Printer battery replacement

[Tom]

This video just dropped - nice solution to a nicad replacement. I'd love to cook a board up which effectively did all of this voltage conversion etc and presented the lithium battery to the printer as a nicad, accepted charge current etc and passed through as a battery when not charging, but this is probably what I'll do...

https://youtu.be/0AsXuKC-e60?si=PAjtouHM11RXyA7q

[1333david]

Thanks for posting the link to the video. I have a Psion printer and was looking to follow lepowerfulpiere's example of parallel wired PP3's as I don't trust myself with a soldering iron for the fix in the video. Here is an extract from his ebay listing "With the advances of battery technology, it is relatively straightforward to replace the original battery packs with PP3 sized rechargeable batteries, and they have the reputation of all original Psion II reliability.
The conversion I have done is to include 2 parallel wired PP3 battery connectors, since there is enough space to fit 2 batteries in, which although they are slightly higher voltage, 8.4v, the capacity is greater than the original 600mA ones.
The printer will run perfectly well with only one battery installed, but since there is space for 2 I thought I would leave the option to get cheaper rechargeables or increased printing time.
The original specifications were about 1 hour battery usage (continual), but obviously they will print now for a lot longer, in battery mode only.
The input power supply is 10.4v, the same as the normal Psion II PSU, but instead of an output of 175mA the printer PSU has a 600mA capacity. The printer needs this to charge the batteries and supply enough power for its usage."

I don't have a Psion printer PSU and am using a universal power supply at 9v. Interestingly the Psion Printer manual states "The printer comes supplied with a 9 Volt mains adaptor and a built-in 7.2 Volt Nickel-Cadmium rechargeable battery" but clearly the PSU is 10.4v. I'm wondering whether the universal 9v adaptor (with 600mA) would be enough to power and charge the battery? I don't want to switch up to 12v as that would be too much. I'm also thinking of just adding a single wired PP3 battery connector but not sure if that's the way to go.

[thesourcerer]

I have tested 5 printers now with 600mA batteries, using only one battery in each and they all work. I haven’t tested the batteries for charge, but I assume with the Psion printer power supply they are charging when connected to the PSU. The 9v universal PSU should also work, since the batteries are 8.4v (as long as it is centre positive)!

[1333david]

Thanks for confirming the one battery solution, Peter. It would be interesting to know whether the battery is recharged in the printer. My knowledge on batteries is pretty basic but I realise my Li-ion batteries which are USB rechargeable will definately not recharge. I also have doubts whether the 600mAh Li-ion batteries would recharge in the printer too. The original printer batteries would have been the old Ni-Cad type and it appears they charge differently to the newer Li-ion batteries (at least the chargers are incompatible). Maybe someone might be able to confirm.
Kind Regards, Dave

[thesourcerer]

I don’t know if they will, but with a print time of an hour, hand held, that is a lot of printing.
Hence my reason for wiring for 2 in parallel!
It is easy enough to take the Li-ion batteries out and recharge them if you are solely using them for portable use, and I can’t think of many applications where you would need more than an hour of continuous printing?

[thesourcerer]

Come to think about it, even with the PSU attached an hour of printing is a lot!