Off topic help needed
Forgive this clearly off-topic request for help. I am working with a friend to identify AC power problems in his shop. To this end I have retrieved my old BMI GS-2 power line monitor out of storage. It is fitted with six (6) double A (AA) size rechargeable batteries that are in very bad condition, covered with white crystalline corrosion. I am guessing these are 1.2 V batteries but I am not sure, nor do I know what type of rechargeable batteries these are.
The instrument was made in the early 1980’s. The schematic identifies these batteries as Gould MS5001. The actual batteries appear to have been manufactured by SAFT in Mexico and carry the number PT 406418 and I’m guessing the number 4882 is a lot or DOM number. Thus far web searching has proven futile.
Any help will be most appreciated!
Thanks for the bandwidth.
I'd guess 500 mah NiCD (not NIMH) batteries.toggle quoted messageShow quoted text
IIRC, at that time, it was all you could get other than lead acid batteries, which would have a very different package. 6 batteries gives you 7.2 volts to 8 volts nominal, which when used with a 7805 regulator (needs about 3 volts differential, not sure that they had low dropout regulators then). This gets you close to the right voltage. You can make a lower dropout regulator with trasistors, so the numbers work.
On 6/28/2021 8:29 PM, ken chalfant wrote:
BMI is very old, may have CAl or other issues. The testing my be easier with a $20 power line watt meter
The old SAFT are NiCd made originally in France. 1.25V.
You can still get NiCd replacements as cells or packs.
I have had very good reliability performance replacing old NiCads with the “Tenergy” brand of battery. I have gone the course using other manufacturer’s products with less-than-desirable results. If you want to build your own battery packs they also offer batteries with pre-installed tabs on both ends.
Not knowing where you live (country) they may or may not be available.
If you need AA or AAA rechargeable batteries that have a true 1.5VDC output
rather than the usual 1.2VDC of NiMH batteries, look at the Tenavolts
rechargeable ones. These use lithium chemistry to achieve a 1.5VDC output.
They need a charger for the lithium cells, so the ones I bought came with a
four-cell charger. They now make chargers that can hold more cells. They
work very well in LED flashlights. The only thing to be aware of is that
they are slightly larger in diameter than alkaline or NiMH cells. I have a
smoke detector that uses AA batteries and they would not fit. I use NiMH
batteries in it, but since the voltage is lower to start with, I get the
"low battery" warnings in a shorter time than I do with alkaline cells. For
AA and AAA NiMH cells, I like the Panasonic Eneloop ones. They have very
low self-discharge so will retain their charge in storage for over six
months with little drop in supplied current. They fall into the
"precharged" class and usually arrive with a full charge and can be put
right into equipment. I have also used Tenergy cells and agree that they
are very good; little difference from the Eneloop ones in terms of mAH
capacity and low self-discharge.
I also avoid using the "quick charge" settings on chargers (if they have
them) since this results in shorter overall life (fewer recharge cycles
before they will no longer hold a charge for a reasonable time). Some
chargers allow you to set a charging current or to select between "fast"
and "soft" charging. If you have the time, use the latter. Some chargers
also have a "condition" mode. This can bring marginal rechargeables (I've
used this with NiMH cells) back to "life". I've used this mode when one
cell in a battery-powered device has gone low but not reverse charged. Even
if it seems to be completely dead, this "condition" mode - which cycles
between a full charge and full discharge several times - can return it to a
state in which it will take a full charge and keep it. Even though NiMH
cells are supposed to have little or no "memory" it does seem to happen and
this condition mode gets rid of it.
On Tue, Jun 29, 2021 at 12:58 PM Greg Muir via groups.io <big_sky_explorer=