Testing AED battery output Voltages

[Hotstuff]

Hi guys

Is anyone out there familiar with testing the operation of AED batteries?

I am a voluntary community first responder and one of my duties is to look after our local public access defibrillators (AED). All of our AEDs are Cardiac Science model G3 and are now quite obsolete so replacement batteries are horrendously expensive and due to their age, are now starting to fail. Our local ambulance service provide all of the AED consumables but are reliant upon old stock and recycled parts so it's frustrating when we replace failed batteries with batteries that have only been self tested.

The AED batteries are Lithium Sulphur Dioxide (LiSO2) and have two output Voltages, +12V & +5V. Upon measuring the outputs I recorded 11.74 Volt at the +12V terminal & 0.0 Volt at the +5V terminal.
I know that the battery is monitored and wondered if I should be getting 5 Volt at the +5V terminal when the battery is removed from the AED body?

Any thoughts?

 

[daleyd]

I can ask my wife, she is a resuscitation officer so does this stuff day in day out.

She won’t be able to help with anything technical (she’ll admit that quite freely ) but may be able to help in some fashion, or ask someone who knows in work next week

 

[Kayos]

Can you get funding for an upgrade?

 

[Blobber]

Cant help with the battery question but I guess that's more perfectly good equipment that's going to be binned and replaced with new just because of a battery supply problem

 

[Robotstar5]

So you're trying to keep obsolete equipment going which if it was needed could literally mean the difference between life or death?, I'd be looking at a programme of replacing them with more up to date/current models. There are charities that can help with supplying AED's.

 

[eddie49]

I have one of those batteries. It is a Cardiac Science "Powerheart" AED G3. I think it maybe accidentally fell into my trolley as I passed the recycling bin at a supermarket somewhere. That does happen quite often.

It is dated 18. Sept 2018, guaranteed for 4 years, and contains LiSO2. There are two sets of brass output terminal contacts. On the set of four I get 12.05 volts. The larger 2 terminals have no output. I will open it up and report back.

 

[Hotstuff]

Cant help with the battery question but I guess that's more perfectly good equipment that's going to be binned and replaced with new just because of a battery supply problem

That is pretty much the case I'm afraid. As the AEDs are obsolete the batteries sell for between £200.00-£300.00.
Our ambulance service have been brilliant in operating as guardian for some public access defibrillators. They are often installed by charitable organisations and then just left unattended. The pads have a shelf life of about two years and the batteries about four/five years so do require maintenance hence our monthly inspection.

Our ambulance service have a small stash of G3 batteries and electrode pads for our region, once their gone the AEDs are not their responsibility so I doubt they'll be replaced due to the cost.

 

[Hotstuff]

I can ask my wife, she is a resuscitation officer so does this stuff day in day out.

She won’t be able to help with anything technical (she’ll admit that quite freely ) but may be able to help in some fashion, or ask someone who knows in work next week

That is very kind of you to offer such help, I have sent an email to the manufacture, Zoll, asking for guidance but I'm not hopeful.

We have a new battery at the ambulance station that I can check out to see what Voltages are present but it won't be available until next week and I was trying to get the AED back into service ASAP.

 

[eddie49]

There are two sets of brass output terminal contacts. On the set of four I get 12.05 volts. The larger 2 terminals have no output. I will open it up and report back.

I have just noticed that there is a diagram showing the set of four terminals, and the battery is called an "IntelliSense". The terminals are marked "-", "+12v", "+5v", and "10101". I guess that the last one is a digital input that enables the missing 5 volts.
The battery case is welded, I will Dremel it open and check for a PCB inside.

 

[Hotstuff]

Can you get funding for an upgrade?

That's a good question but sadly it's not that straight forward. The majority of our PAD sites are located in a small coastal town; they would have been donated by local charitable organisations and then left. The local ambulance service provided a guardian service and ensured that they remained registered as "available" on The Circuit" defib finder and we, CFR volunteers, inspect and maintain them once a month. They really don't seem to have owners any more.

There are grants available to private groups or organisation via the British Heart Foundation but the dates for application are restricted.

It's very much down to communities, charities & businesses to fund the PAD sites and maintain them. Local authorities sometimes have them installed but fail to ensure that they are inspected sufficiently. I've seen evidence at one PAD site that indicated it was inspected just twice a year by contractors.

