Local App - SNAFU :-|

[Lya72]

@dgd,

The micro inverter really injects 200Wh (measured with a wattmeter) and takes 236Wh from the batteries.

I Will go for an EQ at 31.5V friday afternoon.

Today, with the same sun as yesterday but just one load (375 Wh), production was only 1.0Kwh.

I am questionning if an intelligent Inverter/Charger will do better than my actual setup !!

Yann

[Lya72]

@ Erik,

three levels of battery monitors :

Midnite Solar BM              76 €
Victron BMV-602S          210 €
Pentametric (Input + Ethernet + Shunt)   400 €

The first, you must be facing it,
The second, you must have a computer connected to it,
The third seems to be accessed remotly...

Yann

[dbcollen]

and none of them are able to accurately tell you what your real state of charge is.

[TomW]

and none of them are able to accurately tell you what your real state of charge is.

db;

+1

So true.

The only true way to know is to check the specific gravity. Voltage is a fair substitute between S.G. readings.

Just IMHO

Tom

[SolarMusher]

and none of them are able to accurately tell you what your real state of charge is.

False, you just need to calibrate a battery monitor and match 1.265/75 specific gravity with a 100% SOC.
Better than checking SG three times a day...
Erik

[dbcollen]

I call BS on that statement Musher, it is IMPOSSIBLE for an electronic battery meter to account for all the variables involved in battery charging, even a very small error over a few months will add up and tha only way to truly tell state of charge is with a hydrometer.

[djohnm]

Actually, a hydrometer and a SOC meter can work very well together. As Musher points out, calibrating and matching a fully-charged battery (via specific gravity) with a meter reading at 100% SOC will give one a good reference point and enable a quick assessment of state of charge. But, as db notes, over time this alignment is going to deteriorate because of all the variables involved in charging and discharging. Re-calibrate after a few weeks, after your battery is fully charged (after gassing freely, having gone into float, resting and back at your reference SG) and you're back in business. I use a Trimetric this way and it works well in giving me an idea of where things are at without keeping a hydrometer in my hip pocket. The Trimetric documentation actually recommends this periodic 'recalibration,' as I recall.

[dbcollen]

And the variables are variable, change battery temp, and charge efficiency changes, change charge rate and it changes, change discharge rate...... ad infinitum.......

[SolarMusher]

change battery temp

Battery temp sensor...

charge efficiency changes

Set it to auto, it will learn on each charge/discharge cycle...

If a 240Ah battery with a SG at 1.265 has 120Ah out, logically you should be at 50% DoD, SG 1.200, maybe you've heard about shunt?
That's said, I agree with you that a hydrometer could not be accurate to 1Ah, but IMO a BM plus 2 monthly hydrometer controls is a more practical way to monitor a system day after day. Far better than voltage reading.
Do you have a BM installed on your system?
Erik

[dbcollen]

Maybe you have heard of Peukert.... Please look that up before you make another ignorant statement like "Maybe you have heard of a shunt"  Of course you use a shunt, how else would you measure amps in/out. Battery capacity is variable depending on the RATE of charge/discharge.

I am not new to this game, I own a RE buisness and have been living off grid for 11 years.

My system uses 4 different battery monitors, 3  trimetrics, and an outback FNDC, the trimetrics monitor hydro, wind, and battery state, and the FNDC monitors the batteries as well.

what battery monitor are you using that has an "auto" setting?

My home system consists of:

40x 50w first solar fs-50 CdTe thin film panels configured 2 series, 10 parallel into a classic 250, voc 190v
1400w seasonal hydro, 340 ft head, variable flow depending on the stream. 380vac 3 ph @ 90-110hz
10 ft "otherpower" wind turbine
12x evergreen es195 panels configured 4s, 3p voc 131v into a flexmax 80
1100 ah @ 48v battery bank
2 VFX3648 inverters "classic stacked" with an X240 autotransformer for 30a @ 240v
8Kva Isuzu 1800rpm diesel genset as backup

Dustin

"Never argue with a  fool, they just drag you down to thier level and beat you with experience"

[SolarMusher]

Hi db,
Happy to know that you have a bigger than mine, you win...
Erik

[dgd]

Maybe you have heard of Peukert.... Please look that up before you make another ignorant statement like "Maybe you have heard of a shunt"  Of course you use a shunt, how else would you measure amps?

Hall effect sensor?   ?.not so accurate but apparently may be what the classic uses.

Dgd

[dbcollen]

I have tried to explain it several ways, there is no "charge efficiency percent" that you can program into the trimetric or any other meter and have it be accurate because the charge efficiency is HIGHLY variable. 

I will give you some examples,

say you are just running a few lights all night and drain 100ah slowly from your battery bank, the next day your solar may need to put 120ah back in to get the batteries full. no problem, if your meter is programmed for the 120% than it will read correctly. However say the next evening you do a few loads of laundry and discharge the same 100ah, but the washing machine pulls lots more amps than the lights, so even though you pulled the same 100ah you did it at a higher rate. You may need to put back 140ah to get the battery full, or if it is an overcast day and your charge rate is lower you may need to put back 150ah to replace the 100ah you used.

What do you put in the battery monitor for charge efficiency? 120%... 140%.....150%?  a meter has its limitations. it is usefull in the short term to get an idea of state of charge, but since it is unable to accurately track charge efficiency I do not reccomend relying on one to tell state of charge.

Erik,

It is not about "winning" it is about education so people can pass on accurate information instead of recomending people rely on things that may kill thier battery bank.

[Halfcrazy]

I think I better jump in the middle here. Lets keep this more on topic and less personal please. I want to keep this thread going for the sake of helping Yann but if it keeps drifting this direction I may have to close it.

Ryan

[SolarMusher]

Sorry Ryan, I've deleted this post.
Erik