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Discussion Starter #1 (Edited)
I'm starting a new thread on this as the other one was to do with keeping a battery as charged up as possible (https://www.subaruxvforum.com/forum/lighting-electrical/171752-how-fully-charge-battery.html)

Before getting the latest dash cam, the battery in our Crosstrek would routinely be around 12.2V (65% charged), before starting in the morning (i.e. after a short commute then sitting all night). Sometimes the voltage was even lower, rarely higher. After installing the dash cam, with a power shut-off device set to 12.0V, and parking mode enabled, the morning voltage has been 11.9V or lower.

I ran a few tests over the last few days. My watt meter shows the dash cam pulls about 5.5W while in parking mode but does shut off around 12V (and I see this from the recordings, they stop sometime after midnight). The extra drain must be to do with all the other stuff going on while the car is supposedly off. At some point I may try the watt meter on the main battery although it's hard to predict when the fuel pump might kick in or whatever the car does while all the cats are asleep... :D

In Big Bear, over New Year, the battery dropped to 11.2V, even with the dash cam disconnected. It must have been to do with the cold that we don't experience here - it was 13F overnight.

So, I have been looking at dash cam battery packs but they are ridiculously expensive and I've already spent way more on dash cams than I anticipated. Instead, I wondered if I could just connect an SLA battery in parallel, from the ACC fuse. I tried it last night, briefly, with a spare battery for our FiOS panel (12V 7Ah), and a cig port extension:

Dash cam battery.jpg

With the car turned off, the dash cam is powered solely by the SLA battery (and it doesn't matter if it totally drains it, so no need for a voltage cut-off switch (which also means capturing more parking mode video). With the car on, the cam is powered by the car and the SLA battery is being charged. If so, the 7Ah battery should be able to power the dash cam for 12 hours or so in parking mode, and if not I can add another one (I have four spares at the moment, don't ask...)

Anyone see any downsides to this? Obviously, the wiring will be a little, um, neater... :D
 

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I would install a 12V relay so that the relay's coil is powered by the car when it's on. Once the car is powered off, the relay will switch, as the coil is no longer energized, to the SLA battery. If you really want to be fancy, you can even install a battery isolation block so that the SLA will charge when the car is running!
 

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So, the camera is powered solely by the 7Ah battery and that battery is charged only when the car is running.

Interesting and a very cool thought however, how aware of under and over charging sla batteries are you?

In summary: overcharging creates hydrogen and oxygen, undercharging leaves lead sulfate on the plates which crystallizes and permanently damages the battery.

Here’s a quick read: https://www.silvertel.com/images/technical-articles/charging_sealed_lead_acid_batteries.pdf

I’m struggling to find a practical solution in a closed system with only one charge source, the car’s power system. While not a perfect solution, you could introduce solar power to help prevent the sulfate and extend life. However, I highly, highly, highly recommend getting an overcharging protecting circuit. Even if you don’t care about draining it, you probably do care about possible hydrogen in an enclosed, and occupied area. (Yes hydrogen and oxygen make water but it’s also an explosive combination)

They cost like $10 on Amazon and here’s the first link I stumbled upon: https://www.amazon.com/Battery-Charging-Controller-Protection-Automatic/dp/B075NLYJ8S
 

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Discussion Starter #4
So, the camera is powered solely by the 7Ah battery and that battery is charged only when the car is running.

Interesting and a very cool thought however, how aware of under and over charging sla batteries are you?

In summary: overcharging creates hydrogen and oxygen, undercharging leaves lead sulfate on the plates which crystallizes and permanently damages the battery.

Here’s a quick read: https://www.silvertel.com/images/technical-articles/charging_sealed_lead_acid_batteries.pdf

I’m struggling to find a practical solution in a closed system with only one charge source, the car’s power system. While not a perfect solution, you could introduce solar power to help prevent the sulfate and extend life. However, I highly, highly, highly recommend getting an overcharging protecting circuit. Even if you don’t care about draining it, you probably do care about possible hydrogen in an enclosed, and occupied area. (Yes hydrogen and oxygen make water but it’s also an explosive combination)

They cost like $10 on Amazon and here’s the first link I stumbled upon: https://www.amazon.com/Battery-Charging-Controller-Protection-Automatic/dp/B075NLYJ8S
I don't care about the lifetime of the SLA. I'm more concerned about the lifetime of the battery that starts the car, especially when we go up into the snow (we can choose to do that, and leave when we've had enough, LOL).

Perhaps I should install the SLA under one of the front seats (haven't checked for space, yet, and we have the HK upgrade). That hydrogen and oxygen mix would make one helluva seat warmer! :D
 

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Lol.

Yeah those batteries are pretty cheap and should still last quite a while overall but performance will degrade the second the charge drops too low. What last 12 hrs today may last 4 tomorrow and it will no longer suit your requirements. However the real concern is the seat heating potential.

I don’t think there’s adequate room under the seats. The HK isn’t small and you have Eyesight stuff under the driver’s. If you sacrafice foot space... maybe.

