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Ive got a Lutron Homeworks 4 Processor that is c. 15 years old, it has failed where there has been a power outage to the processor and the lithium battery on the PCB has not been able to provide power to retain the processors memory. Apparently this is a common issue with the systems.

I need to de solder the battery from the PCB and the solder a new battery in its place.

The battery spec is : https://www.manomano.co.uk/catalogue/standard-battery/lithium-battery-sl360-pr-aa-36v-24ah-pr-7402307?model_id=7402307

Below ive attached some photos of the PCB from both sides showing the battery etc.

Ive never undertaken something like this before and was looking for some tips / pointers, my main concern is damaging the PCB and heating the battery past its 100C temp limit whilst soldering.

Here are the photos:

component side

solder side

originals

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  • \$\begingroup\$ What has happened to the PCB around the positive connections to the battery? Did the unit get wet? \$\endgroup\$
    – Spehro 'speff' Pefhany
    Commented Mar 30, 2019 at 16:09
  • \$\begingroup\$ I don’t know it’s been in a dry cupboard for 15 years so would be surprised if it’s been wet at any time whilst it’s in use for that time \$\endgroup\$
    – user27511
    Commented Mar 30, 2019 at 16:21

1 Answer 1

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Desoldering this battery should be easy cheesy. 350° at the terminal doesn‘t mean that the whole battery body is at 350°C.

Just make sure that the plus and minus poles don‘t get shorted, and don’t apply too much heat for longer time periods. I recommend using a desoldering gun.

Good luck!

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  • \$\begingroup\$ yes, the warning about heating is just to stop people from putting the battery though a re-flow oven during manufacture or storing the device inappropriately. \$\endgroup\$
    – Jasen Слава Україні
    Commented Mar 30, 2019 at 11:58
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    \$\begingroup\$ The safest approach is to break the welds where the tabs connect to the old battery. Then you can take your time about desoldering the tabs and cleaning up the holes without damaging the board. Soldering the new battery in will then be extremely quick. \$\endgroup\$
    – Dave Tweed
    Commented Mar 30, 2019 at 13:53
  • \$\begingroup\$ Thanks, would a desoldering gun be preferable to a desoldering wick ? With the soldering what type of solder tip should I use and with what type of solder ? \$\endgroup\$
    – user27511
    Commented Mar 30, 2019 at 14:19
  • \$\begingroup\$ Don’t worry if you don’t have a desoldering gun. You don‘t need any special solder tips or solder for this. \$\endgroup\$
    – Michael Haar
    Commented Mar 31, 2019 at 11:36

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