Does Battery Power Affect Signal Strength?

[Guest jeremy]

I've noticed something odd after doing a bunch of cache hunts - If my batteries are at half power or less, my ability to track satellites gets more difficult. A fresh set of batteries tends to get a better lock.

 

Do my eyes deceive me? Or perhaps signal lock can be based on how powerful the juice in your batteries are.

 

Jeremy

[Guest BigFig]

Wouldn't think so. An electronic device is a device, is a device. You'd have to get real marginal on the batteries - like shut down - to see an effect. Digital devices tend to work, or not - or give wild results on the margins. It don't work that way.

Gremlins?

[Guest daviskw]

Jeremy I have noticed the same thing. I thought it was just my imagination. I also noticed that the display seemed to update slower. I also noticed that I seemed to track fewer satellites on low batteries. I am using a etrex but I have also noticed the same behavior on my emap as well

Butch

[Guest puma]

I thought I was the only one! I don't know how, but it also happened to me this weekend. Maybe my imagination. Question, in a hardwood forest without leaves, should I be having trouble getting a good signal? I still think its the batteries.

[Guest O-man]

Yup - me too. I have a Magellan 315 and an Etrex, and have been taking them both along on hunts to compare. I had rechargeable batteries that were at about half strength in my 315 one day on a hunt and started noticing sluggish performance.

 

The terrain was open hillside, but there was a heavy cloud cover and light rain. The pointer would lock in one position and not move for awhile - and I walked past the cache about 50 yards. It then registered that I was on top of the cache.

 

I finally got a clue and turned on the Etrex (fresh Duracells). It quickly reported that the cache was behind me so back I went and went right to the cache. The 315 was still reading incorrectly.

 

I haven't seen such disprepancies before in these units, so it may have been the batteries. Does anyone know what effect cloud cover has on signal reception?

[Guest peter]

Depends on whether the satellites are blocked by the tree trunks or branches.

 

A similar claim was made some time ago on sci.geo.satellite-nav and I tried to verify it with my eMap using two sets of batteries - one fully charged (2.74 V) and one nearly discharged (1.95 V). I couldn't reliably see any performance difference between the two sets of cells when I repeatedly switched between them.

[Guest BigFig]

That's right folks - blame it on the batteries

[Guest BigFig]

That's right folks - blame it on the batteries

[Guest O-man]

I prefer to blame Bad Ju Ju, or Things That Go Bump In The Night. But I am still curious about power/performance.

 

Not too long ago, GPS devices held four batteries as a standard. Have the "electronics" improved so that now they are more efficient with less (two batteries)? Or were the older units designers just being conservative and designing for redundancy (four batteries)?

[Guest bubba232]

I noticed a dramatic decrease in Sat. lock on at around half battery strength. However, I thought it was due to the cold weather while hunting.

I haven't had any problems since, while operating in mild weather and on flat land.

 

Just my observation.

 

Lock-on!

[Guest peter]

quote:

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Originally posted by O-man:

Not too long ago, GPS devices held four batteries as a standard. Have the "electronics" improved so that now they are more efficient with less (two batteries)? Or were the older units designers just being conservative and designing for redundancy (four batteries)?

---

 

I think it's just the quest for smaller and lighter units. My 4-cell GPS12 operated about twice as long per set as my 2-cell eMap, so there hasn't been a big reduction in actual power used (of course the eMap has more memory and processor speed). The units also have some voltage conversion electronics. The 2-cell eMap puts out nice +/- 6 V pulses on the RS-232 port even when the batteries are down to 2 V.

[Guest ba.roberts]

size="2">Originally posted by bubba232:

I noticed a dramatic decrease in Sat. lock on at around half battery strength. However, I thought it was due to the cold weather while hunting.

I haven't had any problems since, while operating in mild weather and on flat land.

 

Just my observation.

 

Lock-on!

---

 

The magellan handbook quotes Acquisition times (under optimal conditions) as :

 

Warm approximately 15 secs

Cold approximately 1 minute.

 

So the weather conditions/temperature were probably significant.

 

I have not noticed any difference in reception even when after the Low Battery warning has come up and I haven't had chance to change the batteries.

 

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Brian

[Guest bob_renner]

With GPS receivers and acquisition times, the reference to cold and warm has nothing to do with the temperature. A cold acquisition means that the satellite almanac data (stored in the receiver) is out of date and the receiver has more data to collect than with a warm acquisition. This is generally due to the receiver not being used in about a week or more.

