GPS + car battery

tryme · 12-22-2005, 06:35 PM

Hi, first of all i want to mention that i have did some search on the forums with no good result. I am sure it had been memtion before on this forums.

Ok, I want to install my BU-303 in my car using the car battery, so that it will be always on instead of spending mins waiting for it to lock on. My question is will the GPS reciever drain the car battery if i didn't use the car for a while? hot long will it last? has anyone here try it ?

marcoiks · 12-22-2005, 06:43 PM

Hey I think the GPS will eventually drain the battery (ie if u dont drive your car for extended periods of time). the question on how long it'd take still remains. Normally these devices have information on how much current they draw, though not exact, or constant, this value can help calculate a round figure on how long this will take to drain your battery

Wiredwrx · 12-22-2005, 08:06 PM

wow, I am saying

to a newbie (don't take is personally, you are new).

No one can tell you for sure how long it will take, only some estimates. There are lots of factors involved such as, how much drain the GPS has, how new your battery is, how well the alternator charges it, how often you drive your car, and for how long, how low your battery can actually go before you can not start your car, which is different for every car, even the same make and model.

On a pure guess, You can probably go 24 hours with out a problem, but that is purly a guess.

Michael

DJiK · 12-22-2005, 08:16 PM

I'd say to wire the GPS Receiver to a switch or a relay (that's controlled by your carputer). By the time your carputer turns on, the GPS should already lock. In case it doesn't, I'm sure you'll still be on your local streets (that you know by heart) when it sees enough satellites.

According to this page, it says that the GPS draws 90mA @ 5V (Not 12V!) so be sure to know what you are doing. At any rate, check how many ampers-hours your battery normally has and you'll be able to calculate how many days it can stay on while being hooked up directly to the battery.

Wiredwrx · 12-22-2005, 08:17 PM

Quote: Originally Posted by DJiK

At any rate, check how many ampers-hours your battery normally has and you'll be able to calculate how many days it can stay on while being hooked up directly to the battery.

Unfortunately, that will not tell him how long it will be before he can not start the car again.

Michael

tryme · 12-23-2005, 12:56 AM

Sorry, actually i just need to know in general will the battery last for a few days. I will install a swich to turn the GPS off if I know i am not going to use it for more then a few days.

roadhog · 12-23-2005, 08:19 AM

You could set up everything how you want it, pop an ammeter inline with the +12v from the battery (i.e. clip the -ve ammeter lead to the +ve battery terminal and the +ve ammeter lead to the +ve battery to vehicle cable) and lock your car. After five minutes or so to allow various systems to stabilise (e.g. Opus, car alarm etc) check the current drain. This should be small... say 100mA. Check your battery's Ah rating for example 300Ah. This tells you how many hours the battery can supply 1 amp for. So the battery should be good for 0.1/300=3000 hours or 125 days.
Of course then your battery will be totally flat...
A better idea would be to check the stats for your starting system, to see how much power is required for starting under the worst conditions and leave a bit in reserve too. Remember all the quoted figures will be for a new battery, starter motor etc. The older they get the less efficient they will be. Then see how many Ah you have spare.
The problem with this is while in theory you may have 12 days and 6 hours due to aging of components etc this value is probably over-rated. YMMV.
I can recommend NOT leaving your opus connected and leaving your vehicle standing for 4 1/2 weeks, as this tends to lead to a dead battery.

QFCK2001 · 12-23-2005, 12:49 PM

My car is draining 550mA, is that normal?

dmurray14 · 12-23-2005, 01:00 PM

I've had my GPS powered by the 5v standby on the Opus for a long time. No problems whatsoever. Can't imagine it draws that much current...

Dan

edikp · 12-23-2005, 01:01 PM

Quote: Originally Posted by tryme

... so that it will be always on instead of spending mins waiting for it to lock on.

How long exactly does it take to get a lock? I have a different GPS receiver than yours and it locks on once I leave my driveway.

Maybe rather than worrying about how to power your GPS, you need to look into finding a better location for it. Or, get a different receiver all together. They're so inexpensive nowadays.

Peoples · 12-23-2005, 01:12 PM

it usually doesnt take mine a long time to get a lock, however....when you shutdown windows or go into hibernate, it needsto sync up with the app again, which sometimes takes a minute.

I've always have mine running....I have a deepcycle battery....but I've got 3 days, no problems at all. If I'm going on a trip, and dont plan on using my car for longer then a few days, I unplug the carcomputer.

edikp · 12-23-2005, 01:23 PM

That's interesting. Is it because it uses USB? Mine is serial and it syncs right away.