There’s no room behind the dash and console for something as big as your previous pic but I do see some small 7Ah batteries that will behind the radio. I have an LC7i behind my radio, it’s 7.5”W x 4.7”D x 1.2”H and there is some space still available.

This 7Ah battery 5.94”x 1.34”x 3.94” but there is no possibility of a parallel install in the dash: https://www.amazon.com/Mighty-Max-Battery-Replacement-product/dp/B00K8917KA

It would be work but you could carve some cargo foam and mount sideways or drop a DIY mount inside the spare. That way you could parallel if desired and still easily access it/them. On the other hand, a physically smaller battery might fit behind the potato compartment, cargo space, next to HK (good luck securing in place) or... the door cavity, lol.
 

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Discussion Starter #6
Lol.

Yeah those batteries are pretty cheap and should still last quite a while overall but performance will degrade the second the charge drops too low. What last 12 hrs today may last 4 tomorrow and it will no longer suit your requirements. However the real concern is the seat heating potential.

I don’t think there’s adequate room under the seats. The HK isn’t small and you have Eyesight stuff under the driver’s. If you sacrafice foot space... maybe.

There’s no room behind the dash and console for something as big as your previous pic but I do see some small 7Ah batteries that will behind the radio. I have an LC7i behind my radio, it’s 7.5”W x 4.7”D x 1.2”H and there is some space still available.

This 7Ah battery 5.94”x 1.34”x 3.94” but there is no possibility of a parallel install in the dash: https://www.amazon.com/Mighty-Max-Battery-Replacement-product/dp/B00K8917KA

It would be work but you could carve some cargo foam and mount sideways or drop a DIY mount inside the spare. That way you could parallel if desired and still easily access it/them. On the other hand, a physically smaller battery might fit behind the potato compartment, cargo space, next to HK (good luck securing in place) or... the door cavity, lol.
I was shopping for a backup battery for our Frontier FiOS ONT, after they told me it was not a part they supported and wanted to charge a fortune to replace it. Turns out it's a common security system SLA. I bought four, online, for less than Frontier wanted to charge me for one.
 

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I don't care about the lifetime of the SLA. I'm more concerned about the lifetime of the battery that starts the car, especially when we go up into the snow (we can choose to do that, and leave when we've had enough, LOL).

Perhaps I should install the SLA under one of the front seats (haven't checked for space, yet, and we have the HK upgrade). That hydrogen and oxygen mix would make one helluva seat warmer! :D
At least on my MY13, I've found that there's a lot of space under that small cubby hole under the cigarette lighter plug. I suspect that it would be the same for the current model.
 

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I was shopping for a backup battery for our Frontier FiOS ONT, after they told me it was not a part they supported and wanted to charge a fortune to replace it. Turns out it's a common security system SLA. I bought four, online, for less than Frontier wanted to charge me for one.
That happens all of the time... The funny thing is each industry that uses those types of batteries overcharge at the point of service (ie when looking for a replacement battery) and you see people like yourself finding a much better deal elsewhere. Example - security systems owners will typically recommend UPS batteries as a replacement as the security system OEM charges an arm and leg for the replacement.
 

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An interesting thread here, it made me appreciate my very old and still very functional dashcam of mine(something like "blackbox W1") because I've never concerned myself about car battery drain, even leaving the cam running all night long after forgetting to turn toggle switch OFF. It only draws about 500-600 mAmps as shown on these pics(recording/screen off)

IMG_20190117_235217502.jpg

recording/screen on

IMG_20190117_234937267.jpg
 

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Discussion Starter #10 (Edited)
An interesting thread here, it made me appreciate my very old and still very functional dashcam of mine(something like "blackbox W1") because I've never concerned myself about car battery drain, even leaving the cam running all night long after forgetting to turn toggle switch OFF. It only draws about 500-600 mAmps as shown on these pics(recording/screen off)

recording/screen on

View attachment 286564
I don't get why the Blacksys DR900S is such a hog. It has Wi-Fi but we also have a wireless security cam in the garage that connects to Wi-Fi and can run for a month on a lithium battery the size of a matchbox...

Edit: yours is only 2.5W with the screen on!
 

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It actually takes less then 2W, the battery was bad, it wouldn't hold a charge and it was constantly drawing an extra ~200mA. I already replaced the battery once, it was time for another. The original was 300mAh, I use lipo for toys 600-700mAh and they last about 2-3 years which is not bad after all the exposure to heat/cold they take. The battery is only needed for setup/lookup etc, it charges itself and should stay charged.

batt1.jpg batt2.jpg batt3.jpg batt4.jpg
 

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As for the power demand from the car battery, I often leave the dashcam on for hours while parking in some questionable areas, shopping malls, stores etc. I think it's negligible, the battery is still in pretty good shape, going into a second winter(northwest) bought my '18 Premium in August 2017, it has over 17k miles right now. I record in 720p, it's really a decent video quality for a car recorder. cam1.jpg cam2.jpg idle.jpg

So, it's just the cam recording with sound, I disconnected the IR thing right away after purchase, don't see any use for that and it actually may require some juice. Same for proximity sensor, g-force - I've disabled that too.
 

