EBME Forums Forums Maintenance Technical Assistance Replacement batteries (Medgraphics)

Well with 278 posts this month there's no change there then!

It's probably the same as every other use, the deciding factor here isn't design it's cost. You'll find that the same battery that goes in the Philips M3/M4 monitor will be the same battery that goes into the equipment that helps someone dig up the road or even perhaps someone's laptop. Even the difference between other medical equipment manufactures like GE could be just programing and a lable. When companies are no longer producing custom built cells and instead use a standard the cost of production falls massively!

Taking that logic one step further, this means batteries from different manufacturers/suppliers, that are functionally compatible but do not necessarily have identical performance, can be offered without the supplier having to have the technical know-how that they would have to if they were manufacturing "equivalent" battery packs, intended for a particular medical device, from scratch.

This is now the problem we face, where previously 3rd parties had to source components and assemble batteries to an identical specification they can now just source "compatible" batteries that they think are the same specification - one step more removed from the product than in the past.

As Isidor Buchmann of Cadex Electronics States in his book "Batteries in a Portable World":


Without a supplier being aware of what "fine tuning" goes into the cheaper "equivalent" battery that appears to have the same characteristics and specifications as the OEM battery that's used and recommended by medical device manufacturers, then being prepared to perform testing and guarantee this, i.e. validate in the device that the battery is intended for, I'd suggest "proceeding with caution" when trying to save money on batteries used in safety-critical applications.

Are you saying that kit ends up being cheaper, then, Chris? I don't think so, Mate. Now that I've looked into things a bit more, it seems that the whole "smart" battery story is very, er, smart. Great technology and all that, but I return to my earlier question of "what is the real benefit" in adopting it?

Myself, I approve of the idea of like-for-like batteries being shared across applications. At least that way prices get driven down, as economies of scale kick in.

I'm interested in the SMBus question, as my guess is that our own dear medical equipment OEM's have their own (proprietary) way of doing things (ie, for commercial reasons). I hope that I'm wrong.

Yes, you're right about all those posts. It seems like I'm using the forum like a blog! Thing is that no-one ever seems to visit my own personal blog, so it's been left rather to wither on the vine. No, this forum is a great place to meet and chew the fat, as it were. I've looked (and continue to look) at quite a few other forums, but this one suits me best (until, and unless, I start up my own, that is)!

It's a fact that smart batteries are more expensive. Charging & discharging algorithm(s), charge/discharge/short-circuit protection, accurate State of Charge (SoC) indicator, accurate State of Health (SoH) indicator. To be smart the SBS forum states that a battery must be capable of SoC indication. You're forgetting single-wire and double-wire battery buses as well, Geoff. They're based on the same principles as SMBus though.

The problems with "smart" batteries are that newer battery technologies, that have overcome the issues with maintaining the battery itself (e.g. Li-Ion, Li-ion Polymer), have been replaced with issues associated with data corruption and calibration of the on-board SoC electronics and incompatibility with the chargers used with them (another reason for not buying non-recommended packs).

To some extent I think the use of SMBus and suchlike has allowed the development of batteries using technologies (Li, NiMH) that, potentially, have significant benefits over the traditional batteries we used in devices in the past, e.g. NiCd & LA- such as being totally maintenance-free.

Without the use of smart technology, i.e. the charging algorithms, protection, etc, then batteries using certain chemistry would most likely present a risk of over-heating or even exploding due to overcharging and short-circuiting because they tend to have a have a high energy-density and chemistry that can become unstable under certain conditions. It has been publicised.

Unfortunately the maintenance-free requirement of the Li-Ion batteries, etc, has been spoiled by the fact that SoC needs calibrating periodically because of SoC "tracking" errors and the fact that the SMBus electronics can become "corrupted". Plus there's the compatibility issue relating to differences in how the SMBus is implemented in the charger and battery as Geoff implies.

The question is if a smart battery had to be designed for the product instead of the product being designed around the battery would it cost more, since one would be a one off design and the other mass production I suspect it would be more expensive.

Of course the extra technology is going to cost extra, but just compare the cost of a Philips M3/4 battery with the cost of going straight to the smart battery manufacturer and see the difference!

And no Universal Charger on the horizon for a while yet, I presume, Richard?

I imagine the equipment OEM's seek out the battery that best fits the needs of their equipment, and perhaps tweak a bit on the control circuitry, Chris.

I presume that going to Philips costs more (?)

I doubt it, the company I use to work for use to buy in exactly the same batteries as the M3. I assume that they can be programmed via the terminals since when you try to use a M3 battery in a GE unit it recognises they weren't purchased from GE! I get a feeling all GE has done is programmed them so that the standard battery can't be used, doubt there's any difference in performance between the batteries purchased from Philips, GE or original manufacturer!

Ps. In the previous use I saw the batteries being used for, the company didn't bother tweaking them, just used them direct from the smart cell manufacturer. Perhaps philips have done the same?

Geoff if your talking about Universal Charger for smart batteries Euro Energy already sell one, one advantage of using off the shelf batteries.

I'd better leave it the guru, Chris.

My thoughts immediately turn to hacking that little beast (not that I would do that myself, you understand). Must get on, Mate, I've got lot's to do this weekend!

Anybody with any feedback on the SBS 3002? How much will it cost me (do I need a 5-terminal AMP connector adaptor)?

By the way, for those out there who may not already know, Euro Energy have some nice .pdf downloads available. Something to read with your cocoa tonight!

The fact is that manufacturers of medical devices will source their packs from a battery manufacturer, to their requirements, design a fully compatible battery charger into their medical device, then sell recommended batteries at a significant markup.

This means that it's unlikely, for commercial and technical reasons, that the identical battery will be available elsewhere, cheaper.

The question when considering cost is whether you're obtaining like for like batteries at a lower cost from 3rd parties. Can 3rd parties be certain that the packs they source, from other battery manufacturers or suppliers, have identical specifications and are fully compatible with the device?

The argument that 3rd parties can supply smart batteries more cheaply can only be supported if the batteries are "like for like" and "fit for purpose". In this respect the 3rd party suppliers are onto a loser if they can't validate their battery and have it recommended by the device manufacturer.

You're right in what you say, Richard. I think we're all agreed, that although the "smart" technology is no doubt very interesting, the way that it's being engineered by our beloved medical equipment OEM's is simply to maximize the gouge! "So what else is new", I hear you say.