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ETrex Legend C cigarette lighter power question...
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ice tres
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Joined: 16 Aug 2005

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PostPosted: Mon Aug 22, 2005 8:52 pm    Post subject: ETrex Legend C cigarette lighter power question... Reply with quote

When I use the cigarette lighter power source, my battery seems to drain fairly quickly. This happens even when the cig. lighter is the only power source the ETrex has been using -- that is, even when I leave the unit in the car strictly for navigation and turn it off when the power from the car battery is off. What gives? Is this a software problem? Anyone else experience this?

Thanks

Ice Tres
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miles58
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Joined: 07 Mar 2005

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PostPosted: Tue Aug 23, 2005 5:56 am    Post subject: Reply with quote

In my Honda, the Cig lighter connection has no power when the ignition switch is off. But, If I connect an external battery to the cig lighter It obviously has power, but so does the radio.

I use a 12 volt UPS battery in my GPS bag with a male and female cig lighter connection so that I can charge that battery when I am in the car and I can still use the GPSr at the same time.

Further, I have two IFinders. One will charge the battery from the cig lighter connection, and the other won't.

I don't know what else is on the cig lighter circuit in my car, but with that 12 volt battery the radio has enough power to play. With your 3 volts in the Etrex, it wouldn't play, but would still draw some juice out of the Etrex with the ignition off.

Try using rechargeables in the Etrex and see what it does. You may be killing alkalines by trying to charge them with 15 volts.
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RINO SHAWN
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Joined: 18 Nov 2004

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PostPosted: Tue Aug 23, 2005 10:47 pm    Post subject: Reply with quote

Just an observation with rechargeable batteries:

I have 2 Garmin's ...my main GPSr is a Rino 110 with optional Mapsource installed...It has a setting for choosing if you are using alkaline or Nimh batteries....I have had pretty good results with that unit running rechargeables...I use the cig. lighter plug in the car...and have not seen any battery drain issues.

My 2nd Garmin is a plain (yellow bannana) Etrex ....It lasts a very long time on cheap alkaline batteries....there is not a setting for nimh batteries. When I use nimh baterries in the etrex...they go dead pretty quickly.....I stopped using rechargeables in the etrex but still use them in the Rino.

Also...miles58 pointed out that several cars only have power at the cigarette lighter when the key is on (especially import cars) ...That would explain the battery draining down in the Legend C ....but only if your leaving it on for periods of time with the ignition turned off......(my Rino starts a countdown timer and shuts itself off (if you don't press a button) when you lose power at the cigarette lighter)

Rolling Eyes just "thinking out loud" Wink
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ice tres
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PostPosted: Tue Aug 23, 2005 11:21 pm    Post subject: Reply with quote

That's a good point about the cig lighter only supplying power when ignition is on but the Legend does automatically turn off in 30 seconds if the power stops from the cig lighter.

I'll have to check out if there are any battery settings I haven't noticed but will just have to use rechargeables otherwise. Thanks!

Ice Tres.
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miles58
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PostPosted: Wed Aug 24, 2005 3:37 am    Post subject: Reply with quote

ice tres wrote:
That's a good point about the cig lighter only supplying power when ignition is on but the Legend does automatically turn off in 30 seconds if the power stops from the cig lighter.

I'll have to check out if there are any battery settings I haven't noticed but will just have to use rechargeables otherwise. Thanks!

Ice Tres.


I don't know if the legend will charge NiMh batteries when it's plugged into the lighter socket. But, if there is a radio on that circuit it could for that 30 second period be easily draw many times the current out of the batteries that the etrex alone draws, even if it can't get enough to play. Fans on that circuit could be even worse.
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Moe the Sleaze
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Joined: 10 Jan 2003

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PostPosted: Wed Aug 24, 2005 3:52 am    Post subject: Reply with quote

A) The different battery settings on Garmin units are only to make the displayed battery level meter more accurate. NiMH batteries put out a slightly lower voltage than alkalines. The setting will have no effect on battery life.

