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Charging NiMH Batteries in Garmin 64s

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My Garmin GPSMAP 64s has generally been very good, but charging the NiMH batteries is an exception. I am using the Garmin plugin (wall outlet) charger that connects to the USB port.

 

For the first few charges, as soon as I plugged it in, it displayed a charging screen with a very large icon of a battery showing the charging progress. However, I have not seen that screen again since the first charges. Now, I get a plug icon in the upper left corner of the screen. Briefly pressing the power button will then display the backlight screen with a much smaller battery icon showing the charging progress.

 

That's OK, but the problem is that after two or three charges, when I plug in for a new charge and go to the backlight screen, it simply states "Battery" with a plug icon and no progress bar. When it is in this mode, it does NOT charge, even if left overnight.

 

The only way to fix it and get back to a chargeable state is to remove and reinstall the NiMH batteries.

 

Any suggestions on how to resolve this issue would be greatly appreciated!

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Charging is enabled by depressing the black switch between the 2 batteries. If you use the Garmin pack designed for this or if you use another means to keep the black button depressed with NiMh batteries installed, the 64 will charge the batteries. If it is depressed with regular alkaline batteries that would be a serious problem so only use the Garmin pack or NiMh batteries if you use something to keep the switch depressed. I use NiMh with a couple of pieces of thin plastic cut from a blister pack and it works fine. If you no longer see the charge icon maybe the switch isn't being depressed.

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Charging is enabled by depressing the black switch between the 2 batteries. If you use the Garmin pack designed for this or if you use another means to keep the black button depressed with NiMh batteries installed, the 64 will charge the batteries. If it is depressed with regular alkaline batteries that would be a serious problem so only use the Garmin pack or NiMh batteries if you use something to keep the switch depressed. I use NiMh with a couple of pieces of thin plastic cut from a blister pack and it works fine. If you no longer see the charge icon maybe the switch isn't being depressed.

 

Thanks for the great explanation! I have implemented your suggestion and so far so good. Hopefully that will resolve the problem.

 

Much appreciated!

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I have been using the Garmin Battery cassette for some time now. My experience in terms of Battery meter accuracy and Garmin response are elsewhere in this forum

Recently I found that the batteries were not charging.

What had happened was that despite the tightness of the fit of the batteries they had lifted off the little switch thus stopping the charge. Pressing them down firmly again did the job

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Garmin firmly warns that no other NiMh batteries other than those supplied by Garmin are to be used in the 64s.  Is there really any danger in doing so?  I place a thin piece of cardboard from a battery package under the two NiMh batteries I use and, as yet, they charge successfully in the GPS.

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I think those warnings are there to absolve any responsibility for anything that goes wrong should you use other batteries and try to charge them from within the unit. In reality, Garmin's battery pack seems to be identical to a pair of eneloops with a thin wrapper around them, which is why you can get away with using other NiMH batteries and a bit of plastic or cardboard to press down the button.

Honestly, though, I'm not sure what sort of charging technology Garmin has in its handheld units - whether it's a true smart charger or one with pre-set charging times. You're likely to get better charging, as well as faster charging, with a good battery charger.

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On 11/11/2017 at 0:32 PM, Mineral2 said:

Honestly, though, I'm not sure what sort of charging technology Garmin has in its handheld units - whether it's a true smart charger or one with pre-set charging times. You're likely to get better charging, as well as faster charging, with a good battery charger.

It is most likely just a simple low rate charge with voltage cutoff.

I find the built in charging great to have.  When travelling, in the car, plug the GPS into a USB cord and it tops up.  Get home from a day hike, plug it in.  I have not opened the battery compartment in years except when on multi day backpacking trips.

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I agree with Red90 100% and do the same thing.  I carry an extra pair of Eneloop Pro 2450 mHa as backup when on long hikes and outings.  Haven't had to use anything but the Garmin battery pack in a long time with my 64sc.

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On 11/16/2017 at 0:32 PM, Timpat said:

I agree with Red90 100% and do the same thing.  I carry an extra pair of Eneloop Pro 2450 mHa as backup when on long hikes and outings.  Haven't had to use anything but the Garmin battery pack in a long time with my 64sc.

I also love the Eneloop's but I charge mine in a dedicated Maha charger.

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I'm using Eneloops in my 64 with the black button depressed by a piece of stiff plastic as suggested. 

With an Anker USB charger I see 350mA into the gps when the large battery icon is on the screen. I'm not sure if the batteries are charging in series or parallel. I'll let it charge and see if there's a cutoff point or not.