 

Bob

 

[This message has been edited by bob_renner (edited 03-13-2001).]

[Guest peter]

quote:

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Originally posted by ba.roberts:

The magellan handbook quotes Acquisition times (under optimal conditions) as :

 

Warm approximately 15 secs

Cold approximately 1 minute.

 

So the weather conditions/temperature were probably significant.

---

 

'Warm' and 'Cold' in this specification are not referring to the temperature but rather how long it's been since the unit was last turned on and had a satellite lock. If it was recent, then the GPS still has valid ephemeris information on the satellites (i.e. their precise orbits) and can quickly get a position once it 'sees' the satellites(i.e. a "warm start"). Otherwise it first needs to find the satellite signals and download the current ephemeris before it can determine your position (i.e. a "cold start").

[Guest mlong]

While the acquisition warm/cold is not related, the temperature does have an effect on electronic devices. In particular the LCD screen will have problems in cold weather -- from sluggish display to low contrast to even complete blanking. If this happens, just warm up the GPS, and you will see improvement. This is inherent in all LCDs, and is not related to battery power.

 

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Matt

[Guest Cape Cod Cache]

Re: battery strength to reception factor.

Imagine a 1970 transistor radio... the radio waves are out there, but getting the unit to work is dependant upon the reciever's processing strength. I use brand-namw alkaline for my GPS (4) and provided recharge batts for my handheld VHF radio. I will reiterate "Be Prepared" (bring extra batteries)

Post Script: I'm looking for a place to get wholesale batteries, should be easy...A weekend skiing or sailing a small boat can eat 12+

[Guest proxien]

hey all:

This is my first post... thanks to everyone who participates in these forumns and conveys some really useful info.

 

Where to buy batteries: COSTCO (or Sam's Club)

 

You have to pay a membership fee, but I managed to save the $45 fee in my first trip.

 

Anyways, about the batteries:

The Costco store brand (Kirkland) rated in Consumers' Reports to be as good as Duracell and Energizer batteries, but they sell them for a much cheaper price. The 24 pack of AA batteries cost me about $8. That comes out to about 33 cents per battery!

 

 

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proxien

[Guest bob_renner]

quote:

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Originally posted by proxien:

The Costco store brand (Kirkland) ... 24 pack of AA batteries cost me about $8. That comes out to about 33 cents per battery!

---

 

The Costco near me has a 44 pack brick of AA batteries for ABOUT $11.??. That's about $.25 each. I don't buy anything else.

 

Bob

[Guest 300mag]

In my global map 100manual they talk about the power save feature.They say it will affect the receivers performance,it also can loose its lock easier on satellites and changes update rate. So maybe this is whats also hapenning when youre units get low on power.

[Guest peter]

quote:

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Originally posted by bob_renner:

The Costco near me has a 44 pack brick of AA batteries for ABOUT $11.??. That's about $.25 each. I don't buy anything else.

 

Bob

---

 

But either NiCd or NiMH rechargeables will be far cheaper than that in the long run. I bought a set of 4 NiCds plus charger over two years ago for $9.95 and they've been recharged about 300 times since then. The run time per charge is about half that of alkalines, so this would have required 300*4/2 = 600 single-use alkalines during that time. Even at the Costco price that would have been about $150 instead of the $10 I paid.

NiMHs give about the same runtime/charge as alkalines and can also be recharged hundreds of times. Well worth the slight initial investment given how much you save in the long run.

[Guest daviskw]

I contacted Garmin and asked how low battery strength could effect my etrex GPS. They stated that the display update would indeed noticeably slow down but that satellite acquisition and lock would not be effected. That would mean that accuracy would not be directly effected but the fact that the display does not update as often could lead to poor navigation.

 

Butch

[Guest Choberiba]

quote:

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Originally posted by daviskw:

I contacted Garmin and asked how low battery strength could effect my etrex GPS. They stated that the display update would indeed noticeably slow down but that satellite acquisition and lock would not be effected. That would mean that accuracy would not be directly effected but the fact that the display does not update as often could lead to poor navigation. Butch

---

 

I decided this thread could use dusting off since I've been noticing some sluggish behavior if the batteries aren't fresh.

 

Swapping out batteries before I head out is a ritual with me, but surprises happen and it's during these times that I'm left scratching my head.