Through the course of volunteering I have found PAD sites in busy outdoor areas with completely dead AEDs and plenty with expired pads yet at face value you would expect the bright yellow cabinets to contain a fully functioning AED.

 

[Kayos]

That's a good question but sadly it's not that straight forward. The majority of our PAD sites are located in a small coastal town; they would have been donated by local charitable organisations and then left. The local ambulance service provided a guardian service and ensured that they remained registered as "available" on The Circuit" defib finder and we, CFR volunteers, inspect and maintain them once a month. They really don't seem to have owners any more.

There are grants available to private groups or organisation via the British Heart Foundation but the dates for application are restricted.

It's very much down to communities, charities & businesses to fund the PAD sites and maintain them. Local authorities sometimes have them installed but fail to ensure that they are inspected sufficiently. I've seen evidence at one PAD site that indicated it was inspected just twice a year by contractors.

Through the course of volunteering I have found PAD sites in busy outdoor areas with completely dead AEDs and plenty with expired pads yet at face value you would expect the bright yellow cabinets to contain a fully functioning AED.

If you need help writing fund applications then let me know, it's part of my day job

 

[Hotstuff]

So you're trying to keep obsolete equipment going which if it was needed could literally mean the difference between life or death?, I'd be looking at a programme of replacing them with more up to date/current models. There are charities that can help with supplying AED's.

You are correct to a certain extent. If the Ambulance service did not kindly donate us the batteries and pads then these PAD sites would not exist.
It's not the ambulance services, or CFRs responsibility to provide AEDs. We are happy to work with local communities but currently that is as far as we are able help.
Edit: Please also be assured that maintaining these AEDs is taken seriously and if AEDs are found to be faulty or unreliable they are either replaced with a spare (if available) or removed from service.

 

[Hotstuff]

I have just noticed that there is a diagram showing the set of four terminals, and the battery is called an "IntelliSense". The terminals are marked "-", "+12v", "+5v", and "10101". I assume that the last one is a digital input that enables the missing 5 volts.
The battery case is welded, I will Dremel it open and check for a PCB inside.

I new someone on here would have at least an idea.

The AED can be interrogated via serial lead and a Windows 95 computer but I doubt we have access to the software.....probably on a floppy disc somewhere.

I suspect that there is going to be a software issue in the middle of this.

 

[Hotstuff]

If you need help writing fund applications then let me know, it's part of my day job

Thank you Kayos, that is a really kind offer. We don't tend to be involved with the funding process but if I ever need any guidance with the process I would be grateful for your experience and knowledge.

 

[eddie49]

The AED can be interrogated via serial lead and a Windows 95 computer

Probably the pin marked "10101" is a serial connection to allow checking of the battery voltage or capacity.

I cut the case at each end, the sides split apart by levering open with two screwdrivers. Inside I found this:

There are four "D"-size LiSO2 cells and a small PCB with surface-mount components.
Apparently this type of cell can range from 1.7 to 2.5 volts, but this battery measures 12v. Capacity is listed as 7.5Ah, and the "scrapped" battery that I have easily lights up a car headlamp bulb.

On the PCB, the plus & minus leads from the battery connect directly via wide tracks to the external "-" and "+12v" connector pins.
The pin labelled "+5v" also connects to a wide track, but the hole at the other end is empty. It is possible that this version of the battery only has a 12v output.

The 14-pin chip is labelled 3436 rA. I have found a datasheet for an Analog Devices switching regulator, number LT3436, but that is a boost converter with 5v input and 12v output, and it is a 16-pin device.
The other two brass contacts on the battery are just a shorting bar.

Maybe the 4 cells could be replaced by any kind of 12v battery, and interfaced to the defibrillator using the PCB? If it is of any use to you, I can send you this battery.

 

[Hotstuff]

Hi Eddie

That is amazing and thank you for taking so much interest and care in looking into this for me.

I removed the battery from the AED last night and reinstalled it this morning and it's presently running without any fault lights or beeps. I'll return the AED to its site this evening and check it again on Monday.

It's interesting to see the inside of the battery and get more of an understanding as to how it works.

If this battery was fitted to say a tool, it would be an interesting idea to repack the the cells and recycle but there is no way the ambulance service would allow AED batteries to be interfered with.

I suspect that there has been a software issue and removing the battery for an extended period of time has cleared or reset the AED fault. I'm waiting for a reply from the manufactures technical support dept so I'll ask them for future reference.

Thank you once more to everyone's interest and input to my question.