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I recently purchased both the 64s and the 64st. Neither one shows a large battery icon when charging the battery packs via an A/C adapter (I've not tried charging via USB). On the "Display Brightness" screen the battery icon has a lightning bolt through it and blinking charge segments. The switch under the batteries is depressed because the option to change the AA battery type is no longer visible. That only happens when a battery pack is used and/or the switch is defeated. I'll try charging by USB in search of that big battery icon.

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35 minutes ago, luvvinbird said:

I recently purchased both the 64s and the 64st. Neither one shows a large battery icon when charging the battery packs via an A/C adapter (I've not tried charging via USB). On the "Display Brightness" screen the battery icon has a lightning bolt through it and blinking charge segments. The switch under the batteries is depressed because the option to change the AA battery type is no longer visible. That only happens when a battery pack is used and/or the switch is defeated. I'll try charging by USB in search of that big battery icon.

This may be a silly question, but you do have the device turned off when you're trying to see the large icon, right? If the unit is turned on, you naturally wouldn't see the large icon, because that would make the device useless. Try navigating to something when the screen looks like this: :laughing:

garmin-ni-mh-battery-charging-adapter-by

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Ha ha. Thank you A-Team. Yes it's there, big and bold. Since both devices automatically turn on when charging, I never thought to turn them off. Despite the new toys, I'm not getting any smarter. Thanks again.

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I have the 64st newest software loaded, running eneloop pro 2550 batteries with a plastic piece covering button.

Does it ever stop charging?  I can pull the batteries out and put in a smart charger and they say full, but when charging via cable in garmin I get a constant charging symbol (battery with lightning bolt and bars going from 1-4.)

I'm afraid there is no stop point and batts will explode?  Anyone know if it stops? thanks

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The charging symbol stops animating when fully charged and shown a solid fully charged symbol. 

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hmmm, thanks. wonder why mine doesnt. That is with non garmin batteries as well?

 

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Hey @-X I got your PM. I put mine on charge to see if I get the same result as Red90, I couldn't remember. 

When you are charging through the USB cable are you using a cellphone charger or a USB port on a computer? I'm thinking the current capacity from a USB port maybe too low to ever terminate the charge. 

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I've tried both charger and a port with same result

Edited by -X

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12 hours ago, -X said:

hmmm, thanks. wonder why mine doesnt. That is with non garmin batteries as well?

 

No.  With a Garmin battery.

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My charging icon never stops animating even when the Eneloop cells are fully charged. What I do observe is the charging current into the GPS drops from about 350mA to about 100mA. So the charger in the GPS must be decreasing the charge to a trickle level on a fully charged battery. 

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Just wanted to update that the animation stops when using eneloop as well. It took a few uses and now the animation stops when fully charged. Maybe it has to adjust to the batteries or something

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Most of the messages in this thread relate to charging the GPSMap 64 while it's powered off, and the general consensus appears to be that regardless of battery type, rechargeable batteries take longer than expected to reach full capacity, though they do eventually get there and the charging symbol changes to reflect that. 

 

My question: Does the same apply to charging the batteries while actively using the unit? I see the same animated symbol when I briefly press the power button, but I have yet to see it indicating what I'd call a fully charged state. Unplugging the GPS after some time shows the batteries to be full, and indeed I get 3 or 4 hours use before the first bar disappears, but on reconnecting it just seems to charge forever.

 

My background: I purchased the GPSMap 64 to use on a multi-day trip, where I will be relying on an Anker PowerCore+ 26,800 USB battery pack to keep me going. The power pack will stay permanently connected to the GPSMap 64, which is fitted with a pair of Duracell Ultra 2500 rechargeable cells. Assuming a conservative 90% charging efficiency I reckon this will be good for at least 9 cycles, and so look forward to 120 hours of continued use as a minimum. Just would be good to not have to keep unplugging it whenever I think it's full.

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Since you will only have the unit on during the day, you are talking 10 to 15 days of use.  There is no reason to plug and unplug and it will make no difference.  There is no "charge complete" indication while it is on, AFAIK.

 

One thing though....  You are mixing up the mA-h ratings.  The "2500" is for AA batteries, which are 1.2 Volts.  The 26800 is for li-ion batteries, which are 4.2 Volts.  This is why life would be much better if they would rate in mW-h....

 

2 AA batteries at 2500 mA-h is 2.4 V, so 6000 mW-h.  26800 at 4.2 V is 112560 mW-h.  19 charges.

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Ok. I have to jump here. I bought a 64s a couple of days ago. I have been learning about how it is different that the eTrex Legend I used to use.  And the issue about battery charging has caught my attention.

