Permanent tablet in vehicle - any ideas on how to keep the battery charged?

Forums › Android › Permanent tablet in vehicle - any ideas on how to keep the battery charged?

awalker

8 posts

Wannabe Geek

#240089 20-Aug-2018 11:07

I would like to permanently leave tablets in our work vehicles. I really need the tablets to be always left on so it encourages people to use them. The issue I have is our vehicles only drive on average for about 1-3 hours each day which isn't enough time to keep the battery charged.

Has anyone come across any elegant solutions that might solve this?

Thanks

MikeAqua

7785 posts

Uber Geek

#2076115 20-Aug-2018 11:28

Run a lead from the section of the fuse block that is always powered. This usually where the fuses for the headlights, hazard lights, interior lights and stereo memory are located

Mike

robfish

683 posts

Ultimate Geek

Lifetime subscriber

#2076120 20-Aug-2018 11:46

.......or run it from the "always on" wire to your head unit.

Rob

awalker

8 posts

Wannabe Geek

#2076133 20-Aug-2018 11:59

My worry is if a vehicle is parked up for several days I don't want any risk of the vehicle battery going flat.

CamH

567 posts

Ultimate Geek

#2076140 20-Aug-2018 12:03

You don't want to run it to always on, or you'll almost certainly have a pile of flat batteries for vehicles that don't move often. We have fixed phones in vehicles (Google Maps, ticket desk etc) and I've just run a power bank from the cigarette lighter and then into the phone. As long as the phone has a good battery and isn't trying to transmit over 4G all the time, it generally keeps charged (always charging off cigarette lighter and then power bank when the car is off).

gnfb

2609 posts

Uber Geek

ID Verified

#2076210 20-Aug-2018 13:26

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MikeAqua

7785 posts

Uber Geek

#2076220 20-Aug-2018 13:43

robfish:

.......or run it from the "always on" wire to your head unit.

Assuming it has sufficient capacity for the charging current.

Mike

MikeAqua

7785 posts

Uber Geek

#2076224 20-Aug-2018 13:47

CamH:

You don't want to run it to always on, or you'll almost certainly have a pile of flat batteries for vehicles that don't move often. We have fixed phones in vehicles (Google Maps, ticket desk etc) and I've just run a power bank from the cigarette lighter and then into the phone. As long as the phone has a good battery and isn't trying to transmit over 4G all the time, it generally keeps charged (always charging off cigarette lighter and then power bank when the car is off).

Assuming the tablet is switched off when the car is parked up, once the battery in each tablet is fully charged, it will draw very little current.

The car battery has perhaps 100x the capacity of the tablet battery so it's difficult to see the car battery going flat.

Another option would be a time delayed relay that switches off x hours after park up.

Mike

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Delphinus

611 posts

Ultimate Geek

#2076254 20-Aug-2018 14:30

Or an app that enables airplane mode when power is not available? Vehicle running = use data. Vehicle stop, enable airplane mode. Should last for days.

1101

3122 posts

Uber Geek

#2076256 20-Aug-2018 14:33

Run a lead from the cars AUX .
It will only get charging power when the car is running or on aux .

Same as car radio, they wont turn on unless key is in & on aux etc.
Not sure how easy this will be with modern car wiring . Car stereo installers will be able to do it properly

mattwnz

20164 posts

Uber Geek

#2076263 20-Aug-2018 14:41

I am guessing they aren't ipad, as ipads have a very long battery life, so guessing the drive time would be enough to top up the charge. Whereas windows tablets I have found tend to be less than half the life.

nickb800

2719 posts

Uber Geek

Trusted

#2076271 20-Aug-2018 15:06

1101:

Run a lead from the cars AUX .
It will only get charging power when the car is running or on aux .

Same as car radio, they wont turn on unless key is in & on aux etc.
Not sure how easy this will be with modern car wiring . Car stereo installers will be able to do it properly

I think this is 'ACC' for accessory in most vehicles

d3Xt3r

688 posts

Ultimate Geek

Trusted

#2076591 21-Aug-2018 08:04

awalker:
1-3 hours each day which isn't enough time to keep the battery charged

Actually, that's more than enough if you charge and power manage properly. I've had a dashboard tablet in my car for several years, and a charge time of only 30m a day was sufficient. The key bits are:

1. Use a quality car charger, preferably one that's QuickCharge capable (I recommend Anker, always worked great). This is assuming of course, your tablet supports QuickCharge or some form of fast charging, if not I'd recommend upgrading to one that does.

2. Use a quality, thick USB cable. This is important so that the resistance is low and there's very little power loss. Most oem cables should be fine, but avoid the cheap dollar store cables.

3. As others have mentioned, switch to Airplane mode when the power is cut off and switch it back off. You can do this easily with Tasker - create a task which toggles airplane mode, but you can go a lot further - like enabling powersaving mode. And if you install Greenify, you could trigger it to hibernate your apps as well. Greenify has a bunch of other options as well, such as Aggressive Doze - this puts your tablet into deep sleep mode as soon as the screen is off. The final step in the task would be to turn off the display. Once you have your tasks set up, just create a new State profile that triggers the task when the power is connected.

4. I'd highly recommend disabling any unnecessary apps that you don't use - the less junk that's installed/running in the background, the better. You can even disable/uninstall system apps with this method: https://www.xda-developers.com/uninstall-carrier-oem-bloatware-without-root-access/

5. If you want to tweak it even further, you could root your device and install a custom kernel, undervolt the CPU and toggle its special powersaving modes via Tasker. (ElementalX kernel is excellent for this). But if you follow all the above steps, this one should be unnecessary.

1101

3122 posts

Uber Geek

#2076633 21-Aug-2018 10:19

d3Xt3r:

Actually, that's more than enough if you charge and power manage properly. I've had a dashboard tablet in my car for several years, and a charge time of only 30m a day was sufficient. The key bits are:
.

It depends on the tablet.

My Lenovo Tablet takes a VERY long time to charge , many hours, considerably longer than a Samsung Tab or a phone.

awalker

8 posts

Wannabe Geek

#2076679 21-Aug-2018 12:03

Thanks for all your feedback.

I've purchased a 30,000mha battery bank to run the tablet from and going to charge the battery bank off the car battery with a high amp charger and see if that gives it enough to keep running. Will let you know how I go.

Aredwood

3885 posts

Uber Geek

#2077149 21-Aug-2018 23:58

Get a 12V latching relay to control the charging. And wire it into the central locking. So the tablets will be charging whenever the vehicles are unlocked. depending on how the vehicles are used. The tablets will get far more charge time. Without the risk of the main battery going flat if a vehicle isn't started for awhile.