Add a load of detail on the 'makita charger protocol' issue.

handbook/charging.html

@@ -12,8 +12,10 @@
 
 
 <h2>Instructions for charging</h3>
-0) <li>If the battery has insulation tape on it (red or earth) it won't
+0) <li>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. Go to <a href="#RCcharge">RC charger</a>.</li>
+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 <a href="#RCcharge">RC charger</a>.</li>
 
 <h3>Using Makita charger</h3>
 
@@ -69,12 +71,48 @@ while (1-5 mins).
 
 <h3>What sort of batteries are they</h3>
 
-The drill batts are 4S2P 14.4V lithium ion packs (8 18650 cells: 4 in
+<p>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).
+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. </p>
 
+<h3>Makita charging protocol issues</h3>
+
+<p>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).</p>
+
+<p>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.</p>
+
+<p>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 &lt;2V for any length of time as they rapidly
+(hours/days?) degrade to useless in this state (and that pair will
+need replacing).</p>
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