Sunday, August 30, 2009

TBs TechNuggets 09 - Inside the PF Rechargeable Battery Box

Have you ever seen inside...?

Again Philo, took some photos from the new Power Functions Rechargeable Battery Box (8878).
Just take a look!

Just a few remarks,
  • Opening of the battery without significant damage, could be a bit tricky but not impossible as Philo have shown.
  • As expected we can see the battery includes internally, two 3,7V Li-Pol standard cells in series.
  • As it seems and as I guessed before, frustrating to see that TLG had available the required space to include some pin holes, in order help fixing this battery in studless buildings.
    Now we should use some modified plates with hole (probably the best solution), or similar.
  • Modifying the electronics board to override the 2h time-out function, seems now a vanished dream since all the control might be inside the Chip-on-Board circuitry (the black kind of a bubble in the PCB left side).
  • As a side note, I should say that against the approx. 4h charging time advertised within the leaflet coming together with the battery, I've measured it to be less than 2h 20', with the official LEGO 10V DC charger (8887).

Again as usual, you may also refer to the source at Philo's BS folder (not yet public at the time of this post).

Thanks Philippe!


Ricardo Oliveira said...

Are you sure they are Li-ion batteries?

The Lithium Polymer batteries are not much recent and TLG could maybe use that technology (lighter and more run time). I know it requires some care with charging and discharging, but the circuit board can eventually include the balancing when charging and cut-off on over-discharging. And curiously, 3.7v is the exactly voltage of a single Li-Po cell.

TechnicBRICKs said...

Ya sure Li-Pol. My Bad!

On the battery side sticker, it is written 'Lithium Ion Polymer', thus the confusion.
Will change it right away.

As matter of fact, the battery is extremely light and the cut-off is controlled. The motors stop suddenly instead of progressively, and it doesn't worth to press the green button again. They won't run anymore, until the battery gets recharged.

Ricardo Oliveira said...

That is a matter I went through recently and I already wondered about using this on NXT.

When I get more time I'll study the dimensions of the back and search for good possibilities! ;-)

TechnicBRICKs said...

But notice that NXT official rechargeable battery, is also Li-Pol.
7,4V / 1400mAh against the 1100mAh for the PF version.

Ricardo Oliveira said...

Oh, I haven't noticed that! And I actually have it... :X Never needed to use it!

I wonder if a 11.1v cell would be dangerous to use... They can be charge until about 12.7v...

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