Charging Garmin batteries while in the 66s

Discussion related to the Garmin GPSMAP 66s/st GPSr
asprin624
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Location: Belgium

Charging Garmin batteries while in the 66s

Unread post by asprin624 »

Been testing the 66s for sometime now. What I find strange is that with the Garmin batteries and a Garmin cable and Garmin Charger it takes for ever to fully charge the Garmin batteries up while in the 66s.
On the other hand if I use Ni-MH 2450 batteries in a charger they fully charge in 1/2 hours to 2 hours. Both tests are done with one point off the battery indicator on the 66s.
I think the batteries with charge faster with the 66s off but does not seem to work. I only see charging going on when the 66s is on. 4 hours plus is a little bit long to charge the batteries. All laptop, smartphones and tablets charge while the are off but that is not the case with the 66s.
ivhs72
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Re: Charging Garmin batteries while in the 66s

Unread post by ivhs72 »

I've had the same experience with the 64sx as well as my 66s. For some reason the charging hardware in the Garmin units don't give enough current to rapidly charge them. It might because of the heat that can be generated when batteries recharge. Just a guess.
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GPSrChive
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Re: Charging Garmin batteries while in the 66s

Unread post by GPSrChive »

Rapid or Fast charging batteries negatively affects their health and total life span.

Garmin have elected to extend battery life by selecting a more modest charging current.

To charge the batteries with unit off, first connect a USB power supply, then once booted press and hold power button to put GPSMAP 66 into a low power sleep mode while the display provides updates on charging progress.

See GPSrChive > GPSMAP 66 > Operation > Power Sources for detailed information.
asprin624
Posts: 143
Joined: Sun Dec 29, 2019 11:34 am
Location: Belgium

Re: Charging Garmin batteries while in the 66s

Unread post by asprin624 »

I do use the power down when charging but still far to long to charge.
The batteries on my eTrex are 5 years old and still going strong.
Can still get 16 to 18 hours out of them.
Plus you can only charge the batteries in a charger.
No way to charge them in the eTrex.
So when we are all about to go back to normal and book a hotel we will have to charge the 66s over night or keep extra batteries in my back pack if I need them.
When we do go out it is a all day thing.
g66
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Joined: Wed Jul 03, 2019 1:48 pm

Re: Charging Garmin batteries while in the 66s

Unread post by g66 »

Loading on an good extern charger, the batteries have about 1/3 more capacity than loading inside the 66

https://www.accu-select.de/

Just my observation
asprin624
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Location: Belgium

Re: Charging Garmin batteries while in the 66s

Unread post by asprin624 »

I fully charged my 66s last night.

Today before I will go out I plugged the 66s back on the charger. As of 1/2 hours now it is still charging it.
Something is not correct with how it charges the Garmin Batteries while in the 66s.
What is missing is showing the percentage that still needs to be charged or how much has been charged.

As I am writing this It just now shows fully charged

Which I find very strange seeing the the 66s was off after last night being fully charged.
Before I put the charger on the indicator show 66s fully charged.

I have many Garmin GPS Units for my auto and they stayed charged for 2 weeks or so.
If I have to charge them with in max 45 mins they are fully charged.

All Garmin products are not equal when it comes to holding a charge and being charged.
I seen no reason why the 66s should take so long to again to be fully charged when only 8 hours ago it was fully charged and the 66s remained off the whole time.

I think at this point I will go back to using other batteries and use an external charger to charge them.
Way to much time is lost to charge batteries while inside the 66s.
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GPSrChive
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Re: Charging Garmin batteries while in the 66s

Unread post by GPSrChive »

It appears you may be making a common false assumption about the charge status of the batteries in your Garmin GPSMAP 66s.

Simply stated, it is not possible for any charging device to accurately determine the percentage of charge in a NiMH battery. This is why all NiMH battery chargers use charging routines with a static charging current over a predetermined length of time. Most do monitor voltage, and will adjust the current applied based on pre-programmed values, but it is important to remember the voltage/current curve is not linear, and is quite flat near the top 1/3 of the battery charge status. These devices can not accurately determine the battery charge value in percentage, and thus none display a digital charge value.

The automotive units you compare the GPSMAP 66s to use Li-Ion batteries which have totally different chemistry and more capability when determining accurate charge level values. These devices can (and most do) display the current state of charge as a percentage value.

Comparing your GPSMAP 66s to any of these devices is an apples to oranges comparison.

When you charged your GPSMAP 66s the prior day until the charge animation stopped, your device batteries were in fact fully charged at that time. When you reconnected external power the following morning after having disconnected the previous evening, the GPSMAP 66 has no capability of determining the battery is fully charged, only that the voltage is very near the full charge value, at which time the unit will commence a trickle charge routine to ensure it is topped off fully, during which time it displays the same charging animation as the day before.

Assuming now that the batteries are not fully charged and ready to go as they were the evening before is a false conclusion.

Of course, if it make you feel any better, you can charge your batteries in external chargers instead of the Garmin GPSr, but this will not actually yield a different result, and may result in reduced battery life do to the aggressive charge routines some external chargers use.
CheminerWill
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Re: Charging Garmin batteries while in the 66s

Unread post by CheminerWill »

gpsrchive wrote: Mon Apr 20, 2020 3:52 pm Simply stated, it is not possible for any charging device to accurately determine the percentage of charge in a NiMH battery. This is why all NiMH battery chargers use charging routines with a static charging current over a predetermined length of time. Most do monitor voltage, and will adjust the current applied based on pre-programmed values, but it is important to remember the voltage/current curve is not linear, and is quite flat near the top 1/3 of the battery charge status. These devices can not accurately determine the battery charge value in percentage, and thus none display a digital charge value.

When you charged your GPSMAP 66s the prior day until the charge animation stopped, your device batteries were in fact fully charged at that time. When you reconnected external power the following morning after having disconnected the previous evening, the GPSMAP 66 has no capability of determining the battery is fully charged, only that the voltage is very near the full charge value, at which time the unit will commence a trickle charge routine to ensure it is topped off fully, during which time it displays the same charging animation as the day before.
Thanks! This is the best explanation of this behavior I have seen.
rockcandymountain
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Re: Charging Garmin batteries while in the 66s

Unread post by rockcandymountain »

I just found this forum and have a few questions concerning the 66 series GPS.

On my 62S I get frustrated by the compass calibration. Im going to buy the 66 and was wondering, since the batteries dont HAVE to come out of the unit to recharge them, the re-calibrating the compass becomes a non-issue, right?

Why, if I turn off a unit, replace the batteries, turn it back on, do I need to re-calibrate, since the unit was off during the battery change,. I know dumb question.
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GPSrChive
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Re: Charging Garmin batteries while in the 66s

Unread post by GPSrChive »

I don't remember the last time I had to calibrate the compass. IIRC the GPSMAP 62 had a 2D compass, while newer Garmin GPSr enjoy a 3D compass.
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