in car surveilance and current draw

Company i wrk for,is giving me this systen to install into cars for live monitoring, the system is designed to be active and recording constantly, my concern is battery current draw when the car is parked for extended periods, haven't gotten the specs on current draw for the system, but was told by manangenent it's approximately 800 milliamps total.
Can i get an input on this current draw??

10W. ie, a dome 10W light; 20 LEDs, etc.

Effects on a battery after let's say a 24 hour period.

A piece of string has a length exactly twice the distance from its centre to one of its ends...

It depends on the vehicle and battery. Some vehicles could be hard to start - especially with older batteries.
And if there are other drains like alarms etc...

The effect will be about twice as bad as a 500mA alarm.

Daily or maybe even weekly engine running (with a ~14.2V alternator and sufficiently long run) should be sufficient to reverse battery sulfation.

Maybe consider a low voltage cutout (battery protector) - even if a 2nd battery is used.

800 milliamps is a lot of draw. A typical Bosch/Tyco relay draws 160 milliamp. An improperly installed starter kill relay will flatten a battery if the car is not driven daily. 800 is 5 times as much as one of these relays. I am not thinking this is going to go well.

You'll have a flat battery every morning.
Make it ignition or acc switched or alarm triggered.

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Amateurs assume, don't test and have problems; pros test first. I am not a free install service.
Read the installation manual, do a search here or online for your vehicle wiring before posting.

Peter, the average alarm R/S draws 40-60 mAmps.

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Amateurs assume, don't test and have problems; pros test first. I am not a free install service.
Read the installation manual, do a search here or online for your vehicle wiring before posting.

Yeah, my bad - out by a factor of 10 but keen to show the non-linearity of battery discharge current to capacity - ie, 800/500mA = 1.6 but it probably has a 2x effect on remaining capacity.


I recall my concern when I left my 10W dome light on overnight when snowboarding. I realised the mistake in the morning when I looked out the window and noted the melted rectangle in the centre of the snow covered roof. Being colder conditions than normal (ie, less battery capacity than its normal 10-20C winter abode) and at the bottom of a long steep drive I was relieved when the beast started normally.
But 24 hours in any climate with that 10W (~800mA) load would have left that car unstartable. (Now having a reduction starter and electronic ignition I could probably survive 2 or more days.)


Funny that I should have considered 500mA for an alarm - you probably know how critical I am about even the 12mA draw of 1980s-1990s Bosch S&L alternators, let alone 40mA alarms and 200mA relays.

My recent Alpine drain of 120mA was enough to make starting difficult after ~4 days.

But 800mA for a car surveillance system...! Ok maybe for a truck (24V thru a converter), but typical 12V vehicles - what would they do over weekends?
Such high-current surveillance should only kick in after the triggering of proximity detectors etc.

The tracker I use for fleets draws 3 yes 3 mAmps at rest and 15 on data send.

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Amateurs assume, don't test and have problems; pros test first. I am not a free install service.
Read the installation manual, do a search here or online for your vehicle wiring before posting.

Darren, take one live it up and measure it.

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Amateurs assume, don't test and have problems; pros test first. I am not a free install service.
Read the installation manual, do a search here or online for your vehicle wiring before posting.

Yup, i will, my response was exactly the same as you guys, but management refutes my logic, because they have no technical background.

LOL! You ain't management eh?

I think it only fitting that the first demo/test install should be to the CEO's vehicle, or whoever antagonises you most. (Sorry mate, I'm over here - ha ha!)

Warn them that if 800mA then it is the equivalent of a 10W bulb (ie, a dome light if not 5W, or 1-2 park lights).
And you might find the 800mA is a peak or an overestimate. (Sales & techies ain't what they used to be.)

Surveillance will draw more than 3-15mA trackers, but anything above a couple of hundred mA full-time seems ridiculous.
As was said, a typical 160mA relay can have disastrous results after a day.


So suck it and see. Just make sure you choose the right sucker.

I'm looking forward to the conclusion of this exercise - except of course that it will all be YOUR fault.   (Where's that "stranded" engineer and management/marketeer joke...?)

Send them an e-mail stating that you do not think it is a good idea. Then do as many of them as they want. Then when they start having problems, you have your e-mail to back you up.

Great suggestion. I used to read-receipt such emails (that's where MS Outlook and similar internal server based system were good) and chase up those that hadn't read them (then denote that instance & outcome in my work diary).

I will follow your advice IAAI..........i will update the thread if anything more comes up.