installed the replacement shunt
Last post I mentioned that I’d ordered a replacement battery monitor.
the original shunt
In 2018 I installed a 75A Drok shunt ($27, but discontinued). It served me well with the 220Ah FLA bank, 100Ah LFP bank, and 100+50Ah bank until I smoked it with a careless short during some kind of battery bank twiddling.
A 75A shunt might seem like a limitation but I don’t have any loads larger than that. My theoretical load is the Instant Pot, ~54A if pulled from battery alone. But I rarely run it without solar doing some/most of the lifting. My biggest practical load, when I am confident in the day’s future harvest, is the coffeemaker. It pulls 46.5A and is running in the early morning before solar harvest hasn’t even met my background loads.
I knew I liked the Drok’s display but didn’t give it much thought. Spoiler warning: this will bite me in the butt.
the shuntless interim
The 100Ah batt has a bluetooth BMS but the 50Ah Chins does not. I suspected they would take/contribute current according to their relative capacity and it was very close. The 100Ah takes a tiny bit more of its share (like 68% instead of 66.6%) but for practical purposes I can look at the BMS and multiply current by 1.5.
But I liked the ability to walk by the display and see what’s happening without opening an app.
the replacement shunt
The Aili is the cheap-shunt darling so I was leaning that way. The one I selected had free shipping to locker and I snagged it.
After installation and a bit of use I realized why I like the original Drok so much: it had all the data I wanted on one screen:
- Amps charging/discharging
- Watts charging/discharging
- volts
- SoC%
- remaining Ah
- time to full (while charging) or empty (while discharging)
The Aili-style monitors don’t have the time estimate1 or watts. That doesn’t bother me, but what is available is on different screens and requires interaction. I find that annoying.
Even more annoying is I knew that’s how they work. I’d seen the pics and vids of them in use. It meets needs, though, and I don’t care enough to replace it. If I were doing it again I’d probably pick this drok. The color screen is not as clean as the old green one but it has all the data on the same view.
{edited to add pic of the offending display}
observations
- the shunt setup continues to align with [BMS x 1.5)
- my daytime background loads right now are ~6A, including the mattress pad on lowest heat for Muffin’s napping comfort.
- cloudy today, but was clear for about 15 minutes just before 10am. 30A net into the bank that early is a nice change from December’s low yield.
review
The Aili-style monitors are fine if you like the display. They are acceptable if you don’t like the display.
Some reviewers said the wiring was too short but I’d say the included 3ft was sufficient for my needs. In any case there is a 16ft wire available for $3. I might pick one up in case I decide to remount at eye level some day.
Some reviewers dislike the backlight but the manual shows how to turn it off. I don’t mind it.
recent solar harvest
There were two utterly overcast days this week where I didn’t reach Vabs. One day produced 780Wh (ouch!) and the day after 1.64kWh. The 2nd day would have reached Vabs if it wasn’t playing catch-up from the abysmal day before.
On clear days I’m starting to see max harvest in the 500s. I’ve seen 600+ but it was cloud-edge effect.
supahbowl
I found a spot with good reception to record the superbowl. I don’t care much about it but it’s a cultural touchstone.
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The time estimate is more interesting than useful for prediction. It assumes a constant charge/discharge rate but solar is highly variable. I suppose if one were idling to charge with a DC-DC it could be useful. Or if one had nearly no solar coming in it could tell you how long until the power goes out… ↩