Spare batteries for your GPS

[sandbagsteve]

Just a note for anyone who uses a handheld GPS powered my AA batteries. NiMh cells are simply awful for self discharging, so unless you top the things up shortly before flying they won't be near 100% capacity.

However, Sanyo have for a while been selling their Eneloop cells, which really don't self discharge. I have around 24 of these that use in my camera/flash rig, and they are simply fantastic. They have been left for several days fully charged, and didn't loose any charge at all. I have actually left one of these cells for 2 months as a test and again it only took a handful of mAhrs to top it off. Almost as good as LiPo or LiIon.

Don't risk using standard NiMh cells - especially higher capacity ones, as it is the higher capacity cells, generally, that have the worst self discharge characteristic.

Sorry to sound like a shareholder, but these things have saved my bacon so many times.

[SNS3Guppy]

If you're at a point where a handheld GPS is saving your bacon, things have already gone seriously wrong in your life. If you're seeing this on a regular basis, you need to rethink the way you're doing business.

A paper chart never needs batteries. Your GPS should be powerable from the aircraft, and your handheld GPS shouldn't really be something on which you're relying. Using, sure...but not relying. Accordingly, it should never be a bad day if the batteries on your handheld GPS fail.

It's very possible to fly without one at all.

[Bushfiva]

Eneloop is indeed good technology.

Self-discharge for standard Ni-MH cells is around 0.7% per day, with the highest-capacity cells hitting 2%/day. Self-discharge for Eneloop is around 15% after one year, with most of the discharge occurring in the first 180 days. Because of the low self-discharge rate, the cells are sold pre-charged to around 70% capacity, so they're ready for use out of the box.

[znww5]

SNS3Guppy - thanks for reminding why I so rarely visit Pprune - home of the 500-posts-a-year finger-waggers :=

If you took the time to actually read the post, you would realise that Sandbagsteve was simply passing on his experience regarding NiMh battery life issues; derived I surmise, from working as a photographer.

He was doing nothing more than passing on information which he considered may be of interest or use to fellow pilots. In that assumption, he was correct as far as I am concerned - thanks for the info Sandbag'.

But thank you for reminding me why I don't waste my time here very often.

[SNS3Guppy]

But thank you for reminding me why I don't waste my time here very often.


Thanks for not wasting more of our time, too. You've done well.

[Zulu Alpha]

There is one catch with Eneloop batteries, they have a lot less capacity than other NiMH batteries.

They start with 2000mAh and after a year discharge to 85% ie 1700 mAh

Other NiMH (Duracell for example) start with 2650 mAh and discharge at about .75% per day so will take about 40-50 days to get down to the same level of charge as the Eneloop.

So, Eneloop are great as a spare set to keep for emergency, but standard ones are better if you charge them more frequently than every 6-7 weeks.

Eneloop are more expensive, so I use Duracell for regular use with a set of Eneloop as an emergency backup.

ZA

[Bushfiva]

I use vast numbers of rechargables (I've a Sanyo charging station which can charge 20 cells at once with storage for 44) and the Eneloops have made a great difference to the way I use such cells: previously, I'd recharge everything before use, but now I'm happy to leave the cells in equipment until I get the low battery warning: in practical use, I get longer real-world use from my 2000 mAh Eneloops that my 2500 mAh stuff in things like GPS, flashgun and power grip simply because there's almost no self-discharge when the unit is off. As a side effect, I'm using up my 1000 Eneloop recharges much slower than other cells.

[BackPacker]

I simply carry an 8-pack of Alkaline non-rechargeable AA batteries in my flight bag as backup. Anyone knows the capacity and self-discharge numbers for those?

Wikipedia suggests 3000 mAh for an average Alkaline AA, but doesn't talk about self-discharge.

I am a firm believer in standardization though. Everything electronic in my flight bag is powered by AAs.

[Fuji Abound]

SNS3Guppy - you do seem to have a knack of turning every thread into a "learning experience". :), and with "it is very possible to fly without one at all" a perfection of the art of the bl**ding obvious. :) Just a thought.

