Battery replacement

[dune]

Best o f luck. would be interested in the result. Btw does anyone have any information on whether NI would change cells if required and at what cost? Whether they will spport the hardware of Adam after launch of Adam2?

I think they haven't responded to it yet. On the other hand, having to ship the tablet to them and waiting for its return might be too much time and money.

[skippyi]

Battery replacement by NI is feasible. I just sent my Adam to them so that they can change battery.
Cost? 30$ for the battery + 13$ work + shipping cost to the service center (20$n for me, I am based in Europe)

[Gosu]

After my clinical rotations started I havent been able to pursue this project fully. But now I might have some time and am going to buy some Li-Po 3.7v cells and connect them and see if it work. I am sure NI did these batteries to cut cost and for the design. But I think they could have gone Li-Po like ipad. Acer Iconia has a 7.4v 3000+mAh cell. Anyway I am going to order them tonight. hopefully work on the connections and charging in the next week or so. Although it worries me I seriously dont want to end up like what PsychodelEKS's project ended up with. Will post the results then.

Any luck?

[IntuitiveNipple]

The three cells used are Sanyo 18650 (Korean regulation R1112). The specifications are:

Part number: UR18650A
Type: Lithium-Ion
Nominal Capacity: 2150mAh (0.43A discharge)
Nominal Voltage: 3.60V (0.43A discharge)
End Voltage: 3.0V
Charging Current (Std.): 1.505A (0~+40C)
Charging Voltage: 4.20V (+/- 0.03V)
Charging Time (Std.): 3 hours
Discharging Current (Std.): 1.075A (-20~60C)
Discharging Current (Max): 2.15A (-20~60C), 4.30A (0~40C)
Internal Resistance: <100mOhms (AC impedance 1kHz)
Length: 64.9mm
Diameter: 18.3mm
End tab diameter: 9mm

Maximum discharge current as a single cell is as above. However after assembling to a battery pack there is the limitation of maximum discharge current because of protection circuit and protection device.

Charge current must be below 2.50A per cell. Charging voltage must be 4.20V. In case of a battery voltage below 3.0V it should be charged with pre-charge current below 0.1A. When the voltage exceeds 3.0V the standard charging rates can be used. Do not constant (trickle) charge. Do not over-discharge below 2.0V per cell. Do not charge outside temperature range 0~40C.

[kwilson73]

Do not constant (trickle) charge.

Does this mean that we should not leave the Adam plugged in to the charger all the time?

[IntuitiveNipple]

Does this mean that we should not leave the Adam plugged in to the charger all the time?

No. That directive applies to the battery controller circuit the cells are connected to. Because Li-ion cells have such stringent requirements all battery packs have a micro-controller attached that manages the charging and discharging of the cells and monitors their temperature. The micro-controller is loaded with firmware that tells it the specifications of the cells connected to it. The micro-controller can communicate with the host usually using something like an IIC (I2C) bus. It is responsible for charging the cells regardless of an external power source being connected.