B) To the best of my knowledge, no GPS that uses AA batteries will charge the batteries in the unit.
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miles58
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PostPosted: Wed Aug 24, 2005 5:07 am    Post subject: Reply with quote

Moe the Sleaze wrote:
A) The different battery settings on Garmin units are only to make the displayed battery level meter more accurate. NiMH batteries put out a slightly lower voltage than alkalines. The setting will have no effect on battery life.

That's what I thought.

B) To the best of my knowledge, no GPS that uses AA batteries will charge the batteries in the unit.


Never read the manual for my iFinder Hunt, but when I have it plugged in to my battery pack and car, the batteries get warm and I never seem to have to charge them. The iFinder Pro I use pretty much identically, but its batteries don't get warm and every couple of weeks I have to charge them.

The way I use it may well be masking the issue, but it seems to be charging them and I don't know where the manual is anymore.
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Moe the Sleaze
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PostPosted: Wed Aug 24, 2005 6:30 am    Post subject: Reply with quote

miles58 wrote:
Never read the manual for my iFinder Hunt, but when I have it plugged in to my battery pack and car, the batteries get warm and I never seem to have to charge them. The iFinder Pro I use pretty much identically, but its batteries don't get warm and every couple of weeks I have to charge them.

The way I use it may well be masking the issue, but it seems to be charging them and I don't know where the manual is anymore.


Attempting to charge non-rechargeable batteries risks causing them to overheat and leak, damaging whatever they are in. It would reguire expensive add-on circuitry for the unit to detect what type of batteries are installed in order to reliably enable or disable the charging process based on what type of batteries are installed. I doubt any consumer-grade GPSrs have that capability.

I'm guessing your iFinder has an internal voltage regulator to lower the 12V from your car to a lower voltage used internally in the unit, and that is what is getting warm.
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RINO SHAWN
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Joined: 18 Nov 2004

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PostPosted: Wed Aug 24, 2005 10:34 am    Post subject: Reply with quote

Quote:
I'm guessing your iFinder has an internal voltage regulator to lower the 12V from your car to a lower voltage used internally in the unit, and that is what is getting warm.


Just out of curiousity....(since I am on my lunch break and have equipment handy) I plugged my "car cord" into a 12V recptacle (booster pack)...grabbed my Fluke meter and measured the voltage at the end of the cable that would plug in to my Rino110.....4.65 Volts. The Rino uses (3) AA batteries. (each battery at around 1.5 Volts) Therefore...at least with this particular model of GPSr.....the electronics to make the voltage correct is inside the cigarette plug base........I have no idea if the Ifinder does it the same way or not......My S.W.A.G. is that if the cigarette lighter end of the cord has a larger than absoulutely necessary size of the plastic....it probably has a small circuit board inside with whatever is needed to make the voltage lower. Wink
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RINO SHAWN
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PostPosted: Wed Aug 24, 2005 10:52 am    Post subject: Reply with quote

miles58 wrote:
Quote:

Never read the manual for my iFinder Hunt, but when I have it plugged in to my battery pack and car, the batteries get warm and I never seem to have to charge them. The iFinder Pro I use pretty much identically, but its batteries don't get warm and every couple of weeks I have to charge them.


Dave, just curious,
Are you using a "home made" , hardwired, or car cord from an unknown source that happens to plug in to your Ifinder Hunt?

Just thinking that possibly it is supposed to have the voltage corrected at the car cord....and maybe you are sending too much voltage in to the unit.

Just a "shot in the dark"...I am probably wrong Wink
Shawn
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miles58
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PostPosted: Wed Aug 24, 2005 1:05 pm    Post subject: Reply with quote

Moe the Sleaze wrote:


I'm guessing your iFinder has an internal voltage regulator to lower the 12V from your car to a lower voltage used internally in the unit, and that is what is getting warm.


