Is there any way to read the voltage of a 12vdc battery into Hubitat?
I'm trying to kick off some actions when a car-type battery drops down to a certain level.
Thanks.
Have a look at the ‘Shelly Uni’
I use a number of these to monitor 12 battery voltage
Andy
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Will do. Thanks a lot.
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You know, I'm trying to steer clear of wifi. This battery is on a standby generator. From one outage experience so far, when the utility power drops so does cable broadband; they don't have battery backups here. So, no wifi linking to the cloud for me, which would rule the Shelly Uni out, I think.
I have a few of these and as far as I can tell, they are their own web servers with local access. I think you can go to the cloud if you want to, but as far as I know, they are primarily local. That shouldn’t stop you.
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Excellent. I'll probably give one a whirl, after I look around a little more. Thanks.
Something like these to monitor the voltage and trigger the relay
Voltage Monitor Relay Module 0V 100V Voltage Tester for Battery Charging Discharging Controller DC 12V 12A|Integrated Circuits| - AliExpress
DC 12V 24V LED Digital Relay Module Relay Switch Control Board Voltage Detection Charging Discharge Monitor Test DC 0 99.9V|Relays| - AliExpress
And have the relay output to the dry contact input of zigbee/z-wave relays like Zooz Zen16/17?
Just an idea, haven't tried this. I go to Ali when I have some idea and usually can find something can be used.
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From your description of the application, here is what I came up with.
- Purchase a low amp battery charger to recharge the generator battery whenever it gets low.
- Use a voltage sensor such as the Shelly Uni to monitor the battery voltage.
3, Power the battery charger though a power plug and write a rule that will power the charger whenever the battery voltage drops below a predetermined value.
Since the battery charger will kick in whenever the battery voltage drops, it is unlikely that this will occur at the same time as a power outage, so using cloud devices is not a deal breaker.
Of course, you could routinely turn on the battery charger for brief periods based on a schedule, for example 1 hour every Saturday morning. You could use the output of the voltage sensor to monitor battery drain and charge rate so you could establish as suitable charging frequency and duration. Maybe it only needs to be recharged once a month. A graph of the voltage will tell you what is appropriate.
I have a portable generator. I had not charged the battery in several months, but when I did charge it, I found the battery was still at 95% charge. However, there is a switch to isolate the battery from the controls so there is little battery drain. If the battery is connected to the control system all the time, the battery drain will be higher and probably at a relatively constant rate.
Same deal with my standby, although I've heard the battery dies in a couple of days with the panel energized. I'm thinking about what if the generator ran autonomously. I had though about stuff like temp sensors so the house doesn't freeze or the food doesn't spoil (maybe), but hadn't thought of the control panel energy consumption. If the battery got down to a certain level, I'd want to startup the gen and charge the battery. If I was home, I'd be running a little generator for a lot of the day, and it would charge the battery.
This concept might not be practical, but it rubs me the wrong way to have the generator running constantly during a power outage while I'm away
If the generator is going to remain connected permanently with the control power turned on, you might want to consider leaving a trickle charger connected permanently to the battery. These devices operate just slightly above the full charge voltage of the battery so that it will keep the battery at full charge without overcharging the battery.
I do not have a Generac unit, but I suspect that they have a trickle charger built. As long as the mains power is on, the trickle charger will keep the starter battery charged. Then when the power goes out, the battery will start the generator and switch the power from mains to backup generator.
The UPS units we often use to power our electronic devices in the event of a power failure also have a trickle charger built in to keep the batteries at full charge until they are needed.
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I'm trying to conserve propane which is hard to come by during an extended outage. When I turn off the standby generator, the battery will deplete in 1-2 days. Plus, the oil level has to be checked. If I was home I could manage things, read the voltage, etc, but away from home it's a different story. If it's screaming away for a week or two solid-not a good scenario. Shutting it off before leaving might be best, as long as the pipes don't freeze in the house-I don't have much in the freezer and don't have a sump pump.
I might try experimenting with the Shelly, but I anticipate ultimate failure, lol.
The Guardian model does just that. There's a battery that keeps topped off via a trickle charger and then starts the generator when commercial power fails. It will also alert you to battery status but alas no HE integration.
Got this Solar panel hooked up to my generator and it works great. Battery stays charged.
You might want to see if you can access the wiring that goes to the switch that turns the controls on & off. If you can, you can then add a dry contact relay such as the ZOOZ ZEN16 Z-wave relay. That allows you to turn the controls on/off remotely. The ZEN16 comes with three separate contacts, so you could also automate the start button if needed. For example, if you only want to run the generator long enough to keep the pipes from freezing you could have a temperature sensor trigger the ZEN16 to turn on the control power then start the generator and allow it to run only long enough to reach a specific temperature. Then the temperature sensor could trigger the ZEN16 to shut the generator down and then turn off the control power to preserve the battery and propane reserve during an extended power outage.
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This is exactly what I'm thinking. I don't think those buttons are accessible on a new machine like mine. Maybe spoof an error code. An added wrinkle is that the transfer switch must shed load before the generator starts or stops. I might have a way around that.
Another problem is that the controls latch on virtually everything, so that most errors have to be physically cleared at the machine. I found one for stop/start that doesn't latch. I'm not optimistic about cutting power to the control panel. Worth a shot though.
I think @mcdull 's solution has promise.
I saw this thing on Amazon. It displays voltage and opens a relay when under a set voltage and closes the relay at a set voltage. The Zen 16 can be set to be normally closed, plus simple automation makes it flexible. The Zen16 consumes a lot less power when open. I think the new multirelay may have features that could make it more reliable, but I have to look at that. The thing is, Hubitat must be counted on to fire up the app correctly to sequence the transfer and startup-I'm nervous about that.
I in the same situation and will be using a Shelly Uni to monitor voltage and a Deltran Battery Tender to keep the battery charged.
Shelly Uni - I just got 4 of them yesterday to monitor voltage and to get notifications if the voltage drops. I ordered 4 of them directly from Shelly Shop USA. It looks pretty straightforward to install them. But I'm not sure yet on whether to use the Shelly app or Hubitat.
Charging - Deltran Battery Tenders, in the classic car world, are the gold standard for maintaining batteries. I've had one on one of my cars for 12 years and the battery is good as new. They have algorithms built to maintain the battery. Battery Chargers (batterytender.com)
WHAT MAKES A BATTERY TENDER® ‘INTELLIGENT’**
- It has internal sensors and intelligent microprocessor controlled circuitry, which enables it to constantly check and adapt to your battery’s level of charge.
- Unlike trickle chargers, which have a reputation for ‘frying’ batteries, it can perform a series of functions based on the level of charge which ensure that there is no damage caused to your battery.
- Whereas trickle chargers are known to over-charge and cause battery ‘boil out’, the sensors in a tender will actively monitor the condition and charge level of your battery using a series of modes to best suit the situation.
(What is a Battery Tender- All You Must Know (batterychargersexpert.com) )
I'm going to try to install the Shelly Uni today, so we'll see how it goes.
I hope this helps.
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Let us know how the Shelly Uni install works out!
As it stands, I setup a Uni yesterday with the Shelly app, but I haven't been able to add it as a device in Hubitat. I've been making some headway, but still no luck. I've also posted in this thread ... Vote for Shelly UNI - #60 by naelgh.