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Discussion Starter #13
As for the power demand from the car battery, I often leave the dashcam on for hours while parking in some questionable areas, shopping malls, stores etc. I think it's negligible, the battery is still in pretty good shape, going into a second winter(northwest) bought my '18 Premium in August 2017, it has over 17k miles right now. I record in 720p, it's really a decent video quality for a car recorder. View attachment 286582

So, it's just the cam recording with sound, I disconnected the IR thing right away after purchase, don't see any use for that and it actually may require some juice. Same for proximity sensor, g-force - I've disabled that too.
Is the 12.1v after being parked for a while? That's what we see all the time, with OAK's short commute. The only potential problem we had was up in Big Bear (13F overnight) when I wondered if it would start. I lived in CT and it can get pretty cold there too!
 

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Yes, parked outside all night long 'till the pic was taken in the afternoon.
Yeah, that's what makes me nervous. Our batteries are always, at best, 50% charged, and that's in mild weather...
 

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Been thinking about that 12.1 resting voltage and while I was running some errands tonight the voltage was pretty steady at 14.3 – 14.4 v on average, no matter what: high speed blower, high beam lights, seat heater and so on. Back at home I looked up Google and it all says that the resting voltage should be at 12.3V. So, am thinking, maybe it is, but when we turn the key into KOEO position we're powering up lots of things, the ECU, HU all the relays, Starlink and what have you. All that load has to lower the voltage right there. So, I have to get direct battery readout, with disconnected terminal to see what the real story is. I mean, they sound(the web articles) like anything below 12.3v warrants battery replacement, I don't have any problems with starting the car in the winter, the starter/engine kicks in in no time. Yeah, winter is tough on battery, especially with short distances to drive, the days are short and cold, always calling for the heat blower, deicing, headlights, windshield wipers and all that. The battery doesn't get a chance to replenish its juices. I can also hook up an external charger and get more juices that way, but it's winter and the charge would probably quickly go back to the “resting” 12.1volts.
 

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Been thinking about that 12.1 resting voltage and while I was running some errands tonight the voltage was pretty steady at 14.3 – 14.4 v on average, no matter what: high speed blower, high beam lights, seat heater and so on. Back at home I looked up Google and it all says that the resting voltage should be at 12.3V. So, am thinking, maybe it is, but when we turn the key into KOEO position we're powering up lots of things, the ECU, HU all the relays, Starlink and what have you. All that load has to lower the voltage right there. So, I have to get direct battery readout, with disconnected terminal to see what the real story is. I mean, they sound(the web articles) like anything below 12.3v warrants battery replacement, I don't have any problems with starting the car in the winter, the starter/engine kicks in in no time. Yeah, winter is tough on battery, especially with short distances to drive, the days are short and cold, always calling for the heat blower, deicing, headlights, windshield wipers and all that. The battery doesn't get a chance to replenish its juices. I can also hook up an external charger and get more juices that way, but it's winter and the charge would probably quickly go back to the “resting” 12.1volts.
The resting voltage doesn't necessarily determine whether or not the battery needs to be replaced but I've been concerned about ours for a while. It's also supplied with 14.3-14.4V while being driven but probably not enough to charge it up enough during OAK's short commute. And then the dash cam was draining it even more.
 

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Resting voltage (provided enough time is given to the battery to rest) is more of a measure of state of charge rather than state of health of a battery. Anyone who equates resting voltage blindly to start of health may need to do some research on the subject matter at hand.

Example - you can have a great resting voltage (ie 12.8V) but can't start your car as the plates inside of the battery are damaged causing you not to have enough cranking amps or cold cranking amps when you need them. On the flip side, your battery can be below 12.1V but can provide those cranking amps when you need them and start the car. The difference is that you might not have enough charge left in the battery at that point to be able to start the car again and again without charging the battery.
 

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Resting voltage (provided enough time is given to the battery to rest) is more of a measure of state of charge rather than state of health of a battery. Anyone who equates resting voltage blindily to start of health may need to do some research on the subject matter at hand.

Example - you can have a great resting voltage (ie 12.8V) but can't start your car as the plates inside of the battery are damaged causing you not to have enough cranking amps or cold cranking amps when you need them. On the flip side, your battery can be below 12.1V but can provide those cranking amps when you need them and start the car. The difference is that you might not have enough charge left in the battery at that point to be able to start the car again and again without charging the battery.
Ours started the car in the mountains after being left overnight, at 13F, when the resting voltage was 11.2V but it cranked really slowly and probably wouldn't have lasted long if the car hadn't started right up. FYI, I'm testing the voltage with a USB adaptor in the cig port, not directly on the battery, and with ACC on, so there's other load from the HU starting up, interior lights on, etc.

rlouie, how long should a battery be left after charging (i.e. driving the car) to get a good sense of the true state of charge?
 

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Discussion Starter #20
I'm charging one of the 7Ah SLAs on my desk with the iMax B6 and it's interesting watching the charging voltage. For the first hour it was around 13.8V +/- 0.2V until it had supplied about 1Ah and now it's steady at 14.7V with 1.55Ah supplied so far in total (almost two hours).
 
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