Battery life affected by paks?

[Daren]

I keep a log of battery changes, and I have noticed some anomalies specifically with the last two batteries I used in one of my LZ64. I always use the same Duracell PP3 and I buy them in boxes of 10, and for the most part have recorded around 6 months between changes, the last 2 however have only been around 2 months.

I know that amount of use will vary over that time, and also that writing to datapaks and using comms link will impact battery life, but in this time period all of those have been below typical. The only thing that has changed is that I have had 2 paks in that LZ64, a 512k flash and a 16k datapak.

Do flash paks impact battery life?

[Martin]

Hi Daren

If you are comfortable that the batteries were 'good' then..
Did you format the flash pack in place?
The technical reference manual - packs section suggests

"Formatting does consume a noticeable amount of power and it is suggested that a power supply unit is connected."

Andrew will know for sure but as far as I know in general use flash packs consume less power than a datapak..
I'm interested to see what Andrew says

Sincerely
Martin

[Daren]

Hi Martin

I may have formatted it on the first battery but not on the second. I put a new battery in on 19/04/24, then on 04/06/24 I got the low battery message which really surprised me, so I put a new one in and removed the packs for now. My other LZ64 and 2 XPs seem to last a lot longer between batteries, but I use them less and they don’t always have paks in.

I’m wondering if it isn’t a pak issue if it might be a bad capacitor in that particular LZ64, anyway I’ll keep tabs on it and follow up with any findings.

I might DIY a little battery tester that plugs into top slot, but might need a bit of info from more knowledgable members with regard to some of the technical details on the Psion side, I can probably cobble up a little microcontroller PCB with a button and LED(s) to give an indication.

[amenjet]

I keep a log of battery changes, and I have noticed some anomalies specifically with the last two batteries I used in one of my LZ64. I always use the same Duracell PP3 and I buy them in boxes of 10, and for the most part have recorded around 6 months between changes, the last 2 however have only been around 2 months.

I know that amount of use will vary over that time, and also that writing to datapaks and using comms link will impact battery life, but in this time period all of those have been below typical. The only thing that has changed is that I have had 2 paks in that LZ64, a 512k flash and a 16k datapak.

Do flash paks impact battery life?

This is an interesting question. One way to look at it is to consider the charge in the battery. This is a bit technical, but in a way it's not. You can use an analogy of a bucket of water, a full bucket is a full battery, and the circuitry in an Organiser uses water to do it's computing. Every time something is done by the circuitry in an organiser a small amount of water is consumed. The organiser is very good at minimising it's consumption, but every time circuitry is used some water is used up. (Going from water to electricity: Current is analogous to water flow, charge is water, so mA is like flow of water and Coulombs is charge, mAh is analogous to a flow of water for a length of time)

So, yes, datapaks will affect battery consumption, the real question is by how much.

EPROM packs: These take quite a current when programming as they are relatively old technology. For a 27C128 the programming pulse is 25mA for 1ms. The current when the device is on is 20mA (more about that later), and there are two supplies, a device supply and a supply for programming.

Flash paks: These have an on current of 20mA and a programming current of 30mA but this is from one supply rail, there's no programming supply for flash devices. the programming time is 7us per byte.

So, the flash devices take 20mA when on and the EPROMS 20mA when on so no difference, but obviously this is more current than having no packs plugged in.
(Excluding the 'active' current that us there when the device is on, which is the same for both device types):

the EPROM packs take 25mA * 1ms = 25uAs per byte
the flash packs take 30mA 8 7us = 21nAs per byte

So, programming a flash pack is about 1000 times better per byte than an EPROM pack. You do have to format the flash pak in the Organiser, though, and that will take charge.

Now, one thing that affects this greatly is that the VCC (power) line to the datapacks are switched on and off. When a datapak isn't being used, the power to it is switched off, so it doesn't really matter how power hungry the pack is when it isn't being used, the supply is off. So, the only time the pak is consuming battery charge is when it is being read or written.

I've just looked up a PP3 and apparently they have a capacity of 500mAh, so dividing that by the figures above we get 20,000 bytes for the EPROM pack
and 23MB for the flash pack. So, looking at those figures, and assuming I'm not totally wrong, it looks like flash pack are much much better than EPROM packs when writing (this doesn't look at reading), to the extent that battery drain for flash packs can almost be ignored, while for EPROM packs it is significant.

Does that help?
Please check these figures.

-o0O0o-

As an aside, I use rechargeable PP3 batteries. they don't last as long and are expensive but you can recharge them. I use the ones with a USB socket in them so can recharge from anything with a USB socket. If you've got two then you can swap between batteries and charge while using the other.

[Daren]

Thanks Andrew, that most certainly does help, it means I can rule out any significant drain caused by the paks, as I had not really read from or written to or formatted them in the timeframe.

Just checked the old battery, giving a reading of 6.2v

[amenjet]

Thanks Andrew, that most certainly does help, it means I can rule out any significant drain caused by the paks, as I had not really read from or written to or formatted them in the timeframe.

Just checked the old battery, giving a reading of 6.2v

Do you know if the flash pack is one of mine? i don't think there's a problem with it, as the switch off of the supply when it's not used means it doesn't draw anything really when not being used. Actually, I've just looked at the circuit of the flash pack and noticed that there are pull-downs on the bus signal (d0..7, SCLK, etc). these are 47k, and will cause current flow when those signals go high. It's not a huge amount of current, about 1mA if all signals are high, but it is an extra drain. So, if you really aren't using a datapack at all, you are better off not having it inserted...

[Daren]

I believe it is as I got it from Peter, I don’t normally leave paks in unless using them a lot, but for some reason I did this past few months, which was what prompted my initial thought that it may be something to do with that.

I have a feeling it might be this particular LZ64 which is the reason for the higher battery drain, I can’t remember if I recapped it or not.

[amenjet]

That is probably one of mine, yes. It would be interesting to note what the battery life is when one pack is removed, i.e. see what the life is when the e flash pack is in there and when it isn't. When the organiser is switched off there should be very little current draw. Inefficient voltage regulators might be a problem, yes, maybe.