[worrab]

Still only deliver 1.2v though - in a 6v setup you're only getting 4.8v. It is possible to obtain rechargeable alkalines (eg CPC | CPC - Over 100, 000 products from one of the worlds leading distributors of electronic and related products. (http://www.cpc.co.uk)) that don't self-discharge very fast and do deliver the full 1.5v. They need a special charger, but the cost of charger with batteries is not dissimilar to the cost of one set of good alkalines.

I've used these a lot - the only real downsides are a) that it's better not to let them completely discharge and b) that the children seem to find them as useful as I do.

[what next]

Hello!

BackPacker: Anyone knows the capacity and self-discharge numbers for those?

They vary widely between manufacturers and battery models. As usual: The more expensive they are, the higher the capacity and shelf life. I think your 3000 mAh figure is a typical value. If you look closely, all alkaline batteries (at least those of major brands) have an expiry date printed of them, normally between five and ten years in the future!

Like you, I always have a pack of new alkalines in my flying bag as backup, but I find four of them sufficent (that cost together as much as one Eneloop cell!). I replaced the last pack recently after carrying with me unopened for over five years... and they still go strong inside some toy of my son.

It is important however, not to leave alkaline batteries inside devices like GPS receivers, because they always draw a little current even when turned off (to power their internal clocks etc.).

Greetings, Max

NB: GPS is here to stay. Learn to use it properly, and the flying experience will gain a new quality: Simply enjoying to be in mid-air, without having to worry about getting lost or infringing airspace. And a spare GPS unit in your pocket will give you a lot of extra peace of mind.

[SNS3Guppy]

SNS3Guppy - you do seem to have a knack of turning every thread into a "learning experience".

That's always the goal.

One might be surprised to learn just how many "children of the magenta line" operate cockpits out there, who veritably curl into a ball and die if they can't follow a GPS to their destination. My comment, therefore, is not without merit.

The handheld GPS is a great toy and a wonderful gimmick, but no replacement for a chart. Often, that's unrecognized or forgotten, occasionally to the detriment and even loss of life of the forgetful.

[Jim59]

I have a Garmin GPS that flattens Ni-MH 2700 mAH AA batteries relatively quickly even when it is switched off (half the charge lost in a month). I found that if the batteries are removed then they hold their charge pretty well. I now insert the batteries just when I need them and am now a happy bunny!

I think the problem is a 2200 microFarad electrolytic capacitor that is connected across the batteries having a higher than I would like leakage current (all such capacitors leak electricity). It is simpler to remove the batteries than get the capacitor replaced with one that is hopefully better.

[modelman]

I have an old GPSMap195 that had quite a thirst for the best Alklaline.I put 6 of them there Energizer Lithiums (Tesco 3.79/4) in and I am still waiting for them to pack in after several flights.:)
p.s. Anyone got an AA power pack for a 195 as it would be nice to have one standing by?
Oh yes,I can still use (and do) a chart,DI,compass and stopwatch.;)

MM

[Fuji Abound]

The handheld GPS is a great toy and a wonderful gimmick, but no replacement for a chart. Often, that's unrecognized or forgotten, occasionally to the detriment and even loss of life of the forgetful.


Well, I am not sure I agree.

I have flown for way over a 1,000 hours using only a hand held GPS. In that time I had one GPS failure (my own fault) and another failure for other reasons. As luck would have it on the second occasion I also had some issues with the radio nav. equipment in poor conditions. I backed up my own nav. with a request to AT to provide me with vectors as I worked my way across Holland, France, and part of the UK; no big deal, but with some complicated airspace to negotiate and no wish to go IMC I was not going to risk infringing.

Hand held GPSs are almost certainly more reliable than most peoples ability to navigate any other way - at least over reasonable distance and terrain with which they are not familiar. Most of the time they are therefore better off following the magenta line and using the moving map to ensure they dont infringe.

The key is for them to have the sense to own up when and if the GPS fails. It may be embarassing but so what - a call to AT will readily sort things out. Those that are the real danger are the pilots that believe their "tradtional" nav skills are up to scratch - they dont know when they are lost, and they dont realise they have infringed. At least when a GPS fails you almost always know it has failed.

I enjoy a bit of traditional nav - it is my sort of thing. However my aircraft has twin IFR approved GPS receivers, glass screens and I still carry a Garmin in my flight bag. Why? Well all the time I dont want to worry where I am it takes care of the chore for me, provides unparalled situational awareness and enables me to transition to IMC should the need or the desire arise. Airways, why would I want to use anything else?

