[volt-nuts] volt-nuts Digest, Vol 24, Issue 19

[shalimr9 at gmail.com]

0.1C is not trickle charge, it is the normal charge rate for 14 hours recharge time.
Most NiCad and NiMH batteries will not like that too much as a trickle charge rate and will get and stay warm, at least those that I have had experience with. The batteries in the HP 8116 function generator were trickle charged at that rate and cause extensive damage when they get tired of it. I have had better luck


Trickle charge would be 1/10th or 1/20th of that.

Didier KO4BB

Sent from my BlackBerry Wireless thingy while I do other things...

-----Original Message-----
From: "Dave M" <dgminala at mediacombb.net>
Sender: volt-nuts-bounces at febo.com
Date: Mon, 22 Aug 2011 10:16:18 
To: <volt-nuts at febo.com>
Reply-To: Discussion of precise voltage measurement <volt-nuts at febo.com>
Subject: Re: [volt-nuts] volt-nuts Digest, Vol 24, Issue 19

> Subject: Re: [volt-nuts] Battery pack info for Fluke 731B
> Message-ID: <4E517BCA.7080103 at pacific.net>
> Content-Type: text/plain; charset=ISO-8859-1; format=flowed
>
> Hi David:
>
> You can buy battery packs ready made or buy individual cells with tabs
> for easy soldering from:
> http://www.batteryspace.com/NiCdBatteriesAndPacks.aspx
>
> Have Fun,
>
> Brooke Clarke
> http://www.PRC68.com
> http://www.End2PartyGovernment.com/
>
>
> Dave M wrote:
>> I bought a Fluke 731B DC Reference Standard at a hamfest yesterday.
>> It seems to be working in all functions, but is missing the 10-turn
>> indicating dial on the front panel, and the battery pack.  I think I
>> have found a suitable replacement dial from Digikey (Digikey pn
>> SP015-1-11-ND).
>> I need to know the voltage and current rating of the battery pack.
>> Does anyone have any info on the battery?  I know that it's a NiCd
>> pack, and I suspect that it's a 12-cell pack (14.4V), but that's
>> just a guess.  The manual just gives Fluke's part number for the
>> battery; no other data.
>>
>> Thanks for helping,
>> David
>> dgminala at mediacombb dot net
>>

Aargh!  I had to cancel the order that I had placed with 
http://www.batterystation.com because they couldn't put tabs on those cells. 
Seems that they were a special lot somewhere in a warehouse in the far west 
that didn't have a welder to attach the tabs.  So, I went to the site that 
Brooke suggested (batteryspace.com) and ordered two of the 7.2V 1600 maH 
2/3A NiMh packs for $12.95 each.  Higher maH rating, plus already assembled 
into a pack.
As an afterthought; I'm wondering if I could install a "smart charger" 
inside the unit to properly charge the battery pack instead of leaving it on 
trickle charge all the time.  From the schematic, I'm guessing that the unit 
trickle charges the battery pack at around 10ma.  Normally, NiCd and NiMh 
batteries like to be trickled at 0.1C, which would be 160ma for the battery 
pack I've ordered.  I doubt that the little power supply in the 731B could 
handle such a drain.  That's why the thought about installing a smart 
charger.  Are "smart chargers" quiet or do they emit any EMI or RFI that 
might conduct to the output of the unit?

Thanks for all the info and advice.
David
dgminala at mediacombb dot net




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