[Guest Ascension]

quote:

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Does anyone know what effect cloud cover has on signal reception?

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I have seen definate negative affects in cloud cover, at least in very overcast skies. I went out Saturday soon before it rained and then on Sunday after it had cleared up and my reception and accuracy was much better. Of course it could have just been the posistion of the sats the first day.

 

[This message has been edited by Ascension (edited 29 October 2001).]

[Guest JasonW]

I can't say for definite why it happens, but I too think that it's more difficult to obtain a lock with low batteries - I can only assume that it's down to the amplification that's required in the RF part of the receiver either not being as clean (or as high gain) as with new batteries..... as all the digital stuff should be voltage level independant (unless it drops below the operating voltage of the digital components of course) but might happen more slowly.

 

This is of course pure speculation on my part

[Guest JasonW]

I can't say for definite why it happens, but I too think that it's more difficult to obtain a lock with low batteries - I can only assume that it's down to the amplification that's required in the RF part of the receiver either not being as clean (or as high gain) as with new batteries..... as all the digital stuff should be voltage level independant (unless it drops below the operating voltage of the digital components of course) but might happen more slowly.

 

This is of course pure speculation on my part

[Guest Vagabond]

Haven't really noticed any difference on low batteries on my Lowrance 212 (I keep the power saver turned off because it will effect the signal) when my batteries get to low the unit shuts down then I stop and fumble around for 4 fresh ones.......

[Guest Vagabond]

Haven't really noticed any difference on low batteries on my Lowrance 212 (I keep the power saver turned off because it will effect the signal) when my batteries get to low the unit shuts down then I stop and fumble around for 4 fresh ones.......

[Guest k2dave]

I am supprised that lower battery voltage actually effects performance unless those units automatically switch to power saving mode as the batts deplete. I have not noticed any change in performance with new or used ready to quit batts. I use a 4 batt 3+ maybe it effects 2 batt units?

[Guest progun]

I just did some testing with my Magellan 315. For my test I am using brand new Energizer e2 Titanium batteries as well as a set of Rayovac NiMH rechargable that are showing about 2/3 charge. I am also testing this in my house in order to block signal as well as outside.

 

I started outside and fired the 315 up with the NiMH, got an almost instant lock. Turned the unit off and went inside. Turned back on and it took about 5 minutes to find the first satelite and about 2 minutes after that to get a fix.

 

I changed batteries and went back outside. Got exactely the same results, almost instant lock and fix. When back inside and went just over 6 minutes to find the first sat and about 1 minute more to get a fix.

 

The only performance difference that I see is how long the batteries actually last.

 

Scott

[Guest peter]

I compared new alkalines to nearly depleted NiMH cells in my eMap under poor signal conditions inside my house. I saw no consistent difference in signal strength, number of satellites received, or time to lock.

[Guest tak1]

By the way, don't buy the "el-cheapo" brand batteries from the drugstore. They don't hold a candle to the brand-name batteries, mostly Duracell Ultra.

 

L:K

 

Never mind having Survivor in Africa or Australia, they should have it in a really harsh environment, in Saskatchewan.

[Guest ClayJar]

I thought the power drain of a "standard" GPS receiver was low enough that the various high-drain alkalines don't have a performance advantage over standard quality alkalines...

[Guest Choberiba]

re than x2 for some reason. I'm aggressive at keeping my NIMH topped off, so I'm rarely running all that low anyway.

[Guest ClayJar]

quote:

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Originally posted by Choberiba:

You didn't spring for the light saber accessory?

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Aw, man! I knew that Garmin would come out with something uber-cool to make up for the patch antennas.

[Guest k2dave]

tak1 How much runtime do you get w/ the ultras and the standard duracells (and the el cheapo alk batts)? If you know the times please post them and is that time your estimate or your gps's battery timer. IIRC The ultras usually cost about 2x standard batts. And as pointed out are made for high drain devices.

[Guest averk]

Looking at the receiving part of a GPS unit it is indeed a regular receiver. Pending signal strength, the signal probably is either amplified, and/or send through a DSP unit and or A/D converter, or all of the above. Most of these circuits are analog, and would thus be suffering from a low batterie voltage. This is total speculation on my side, but I have seen similar issues with Wireless Mic's, camera's and radio's

 

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[+Owenses]

Absolutely! Battery power does greatly effect received signal strength. Especially if you are using NiMH batteries.