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raistlin295 Occasional Visitor
Joined: Jun 13, 2005 Posts: 28
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Posted: Thu Feb 22, 2007 5:45 pm Post subject: Holux GPS 240 data backup battery. |
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I wonder if anybody can help with this please?
I leave my GPS receiver permanently in the car with the hardware switch set to on.
With the GPS 236 there wasn't a problem as I could remove the main battery and the backup cell on the PCB would maintain the data.
I now have a GPS 240 and it appears that I cannot remove the battery.
Therefore, it stays on when I switch the ignition off and the battery discharges overnight.
My problem is that it then seems to want to spend 20 minutes re-gaining data.
So, does anybody know if the GPS 240 has a backup battery please?
If not, I'll have to arrange for a permanet 12 volt feed to it, in which case, does anybody know the current consumption please?
I'd hate for it to discharge my car battery
Thanks for any help.
Paul |
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nemogps Occasional Visitor
Joined: May 07, 2007 Posts: 4
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Posted: Mon May 07, 2007 10:38 pm Post subject: |
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I think I would feel ok with a hardwired connection that bypasses the ignition switch. The current draw is 75-85 mA according to the manual. This would take some weeks or even months to drain a car battery. I guess I didn't realize that the GPSlim 240 receivers don't have an automatic shut off when they lose the bluetooth connection for a few minutes. I know some other makers include that and I thought by now everyone would be doing it. |
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mikealder Pocket GPS Moderator
Joined: Jan 14, 2005 Posts: 19638 Location: Blackpool , Lancs
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Posted: Tue May 08, 2007 7:39 am Post subject: |
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Using the 85mA figure if left powered for 24 hours it will have consumed 2AHr out of the batteries capacity, have a look at the ident plate on your car battery it will have a figure in XXAHr (where XX is a number).
Once you have the figure halve it and that is how many days your GPS will remain powered from the battery - please note below a certain level there will be insufficiant power remaining within the battery to start the car.
If using the car daily you will be fine, but I wouldn't leave the GPS powered up if going away for a week or more, the chances are the car won't start after a week, unless you have a huge battery fitted - Mike |
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nemogps Occasional Visitor
Joined: May 07, 2007 Posts: 4
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Posted: Tue May 08, 2007 4:13 pm Post subject: |
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mikealder wrote: | Using the 85mA figure if left powered for 24 hours it will have consumed 2AHr out of the batteries capacity, have a look at the ident plate on your car battery it will have a figure in XXAHr (where XX is a number).
Once you have the figure halve it and that is how many days your GPS will remain powered from the battery - please note below a certain level there will be insufficiant power remaining within the battery to start the car.
If using the car daily you will be fine, but I wouldn't leave the GPS powered up if going away for a week or more, the chances are the car won't start after a week, unless you have a huge battery fitted - Mike |
I think your analysis is a bit pessimistic. A typical battery in a smaller care like a Honda has 100 minutes of reserve capacity at 25 Amps, which is over 40 AHr or 20 days. At lower currents it improves. So you should feel comfortable letting your car set for a week or two unless you have comparable power drains from other accessories. I know the clock, radio and possibly other gear uses a small amount of current to power backup memory. But this really should be low milliAmps and not be important. It is easy enough to measure. |
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jimbo_hippo Frequent Visitor
Joined: May 18, 2005 Posts: 444
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Posted: Wed May 23, 2007 12:08 pm Post subject: |
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If you want some real world results, I have a 236 in the other half's BM and a 240 in my car. Both are wired discretely, permanantly on and have been left at airports for over a week with no starting problems on return.
I opted for the 'permanantly on' approach because I got fed up of waiting to get a signal in central London which can take an age unless you have it on the dash. I avoid the dash as I have hopped out on a phone call a few times and left it there which is barmy I know.
My car is new but the BMW is a 98 523 touring which we've had for 4 years and we've never changed the battery so it must be a bit weary by now. Still no problems.
Out if interest, are some cars clever enough to switch off accessory circuits when power drops below a point? The BMW does all sorts of wierdery with the air suspension, lights and so on with the engine off so would assume there is some way of prioritising power for startup over gizmos? _________________ Tom Tom GO 720
Orange M3100, Orange SPV M5000
TomTom Navigator 6, Destinator 6
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