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Re: Rolls PB224 power options

Subject: Re: Rolls PB224 power options
From: "Walter Knapp" waltknapp
Date: Sun Jul 2, 2006 8:37 am (PDT)
Posted by: "John Hartog"

> If you want to stick with the internal 9V batteries, Walt suggested
> this: "The Maha MH-C490F charger can charge the newer 8.4V & 9.6V Nimh
> batteries in two hours. 1-4 of them at a time. Works off 110V, car
> battery or I've tested it with a solar panel. There is also a 10
> battery version but it's 110V only.
> You do need the newer batteries designed for fast charge. I use
> Powerex 9.6 volt, but there are other brands. Probably other fast
> chargers too."

As a farther update, technology moves on. There are now NIMH 9.6 volt
batteries of a capacity around 225mah. And there's a 9 volt Lithium
Polymer rechargeable battery of a capacity of 500mah (requires a new
charger and I'm not sure of the actual battery voltage). Here's a few links=

The use of 8.4 volt rechargeable probably means that the battery is
barely used before the voltage drops low enough to interfere with
operation. This could especially be true if you are not fully charging
the batteries. Use only the newer 9.6 volt batteries (these often
measure just over 10 volts fully charged), and charge with a charger
designed for them. Note that because of the way the rating system works
they should still be at 9.6volts when 80% discharged. Regular alkalines
are rated differently, their voltage rating is for new, unused batteries
and drops rapidly in use. If your equipment is detecting voltage to give
low battery indications you may not be getting the full capacity of
alkalines either.

It is important with rechargeable to use a quality charger. And note
that when most newer chargers indicate the battery is charged they have
just switched from fast to finishing charge and the battery is at about
80-90% charged. For max charge leave the battery in the charger for a
couple more hours. If you are using a older trickle charger designed for
nicads, you should note with the higher capacity batteries your charge
time may be over 30 hours and the charger may not be capable of getting
the battery to it's full rated voltage.

I'm not a fan of external battery supplies. Just another thing to tangle
in the bushes out in the field. It's better to update your battery types
for internal and have extras. I'm not sure right off what the power draw
of the NT mics is, Rode's instruction manual only lists phantom power,
not the draw. There is also the problem of just how efficient the Rolls
power supply is.


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