Dead 276C Battery

[kiwitonita]

Hi - thought I'd post some findings here in case it helps anyone else repair a 276C battery.

Had a look at a battery pack out of a Garmin 276C today - an 8.4 volt Lithium Ion - it was dead flat and the GPS would not charge it at all. A new battery as shown here is quite dear so it was worth reviving the flat battery. It had never been charged apparently since new a few years ago. The message on the GPS screen was "Battery Missing".

Part number on the battery is: 011-00955-00 and I have a 478 with identical looking battery, part: 011-00955-02. Garmin site lists it as: 010-10517-00

Comments here indicate it's not unusual for the battery to give up early: http://www.gpscity.com/276batlithium

Opening the case revealed a very complex circuit on the end of the cells so it was never going to be any good trying to charge the battery via the external contacts. With nothing to lose, I tried connecting a variable power supply to the battery + and - terminals on the edge of the circuit board. They can be seen as B+ and B- in the photo.

Applied 7 volts at 200mA all day to the B+ and B- terminals and it seemed to recover nicely. The battery is now charging inside the GPS so we'll see how it goes.

Update: The customer reports the battery pack is behaving well now.

Photos are http://s36.photobucket.com/albums/e8/KiwiGPS/276C%20Battery

[tgsnoopy]

It's not uncommon for lithium rechargable batteries to go dead flat over time.

Some chargers will indicate something is wrong initially whilst still trying to put a little charge into it. Over time the lithium will recover enough for the charger to see it and a normal charging cycle will occur.

Unfortunately a lot of chargers just do nothing and say the battery is stuffed.

You'll find it will be prone to an elevated rate of self discharge when stored between uses, but otherwise it should work ok.

I regularly see the problem with Li-Ion batteries on handportable radio devices. Particularly the mega expensive batteries on the Zespri Teklogix barcode gear at the start of the kiwifruit season

Good on you for trying and having the success you deserve.

[Gr8dad]

Had a problem with a bunch of AAA NiMH rechargeables tonight. They have been sitting in a set of two-way radio's for quite a while. Needed to charge them for work tomorrow, but the charger only recognized 2 of the eight.
So remembered this thread and "jumpstarted" each with 6v, 400ma for 10 seconds. Bingo, charger can "see" them again and is happily charging again!

Thanks for this advice.

[pricestavern]

OK, newbie here and I have the same "dead battery" problem. Very informative post, pictures are great, but how do you open the battery case?

[kiwitonita]

Sorry, can't remember but I think it involved a Stanley knife. It can't have been too hard otherwise I'd recall - after all I was working on a customers battery and it went back together nicely looking none the worse for the dismantling.

[kiwitonita]

While getting a Garmin 478 ready to sell I soon found the battery was flat and would not charge. So it was a good opportunity to record how to get the case open. The 10 additional photos are all added to Photobucket in the link in the first post. After peeling off the label it's just a matter of pushing a thin, sharp blade down just inside the edge of the case then working around to gradually lift the black cover away from the battery pack. All that holds it is strong, double sided tape.

Here's the first photo - no use taking up bandwidth to with the others in case it's of no interest.



With the battery catch away from you there's no danger of nicking the wires if you keep the blade away from the far left of the case - as you'll see in the photos. Getting the blade started takes a bit of force so it cuts through into the cavity. The battery pack is also held in with double sided tape but lifts out OK.

[kiwitonita]

Have another battery to restore now so instead of dismantling the shrink wrap cover it was easier and a lot tidier to just access the terminals at the top:

[skipperdoug]

I came across this forum while trying to sort out my dead 276c. It appears that if the battery gets too dead, that the unit cannot recognize the battery, and that the unit will not power up, even when plugged into an external power source. To fix this, I took the battery out of the unit, connected external power via cable, and then found that the unit would power up normally. This confirmed that nothing else was wrong with the unit. With the unit powered up, I then replaced the battery and left the unit on overnight. By the following morning, I was able to disconnect the external power cord, shut the unit down and restart it on the internal battery only. The battery appeared to be fully charged, and to confirm that, I let it operate for 3 hours on battery only. The battery was still showing as about 85% full, so it appears that the battery is functioning normally, and almost like it was in new condition. I think the cause of the problem, is simply leaving the unit for two long, between charges (in my case it was almost 4 months since I had charged it). I would suggest trying this before pulling the battery apart, as shown elsewhere!
Doug
Gulfstar 40
Soon to be crossing the Pacific en route to NZ/OZ

[kiwitonita]

Good to hear your battery recovered OK and all the best for your trip over the ocean.

I've just received a couple of new old stock 5 year old 276c batteries that were dead flat, or rather in a coma, not dead. The 276C did not help recover charge so this time removed only the name cover and inserted pins through the plastic covering where the terminals are:



Overnight at 8 volts and 150mA worked a treat.
The battery cover went back on neatly and is now in the 276C reading "Charge Complete" after a few minutes of 'Charging Battery".

Discharge and recharge the battery 5-6 times to get it back to good health. You'll note after each recharge the unit will run longer before switching off.

[khorrassany]

Hi,

I'm new to this forum, although with very little electronic knowledge still wondering why Garmin didn't make the 276c work with AA or AAA batteries from the first place??!!!

Anyway I have a lot of problems with the main battery of my 276c and almost has to replace it every 18 month! After some search online today I see there is a lot of success stories with reviving the batteries, but I was wondering if anyone with some knowledge can help to make a combination of normal batteries that will give 8.4v/2200mAh and will fit in this battery pack and are easy to replace ??

It might sound like a stupid idea but it's much more reliable than this crappy battery.

Cheers from Egypt
Issa

[tladams123]

I just did this to a dead 478C battery and it worked perfectly!! It's charging now, so hopefully after a few discharges it'll be good as new!! I'm just glad I got rid of that nasty "battery missing" message. Now I just gotta find a couple of older batteries I have laying around for this GPS so I can do the same thing to them. Thanks!

Tim