I have a Jabra BT135 and after charging I get an annoying periodic ring tone as if it hasn't charged. I tried leaving on until fully discharged before re-charging. Didn't seem to make any difference.

Your description suggests one or both of the batteries are sulphated - been allowed to remain partially discharged or even fully discharged for a few weeks or more.

Charge the batteries, allow them to stand for a few hours and connect a voltmeter. A healthy young battery should read 13/13.2 volts while an older battery that is still serviceable might only achieve 12.7. Much below this and the capacity will be much reduced.

If these are the sort of voltages you have, the charger is probably ok. Ride the scooter until the battery indicator shows recharge is needed and test the voltage again - if it has fallen considerably, at least one of the batteries is faulty.

Traction, semi-traction or deep cycle batteries are the only ones that should be used and cheaper batteries will serve for a time but rarely survive the warranty period.
Batteries that are discharged generate heat when recharged and it is the heat that shortens battery life. Batteries last longer if they receive a top-up charge after each use.

Never leave a battery in a discharged or semi discharged state...

Do you mean a charger plugged in for four months ? or the battery pack on the scooter for four months ? if it not charging and left on the scooter they will discharge and may never recover.

Leaving it on charge for four months ?, the charger will go into trickle charge mode once it fully charged the batteries, manufacturers will agree this is a good thing , if left for weeks and weeks , it should be charged up fully once a week if not in use and i recommend removing the battery case as i seen issues arise from leaving a battery pack on a scooter for long periods of time, for starters they discharge quicker,.

Try fully discharging the battery first and let it sit for a few days. Then fully recharge before use. What happens with battery operated drills is the batteries develop what is called memory of the charge level when they are recharged and will not charge past that point but the charge light will show full charge. It happens when the drill is used for a period of time and then the battery is placed in the charger ready for next time instead of using the drill until it is flat or leaving a partially used drill on the bench and not recharging it until it is flat

What kind of phone do you have? I have heard people with LG phones say that it does not pair with their phone. If this is not an issue with you then these steps may be more helpful:
1. Charge your Jabra BT135 until the solid blue LED turns off
(approximately 2 hours)
2. Make sure the Jabra BT135 is switched off
3. To put the Jabra BT135 in pairing mode, press and hold the multifunction
button until the LED stops flashing and turns solid blue
4. Set your mobile phone to "discover" the Jabra BT135 (see your phone
user guide)
5. Press Yes or OK when asked if you want to pair the phone with the
Jabra BT135
6. Enter passkey or PIN = 0000 (4 zeros), then press Yes or OK
7. Your phone will confirm when pairing is complete and your headset
will flash

Hey there sanjeev! There should be an USB port on the back of the headset, it is the micro-usb port. Therefore, if you have a cable from your camera, mp3 player or any other gadget that uses a micro-usb port, take their cable, plug it into the headset and let it charge! :D
I hope it helped! Take care! :)

The blue light should go out.

I charged mine until the light went off

BATTERY TIPS

Now a days in LITHIUM BATTERIES are used no memory effect

always charge battery for 16 hours when first use new

never keep ur battery fully discharged for long time when u store ur camera always keep it half charged or fully charged when storing for longer period

it is good to fully discharge once in a month but dont make it ur habit

pls rate me FIXYA for help

Firs turn it off then..........
then hold the button for 10 seconds
.......................................................
it will now pair with your phone
the code is "0000"