Rechargeable battery - GPS question

[Peakbagr]

I could us a little advice. Had a pair of NiMH batteries in my GPS yesterday. Turned on the GPS(60CSx) at the trailhead. Battery meter showed full capacity and the meter was set to rechargeables. 4 Hours later, I was down to 1/4 power left and turned it off.

I'd recharged the batteries 7 days earlier and hadn't turned the GPS on other than to recalibrate the compass. WAAS is off as it always is.
I know I should be getter much better life out of a charge. Is it likely one of the batteries is bad(I have 8 batteries and I try to interchange and charge them to keep even useage)?
How much drain does actively using the GPS add to just having it on and running a tracklog? I find myself using the various features of the GPS while walking and on breaks. Is this a signifcant user of extra batter power?
Does charging the batteries and leaving them in the GPS for a week cause them to lose power?

Thanks

 

[DougPaul]

I could us a little advice. Had a pair of NiMH batteries in my GPS yesterday. Turned on the GPS(60CSx) at the trailhead. Battery meter showed full capacity and the meter was set to rechargeables. 4 Hours later, I was down to 1/4 power left and turned it off.

The battery meter is not very accurate, particularly for batteries with a rectangular discharge curve (NiMH, NiCad, Li).

I'd recharged the batteries 7 days earlier and hadn't turned the GPS on other than to recalibrate the compass. WAAS is off as it always is. I know I should be getter much better life out of a charge. Is it likely one of the batteries is bad(I have 8 batteries and I try to interchange and charge them to keep even useage)?

Possibly, or inadequately charged. What charger do you use? A smart charger with individual charging circuits is best. Charging too fast can also overheat and damage the cells. (I have stayed away from the fast chargers. About a 2hr charge time is about best, IMO.)

How much drain does actively using the GPS add to just having it on and running a tracklog? I find myself using the various features of the GPS while walking and on breaks. Is this a signifcant user of extra batter power?

Only the light adds significant drain on the 60CSx. (The compass can also be significant on other models.)

                                     ma
                -------------------------------------------
                   60CSx           60CS            Vista
                -----------     -----------     -----------
GPS off                  40              50              55
GPS norm                100              70             120
light 100%      +170    270     +180    250     +30     150
compass           +0    100      +50    120     +35     155

Does charging the batteries and leaving them in the GPS for a week cause them to lose power?

Shouldn't cause a significant loss. There are now some NiMH batts that are designed for long shelf life that are getting good reviews. (Sanyo Eneloops appear the be the best of them.)

Doug

 

[Peakbagr]

I use a SunPak Pictures Plus recharger. Described as 'microprocessor controlled' Ultra Fast. It has 4 bays for charging and you can select to charge either 2 or 4 batteries. And the batteries are Sunpak 1.2v / 2300mAh.

They usually recharge very quickly (under 2 hours), but seem very hot when the charging cycle is over. Hot enough to be a little uncomfortable to handle and I usually let them cool before before putting them in any device.

DougPaul, are you saying that the the battery meter is inaccurate enough that the batteries might have had more of a charge left than was indicated?
A few weeks ago I was down to 1 of 4 power bars left and ran the GPS until it turned off due to battery power. Same situation - newly charged batteries died on a summer dayhike of moderate duration. Maybe I should ditch this pair of batteries and see if the problem goes away?

Thanks

 

[DougPaul]

I use a SunPak Pictures Plus recharger. Described as 'microprocessor controlled' Ultra Fast. It has 4 bays for charging and you can select to charge either 2 or 4 batteries. And the batteries are Sunpak 1.2v / 2300mAh.

Sounds like you need a better charger... (The Maha MH-C401FS is much better. There are also newer chargers that will measure the cell capacity.)

They usually recharge very quickly (under 2 hours), but seem very hot when the charging cycle is over. Hot enough to be a little uncomfortable to handle and I usually let them cool before before putting them in any device.

I had a charger that would charge (empties) in about 1 hr. Damaged my batteries by overheating them...

DougPaul, are you saying that the the battery meter is inaccurate enough that the batteries might have had more of a charge left than was indicated?

The meter simply indicates voltage. Voltage is an inaccurate measure of charge in NiMHs.

A few weeks ago I was down to 1 of 4 power bars left and ran the GPS until it turned off due to battery power. Same situation - newly charged batteries died on a summer dayhike of moderate duration. Maybe I should ditch this pair of batteries and see if the problem goes away?

Sounds to me like you have cooked your batteries.

BTW, it is ok to run your GPS until it shuts off on its own. That occurs when the voltage drops to about 2.0V--still high enough that NiMH batts will not be damaged.

Doug

 

[hardyb]

Lithium Batteries

I had the same problem on Saturday with my Garmin. I put 2 brand new fully charded 2650 NiMH in and they only lasted about 4 hrs. I have found that the only batteries that will last a full days hike is a set of brand new Lithium's. As for the battery meter my Garmin Legend has different setting for the meter depending on what type of battery you are using, this gives you a more accurate battery level reading.

 

[DougPaul]

I had the same problem on Saturday with my Garmin. I put 2 brand new fully charded 2650 NiMH in and they only lasted about 4 hrs.

It takes several charge-discharge cycles for NiMH cells to reach full capacity. You did not state what charger you used--some are better than others.

Manufacturer's ratings are often not very accurate and are typically made at significantly lower current drains than drawn by GPSes.

I have found that the only batteries that will last a full days hike is a set of brand new Lithium's. As for the battery meter my Garmin Legend has different setting for the meter depending on what type of battery you are using, this gives you a more accurate battery level reading.