It'd be my guess that both iFinders have a similar regulator to drop the 15VDC cig lighter output down to 3.

I have no real idea why the Hunt gets warm otherwise, since the batteries themselves get warm about like when I charge them. Nothing would preclude the unit getting warm and transferring the heat to the batteries I suppose, but then the unit itself should get noticeably warmer than the batteries. and I did not notice that.

Now I gotta go hunt down the bloody book and see it it tells me anything. I almost made it a year without looking at it.
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miles58
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PostPosted: Wed Aug 24, 2005 1:10 pm    Post subject: Reply with quote

RINO SHAWN wrote:
Quote:
I'm guessing your iFinder has an internal voltage regulator to lower the 12V from your car to a lower voltage used internally in the unit, and that is what is getting warm.


Just out of curiousity....(since I am on my lunch break and have equipment handy) I plugged my "car cord" into a 12V recptacle (booster pack)...grabbed my Fluke meter and measured the voltage at the end of the cable that would plug in to my Rino110.....4.65 Volts. The Rino uses (3) AA batteries. (each battery at around 1.5 Volts) Therefore...at least with this particular model of GPSr.....the electronics to make the voltage correct is inside the cigarette plug base........I have no idea if the Ifinder does it the same way or not......My S.W.A.G. is that if the cigarette lighter end of the cord has a larger than absoulutely necessary size of the plastic....it probably has a small circuit board inside with whatever is needed to make the voltage lower. Wink


I just measured mine. 3.65 VDC to run the unit which takes 2 AAs.

If they get warm they are likely charging. I will connect it up to the unit with the batteries out and measure what's on the battery terminals later and let you know.
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miles58
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PostPosted: Fri Aug 26, 2005 6:54 am    Post subject: Reply with quote

Took the time to measure at the batteries with the iFinder Hunt connected to an external battery, 3.35 VDC. That will definitely charge the batteries. I have no idea what kind of charge current it can provide, probably not a lot at that voltage. but it will charge them.
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RINO SHAWN
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PostPosted: Fri Aug 26, 2005 10:15 am    Post subject: Reply with quote

miles58 wrote:
Quote:
Took the time to measure at the batteries with the iFinder Hunt connected to an external battery, 3.35 VDC. That will definitely charge the batteries. I have no idea what kind of charge current it can provide, probably not a lot at that voltage. but it will charge them.


Wish my GPSr worked that way!! Guess you know now to definateley only use rechargeables Cool

I'd be guessing that in the electronics in the unit ...or possibly even in the cigarette lighter cord...is a diode or something making the current a (one way) deal.....(kinda like how Motorhomes have a rectifier bridge setup that allows the RV battery(s) to get charged by the vehicle but the current cannot flow the otherway to "suck" the energy from the starting battery so your not left stranded)
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miles58
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PostPosted: Fri Aug 26, 2005 11:14 am    Post subject: Reply with quote

RINO SHAWN wrote:
miles58 wrote:
Quote:
Took the time to measure at the batteries with the iFinder Hunt connected to an external battery, 3.35 VDC. That will definitely charge the batteries. I have no idea what kind of charge current it can provide, probably not a lot at that voltage. but it will charge them.


Wish my GPSr worked that way!! Guess you know now to definateley only use rechargeables Cool

I'd be guessing that in the electronics in the unit ...or possibly even in the cigarette lighter cord...is a diode or something making the current a (one way) deal.....(kinda like how Motorhomes have a rectifier bridge setup that allows the RV battery(s) to get charged by the vehicle but the current cannot flow the otherway to "suck" the energy from the starting battery so your not left stranded)


Yeah, it'd only take a single diode to accomplish it. I think it must have had the batteries down a ways and then I left it plugged into my bag when I noticed it charged the batteries. With the way I normally use it the unit is mostly plugged in so it would have high enough internal resistance in the batteries that they wouldn't charge hard and warm up.
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