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

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Wookey 2017-08-06 13:49:29 +01:00
parent 2eedf99900
commit b91d5bead9
1 changed files with 42 additions and 4 deletions
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46
handbook/charging.html
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@ -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
charge on the Makita standard charger and the Balance/RC charger should be used. Go to <a href="#RCcharge">RC charger</a>.</li>
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. 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>
</body>
</html>