Replacement lipo batteries for Palm OS devices & PDAs

Ok, here’s a hot tip for refurbishing Palm & PDA devices with dead batteries.

If you search “palm battery tx” or whatever, on ebay or aliexpress, you’re bound to find lots of batteries with this “CS” logo. That is Cameron Sino , who have batteries for almost every model out there. They do not sell direct to individuals, but they have numerous resellers on ebay and aliexpress. Most of the time they are of good quality, but personally I’ve received a few that are old and have run down simply from sitting on a shelf. Anything less than 3.2V on a lithium battery should be discarded.
However, CS batteries are far from cheap. For some models they may be the best option, especially if your battery has three wires, or some obscure connector that you’re not able to source or solder.

BUT, you can get cheaper replacement lipo batteries from aliexpress if you know what you’re looking for.

Most PDA’s use lithium-ion batteries, in polymer pouches – commonly referred to as li-po batteries. There is no standard on their shape or configuration, and most products have sufficient volume that they are able to order a custom battery to suit their need, as long as the shape is some kind of rectangle (unless you’re apple…).

To find a replacement, you only need to match a few things:

  • Size – the new battery must fit inside the old product, so it must be the same size in each dimension, but it is fine if it is smaller! Batteries can swell, so don’t try to fill the product completely, make sure there is a bit of breathing room inside the product.
  • Voltage – the new battery should be the same voltage as the old battery. Most commonly, this is 3.7V for a single-cell li-po.
  • Connector – if you can solder, you can cut off the connector on the old battery, and then solder it onto the new battery.
  • Capacity – It actually doesn’t matter too much if the capacity is different, and you may find that new battery technology enables you to get a higher capacity battery to replace your old battery. However, the new battery should approximately (+/- 25% ) match the capacity of the old product for other reasons. Li-po batteries can only put out a limited “peak” power, which drops as the battery goes flat. If your battery is too small, you may find that it is unable to power the device, and you may find that when you get to 30% charge, that the device just “dies” randomly.

Now for the hot tip. If you look at an old replacement battery it will typically have some numbers printed on it. This can often tell you the exact size of the battery you are looking for. Yes, you can just measure the battery, but often old li-po batteries swell up, and this can make it impossible to measure the original physical size of the original battery.

You will probably find a code like “255050” printed on the battery, and often this is the size of the battery. This is the format:

  • Thickness of the battery in mm, to one decimal place (e.g. 2.5mm)
  • Length of the battery in mm, rounded to 1mm (e.g. 50mm)
  • Width of the battery in mm, rounded to 1mm (e.g. 50mm)

Those dimensions are then written in sequence, as thickness+length+width, e.g. 255050. As long as you have an approximate dimension, you may find the exact measurements encoded in those printed numbers. Sometimes, a battery will be labelled with other numbers too, like a date code or batch number, 14061325505010, but its a useful tip. Those numbers can then help you to search for a compatible size battery.

E.g. a battery that is 8.0mm thick, 25mm long, and 40mm wide is an 802540 – and searching “lipo 3.7V 802540” shows up a result:

Correct LiPo Sizes for Common Palm Models:

  • Tungsten TX: 503760 (I recommend this item: https://sampin.ch/TX-batt )
  • Tungsten T3: 523450 (523452 will fit too)
  • Please comment below if you know of others 🙂

Sourcing

You may not always be so lucky, and you may have to browse lipo seller stores to find one with the right connector, or of a similar size. So, here’s a few sellers I’ve found on aliexpress stocking a good range of li-po batteries in different sizes.

EHAO Technology Lipo Battery Sellers

EasyLander Lipo Battery Sellers:

Liter Energy Lipo Battery Sellers:

A few more notes:

  • This post also applies to lipo batteries for MP4 players, GPS units, portable DVD players, etc.
  • Avoid batteries for helicopters or quadcopters – they are typically rated for high short term power output, and not for long-term quality, or long term capacity. Often they also lack the protective charging circuitry required too.
  • Three wire lipo batteries are less common, but are still available.
  • If you need a specific connector, contact the seller, they may be able to add the connector you need for a minimal extra cost.
  • Connector Types
    • Common connector types from small to large, include JST ASR 1.0mm JST SH 1.0mm, JST ACH / ACHF 1.2mm, JST ZH 1.5mm, JST PH 2.0mm
    • To help identify your connector, some common examples can be seen here and here.
    • The official JST website also is useful here and here.

However, you may prefer to simply order a Cameron-Sino battery if that sounds too difficult. They are specifically designed for each device, which can be an easier option.

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