Put this into your search engine, aili battery monitor
Funny, I just found that aili monitor on my own and came back to thread to ask whether any members here had experience with it.
Do you use one?
That where the shunt will need to be. To measure current into or out of the battery you need a shunt in the negative path. The volt drop at full current is 50mV, I am sure your inverter will tolerate that.
I understand that shunts are normally positioned on the battery output and that this is necessary to monitor current into or out of the battery.
I’m not interested in measuring current out of my battery, merely current in (as a reality-check on the daily kWh generation being reported by my SCC).
As far as my inverter being able to ‘tolerate’ a 50mV drop, that’s a fortunately a problem for my rig. I’ve already gone to the trouble and expense of using 2/0 Welder’s cable between battery and inverter to keep round-trip cabling resistance down to under 0.5mOhm. Adding another 0.5mOhm or even 0.25mOhm into that high-current path when it is not needed would make no sense for me…
That may be true, but having invested in your battery pack, knowing the status and history of the charging of the battery may prevent costly mistakes, smarts are useful.”
I fully discharge every night and there is no value to me in tracking that discharge or knowing the SOC of my battery during discharge (it is what it is).
The ‘smarts’ I want are first and foremost to have a reality check on the kWh of daily PV generation being reported by my SCC. For that, I only need a shunt on the incoming charge wire from the SCC and the only issue I have is how to reset the monitor every night. In a pinch, I can reset it manually however frequently is needed to keep it from maxing out (since it will only ‘see’ increasing charge, never decreasing).
Ideally, I’d like a data logger so that I can both start to track seasonal PV generation as well as monitor when battery capacity starts to decline (which will translate to higher voltage at equivalent SOC).
But I suspect any ‘smart shunt’ with data logging capability is going to cost a pretty penny more…
Getting back to solving your problem,
Is the battery a DIY or ready built?
If DIY what MBS?
I’ve got a 560Ah 8S2P LiFePO4 I built with a Heltec 300A BMS.
What is the battery voltage at the end of the days solar charging?
I just finished rebalancing the battery from top-balanced to bottom-balanced.
For the first time last night, after LVD at 24.0V (~3.0V / cell), which typically happens around 9pm, when I check the battery before the SCC begins charging the next morning, the battery has recovered to 24.034V and all cells are within the same +/-mV of each other…
As far the peak battery voltage during daily charging, it varies depending on production. (season, weather, etc…) as well as consumption (discharge kicks-off once the battery reaches ~50% SOC).
My SCC never gets out of Boost (CC) mode and generally the battery never gets charged up beyond ~50% SOC (though that should change next summer).
What is the battery voltage first thing in the morning , or at bedtime?
As I said, LVD is currently set at 24.00V (~3.0V/cell) (typically by ~9pm) and has generally recovered (reached equilibrium) to 24.03 to 24.04V by morning.
Peak voltage I’ve reached during charging has reached 26.9V once but in general remains under 26.6V. I’ve got things programmed so that self-consumption kicks-off once battery has reached ~50% SOC (typically late morning) and continues through the rest of the afternoon and through the evening until LVD at ~5% or 11% SOC (depending on which ‘tables’ you believe).
Now that I’ve finally achieved bottom-balance at 3.00V (or 3.04V after equilibrium has been reached), I’ll probably increase my LVD setting so that the battery remains within a range of ~20% to %90%…
How are you measuring these voltages?
Are you running out of power, or just concerned by the MT50 readings?
I’ve got a BattGO monitor which provides cell voltage as well as battery voltage.
The main concern I have is getting an accurate measurement of daily PV production (ideally by season). I’m planning to expand the PV array in ~2023 and an accurate assessment of how much I’m actually getting now is the only way I can properly plan the size of the expansion…
I don’t have an MT50 but have a laptop with Epever SW hooked up.
Everything is working well - daily PV production is being stored up and time-shifted to cover evening consumption, but either my 14kWh battery has far less capacity than it should (with cells that have been fully capacity tested) or the daily power production I’m getting is greater than what the SCC is reporting.
The problem with these cheap Chinese ‘boxes’ is that when there us a discrepancy in what they ‘report’, it’s impossible to know which box to trust…
I re read this statement, can I assume that all your loads are taken from the Epever load outputs, and there is nothing else connected to the battery except the Epever?
Mike
No, I’ve got an Epever AN6420 with no direct load output but two dry contacts for load control.
The dry contacts have been programmed to control ON/OFF of 2 1000W GTIL inverters, so once battery has reached ~50% SOC the GTILs begin converting up to 2kW of self-consumption and that continues until the battery has been drained to ~5% or ~10% SOC (generally around 9pm or so).
The SCC has no visibility on load consumption, only battery voltage, and the GTILs struggle to function at 24V (hence the importance of minimizing cabling resistance between battery and GTILs and the lack of appeal of attempting to measure load consumption by adding a shunt in that high-current pathway…).