In message <00f901c3faea$938787d0$0402a8c0@xppro>
          John Ferrell <johnferrell@EARTHLINK.NET> wrote:

> The first pack I had was a Lithium. They were expensive and replacement
> cells were impossible to buy.
I'm not a great fan of Li-ion batteries. Well, except for the one in my
mobile phone... Eight days standby with the LiIon vs. three to four days with
a NiMH. No competition :)

> I have extensive experience with NiCads and several chargers from another
> hobby, RC airplanes. Other than the numbers, NiMh seems to behave similarly.
I've got some GP (Gold Peak) 150AAH cells that I've just soldered into a 4.8V
1500mAh pack - now I just need a charger. Now where did I put those
MAX712s...
And, yes, the pack has a thermal fuse fitted. 103 Celsius.

> BTW, If you choose to fabricate a NiMh fast charger, do not rely on
> detecting the voltage turn down to stop the process. It is easily missed and
> there should be some sort of limit on the total charge.
The MAX712 I wanted to use has three cutoff signal sources - Dv (voltage
dip), Dt (temperature peak) and time (pretty obvious). I'm planning to build
a two hour charger. GP's datasheet says the timer should be set to 105% of
the theoretical maximum charge time. For a 2-hour (120min) charge, that's 126
minutes. I'd be tempted to set the MAX712 a bit higher than that - around
135mins.

> The charger I use
> for RC batteries allows me to set the overcharge limit if the turn down is
> missed. I usually limit the charge to 120% of the batterry rating.
I don't ever go above C (battery capacity), and I usually charge the
batteries at C/2 (fast 2-hour) or C/10 (trickle).

Now to see if the Bq2014 will behave a bit better if I connect it up to the
new, drained battery pack. Fingers crossed.

Later.
--
Phil.                              | Acorn Risc PC600 Mk3, SA202, 64MB, 6GB,
philpem@dsl.pipex.com              | ViewFinder, 10BaseT Ethernet, 2-slice,
http://www.philpem.dsl.pipex.com/  | 48xCD, ARCINv6c IDE, SCSI
... Old age is better than the alternative.

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