Reviving Sony Info-Lithium Batteries

Repairman

Active Member
Hi all, I'm new to this forum. :hiya:


This is short article that I wrote for another forum about the use and repair of Sony Info-Lithium camcorder batteries. It may help someone who is technically competent to carry out the procedure...


If you’ve bought a Sony Camcorder in the past few years you’ll probably be using these, and you’ll know just how expensive they are to replace or upgrade.


Firstly, if you want to get the maximum life out of them they must be used, and topped up regularly. They discharge (without use, removed from the camera) at approximately the rate of 10% a month. So if you only get your camcorder out of it’s case once a year for holidays you’re probably going to end up with a dead battery. If a battery is allowed to discharge completely it usually looses it’s ability to hold a good charge. If you’re lucky enough to get it to charge (usually in the camera with the mains charger) you will probably find that although it reads as charging 50% or 100%, when you go to use it the charge will die away in a few minutes, not the hour or two that it indicates on the screen.


If you charge the battery, keeping it topped up every month or so you should have no problems.


However if you should get a battery that won’t hold a charge then all is not lost. I had a high capacity one which would not charge at all; it just said ‘Low Battery’ on the screen. With absolutely nothing to loose I set about trying to rejuvenate it.


Before we start let me point out that this procedure is meant for someone competent in electronics with the correct equipment, and I offer no excuse if something goes wrong.



But at £40-£60 for a replacement I felt that I had to at least try.


Firstly, it’s simply no good trying to force charge the battery from the connection sockets; it won’t work as these do not go directly to the cells themselves. They go to a small board with several computer chips and components that is the actual Info-Lithium system.


This system was originally invented to let you see how much battery power was left and how many minutes of record time you had left. In my opinion the prime reason for this system was so that no other make of battery that fitted (after-market types at a fraction of the price) would work in the camera. There is in my mind a whole host of electronics on that board that are totally unnecessary for just measuring charging current and voltage.


To rejuvenate the cells you need to get the casing apart. A junior hacksaw is ideal; cut around the false seam on the battery all the way round. Don’t go right through the plastic but most of the way, and finish off carefully cutting round the remaining plastic with a Stanley knife. The large part of the casing can then be easily removed.


Inside you will find two cells with a tap connection between them and the Info-Lithium PCB. Be careful not to pull off any of the connections yet. On the board you will normally see B+ and B- marked and one other connection to the cells (centre of the two cells).

Mark the board and battery strips with red and blue markers just in case you forget the polarity. Unsolder all the three connections to the cells. Leave the connections to the output pins on the case as they are.


With the aid of a variable voltage power supply connect directly to the cells and apply a voltage until your multimeter in series with one lead reads around 250mA. watch the current over a period of time and increase the voltage to keep the current the same (250mA).


If you have a separate meter to monitor the voltage keep checking this as well. You should see a gradually rise from a few volts to a maximum of 8.4V for a fully charged battery. If you cant see any charge in the battery you may have a completely dead cell. If this is the case you have come to the end of the road. But if you see the voltage across the cells rising you probably have a good chance of reviving the battery. The centre point between the two cells should be around half the voltage across the two.


This may be enough to revive it, but if not discharge the cells by putting a 10ohm wire-wound resistor across the terminals. Don’t burn your fingers, the resistor gets hot. Discharge it until around 2 volts remain; don’t discharge it completely Li-ion batteries don’t like it. If the cells get hot STOP, as they have been known to catch fire. Unlikely but don’t leave this process unattended. After a discharge recharge the battery again as above. When you have at least 7.5V across the two cells you can reconnect them to the PCB and try to charge in the camera. It will probably read around 50%. Just leave it to charge until 90% or 100% is reached.


Next check the battery capacity by using record and see if it lasts or discharges quickly. If all is OK it should last nearly as long as it did when new. If it dies quickly then it’s unlikely to be revived.


Finally, if you have two completely dead cells in the Sony battery you could in theory buy an after market battery of the same type (but without the PCB inside) and fit the cells from that new battery into the original one with the PCB.


Have fun.

Mike.
 

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