A GPS handheld or otherwise is not a toy - it is a serious piece of kit packed with technology. The chances are with a permanent power supply and an external aerial it will prove as reliable as a panel mounted unit, will have a failure rate way lower than your engine up front without any maintenance and, if you carry two, I doubt in a lifetime you would ever see a simultaneous double failure. In fact I have had more engine shut downs in twins that handheld GPS failures. :) Fortunately I am ahead of the game in singles. :) :)

[n5296s]

The handheld GPS is a great toy and a wonderful gimmick, but no replacement for a chart
I guess I'm missing something here. A chart is very valuable and it's not at all a bad idea to carry them round with you, but I've yet to see a chart that will tell you where you are...? :hmm: A GPS, on the other hand, is quite good at this.

A handheld GPS is therefore a pretty useful emergency backup for whatever in-plane navaids you have (a 530 and 430 in my case). Of course the perfect pilot knows where they are when the alternator dies and the battery shortly afterwards, but that still won't help them get down through 10000' of clag to make a safe landing, or fly safely to a place where a VFR descent and landing can be made. A handheld GPS is quite capable of doing just that. I'm not at all clear on how any number of charts can do it.

And for something you only use in an emergency, some kind of sure-to-be-there power source is extremely important. (Which is why I carry a big bag of new Duracells round in my flight bag - having learned the hard way that cheap no-brand alkalines are often dead when you need them).

So not only is SNS a tedious didact (in this instance at least), but also what he is saying doesn't make any sense.

n5296s

[dublinpilot]

One might be surprised to learn just how many "children of the magenta line" operate cockpits out there, who veritably curl into a ball and die if they can't follow a GPS to their destination. My comment, therefore, is not without merit.


With all due respect SNS, your comment was off the wall, because you failed to read the post correctly.

I have around 24 of these that use in my camera/flash rig, and they are simply fantastic. They have been left for several days fully charged, and didn't loose any charge at all. I have actually left one of these cells for 2 months as a test and again it only took a handful of mAhrs to top it off. Almost as good as LiPo or LiIon.

Don't risk using standard NiMh cells - especially higher capacity ones, as it is the higher capacity cells, generally, that have the worst self discharge characteristic.

Sorry to sound like a shareholder, but these things have saved my bacon so many times.

The poster clearly is a photographer. He says that he has 24 of these "that use in my camera/flash rig". If they saved his bacon, they presumably he's a professional photographer, and used them when his camera batteries ran out, and otherwise whould have been in a very embarrasing situation.

He at not time in his post suggest that he even uses a GPS, never mind stating that he uses these batteries in one. He certainly hasn't stated that he depends on a GPS.

He was simply letting people know about these types of batteries, in the though that people who use GPS might like to know about them.

You made too many assumptions, and are not trying to defend the indefensible. You've be better off acting like a man and saying sorry and treating it as an opportunity to learn :)

[Fuji Abound]

You've be better off acting like a man and saying sorry and treating it as an opportunity to learn


Cough. Erm HF.

[what next]

Hello!

SNS3Guppy: One might be surprised to learn just how many "children of the magenta line" operate cockpits out there, who veritably curl into a ball and die if they can't follow a GPS to their destination.This is why a good set of spare batteries for their spare GPS unit is so essential :O

Cheers, Max

NB: I would like to hear from one single accident that was caused by the GPS packing up on someone following the magenta line (in daylight VFR) instead of the pencil line on his map. Can anybody name one?

[FullyFlapped]

Guppy :
The handheld GPS is a great toy and a wonderful gimmick, but no replacement for a chart.
I'll remember that the next time I'm above a solid overcast with no electric ... and yes, it does happen ....

Separated at birth : SNS3Guppy and DFC ??

[flybymike]

As a matter of interest can anyone recommend a suitable/good external battery power supply to be used outside the GPS unit where the aircraft has no on board power socket and such that the GPS batteries inside the unit then become back ups to the external one? I am aware that some people use sealed lead acid or Lithium ion batteries for this purpose.
What size batteries offer the best endurance, useful life and capacity? Weight is an issue with SLA batteries and some saythat lithiums present a fire risk.

[dublinpilot]

Can your GPS unit be powered off a USB port?