT that means you need an ammeter and a charger that stays at 14.6ish until you see the amps get down to that.

I use my Trimetric monitor for the ammeter, and my adjustable voltage PowerMax for the method to hold voltage constant without the thing changing "stages" on me when I don't want it to. So that is the same as with my old AGMs too.

It works so the amps get down to around 0.4/0.5 and then next time you look it is 0.6/0.7. That is typical AGM action. Once it is full the amps just go to heat, and as it heats up it takes more amps. So you have to be there to stop the recharge when the amps begin to rise again. Same as regular AGMs.

What is different here, is the high discharge rate allowed with these SiO2s, so I can run the microwave etc on the 200AH bank no worries, and that you can run the bank down to below 20% SOC no worries (another job for the Trimetric to help keep track of how low you go)

It will be over a month now before the next time the camper goes anywhere, so I am floating the SiO2s till then as suggested by Trojan for AGMs. When the camper is busier I will have to decide on the "float or not" question. I think now I will ignore Trojan's guideline, because the batts are too hard to get at for wires off disconnect, and I don't have a remote disconnect method that does not add wire to the inverter-battery distance for more voltage drop. Worry about that next year! 🙂

[StirCrazy]

pianotuna wrote:
steve 4 is not 2. Unless you are using some sort of higher math? lol!

I was trying to figure out why you said that in the first place haha, the only place I have a microwave is the 5th and it has 4 and works gread. the TC doesnt have a microwave so I dont have to worry about running it on the two 6V I have in there.

Steve

[BFL13]

Actually, many (all?) battery specs have the same floating voltage as these SiO2s. (2.25 a cell) My AGMs did and also the flooded batts I have had.

PD's are used successfully with all those other batteries according to various reports

Moved to its own thread----

[pianotuna]

ScottG,

My guess is only if you can do a full recharge every 30 days.

They are advertised as being able to sit uncharged for up to one year.

I'd write to the seller and ask.

[BFL13]

https://www.gliderpilotshop.com/lead_crystal

I am not an expert so it is just my opinion, but I don't see why sitting at 13.2 instead of 13.45 (see above charging info) would matter for RV work between trips or even for a few months.

You can leave the battery partially charged for long periods no harm, and the worst that 13.2 could do is fail to keep up with a slow discharge.

It looks like leaving them hooked up to the LP and stereo and disconnect open is the worst thing where it says they will get a little sulphated over time. In that case 13.2 between trips must be better, and you also get a shot of 14.4 every so often.

RV use does not match "cyclic use" unless full timing or "standby use" , so you can do whatever makes sense IMO.

[ScottG]

Can Si02 live with a 13.2VDC float (PDI storage) voltage?
Some literature suggests they want 13.5 min..

[BFL13]

The MW draw vs battery AH has two things:

1. the discharge rate wrt what the battery is designed to handle without harm (I think I warped the plates of my AGMs from that)

2. the voltage drop that will alarm off the inverter.

A pair of 6s will keep the voltage above 11v alarm down to about 75% while four will let you keep the MW on till about 50% SOC.

A MW draw of say 120 amps on 235 AH bank is just too high for ordinary batteries. 120 amps on 470AH is ok.

The SiO2 feature I am using it for is that it can take a high discharge rate. It even holds its voltage up fairly well, but not as well as Li batts do down to low SOCs.

That feature means you can do big draws in the TC with SiO2 where there is limited space for batteries, such as four 6s.

Same thing with Li for that plus an advantage in being of lighter weight that might matter in a small RV. However, the Li is way more expensive and it has the cold weather issue to be overcome (heat pads or whatever) Also it has the BMS to complicate things, which SiO2 doesn't need.

You have to get your priorities straight with all that money at stake. Most folks don't need Li or SiO2 to get the job done. If the TC we got were not so awkward for battery space and inverter space, I would have been able to do the job with ordinary batteries. Way I look at it now looking back at buying this TC, it just adds to the initial (low) cost.

Rationalizing after the fact is the way to stay sane. 🙂

[pianotuna]

steve 4 is not 2. Unless you are using some sort of higher math? lol!

[StirCrazy]

pianotuna wrote:
Stircrazy,

You won't do well running a microwave from twin six volt batteries.

