Had to Lower My Solar Float Voltage-Update

[BFL13]

Updated 9 July

Just a note for folks in a similar situation.

My usual procedure in a normal summer here with my set-up with the Eco-Worthy controller (adjustable Absorb and adjustable Float ) is to set Vabs at 14.8 and then, since it immediately goes to Float (no time at Vabs) I set the Float as high as it will go, which is 14.5 so it stays there till dark.

Somewhere not long before dark the batts are at "true full" by baseline SG, which I can tell because the Trimetric reads 15AH "over" (into positive)and this corresponds to baseline SG. Supper and evening usage of the big draws via inverter (microwave etc) keeps the batts from going on too long at the high voltages, losing positive plate and water.

Well not this year! We are having fabulously good weather, thanks to some giant squids off Peru or whatever it is, so now the batts are getting to baseline SG mid- afternoon and IMO spending too long at high voltage before dark.

So the new drill while this lasts, is to lower the Float voltage to 13.8 once the Trimetric says we are at 10AH over, which is about 3:30 pm these days. I will keep track and adjust as required of course.

The EP Solar controller I had before had a fixed charging profile of getting to 14.6, stay there for two hours, then drop to 13.8 till dark. That would be perfect right now, but with this controller, I will have to do manual resetting of the Float till the weather gets back to normal. Put it back to 14.5 in the morning then to 13.8 mid afternoon.

Lesson is---keep an eye on things and adjust as required. Solar is not a set and forget system.

[MEXICOWANDERER]

A peek into the cells is a peek into the chemistry. Electrolyte should not render bubbles at 25c which I imagine is not too far off of BFL's afternoon temperature. Not at 13.4 - 13.6 volts.

Long-term float is definitely different than daily cycling float voltage. My Lifeline for instance would have a 13.8 - 13.9 float voltage setting for float if it endured daily deep cycling duty on solar voltaics.

BFL's observations are worth their weight in gold. I hope folks are weighing his conclusions seriously. The art of Trends & Tendencies cannot be omitted from proper battery management.

Battery OEM have made it harder and harder to glean information that would CORRECTLY aid battery management. For instance the percentage of antimony in a flooded battery is critical beyond belief.

But I read zero anywhere about antimony content except in ads for 2-volt cells.

What is the antimony content in a Johnson Controls deep cycle car jar?

Deka?

Trojan?

US Battery?

A chart would be useful but I cannot afford international telephone calls to query individual manufacturers.

Anyone out there care to make a phone call or two?

A group 27-cyclable battery would be an excellent DUS (device under study)

[time2roll]

OK. I figured 13.4 could be a more permanent setting.
I wonder how bad it would be after two weeks camping....
Impossible to know.

[BFL13]

smkettner wrote:
Why not hit the middle at 13.4?

Have to pick something! The idea is just to not leave them at 14.5 so long. 13.6 is good enough for the converters, so it is good enough for me 🙂

Once this stretch of sunny days ends and we go back to normal mix of sun/cloud days, I will put the Float back to 14.5 as before.

[time2roll]

Why not hit the middle at 13.4?

[JiminDenver]

Looking at the newer model.

It has a adjustable absorb voltage time of 10-300 minutes. Is still limited to 275w, and they have raised the back up to improve air flow around the controller.

on edit

Thinking about it, the absorb time is the biggest improvement. I don't doubt 275w will max it out, 250w is doing 18+ amps now. A 275w mono is usable with the older model, so are a pair of 140w panels.

had they added remote temp sense we could have almost had a respectable controller. 🙂

[BFL13]

JiminDenver wrote:
So lets see. They set it at 42v first, changed it to 45v and then back to 42v for the original and 50v for the newer that you can't tell a difference in.

Considering that people have been using the original version with two 12v panels for years, I wonder if only the new units are 50v because you wouldn't need to buy a new one if you knew the old one would do just fine.

It is still possible that those people were using their 22v panels (total 44v) when the panels were at 20 each, so the 42v one did not fry.

My 130w panel in the sun was normally at 20.3Voc rated at 21.9Voc STC
Voc is reduced by panel heating and any sun on it heats it up.

[JiminDenver]

Found this on ebay. I wonder if it is the new model. It certainly looks different to me.

click

[MEXICOWANDERER]

Jim kudos on your sense of deduction 🙂

[JiminDenver]

So lets see. They set it at 42v first, changed it to 45v and then back to 42v for the original and 50v for the newer that you can't tell a difference in.

Considering that people have been using the original version with two 12v panels for years, I wonder if only the new units are 50v because you wouldn't need to buy a new one if you knew the old one would do just fine.

[BFL13]

JiminDenver wrote:
Hmmmm

How would you make sure you were getting new stock over old. I guess by buying only from the website at full price. Oddly the two people I know of using two 12v panels in series have older Eco-Ws.

At least the NEW Eco-w and a pair of hinged 150w panels would make a sweet portable.

I had a series of emails with Eco-W and it turns out that:
A. the new ones are 50v and the old ones are 42v
B. you can't modify the old to be like the new, and
C. You can't tell the difference from the outside looking at it whether it is a 50 or a 42. (say you got a used one and wanted to know)

I suppose that means you could tell from the new circuit board somehow, but I won't ask them about that. 🙂

There are obvious comments to be made about that whole thing, but would be fruitless. Eg paint a blue dot on the new ones. Anyway that's how it is.

[BFL13]

New snag. When the controller is in Float, it will still provide the amps to run loads and keep the battery up.

But with the batts full and voltage at 13.2, when I turn on small loads the amps on the Trimetric go negative (charging light also goes out) and then after a while the amps come back and go positive and the charging light comes back on. The controller stays in Float for these small loads (laptop, turn on a light or two, etc)

The usual thing with those three- stage converters is that they will be in 13.2 with no activity, but if you start using your 12v things, they jump back to the standard 13.6v level. I think I see why.

So I reset the Float voltage to 13.6 and now small loads still cause a short duration drop in the amps to the battery, but the amps stay positive and the charging light stays on.

I think Mex recommended 13.2 thinking it would be a "storage" rather than a "still camping using 12v stuff" situation. Anyway, I am now leaving it at 13.6v and we'll see how that works.

[MEXICOWANDERER]

Full Mosey

Floating AMPERAGE should be your guide. With a load disconnect check both voltage and amperage down to second after decimal point amperage. Doing so is worth it's weight in big denomination banknotes.

[BFL13]

I just asked Eco-W about that. I will post what they have to say.

[JiminDenver]

Hmmmm

How would you make sure you were getting new stock over old. I guess by buying only from the website at full price. Oddly the two people I know of using two 12v panels in series have older Eco-Ws.

At least the NEW Eco-w and a pair of hinged 150w panels would make a sweet portable.