Anyone have a line on batteries for the NLS

[Allison]

>
>Subject: Re: Anyone have a line on batteries for the NLS
>   From: ard at p850ug1.demon.co.uk (Tony Duell)
>   Date: Sat, 07 Feb 2009 19:32:31 +0000 (GMT)
>     To: cctalk at classiccmp.org
>
>> 
>> On Thu, 5 Feb 2009, Allison wrote:
>> > The only reason batteries are needed to run the NLS is the charger is way
>> > too small run run it directly.
>> 
>> I found THAT out the hard way.
>> When I sold my NLS215 at VCF, I had to sell it "AS-IS" because the
>> batteries wouldn't take a charge.
>
>That's quite common with devics powered with rechargeable batteries -- 
>the charger on its own can't supply enough current to run the device.

For the NLS 'scopes the battery is between the charge source and the 
scope power supply so if it's open (badly sulfated as the battery is 
lead acid gell type) the PS has to carry the load. It's only a charger.
if you substitute a larger charger then you find the charge circuit
does not have the capacity to start the unit (initial surge current).

>Assuming the battery pack is just a battery (that is, no 'battery 
>management' circuitry), you can often run the unit from a bench power 
>supply connected to the battery wires _with the battery disconnected_. Of 
>course this assuems you have a suitable PSU...

The pack in this case is just 3 2v cells and the "management" is the 
charge circuit on the rear board.

In this case (nls miniscopes) a 6V PS can substitute for the battery at 
less tha 1A (must be connected to the ground and +6V termianls of the 
battery connection point internally).  Only if the battery is removed first.
Note that is the battery has failed (usually sulfated from not being kept 
charged) they tend to build corrosion around the terminal, they are best 
removed and recycled as any gelled lead acid battery should be.

Since I use my miniscopes intermittently I've long since removed the 
battery and disconnected the internal charge circuit (pull the fuse).
The battery area has a small board inserted to allow it to accept any 
voltage from 9 to 30V and run from that.  Since I have a number of small
12V gell cells that fit nicely in the probe pocket of the carry case 
this proves more useful and maintainable.  The change is completely 
reverseable and the ability to use a larger and longer lasting 12V 
battery as source is very handy.

The NLS is somewhat unique as it uses a lead acid type rather than NiCd, 
Nimh, lithium or even common dry cells. In an emergency I have run it
off 4 'D" sized alkaline cells in an external holder for many hours.


Allison