CUCC Expedition Handbook

Drill Battery Charging

Instructions for charging

  • If the battery has insulation tape on it (red, green, or earth) it won't charge on the Makita standard charger and the Balance/RC charger should be used. All batteries will charge on the RC charger, but not as fast as on the Makita charger. Go to RC charger.
  • Using Makita charger

    1. Make sure charger is powered (flashing green LED).
    2. Plug batt into Makita charger. It should start charging.
    3. Look at the LEDs for status - the legend is printed on the charger. If it flashes 'broken battery' (flashing red and gren LED) at you after a few seconds, use the yellow (Pro-Peak Prodigy II) RC charger instead.
    4. Eventually it should show '100%' (steady green LED) (in about 1 hour max). You are done.

    Using Pro-Peak (or Accucell 6) RC charger

    1. Make sure charger is powered (display lit up)
    2. Connect charger to battery (either hardboard adaptor or empty Makita base adaptor). Check polarity is correct with hardboard adaptor.
    3. Check display says 'Lion' or 'Lipo' and '14.4V' and '3A' and 'CHARGE'. Hold down 'start/enter' button (on right). It will do a battery check.
    4. If it shows '4' as the number of cells, then press 'start/enter' again. Charging will start (fan comes on, display changes). If it shows anything else like 'polarity reversed' or 'connection break' then fix the connection to the battery. If it shows '3' as number of cells it is probably knackered, but possibly can be coaxed back into action. Find a battery expert - don't just use the charger anyway.
    5. Once it beeps and says 'FULL' (flashing) then you are done (should be less than 2 hours). Display shows number of mAh put in in bottom right. Should be a number like 250 for each hole drilled (between 50 and 2900 depending how discharged it was).

    Can I tell if a battery is already charged?

    Simplest it try to charge it again and find that it says it is done in a couple of minutes. This may waste a 'life' on batteries that still work on the Makita charger. Checking it on the RC charger will not waste a life. It will quickly rise to 16.4V, and the current drop to 0.1A or so. That indicates a full pack. It will tell you so after a while (1-5 mins).

    What sort of batteries are they

    The drill batts are 4S2P 14.4V lithium ion packs (8 18650 cells: 4 in series, each being a parallel pair). This means that they are charged as 4-cell packs, to 4.1V per cell-pair. They can be charged at up to 3A rate. Battery 1 has connector wired as balance connector. No other packs have this yet (2017). The official Makita packs use Sony SE US18650VT (1.5Ah, 20A high-drain) cells, and we have a few with with Samsung INR18650-13Q (1.3Ah high-drain cells). All give a reliable 2.3-2.6Ah capacity in practice, even after 9 years expo useage.

    Makita charging protocol issues

    Makita have put very 'conservative' software in the batteries which will stop them working on the Makita charger, even when they are in fact fine. The monitoring board is powered off the 1st cell pair so that one tends to get discharged more than the others when left sitting for the 11 months of not-expo. If an unbalanced (or over-disharged, or too-hot) pack is inserted into the makita charger the charger and battery will do serial-coms negotiation, the charger will refuse to charge the battery and the battery will remember this. If you try this 3 times, the battery will mark itself bad and will never charge again on a makita charger. Only a replacement monitoring board can fix this (or new software if we knew how to nobble it).

    Such batteries are normally still fine and charge on a sensible (RC - Radio Control, because RC people are the main market for these chargers) charger, possible after a balance charge to get the cells in the pack in sync again. Expo has a couple of these and will be getting more. Unfortunataly Makita don't build the 14.4V packs with balance connections to the cells, so the PCB has to be replaced to make this work easily for expo, which is the plan for 2018.

    Note that the drills have no battery-voltage monitoring at all, and the monitoring circuit is bypassed when conected to the drill (the charger uses a different connector-pair from the drill - that's why there are 3 slots). Thus the drill can easily be used to over-discharge a battery, so please stop drilling when it gets slow and put on a new batt, unless it's an emergency. Drilling with an excessively-sagged voltage is a good way to knacker the weakest cell-pair. If your battery does get to this state, try to charge it up as soon as possible. Cells must not be left at <2V for any length of time as they rapidly (hours/days?) degrade to useless in this state (and that pair will need replacing).