They do, of course, as do 'all' the others? As Mayson said to Dixon, 'just draw the line.....'. They decide when to shut down. This is known as 'depth of discharge', sometimes 'DOD' in geek circles. But remember, every .1 Volt means a 10% change in useful capacity. How do you think Sales feels about harder to sell lower run time numbers and longer times before customers come back for more? If they get too conservative with it, the competition will steal the customers......we being so addicted to numbers.
FWIW, they could easily cut 10% of to top of the charge, four minutes run time, and DOUBLE the cycle life of the battery. This is covered in the BU stuff. A 10% drop doubles Li-ion cycle life. From say 300 to 600. Pretty useful, IMO. Drop it another 10% and it doubles again! 1200 cycles at 80% of the former 300?
But 300 is enough to get it out of warranty..... They don't charge to 4.3 Volts since that would no doubt cause too many returns (very expensive, each one 'wipes out the profit' from a bunch of new sales).
Not that HR is alone in this. In fact, LiPo cells like we have here 'die on their own' in a few years anyway. But the idea is so common, that is makers want to push the limits, that NOBODY (I could find) makes a charge controller for commercial Li cells that doesn't push 4.2 Volts (typical 4.15 to 4.25) since they couldn't sell it to anyone...... There are competitive ICs to do this, of course, but they all use that 'right to the wall' number. Except the military, which often demands a 3.95 Volt charge limit. Knowing it will cut run time 20% but in exchange give service life in the field to match the unit (no replacements with the bad guys shooting at you). The only 'off the shelf' IC I could find was a mil spec part that costs more than a F2 and took 6 weeks for delivery. So I built this, originally for Solo:
At the top is a little computer and other parts that control the 12VDC to the unit. When you push the button charging starts as the unit watches the current. You'll note from the BU stuff that the charge current starts to cut back as the cell reaches full voltage? Shifts from constant current to constant voltage mode, reducing the current to stay 'under the line'? My Gadget senses that and at a point set by the adjustment above the go button, cuts the charge off about 20 minutes early and runs the beeper to wake you up. Faster charges (the last bit is slow.....) and longer battery life.
The part below reduces the 12VDC for units like Ascent, the big FMs and others that charge at 9 Volts instead.
So that's my take, they could easily make it work.....if they were so inclined. But
universally (?) they opt to be competitive and 'use logic'. Sales logic.
OF
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