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Joined: Jan 2010
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Hi, I did my first lifepak 12 coin battery change only a couple of weeks ago, the lads here change them on a 5 yearly basis with no troubles.
The trick is to put 3 volts across the battery contacts whilst you remove the old cell, being sure that you do not allow the top spring contact to short out to the base ( an old toothbrush handle is used to pry up the spring and slip it inside the hollow of the handle).
We have changed these well before they need doing and we have only ever had to send one back when the 3 volt connection was lost whilst doing this.
It is true that the config has to be done by Physio Control when this is lost, not something you can do from all the test and tech modes, I think it is because it holds things like serial number etc.
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Joined: Feb 2004
Posts: 14,660 Likes: 61
Super Hero
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Super Hero
Joined: Feb 2004
Posts: 14,660 Likes: 61 |
That's nice information, Mithrandir. But a bit too late to help Ajesh Nanu, unfortunately.  That technique is a good one (and I like the "special tool"), and I would recommend something like that when changing any coin cell that is used for config retention. In that, it's probably a good idea to maintain the *voltage (usually 3 volts, as you say) whilst you slip in a fresh cell. I guess that it's the Serial Number that is the problem (once it becomes lost), as we wouldn't want one re-entered incorrectly, would we? Although I can't help wondering what it is that the manufacturer does when you send the defib(s) back to them. Some sort of simple re-assignment by a PC over the serial cable, I suspect. But they would know the "codes", wouldn't they! * Although in my experience you can usually get away with a simple swap in and out on stuff like PC motherboards. If I remember rightly there is often a Big C (capacitor) around that holds the voltage long enough to allow a cell change - in a well-designed circuit, that is!
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Joined: Jan 2010
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Geoff, I usually disconnect the unit from the mains, remove its batteries, because the voltages inside a Defib are enough to make me a bit chicken. The rail capacitance of the memory circuit might well hold up long enough for a simple swap, but it is not worth the risk.
But Ajesh's problem is a good reason for us all to take preventative maintenance, that is why here it is policy to chage these batteries at 5 years, we all know they have a shelf life of around 10 years, but at £1-50 a cell from Physio control it is a lot cheaper that returning one for reconfiguring.
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Joined: Feb 2004
Posts: 14,660 Likes: 61
Super Hero
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Super Hero
Joined: Feb 2004
Posts: 14,660 Likes: 61 |
Yes. You're right of course about "safety" around defib circuits! And no doubt it's a bit tight in there. Anyway ... all that we've said won't help much if the coin cell was totally dead, as it were. Your second point is well taken, and we've all learned a lesson there. Five years it is, then!  Meanwhile, I'm wondering if "they" re-flash the memory variables using the PC Card (PCMCIA) slot, or some such thing? I'm just imagining what's going to happen when LP-12's start turning up on the "Charity Scene" in a few years time (complete with zilch config settings, of course). 
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Joined: Feb 2004
Posts: 14,660 Likes: 61
Super Hero
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Super Hero
Joined: Feb 2004
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@Nanu:  it's bad news, I'm afraid.
The device configuration data consists of the manufacturing code, device profile (options, features), serial number, calibration data, and user setup configuration. This data is stored on a 32-kilobyte memory device that is powered by a coin battery located on the A01 system PCB. If this coin battery is improperly replaced or is dead, the the device configuration data will be lost.
To check if your device has lost the configuration data information, turn on the device and press the CODE SUMMARY control. A device that has lost configuration data will not display a serial number* on the Code Summary printout and may also list an incorrect Device Profile.
The LIFEPAK 12 defibrillator/monitor device configuration data may be loaded only by authorized Medtronic Physio-Control personnel. Contact your local Medtronic Physio-Control representative for assistance.
"They" obviously don't want folk enabling "features" willy-nilly, as it were!  * If the configuration data is valid, the serial number will be shown at the bottom right of the printout.
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@mithrandir@ as you said the +pin of the battery is visible but what about the -pin. could you kindly elaborate the technique of replacing the battery, as the negative pin is not visible.
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Joined: Jan 2010
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Nanu, I use one of the pcb mounting screws. I am sure that a volt meter will confirm you have the right screw. I can not be more specific because I cannot be sure we all have the same issue PCB. The negative of the battery will be zero volts, that should be easy to find.
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