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695/695 large battery up time upgrade

ob_seven

Member
Hi Folks,

Just to make you aware about a simple upgrade possible on your 695/696 Garmin GPS.

I found the alternate source for NiMH battery packs, from medical monitors, but while this is the 100% perfect replacement part, battery lifetime of the 695/6 is not so great, specifically when you bump up thebacklight to 9 or 10 level.

nIMH also tend to age rapidely, and you endup with a poor autonomy. And they also self discharge fast.

I did swap the battery cells to Li-Ion. I use 4 18650 cells, in 2S/2P configutation. This means 2 cells in parallel, and eacn double cell in series.

this way, using Samsung 3450mAh cells, you get about 7000mAh, which is almost twice the 3800mAh of the genuine niMH pack.

Those cells do fit nicely in the original battery box.

Of course, you need to add : a passive balancing module, to be sure that when charging, all cells are properly balanced.

I picked that one, a 2S 20A module :

https://fr.aliexpress.com/item/1005...id=2022123102164717926849766277480015574719_1

You also need a dedicated USB charging module. I pick up that one on Aliexpress. 2S and 2Amps. Not above, as 4 amps is heating too much.

https://fr.aliexpress.com/item/1005...00030900317118!sea&curPageLogUid=LqKHKgtgRHw0

Using a dremel, you just have to make a small hole in the bottom of the battery case to fit in the USB C plug. Charging will ONLY be done through that USB C plug. The 4 pin Garmin plug, and the USB are not used anymore, and this is great for those who actually broke those plugs!

Lastly, to get the right calibration of the battery gauge on the screen, there is one modification / resistor replacement to be done on the battery pack PCB. There is a large 2512 SMD resistor of 15mOhm. This needs to be changed to a 8mOhm resistor.

a link is there :

https://fr.aliexpress.com/item/1005...t_main.86.3f5f5e5bAg0bpt&gatewayAdapt=glo2fra


This is to fool the battery bq2019 gauge sensor IC, and get him to beleive the battery capacity is unchanged, while we did change it. This is the only way I managed to get the battery gauge to be precise. I even read the battery chip memory content, and looked at increasing the battery capacity there, but the 695 software cannot cope with that, and overwrites the battery capacity in Coulombs back to 13680...( 3800mAh = 13680 Cb) as soon as the GPS is powered up.

With all that, you get a nicely 695/6 with up to 7 hours battery lifetime , very little autodischarge.

The only thing is :
1 - always use the new USB C port to charge the GPS
2 - always turn it on to get it charged, as otherwise, the battery gauge / level is not updated.

I will post below pictures and schematic of what I did.

Cheers!
 
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Some picts

Here are some pictures of the actual implementation
 

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And here is the schematic. It is needed to connect a ground directly on the left of the sense resistor, so that the battery gauge remains accurate, and sees the charge being done by USB-C charger.
 

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That's some pretty heavy surgery. No doubt the battery and charging system is the failure link in most 696s , That's why Garmin produced the 796. And also reflected in the resale value. I don't have any experience with either. But admire someone who has the abilities to detect the failure and apply a fix. As for me my only choice would be to buy a 796 .
 
Hi

Not so complicated, and the nice thing about it : all modifications are done inside the battery pack ! If you have a friend who tinkers a bit in electronics this is easy to do, and not expensive at all!

Last cherry on the cake : a simple usb c charger does the job! I use an old iPad usb charger with usb A to usb c…. Way smaller and lighter than the original charging block!

Cheers!
 
Nice! IF Garmin has any other product lines using this battery pack, I would make a Y-tube video of the process and see if it grows legs.
 
Hi

Not so complicated, and the nice thing about it : all modifications are done inside the battery pack ! If you have a friend who tinkers a bit in electronics this is easy to do, and not expensive at all!

Last cherry on the cake : a simple usb c charger does the job! I use an old iPad usb charger with usb A to usb c…. Way smaller and lighter than the original charging block!

Cheers!

The NiMH batteries are about a thing of the past but there are a lot of "dead" 695/696 over on this side of the pond that could use CPR. You might be able to fix quite a few if the shipping charges aren't excessive.
 
Excellent project description!

Might I suggest two follow up projects that might help a great many of us?

BU battery retrofit for the Dynon D-100/120/180 screens.
&
BU battery retrofit for Dynon's Skyview series.
 
Well

I have a d100 and an ems120 and never bought the battery pack for the issue of aging…!
I am finishing my plane and preferred to have an external battery for emergency as I also need to power my plasma 3 ignition with a backup.

So external emergency battery unit for dual plasma and the 2 dynons….

Cheers!
 
Havent fired my 696 up in awhile so it will probably have this BATTERY MISSING error again, and will need jumped again. This makes your 696 find the battery and charge it. Found this info online and screenshot it and uploaded the screens, this fixed my battery missing error a couple years ago.
.
 

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[Indeed, if battery level goes to zero, you need to jumpstart it.
However, your cells are already damaged.... Time to replae them, eother NIMH like genuine with the medical battery pack, NIBP730, or using Li-Ion like I described above.

Cheers.
 
Well it didn't last long... half hour maybe. Funny thing is it still showed full battery and just quit, couldnt fire it back up until I plugged it into the lighter, you must be right, time for new bat
 
HI There,

After nearly 1 year of using Li Ion cells into the 695 I can tell you this is a true massive improvement. Very little auto discharge, and really large autonomy.

I will work on resetting the battery gauge IC so even loading the device while turned off, the proper battery gauge level will be set correctly after battery charging.

I will publish a small PCB design for that, so it will make a very clean upgrade.

Cheers.
 
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