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I have full sun on 12 x 270W panels now at noon that were up to a combined 1300W much earlier this morning around 8am in partial sun but for the last few hours seem 'throttled' around 500W:
Is it possible that the last 8% of the lead acid battery bank is being charged very slowly to prevent gassing or something?
Charge mode is "Absorption" which I thought used as much current as possible?
Site at: https://vrm.victronenergy.com/installation/34733/share/07ef9055
Are you using a battery monitor (BMV-700 or 712) or the internal battery monitor? It seems to rather be not calculating SOC correctly, as your battery is clearly fully charged or very close to it, judging by the battery voltage and current
Internal on MultiPlus-II. Is this possibly because I have set charge efficiency to 0.8 in "Battery Monitor" configuration in VE Configure 3?
I plugged an electric kettle in to increase the load and sure enough, the solar responded:
Hi Warwick. Ta for the guest VRM access. (Love my VRM.) Random gleanings..
* Murraynated is right, your SOC is misleading you. Ignore it until you can sort it.
* You're not using your batts virtually at all for your loads. Maybe that's what you're wanting, just as a ups?
* Grid power all night, batt V just 'settling' overnight. Solar comes on, winds up early to Abs. Must back off to keep batts from overcharging. (The issue you asked about)
* Abs carries on far too long for batts just idling all day/night. The standard algorithms wouldn't do that, so maybe you've a special setting input there?
* And even while solar is available you still have some grid input?
It all depends on what you're trying to achieve. You won't get much input from the solar the way you're set up now.
Hey John
I have it set to use up to 20% of the battery.
My logic is this:
1. I introduced the batteries and inverter first primarily as a battery backup to get us through outages and rolling blackouts in South Africa;
2. When I added the solar, rather than choosing "Keep Batteries Charged", I wanted to get some benefit from the batteries so made the following assumptions:
2.1. Lead acid battery bank has 50% usable capacity;
2.2. Since I have never used more than 15% during a power outage, allowing the occasional 20% to be used by ESS should leave me a theoretical 35% for backup power before cutoff.
I am sure that in practice I will learn the actual limits - but I need to figure out how to get an accurate SOC first.
SOC Issue
Do you think me changing the "Charge efficiency" value in VE Configure 3 messed up the SOC / Battery monitor value? I have tried to change it back to 1.0 (the current live value), but the % hasn't changed in the past couple of hours since changing it back (remote VEConfigure):
I only connected the MPPTs and panels on Sunday. These are my first few days but at the same time as enabling the ESS, I broke the golden rule (change on thing at a time) and also changed the "Charge efficiency" value to 0.8.
This is the previous week where you can see battery SOC is at 100%:
This is this week where you can see ESS making use of that top 20% of the battery bank:
Here's a snapshot of it right now:
Ps. For context, this is what the bank looks like (needs lot of tidying but a work in progress):
Yeh, you provide great info. ESS though is outta my pay range, and I do this for free.. :)
Not a big fan of SOC myself, but if this is what your system is working off, then you've gotta get it right. Not sure why your settings there won't stick, but work on it some more.
Likely that 80% is too low, but if you can work out the best spot then you've a chance. When you know you have fully charged batts and the SOC isn't showing 100%, then you need to make it show 100%.
You could also relax your ESS setpoints (within reason) if the SOC is too hard to nail down.
VRM is a great asset, and if you can 'get-to-know' your pb's via V, the A they can handle, and the dynamics of that, then you'll get on top of it.
That long Abs with full batts would worry me a little too, so consider that as well. The 'balance', hey..
Sorry, but 'vague' is what I excel at with someone else's batts.. :)
Hi John
I rebooted the MultiPlus II early this morning and it seems the change of "Charge efficiency" from 0.8 to 1.0 came back into effect. The battery showed at 100% by 09h00.
I will leave it like that for now.
Thanks again for your help.
Just a comment on your question "Charge mode is "Absorption" which I thought used as much current as possible?"...
I don't think that is the case.
BULK mode is typically the high current mode and the Voltage builds up as the battery gets to a higher SOC (around 80% or so) (BULK is also called CC - Constant Current).
Absorption Mode (also called CV - Constant Voltage) is where the voltage is at the high voltage, and the current starts to decline as the battery approach 100% SOC. The chart below from a charging test I did shows that quite well. Around 18:00,the mode changes from Bulk to Absorption.
Thank you for this. You are absolutely right.
It looks like it was close to 0A by 11:00 this morning:
