Battery connection points on a qimi ??

[techy]

Forum ,


is there a way to add a backup battery to a standard qimi ??

i have a qimi without a backup-battery .

It looks like it never had a battery connected ( no remains of solder-points )

I would like to add a 4,8V nicd( nimh ) battery


does anyone have an image of the different types ??




all help highly appreciated ,



techy

[tofro]

Forum ,
is there a way to add a backup battery to a standard qimi ??
techy

There used to be versions with and without backup batteries around.
There's quite a number of qimi manuals on Dilwyn's home page, including a circuit diagram of the battery version that might help you
http://www.dilwyn.me.uk/docs/manuals/index.html

Regards,
Tobias

[techy]

danke tobias ,

batterie gleich am platine loten ??

jemandem ein high-res foto ??




techy

[techy]

Can someone please confirm the 2 positions i have marked in the picture ( two red arrows in the top right corner ).

the right one should be minus , the left one plus .


please correct me if i am wrong .




techy

[belg4rion67]

I don't know if you still need info about battery connection but if is it I've Qimi with battery cable mounted and I can send to you some pictures.
If you have tried your idea could you tell me if 4.8Volt battery is ok for use with Qimi?
On my interface is mounted a 9Volt (battery transistor in Italy) plug cable but I'm sure that that tension is too high for ZX8302
Bye
Paolo

[techy]

Hi ,

Sorry for the delay in answering ( too occupied with other things ) .

Yes please sent me a good picture of the pcb with the power cable connection visisble .

And , i rather keep the battery voltage low , as far as i can see from the schematic it should be at 5 Volt.
As far as i can remember , in the original design a 4,8 volt nicad mini battery was mounted ,

qimi.png (9.38 KiB) Viewed 6254 times

[belg4rion67]

hi, in attached image you can see a particular of flat cable of my qimi: first red wire at left and second one are battery connections (red is + and second wire is -) I've used a cellular battery (3.7 volt) and it works fine
now my ql does not lose time...
As the image is heavy I post a link to my dropbox so you can see in your browser;)
Ciao!
Paolo
https://www.dropbox.com/s/7qva8lq2mluic ... 175653.jpg

[Silvester]

The original nicad battery fitted to my QJUMP QIMI was rated at 3.6V 110mAh. Anything with a higher voltage may not allow the transistor to perform correctly. The circuit works by holding reset low (and thus PCENL high) until the 5V line is well established protecting the ZX8302 clock from corruption (apparently the 68008 was prone to indulging in a little mayhem beforehand).

A flat or disconnected battery causes the reset line to be held low. When the Gold card came out with its RTC the QIMI battery wasn't needed, so the solution was to simply remove the battery and tie the + & - together.

Therefore I think you may find that the battery-less version of QIMI has a link between the + and - connection points somewhere (or uses a small resistor), so I would at least check with a meter before connecting a battery in case it gets short-circuited.

BTW the 2k2 in the battery charge path is a little mean (=0.73mA, spec says for 110mA nicad it should be 1mA for constant trickle, with 11mA max charge). It was OK if you had the QL on 4-5 hours a day, not otherwise. Before the Gold card arrived I recall on several occasions having to remove the QIMI battery and give it a proper full charge.

(re-edited on 19 May: increased assumed charge value from 0.4 to 0.73mA since pin 40 of ULA contributes via internal diode)

[prime]

BTW the 2k2 in the battery charge path is a little mean (=0.4mA, spec says for 110mA nicad it should be 1mA for constant trickle, with 11mA max charge). It was OK if you had the QL on 4-5 hours a day, not otherwise. Before the Gold card arrived I recall on several occasions having to remove the QIMI battery and give it a proper full charge.

What i do wonder is how easy it would be to adapt that circuit to an Ni MH battery as NiCd are pretty hard to get hold of. Or how easy it would be to use a non-rechargeable battery like a group of 3 AAA or a CR2032 (or something like that).

Cheers.

Phill.

[Silvester]

Just tried 3 Ni-MH AAA batteries via 2K2 resistor into pin 40 of ZX8302 (unpowered populated QL PCB, with pin 40 isolated from socket). The current drawn was 52uA (microamps) at 3.9V, better than I expected (BTW for the Super/Gold card RTC which uses MM58274C chip, datasheet quotes 10uA at 2.2V)

I also discovered that there must be a internal diode between ZX8302 pin 11 (Vcc) and pin 40 (battery). With pin 11 at 5V it outputs 4.4V on pin 40; with a 220 ohm resistor to 0V it drew 20mA !. Therefore, to use an isolated non-rechargeable battery, a diode will be needed between it and pin 40 (with 3v9 zener diode in place of battery in original circuit).

Given the apparent very low current drawn by pin 40 of ZX8302 and the long shelf life and capacity of modern Ni-MH I, personally, would just use the same circuit with 3 Ni-MH AAA batteries (cheap/available, and there is just enough room adjacent to the expansion connector). The charging current is going to be limited by what the ZX8302 internal diode and transistor emitter-base will safely allow. I would be reluctant to reduce the pair of 2k2's below 470 ohm, in case problem with battery connection damaged ZX8302 internal diode.

Probably not enough charging current for very long term use, though it would be interesting to see how long new 900mAh AAA Ni-MH would last. I have some I havent recharged in 9-12 months and they still are good at 1.2V