I have no trouble in getting 12+hrs out of a set of NiMHs. I carry lithiums as spares or save them for winter or for when I am skimping on weight.

BTW, the current drain for the Legend is the same as for the Vista, except it has no compass.

Again, the battery meter is not very accurate for cells with rectangular discharge curves. This includes lithium cells. I simply leave the meter set for alkalines and take the battery type into effect when reading the meter.

Doug

 

[Neil]

I would consider 7 days a sufficient time for rechargeables to lose some charge. I usually charge mine the night before and leave them on trickle charge in the same charger DP mentions and grab them on the way out the door.

My battery indicator starts with 4 bars and very quickly drops to 3. Soon thereafter it's down to 2 and it stays there for most of the day.

 

[DougPaul]

I would consider 7 days a sufficient time for rechargeables to lose some charge.

Sure, you will lose some charge in 7 days, but if you only get 4 hrs out of them, there is still something wrong.

I have left mine sitting around for several months and they still have significant amounts of charge left.

Doug

 

[Peakbagr]

The same thing happened on a previous trip and it was 4 bars, 3 bars, 2 bars, 1 bar and the next thing I knew the GPS was off and the batteries exhausted.

Couple of questions:

Is there a way to tell which of the batteries is cooked or shot? (like put on a battery tester after they've been charged?)
And is the Maha MH-C401FS the charger I should get or one that measure cell capacity ?

 

[DougPaul]

The same thing happened on a previous trip and it was 4 bars, 3 bars, 2 bars, 1 bar and the next thing I knew the GPS was off and the batteries exhausted.

This is usually what happens--the question is how long it takes...

Couple of questions:

Is there a way to tell which of the batteries is cooked or shot? (like put on a battery tester after they've been charged?)

A simple tester will not tell you what you want to know--it is no better than the battery meter in the GPS. The simplest method would be to put them one at a time in a 1 cell incandescent flashlight (not an LED light) and see how long each lasts*. Another way is to put them in a GPS and see how long they last--the GPS can measure the time for you, but can only test pairs. (One way of doing the GPS test is to pair the unknown cell with a known good cell. The unknown, if bad, will become exhausted first and the GPS will shut down. You can then measure the voltage of the cells to verify that the unknown was weaker than the known good cell.)

There is a good chance that you have fried all your cells. Some of mine are several years old and still going strong. (They should last 500-1000 cycles if treated properly.)

And is the Maha MH-C401FS the charger I should get or one that measure cell capacity ?

The 401 is a good charger, but it does not measure cell capacity. There are newer chargers that will. Choose for yourself. http://thomas-distributing.com is a good source. (Standard disclaimer: no connection, just a customer.)

* Only do this with a single cell flashlight. If you do this in a multi-cell flashlight, you can damage the cells by reverse charging one or more of them. The GPS is designed to shut down before any of the cells are damaged.

Doug

 

[SherpaKroto]

I've had good luck with the NiMH in my Garmin Summit, typically getting a full day. There are a number of settings that you can make to increase battery life, so an in depth review of the manual might shed light. I know it helped me. I also use the Maha charger and it is great (Dave Metsky recommended it years ago, and it's been a great buy)

 

[DougPaul]

There are a number of settings that you can make to increase battery life, so an in depth review of the manual might shed light.

In general, the backlight consumes additional current, so turning it off or down (on models with adjustable intensity) will help. On some models, the magnetic compass consumes extra power, on some it is negligible.

Battery-saving mode is often a false economy--it basically cycles the GPS chipset on and off, but can lose lock in less than optimal receiving conditions (such as in the trees).

The ultimate in saving power is to leave the unit off and only occasionally turn it on as needed to get a fix. One can easily get weeks of battery life by this method.

Doug

 

[SAR-EMT40]

Kind of specialized but this is an excellent recharger. Made for NiCad, NiMH and Lion batteries. It works great, doesn't cook batteries because there is also an overtemp sensor on it. It is also made for power packs of all kinds. I have been using it for at least 6 years (more I think) to recharge not only my radio battery packs (mostly LIon) but also tons of AA and AAA batteries and it works great. I have been using the same NiMH batteries (12 or so AA and 10 or so AAA) for many years. I threw (recycled) all of my Nicad batteries away years ago. Don't have one in the house.

Keith

Maha C777plusII

 

[Peakbagr]

My batteries are toast. I think I cooked them during charging cycles. Out yesterday and was down to the last gasp of battery life when a 7 hour hike ended.
Went to the site Doug recommended and just ordered the MH-C 800S. I like its display of individual battery status and the soft charge feature.
Also picked up an 8 pack of MaHa Power Ex 2700 mAh AA's. I like the warranty as well.

Gonna dump the Sunpak cooker and the 8 Sunpak batteries.
Are NiMH batteries OK to throw away in regular trash, or are they considered envionmentally toxic?

Thanks for the good contributions on this thread.

 

[DougPaul]

Are NiMH batteries OK to throw away in regular trash.

Yes.

NiCad, mercury, and lead (car storage) batteries are the common trouble makers and should be recycled rather than discarded.

Doug

 

[CaptCaper]

I've used MaHa chargers and Powerex for years and still have the original ones. I use them in remotes,weather radios,clocks,etc.

Even my old 1800's will run the 60CS Garmin all day with out a change. That's with Wass on. Compass off. I won't run with out WAAS on data isn't as good. . I always fly the best way. ..Or I don't fly.

 

[Viewseeker]

i have the garmin vista cx and non -rechargables run best in it. I still can only get one day out of a set before they go down, while running waas, tracks and the compass.