CUCC Expedition Handbook

Makita Drill Battery Charging

[None of this applies to the Bosch drills and their battery packs.]

Instructions for charging

Please check with a battery nerd whether this is still up to date. It was valid on Expo 2022.

We have 2 types of batteries:

  1. Blue taped, which are original Makita
  2. Green taped, which are modified by us

Batteries need to be charged on compatible chargers.

We have 3 types of charger:

  1. Standard Makita, both 12V at top camp and 240V at base camp.
  2. ┬┤Triple' balance charger made of 3 makita chargers munged together.
  3. Accucell6 (or older Pro-Power Prodigy) 'RC' chargers plus adaptor to connect to batteries

1 will charge only Blue-taped standard batts. Do NOT just try again more than once if you get an error. 3 tries can make a battery permanently unusable. This is the normal charger to use for Blue taped batts.

2 will charge only Green-taped modified batts. Charge Green-taped batts on this.

3 can charge all the batteries, but needs to be set up correctly. See below. It is normally used for diagnostics and recovering over-discharged packs which will not charge on the normal chargers.

Using Balance charger

This is the set of 3 (2 half-width) chargers made from old green/turquoise Makita chargers. They have a set of 4 LEDs. (The full-width one only has 1 LED in 2018). Charges at 40W.

  1. Make sure charger is powered (flashing green LEDs).
  2. Plug batt into charger. After a few seconds it should start charging.
  3. Look at the LEDs for status - the legend is printed on the RH end charger. Steady red for bulk charging to 80%. Steady orange for last 20% charging. Steady green for finished. If it flashes red and beeps (repeated 5 times) something is wrong - see table. If you get an 'undervoltage' reading, use an RC charger instead to get the charging started.
  4. Eventually it should show '100%' (steady green LEDs). (1hr 50 max possible charge time). You are done.

Accucell 6 RC charger

This is the black all-purpose charger with LCD display. Charges at up to 50W

The Yellow Propeak chargers do the same job, and instructions are similar, but have no fan, no backlit display, and if pack is low voltage will charge at C/10 (10% of normal) until voltage rises sufficiently. Charges at up to 50W.

  1. Make sure charger is powered (display lit up)
  2. Connect charger to battery (either hardboard adaptor or empty Makita green/turquoise 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 "Enter, Start Stop" button (the one at the right-hand end, the 4th one from the left) . It will do a battery check.

    LiIo CHARGE
    C=3300mAh 14.4Vp

  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 may be knackered, but more likely is just overdischarged, and thus can be coaxed back into action. Let it charge is if 3-cells for a minute or so, then restart. It should now register 4 cells.
  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).

Background knowledge about drills and batteries

This information will not go out of date.

Drills - read this!

Note that the drills have no battery-voltage monitoring at all, and the monitoring circuit in the battery is bypassed when connected to the drill. 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 battery, unless it's an emergency. Drilling with an excessively-sagged voltage will 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 - which means reassembling it back in Cambridge and welding in a new cell pair).

Makita charging protocol issues

An unmodified Makita mains charger

Makita have put very 'conservative' software in the batteries (as bought) which will stop them working on an as-bought, unmodified Makita charger, even when they are in fact fine. The monitoring board in the batteries is powered from the 1st cell pair so that pair 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-comms 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 circuit board in the battery 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 chargers capable of doing a "balance charge" (Black Accucell6 and older Yellow Pro-power Prodigy II). Unfortunataly Makita don't build the 14.4V packs with the necessary connections to the cells, so the circuit board in the battery has to be replaced to make this work easily for expo. For 2018 this was done for 7 of our packs, and 3 automatic balance chargers were built by Wookey.

Further explanation: the charger uses a different pair of electrical connections from those used by the drill - that's why there are not just two electrical connectors in the charger - to accommodate those extra connections.
A close-up of the control panel of an unmodified Makita mains charger

Types of charger

We have these types of charger; the non-mains chargers are all at top camp and can run all night using the car batteries:

Makita batteries

New for 2018 is varying battery capacity. We have 3Ah, 4Ah and 5Ah packs. Bigger packs will take longer to charge from empty. The capacity is on the cell label next to the yellow connector.

Each pack has a sliding indicator on the side. This is entirely manual, but is very useful for indicating when a pack is known to be charged, flat, or partly discharged. Slide the slider to show green for full, red for flat, half and half for 'partly used'.

Makita batteries: blue and green taped

If a battery has green insulation tape on it it has been modified by us and will not charge on an unmodified as-bought Makita charger.

All batteries will charge on the RC chargers, but not as fast as on the as-bought (mains power only) Makita charger. Go to RC charger.

Can I tell if a battery is already charged?

Simplest is try to charge it again and find that it says it is done in a couple of minutes (Up to 4 mins on the balance chargers). 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.

At end 2017 we bought two 4Ah packs. The non-makita one uses LG DAHD21865 cells (2Ah, 25A). I can't read the Makita cell type without unwelding the pack. For 2018 we made 3 new 5Ah packs from Samsung 25R cells (2.5Ah, 20A) (Sponsored by uk18650.com).

The drill discharges at 26A current draw when drilling (~400W), so that's 13A per cell in a 2P configuration.

Using Makita mains charger

This is the green/turquoise charger with 3 LEDs, and diagrammatic charging info on RH side. Charges at up to 100W.

  1. Make sure charger is powered (flashing green LED).
  2. Slide battery 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) charger instead.
  4. Eventually it should show '100%' (steady green LED) (in about 1 hour max). You are done.

Everything below here may be out of date due to breakages

Pro-peak Chargers (~2010-2019)

Short Instructions

First insert the battery.

Check that screen looks like this: Displaying

LiIo CHARGE
C=3300mAh 14.4Vp

If this is not the case then move to the long instructions.

If it is showing exactly as shown above, hold down the "Enter, Start Stop" button (the one at the right-hand end, the 4th one from the left) for two seconds. The screen will display "battery check" and then start charging.

The screen will then look something like below (but with different numbers) when charging:

CHG 0.04 00002
LI+3.26A 15.331V

If this is not the case then move to the long instructions.

Long Instructions

First insert the battery.

If the charging screen is not displaying the settings shown above then the correct charging settings need to be selected. You can do this as follows.

Now hold down the "Enter, Start Stop" button for 2 seconds until "Battery Check" is displayed and the screen looks similar to below, but with different numbers:

CHG 0.04 00002
LI+3.26A 15.331V