Psion Series 7 Battery Service

Psion's diagram of the underside. The lithium backup battery door is on the left; the inset shows the reset button inside that compartment beside the coin cell.

Battery service for the Psion Series 7. The Series 7 and the Psion netBook use the same main battery pack, sold by Psionex as the NB3000 for the netBook, netBook Pro and Series 7. The pack rebuild is described once, on Psion netBook Battery Service.

Main article: Psion netBook Battery Service

Safety

Read Battery Refurbishment before opening any lithium pack. This one holds three 18650 cells in series, up to 12.6 V when fully charged, and the cells are live throughout the work.

• Switch the machine off before removing the main pack, and watch the screen while doing it; see Changing the main pack.
• Never wire cells directly to the pack's external contacts. The controller board balances the three cells; without it one cell will eventually be overcharged or over-discharged while the pack appears healthy.

Battery specification

Psion Series 7 power

Item	Specification
Main battery	Li-ion pack of three 18650 cells in series with a controller board, 10.8 V, 1500 mAh. OpenPsion and Eric Lindsay give 11.1 V and name the cells as Panasonic CGR18650H. The Series 7 FAQ describes three 3.6 V cells.
Backup battery	CR2032 lithium coin cell. Psion's netBook datasheet gives it a 55-hour lifespan.
Mains adapter	15 V DC ± 10 %, 1.5 A; input 100-240 V 50/60 Hz, with a ferrite core on the lead. Connector 4.75 mm outside, 1.75 mm inside diameter.
Running time	Up to 8½ hours, with a 2½-hour recharge (netBook datasheet). The FAQ reports over 10 hours at minimum brightness with no peripherals, and about 50 % less at full brightness.
Charge time	Up to 3 hours, with the machine on or off.

The Series 7 cannot run on AA cells; the Li-ion pack is its only internal power source. Do not use another Psion mains adapter: no other EPOC or SIBO machine's adapter matches the Series 7's voltage and current.

The FAQ describes the pack as "a sealed, non-serviceable unit". No factory rebuild procedure exists, and the case has internal locks that break when it is opened. Owners have rebuilt packs regardless; see Psion netBook Battery Service.

Charging and the charge LEDs

Charge LED indications

Indication	Meaning
Right-hand LED green	Mains power present. Normal whenever the adapter is connected.
Right-hand LED yellow, red LED to its left glowing	Charging. The brighter the red LED, the more charge is still needed.
Red LED dimming	Charge progressing normally.
Red LED out, right-hand LED back to green	Charged to about 70 %, not full.

Charge for the full three hours, not until the LED goes out. A pack that seems to be losing capacity may simply never be filled.

Two more behaviours are normal. The display does not dim as the battery drains; it brightens slightly when the adapter is connected. And the machine stops abruptly instead of fading: Li-ion machines cut out well before the cells are exhausted, so audio, CompactFlash writes and the serial port work right up to that point.

Changing the main pack

The internal C: drive is RAM. A microswitch in the battery lock is meant to switch the machine off as the catch is released, leaving the CR2032 to hold RAM. On some machines it switches the backlight on instead: the screen lights but stays black, the system does not shut down, and when the pack comes out RAM is lost. Data, applications and settings go, and on a netBook the operating system too.

1. Back up to CompactFlash or a PC.
2. Slide the catch and look at the screen.
3. If it lights but stays black, hold the catch open with one hand and switch the machine off with the other.
4. Then remove the pack.
5. Change one battery at a time. With both out, RAM is lost.

One of the rubber feet is on the underside of the battery catch. Sliding the machine across a desk or carrying it loose in a bag has dragged the catch open and reset the machine, so check the catch and foot.

Backup cell

The backup cell is a standard CR2032, still sold by Psion specialists. Psion's netBook datasheet gives it a 55-hour life holding the machine's contents, so it is not a way to keep data through storage. Replace it if its age is unknown.

Storage

• Give a stored pack a full three-hour charge every three months.
• Lithium cells age from their date of manufacture, not from first use, so an unused new-old-stock pack is as old as its cells.
• Li-ion cells have no memory effect, so there is no need to discharge them fully before charging.

Rebuilding the pack

The procedure (opening the pack, choosing cells, spot welding, transferring the controller board, reassembly and first charge) is on Psion netBook Battery Service and applies unchanged to the Series 7. The author of the OpenPsion rebuild guide worked on a Series 7 and got 12½ hours from 2200 mAh cells, where the original pack gave 7.

If you are rebuilding a dead pack, the battery management controller seems to go into a "storage or transport" mode which cuts power to the gold pads. If you replace the cells, the voltage is correct across the pack but you receive no voltage on the gold pads, follow the jump start procedure below.

• Solder two lengths of wire to the pads on the back of the board (where the gold pins connect to). ENSURE THE POLARITY IS CORRECT!
• Set a bench power supply to 12.6v at 200mA.
• Supply power to the pack for approximately 20 seconds.
• Check for voltage from the pack once bench power is removed.

Read Battery Refurbishment before starting. It covers safety, cell selection and welding.

Related pages

• Psion Series 7
• Psion Series 7 General Maintenance
• Psion Series 7 Troubleshooting Guide
• Psion netBook Battery Service
• Psion netBook Pro Battery Service
• Battery Refurbishment
• Battery Explosion, Capacitor or Corrosion Damage
• Recommended Tools