I dont have a microwave in the truck camper, and the four 6V 235AH batteries in the 5th wheel run the microwave just fine. to be hones we dont use the microwave a lot, making popcorn and a couple other things but the batteries in the 5th handle it fine so never worried about it.

Steve

[pianotuna]

Stircrazy,

You won't do well running a microwave from twin six volt batteries.

[BFL13]

Edit-- might be some confusion! I did not say that it was only $300 more to get the same AH. Obviously 230 AH is more than 100AH. I already have one SiO2 (expensive) so adding another to that would also be expensive to get 200 instead of the 230 for the 6s there now. (but hard to get at--unsat) It is just that if I left the 6s in the TC I would need to get two for the MH to get back to having four there. Clear as mud?
-------------

Not clear what Azimuth is doing for price just now. I think the prices are coming down somewhat. They still have a bunch on the shelf they just got in that are not exactly flying of the shelf. I found that if you get hold of them and do your best bazaar routine, you might get a deal.

I would not buy them at all unless you had a special need that only they can fill compared with ordinary AGMs. I hope I have made that clear in this thread--not suggesting they are better in every case. In fact IMO, probably few cases. But when needs must--yes.

My special case was I needed to run the microwave at fairly high amps wrt to the battery bank AH, and the batteries were hard to get at. So Wets are no good being hard to get at, and I had no luck before with AGMs doing that work, where they apparently warped their plates the way I was doing it, and want to keep doing that. (I have no trouble in the C doing that with four 6s, but can't do that in the TC with limited vented space for batts you can get at)

Ta Da! The SiO2 is the right answer for the TC. But not enough AH for the other loads to last a few days as with regular camping work. No problem as DW was only going to be day-running or maybe one overnight at the dog training place. Then of course-- she moved the goal posts and wants to be able to stay longer, but still use the TC instead of the C because of parking space. Well drat! So out comes the Visa card for another SiO2 to make up the AH and still be ok where it is hard to get at. At least that puts all four 6s back in the C where they belong. Oh well. 🙂

Just how it is in the big city! 🙂

[StirCrazy]

BFL13 wrote:



--On price-- Azimuth is selling the 27 size 100AH at $628Can (also their US site says $449 US--which is lower at 75 cents conversion) but they have all sorts of sizes and prices.

http://www.azimuthsolar.ca/product-category/batteries/sio2/

I can get two 6s at Can Tire (they are East Penn GC15s 230 AH--an excellent 6) for just under $400 with tax, no shipping. That is nearly $300 less than the SiO2 with tax and shipping.

It could be worse --check out what Lis cost! (Way more)

Have to wait for the BC govt buy my vote money to show up or else win the Lotto I guess.

300 less and twice the AH or a little bit more usable amps. I am going to have to go back and read this all over again. I am surprised with all the other types of battery prices coming down these are still that much. lots of questions yet before I cn buy them.

Steve

[pianotuna]

Here is a video where they took SiO2 to zero volts. Every day for six months? (not quite sure)

This after 4 weeks:

https://www.youtube.com/watch?v=cawNUyLAnP8

This after 6 months?

https://youtu.be/O45eLd5YotM

It is a bit old 2012

[BFL13]

PT, don't forget that your SOC when amps start tapering depends on the charging rate, so at 25% it would be at a lower SOC than at the 19% I was using.

I don't have a charger that can do 25 amps. Nearest I can get is my Vector chargers with their 20 amp settings (eg my 1092A with 2/10/20/35)
It happens that mine does 19 at the 20 amp setting. The charger seems to be set for 14.7v and battery voltage got there by the end.

If you are recharging on gen and stop before the battery is full--as usual with gen charging to not waste gen time with tapering amps, then battery voltage would still be under that 14.7 when you stop.

Eg, when doing a 50-90 using 14.8v charger setting, battery voltage might be 14.5 when I stop. Also there is voltage drop in there, but by the time amps taper down that becomes less so battery voltage is closer to charger voltage. Even so, you don't see battery at the same voltage as the charger until amps stop flowing right at the end of a full recharge.----You know all that, but some might not, so I want to be clear.