 

I have placed a strip of plastic under the batteries and have installed a couple of eneloop Pro NiMH 2450 cells. The battery type option does not appear on the system screen as it did before adding the plastic so I am assuming my plastic strip is depressing the switch at the back of the battery compartment.

 

I've plugged the USB cable into the GPS and into a generic single port USB charging hub. I can navigate to a screen the shows time/date, backlight level, battery charge status and GPS signal strength. But there is no indication that the batteries are charging, yet I know that must be nearly dead as they quit on me earlier today. When I turn the unit off the screen goes and stays blank/black.  I can't find anything with a blinking charging segments or lightening bolts or the picture A-Team shows on his display.

 

Should the unit charge the batteries using the hub I'm using? I tried plugging the USB cable into a USB port on my computer and I don't see anything any different.  

What am I doing wrong?

 

Thanks.

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dbrents, read my earlier post on this above, the gps requires about 350mA from the USB port while charging the batteries. A USB port on a computer or hub cannot supply that much current. Try charging from a cellphone charger and you should see the animated icon while charging with the gps switched off.

 

Let me know if that works.

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USB 1.0/2.0 is good for up to 500mA.  USB 3.0 good for 900mA.   I've got the same eneloop hack as dbrents on my OR700....360 mA charging.

 

IMG_0754.JPG

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2 hours ago, jimlarkey said:

USB 1.0/2.0 is good for up to 500mA.  USB 3.0 good for 900mA.   I've got the same eneloop hack as dbrents on my OR700....360 mA charging.

 

 

You are correct, I was mistaken about that. I went back to double check and get 350mA charging from USB or Anker USB charger.

 

But to get the animated charging icon the gps can't be mounted as a removable drive. I don't know how to get a charging indicator when mounted as a drive.

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Thanks for the reply. I made a couple of adjustments and now things seem to be working fine. I have the plastic in place behind two batteries. When the unit is on I get a charging status now on the screen I described above. And when I turn it off I get a screen that has Garmin and a battery with a lightening bolt and the standard indication the battery is being charged. I'm using a cellphone-type charging hub that is actually used for some other battery powered device with a USB interface.

 

Things are now good and all is happy!

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On 12/3/2017 at 12:12 PM, geo climber said:

I'm using Eneloops in my 64 with the black button depressed by a piece of stiff plastic as suggested. 

With an Anker USB charger I see 350mA into the gps when the large battery icon is on the screen. I'm not sure if the batteries are charging in series or parallel. I'll let it charge and see if there's a cutoff point or not.

If it's done right, the cut-off point you'll be looking for is the point at which the voltage actually DROPS just a bit after increasing for some period of time to get the cells charged.  Assuming the charge rate is high enough to exhibit this effect, you'll see the upward trend, then a leveling off, then as soon as there's a dip of something on the order of 0.1V, the charge should shut off.  Unlike NiCad, NiMH doesn't drop much, less so at low current charging, so the charger has to be paying good attention to what's happening across the terminals. 

 

How much of your 350mA is supporting the electronics vs. charging the cells would be good to know to establish a charge rate.  What current do you see in 'idle' mode vs. the 350mA in 'charging' mode?  If the device uses, for example, 150mA idle, then you've got roughly 200mA @ 5V (1W) to work with, or about 350mA for the pair at 2.8V. (serial) charging.  If 350mA charging, then that's enough to do a decent -dV cut-off, and that's what you should see at the end of the charge.

 

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I just tested and it pulled dead on 0.5 A when charging.  0.15 A when the charge is complete.

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Sounds like we've got about a 350mA charge going, then, with the rest of the electronics pulling down around 150mA..  The latter is what I thought I had recalled from a previous test.  At least I hope all or nearly all of that 150mA is the device power.  Don't really want to sit with more than a 0.05C trickle charge on NiMH cells, if any at all.

 

0.35A is cutting it a little bit thinner than necessary for a series wired charge for a pair of AA cells (that would provide  only about a 0.16C charge for each single 2200mAh  Eneloop or equivalent), and  I wouldn't go any lower than that for a couple of reasons.  Could be cost savings on the charge circuit?  That said, a charger with a good A>D will pick up the voltage well enough to terminate the charge, even at 0.16C.

 

You didn't, by chance, observe the voltage across the pack as it transitioned from peak to end of charge, did you?  As noted, if done nicely with -dV charge detection, a 0.1V drop is all it takes most chargers to trigger a shutdown.

 

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Later in the charging cycle, the meter showed it cycling back and forth from the 150 to the 500 every few seconds.  They probably do not pull more than 500 as that is the USB standard limit.

