birdibird wrote: ↑
Sat, 20 Apr 2019, 08:34
I have been running my 5048MG now for half a year batteryless, charging our Renault Zoe electric car fine.
'Granny' cable with either 10A or 13A is working great: when the power is not there (clouds or so), the PIP lowers the Voltage, and the car even kept on charging under 100V!
Wow. I think you're pretty lucky with the Zoe charger. Many chargers would just draw more power from the lower mains voltage, to maintain some desired charge current. I gather you don't connect many, if any at all, other loads to this batteryless system.
Now I connected them in 4p4s to the PIP.
Settings set to Bulk 55.2, Float 52.8, cut-off 47.5, 32 to AUT
01 to SOL, 16 to OSO, 02 to 80A, 11 to 20A
12 to 48V, 13 to 51V
Those settings sound fine, though if you don't connect a generator to the AC input, I believe that settings 12 and 13 won't do anything.
How does it work here with CV and CC on the PIP's?
It's supposed to charge the battery until it reaches the Bulk/absorb setting (setting 26, Bulk charging voltage). This is the Bulk stage. Once it reaches that point for a certain period of time (a few seconds, but with no dips more than a few volts below that level), it should keep the battery voltage near that setting. This is the Absorb stage. It can't keep the battery voltage near setting 26 if there isn't enough solar power available, but it should keep aiming for that voltage during this stage. This continues until the charge current reduces to a special value. When that happens, the charger changes to float mode, which is another "constant voltage" mode, where the voltage set-point is now the one from setting 27 (Float charging voltage). This is the float stage, where the battery is considered full. However, while the loads exceed PV power, the battery will discharge, and if it discharges enough, another charge stage will commence.
-I hardly saw the PIP bulk charge 55.2. How can I check that what mode it is using? Does Watchpower tell me?
I don't believe that Watchpower will tell you. If you can see the green LED in the middle of the LC Display panel, it will be flashing during either the bulk or absorb stages, and will be on solid in the float stage. When charge sources are not available, it will be off.
If you're not seeing 55.2 V often, it could be due to the premature float bugs (more below).
I first set Bulk and Float both to 56 (and later 55.2) as I have seen others do that, to charge the batteries on a higher V.
I don't know why others do that; it just leaves the battery at a high voltage too long, which is not good for long life.
-But I also read in these forums people having lower Bulk settings, close to Float, around 53. Why is that?
That's probably for people with boxed LFP batteries, which often come with 15 cells in series. So 53 V for them is 3.53 VPC (Volts Per Cell), equivalent to 56.5 V for 16S batteries.
-settings 12 to 48V and 13 to 51V: does this do anything with only Solar?
My understanding is that these will do nothing for your configuration, as it's never possible to go to line/bypass mode.
-Today l didn't touch my settings (Bulk 55.2, Float 52.8, cut-off 47.5) and I never saw the PIP charge above 52.8. It was mixed cloudy, raining and now and then suddenly blue sky. At the end of the day I saw the V declining, while I hardly had any loads, and when the PIP hit 48.6V it suddenly switched off and I was in the dark. What happened here? (I saw fault code 4 when it was still around 49.5V)
That sounds like the dreaded permature float bug; more below.
-Is this all related to this 'float bug?'' I thought I read I had to make sure to have the settings 02 and 11 < *5, hence the 20A choice. Or is that only if I would use AC in?
Juggling settings 02 and 11 is only to demonstrate the premature float charge bug to those who can't believe that a modern manufacturer would release products with such a glaring bug, and not fix them even in newer products. Setting 11 is maximum utility charging current, so it has no effect for you (unless you connect a generator).
My firmware version is 71.40
That sounds like the most recent firmware for your inverter. Sadly, there is no patched firmware for these, and may never be.
The premature float bug arises because the inverter should only go to float stage when two things happen: the current is low enough (they do this, obviously), and the battery voltage is high enough (this is where they screw up). Obviously, on a cloudy day, the charge power will fluctuate wildly, from the nameplate rating of the panels (or even a little more for a few seconds) down to nearly zero. So the charge current will vary from the maximum allowed by setting 02 (maximum charging current) down to almost zero. So plenty times, well before the battery is fully charged, the charge current criterion (that the charge current falls below about a fifth of setting 02) will be met. But there is a voltage criterion as well, as there should be (otherwise the charging would stop at the very first cloud, and that would be blatantly obvious). The trouble is, the factory firmware uses the wrong voltage setting to compare against. It should obviously be checking for the battery voltage to be at or near the bulk/absorb setting. Instead, they check for being at or near the float voltage setting. Even worse, they don't insist that the battery voltage is exactly the float voltage setting; half a volt less will do. With an LFP battery, the float setting is near the long flat voltage plateaus in the voltage versus state of charge curve. So if the battery has had a decent burst of charge for a while and hasn't had a lot of time to settle back to its steady state voltage, the SOC could be as low as 45% or a little lower, and it will still pass this "voltage criterion". So your charger could stop charging as it sails past 53.8 - 0.5 = 53.3 V, or 3.33 VPC, quite a long way short of 55.2 V and 3.45 VPC!
LFP batteries don't need long equalisation, but you might have to resort to setting 32 (Bulk charge time, really absorb state time) to force the charger to give a longer period of time when it's aiming for the bulk/absorb voltage. Unfortunately then the second charge bug comes in to play: all time after the first time that (absorb setting - 0.5 V) is seen is counted as absorb time. So there is no extra time for cloudy days. But at least, it must have seen nearly the absorb/bulk voltage at least once (so that's some 80% SOC already), and you can give a generous time for "absorbing" to take account of "average" cloudiness, at the expense of a little extra time at high battery voltage, and therefore at a small expense of battery life.
Please complain to your reseller, and to Voltronic Power! @Weber
and I grow weary of patching version after version of firmware, when the fix is so simple.
[ Edit: "charge current" → "charge power" ]
Nissan Leaf 2012 with new battery May 2019.
5650 W solar, 2xPIP-4048MS inverters, 16 kWh battery.
1.4 kW solar with 1.2 kW Latronics inverter and FIT.
160 W solar, 2.5 kWh 24 V battery for lights.
Patching PIP-4048/5048 inverter-chargers.