Charge Maintain Battery, While In Use.

[Shockah]

Aloha from the warm Pacific!

Been a while since I visited this site.... took me a few seconds to get use to navigating around the new format.

Anyway, thought I might get an answer to a question regarding Charging a Battery while it's used 24/7.

I've got a friend who has a van loaded with tools. He installed a Home-Type Camera/DVR system in it. 95% of the time, the van is parked in his driveway. He has a wall outlet right next to his van that he plugs the system into.

Now, he also wants this system recording while it is driven/parked away from his house a 48hours at a time.

The system is actually powered by 12 volts, via the adapter at the wall socket.
He wants to power the system with a battery (adequately sized) while unplugged from the wall....
and rig a battery charger to it, which he can plug in the wall while it is parked at home.

So, long story short.... any recommendations for a 24/7 battery charger/maintainer that will float the battery at 13.2v after charged and while powering surveillance system?
I realize the charger output would have to be more than the watt-hour draw of the system... but how much more?

I have not measured the total draw yet, but let's say his daily is 360wh (15w*24h) draw with a 150ah AGM Battery,,, what size charger should he have?

Also, I know someone will bring it up... there will be a LVD in use between the battery and surveillance system.

Thanks in advance.
I'm gonna read some of the other topics here now.

[Sunking]

Not enough information to answer your question. But I can give you a ball park.

The charger has to have enough capacity to run the device and charge the battery. At a minimum he wants a charger that will deliver at least a minimum C/12 charge current, and no more than a C/8 charge current.

So lets use your example his gizmo burns 360 wh per day on a 12 volt battery. You size the battery to provide 5 day reserve of 5 x 360 wh = 1800 wh. It would require 1800 wh / 12 volts = 150 AH 12 volt battery. Assuming the gizmo draws a steady current over 24 hours is only drawing 360 wh / 12 volts / 24 h = 1.25 amps. Small enough we can ignore it. So for a 150 AH battery he is looking for a 13 to 19 amp charger and there is a lot of 12 volt 15 amp chargers on the market. No need to buy an expensive 3 stage or aka smart charger, a 15 amp Float charger will work.

[Shockah]

... and that's why I came here!

Appreciate the quick response Sunking... I hope Panama is treating you well.

I do know the cameras burn twice as much at night because of the infra-red.
I'll be confirming the actual wh burn tomorrow. If the numbers are far off, I'll update the question...

Mahalo!

[Sunking]

... and that's why I came here!

Appreciate the quick response Sunking... I hope Panama is treating you well.

I do know the cameras burn twice as much at night because of the infra-red.
I'll be confirming the actual wh burn tomorrow. If the numbers are far off, I'll update the question...

Mahalo!

I think you can figure it out. As long as the maximum current draw is less than C/100, you can ignore it. Just stay in between C/8 and C/12 of the battery capacity. But you can check back and I will run the numbers if you want. Only takes a few seconds.

Panama is good. I do miss good ole USDA beef though. Reminds me a lot of Hawaii climate and food wise. Almost identical in that respect. Kind of cold here tonight at 64, burrrrrrrrr.