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Ah, I didn't think to ask what you had connected as a power source.  Many PC's and other 'hosts' are indeed limited to 500mA as you suggest, so that is the max  current draw you would have ever seen during charging.  The actual available current from the host  is what is is (could even be a miniscule 100mA).  While 560mA has been pretty universally adopted as a reference, it's not a guarantee (either high or low).

 

Nominally, a part of the original ''discussion'' between a real host (not a wall wart) and a powered USB  device after physical  connection is to share current information as part of the "Device Descriptor", providing the powered device information about what will be available.  The host can, for example, even deny a request for 500mA of current at the port.  It's up to the powered device to manage within whatever constraints might be supplied by the host.  In fact, until that 'discussion' happens and everyone knows what is allowed, the powered device should never exceed a 100mA draw.  Only when and if it is advised that  it is permissible should it exceed 100mA!

 

However, the Garmin would be able to handle more than 500mA  if more were noted as available from a host and if the Garmin's internal charger circuit is capable of exceeding 500mA.  Apart from a Garmin charging circuit that can't handle more than 500mA,  there are technically no reasons to limit it to 500mA.  But if you had it plugged into a PC or other host, and not a wall wart, then the 500mA limit may well have been a result of the host's limit.  OTOH, if you plugged it into a 2.5A wall wart, I wonder what you'd have seen.  Or is that what you were using?

 

What IS weird is that cycling you are talking about.  Normally, a NiMH charger will operate at a continuous current, watching as the voltage across the cell(s) rises.  As the charge nears completion, the voltage curve flattens out at the top, and eventually begins to drop.  The cease and desist order goes out when the voltage has dropped a predetermined amount from the peak voltage, typically on the order of 0.1V.  After that, the charge is either shut down completely, or a tiny trickle maintenance charge is applied.  The hammering of the cells that you are seeing every few seconds after the -dV is reached is peculiar, to say the least.  I wonder if it is just trying to assure itself that the -dV A>D reading is real?  How long did that cycling continue before it finally shut down?  You've got my curiosity going now!

 

 

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I just double checked in a 2.1 A USB power supply and it charged at 0.5 A.

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I don't have a Garmin 64 but I did log the charging current in my OR700, which might have a similar charging envelope.  Power source was an  Anker PowerPort+ 1 Quick Charge 3.0 Wall Charger.

The full charging time was about 4 hours, with 1-second sampling, so displaying the full graph would be difficult to display w/o zoom feature.  I did notice 3 distinct patterns in the 4-hour long charge, bringing the Eneloop HR6's from 1/2 discharge to full charge.  A sample of each of the 3 distinct charge envelopes is shown below.

The charging algorithm is not as simple as you might think, or want it to be.  I've noticed this in other chargers as well, so it's not a Garmin thing.

Garmin Charging.jpg

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Interesting graphs, but ... Am I missing something here?  That looks for all the world like an attempt at a constant voltage charge of around 5.2V, not constant current.  That would be VERY atypical for a NiMH charging method.

 

 

 

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Life is not simple...."not constant current" like one would like to assume.

Each manufacturer has their own charging algorithm.  I could post the MAHA, or LiitoKala envelopes, which all very in current profiles, and different from each other.

"The MH-C9000 uses a combination of Negative Delta V, Zero Delta V, Peak Voltage, time and temperature to determine the end-of-charge. In addition, proprietary algorithms are used."

Cheers.

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The graphs are not the power to the battery, but to the device.

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Ah -- I had thought we were looking at battery pack, not device with the graphs that were supplied.  My bad!  Then yes, it would of course  be 5V all the way across.  I assumed that since voltage was being supplied in the graph, it was thought by the poster to be in some manner significant to the question at hand.

 

It would be necessary to monitor the voltage across the battery pack to see the -dV, and in to be wired in series with the batteries to see the specific current.

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Hi there just got a 64s and had been using AA Nimh 2300 mAh but I got a hold of some 2700mAh can these be used in the 64 or are they to powerful not sure I have know idea I find the 64 uses lot more power so thought I give these ago 

 

please any help to understand would be great

 

thanks

 

LWM

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Hello all,

 

I have a 64S, and it seems as though charging the (Garmin) battery pack is not working properly. Every time that I try connecting a USB power source, the Garmin will briefly appear to be charging and then state "External power lost, turning off in 30s". Then, it seems the connection is restored and the warning disappears. This keeps happening.

I have tried this via a USB wall charger, battery pack and computer USB port. No difference.

 

I have returned the battery pack and got another one. This has not changed things. Has anyone else experienced this problem? Some people seem to have noticed this with other Garmin devices, but I have not seen anyone report this with the 64S. Worst case, it seems I'll have to return the device itself.

 

Thanks for any help!

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It is the cord or the connector on the GPS.

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