What is the approximate expected duration one of these batteries will keep the sensor powered on?
I'm currently testing one with a 1100mah battery and motion sensor connected. it's at 6 weeks and still going.
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I think you guys have jinxed me! It finally went offline today, with voltage showing 2.1v. So slightly under 7 weeks, with 7/8 motion events a day. Kudos to @iharyadi .
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Wow, that's what I call staying power!
Thanks for doing the test and posting your results.
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Hello Everyone,
I want to let everyone know that I do not have any Arrival Sensor from the last batch. I have started to look into making improvements for a new butch in the event that I will make a new batch.
During this process of making a revision, I found an unfortunate error on the battery protection wiring on the current batch. Although the sensor is fully functional, the battery protection is important to make sure that the battery is used properly. There is a risk of damage to the battery during usage. Using damaged battery could cause fatal accident. I have not heard any issue on the field at this point. However, I want to make sure that I disclose the issue so that everyone can take action. If you decided not to use the sensor as one of the solution, I would be happy to refund your payment for the cost of the sensor. Please send me an PM.
I will correct this error if I decided to run a new batch. I have not committed to make a new batch at this moment.
I am aware that from the feedback that some of us including myself is excited about the sensor and its potential. It would have been a painful to loose the functionality. Again, I offer to refund your cost of the sensor if you decided not to use it. But, If you sill want to continue to use the sensor, to minimize the risk, you can use a protected battery. A protected battery contain the protection circuity in the battery itself. This configuration is not something that I have designed for. I cannot for sure that it will eliminate any risk with this configuration. If you like to have more information, please feel free to PM me.
I am just a like a hobbyist who want to make improvement to our smart home. I make some sensor to share with the community because I feel that it would improve our experience. I would like to apologize for this unintentional mistake.
Thanks
Iman
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Thank you very much for sharing this important information, @iharyadi, I and I'm sure everyone else using this appreciates your frank communications.
I have a question - if I remove the battery from the device, I assume that removes the risk? I.e., I might remove the battery and use the sensor powered on all the time via USB power from the car. Is that a safe approach?
Regarding another batch - I would be pleased to purchase two updated units if you do decide to make a new batch. My wife loves the automatic door opening.
There is no need for you to refund me for the units I have purchased.
Thanks again.
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This is correct. It is just we loose the power source detection capability. We only have one timeout to play with.
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I guess my other comment would be if there is anyone here who has sufficient expertise in these types of circuits/batteries can help confirm if a protected battery would resolve the issue I think we'd all be interested in that info.
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Can you expand on the scenario in which the battery would be damaged / dangerous? Is there a way to add a protection board between the device and the battery, or a protected battery that is known compatible?
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The battery protection function is to cut the battery from the sensor when it is over discharge, over charge and short circuit.
I do not think over charge is a risk. The charger itself will ensure that it will not over charge. However, having independent circuit to double protect over charge is nice to have.
Short circuit may happen when there is a component failure. This is not likely to happen. But, having battery protection that can detect short circuit and cut the battery, it would minimize the issue.
Over discharge is the one that likely to happen. This is when the battery is let to drain. Although, this is not likely happen if you drive your car daily. I would not speculate to what would happen since there are other functionality that would prevent any dangerous event. The charger will perform trickle charge in this event. But, I personally want to make sure that I inform everyone that this can happen with the current board.
There is a battery that has protection circuit built in. Using this type of battery will protect the battery externally from the 3 condition I mentioned. I know that I sometime got these type of battery when I buy one from a vendor in amazon. However, the best way to ensure that you get one of these protected battery is to ask the vendor.
I hope this help everyone.
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Okay. Based on that, I'm not feeling particularly concerned. @Greenwave showed 7 weeks on 1100mAh; my battery is 500 mAh, so probably 3 weeks. I don't think the car's ever going to go more than a week without being driven while we're at home, and I can live with needing to manually disconnect it before a multiweek vacation.
That said, this battery is both large enough to expect several months out of and explicitly says it has built-in protection, so it might be a prudent investment. I think the connector is the same.
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@iharyadi, you are the best! One of the reasons, and there are several, that I like your devices is that you are VERY supportive and, like here, proactive. You take care of your customers as well as anyone and far better than most. We all make mistakes but not all of us own up to them and then bend over backwards to make it right.
I missed out on purchasing these sensors when they were still available and I'd dearly love to have 2 of them so I hope 
you make another batch. I will gladly pay you 150% of the price you cited for these.
In the same vein, I hope you make more of the environment sensors and I'll pay extra for those too.
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Belated question about this experiment.... How accurate was the battery level indicated by the device to Hubitat? My sensor had never reported less than 100%, so I've always been a bit suspicious.
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Same. I'd also like to know what the reported battery levels are. My sensor is hard-wired into my car, so removing it to test the battery will be cumbersome.
The battery level is reported as %.
The tricky part is to estimate based on voltage to %. I do not have current consumption meter. It would add the cost to the sensor to add current meter.
Translating voltage to % is tricky since when the sensor is at 3.7 V, it is consider full. The battery voltage will be flat at this nominal value for very long time since the sensor use very little current. When the battery is closed to depleted, the voltage will quickly drop. This is when it is close to run out of battery.
Here is a typically lithium battery consumption. As you can see that there is long time where it is at 3.7V
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Thanks for the heads up @iharyadi, you're right to be over cautious. Actually last year I did have a 450mAh battery go dead on me after being plugged in but without power over a month.
The battery I'm using now seems to have the protection you mentioned.
I seem to remember @iharyadi that you mentioned you would make some adjustments in how voltage reporting is done from the device, less bouncing of reports and more accurate. As a fully charged battery with a Multimeter shows 4v, but device reports 2.9v. Very happy with all your work, I'm still amazed a huge multi national hasn't gone into partnership with you yet.
@LosinIt If you don't have one of these and if you really really want one I may be able to spare a unit, PM me an offer if interested.
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Hi Everyone,
I have a message dropped by non user from another community which ping me about liability. I am grateful for the reminder. In turn, I want to make sure that I clarify for all the user of my Arrival Sensor.
This is a hobby project under development. I make small quantities for my self to use and develop. In doing so, I have left with more sensors than I can use. I share the sensor with the community because it could be beneficial for others in the community. In turn, the interested community member can turn this as "Do it yourself" project.
I build this sensor for my own use with safety in mind. To the best of my knowledge, I have build the sensor by minimizing any issue that I am aware. However, with any product there is always a risk. When I know a mistake has been made, I communicate it to the user in the community.
I want to make sure that I use this opportunity to let everyone know that "the use of this sensor is at your own risk".
If for any reason for any user who use my sensor believe otherwise, I would be happy to offer refund. You can stop using the sensor.
I apologize if this warning sound harsh. It is not my intention to do so. I just want to make sure to clear any miss understanding about this topic. I am aware that many user of my sensor, this and others, what you are getting into. I sincerely appreciate and grateful for your support.
Thanks
Iman
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I think the majority of us realize it's a use at our own risk thing. I also say I appreciate all you've done...
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Thank you.
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