Favorite reverse bias protection for battery circuits [Design]

Prev: ESD and surge Protection
Next: Investment Analysis and Portfolio Management Reilly 9th Edition complete Solution manual is available for purchase at affordable prices. Contact me at alltestbanks11[at]gmail.com to buy it today.

From: Joerg on 16 Mar 2010 20:32

D Yuniskis wrote:
> Hi Joerg,
>
> Joerg wrote:
>>>>>>> I take it you aren't making a custom (molded) case?
>>>>>>> Why not purchase COTS battery holder that *is* "keyed"?
>>>>>>
>>>>>> Anything other than AA cells is expensive. And as Charlie wrote AA
>>>>>> cells are difficult to key without going to precision molding or
>>>>>> milling.
>>>>>
>>>>> Yes. Find a battery holder that someone *else* has incurred
>>>>> the cost of that molding! Preferably, something that lets
>>>>> the user access the "battery compartment" without having
>>>>> to disassemble the device itself.
>>>>
>>>> Very tough. I had tried that at times in the past and there ain't
>>>> much out there. Even the ready-to-go enclosures with built-in
>>>> compartment that I came across aren't really good in that respect.
>>>
>>> I've been eying the Bulgin products. MPD and Keystone
>>> tend to be bottom feeder designs which haven't impressed
>>> me. But, I'm currently designing for much higher power
>>> requirements so batteries (at least standard cells)
>>> aren't an option.
>>
>> Their battery holders don't look particularly well keyed either:
>>
>> http://www.bulgin.co.uk/Products/BatteryHolders/BatteryHolders.html
>
> I've been through their site and haven't been able to find
> any mechanical drawings *or* photos that show enough detail
> to decide. I have a few on my next Digikey order just to
> "evaluate" -- though it would be hard to come to a conclusive
> decision for *all* of their products based on a sampling of
> a few... (if I like the quality -- touch and feel -- I will
> followup with a call to the manufacturer)
>

Yeah, their "datasheets" are not much to write home about.

>>>>> OTOH, if he is making "one off", a bit of plastic glued on either
>>>>> side of the '+' holder terminal can do the trick.
>>>>>
>>>>> I'd also look for those (camera?) batteries (two cells side
>>>>> by side... 3V?) as I think that is keyed (at the very
>>>>> least, it eliminates the problem of putting one cell in
>>>>> correct and one backwards)
>>>>
>>>> I have one, in case of a trip way into the boonies (those are Li
>>>> batteries so they'll last longer). Very expensive, not really an
>>>> option for everyday use.
>>>
>>> Are you sure? ...
>>
>> Yup:
>>
>> http://www.atbatt.com/product/14514.asp
>
> No, that's not the same battery. I'll have to find one of mine
> and see what size it claims to be...
>

But that's what you need when you want to replace two AA's. And you can
still reverse it.

>>> ... The ones I have are made by Duracell (though
>>> none of them are in convenient places for me to examine).
>>> I would imagine a "colorimeter" sees infrequent use so
>>> you would want a battery that's going to be "there for you"...
>>> (My pet peeve re: flashlights is you use them so infrequently
>>> that the batteries are *always* dead when you need them)
>>
>> That's why everyone here knows where the spares are. There are also
>> spare flashlights.
>
> We now use "emergency flashlights". I've disciplined myself
> to give each one a "quick wind" whenever I come across one
> just to keep the battery fresh.
>

We have two of those as well. But I am afraid there's just a puny NiCd
in there which will die some day, plus it has very little runtime per
charge. The old D-cell lights can go for hours. Ok, they don't have a
built-in NOAA radio.

> I recently came across one of these "emergency" devices
> that stores energy *mechanically* -- no more dependence
> on Li cells (going bad from lack of use). I need to
> see what other offerings they have.

I was (so far) rather disappointed by all this alternative stuff. It all
broke in due course. Nothing beats the old 2-cell $2.99 flashlight. Ok,
on the job I also carry a tiny MagLite Solitaire that needs only one
AAA. That has saved the day quite a few times. PHUT .. *BOOM* ... "S..t!
I can't see anything and somethin's glowing over here!" ... "Wait, I've
got a li'l lamp"

--
Regards, Joerg

http://www.analogconsultants.com/

"gmail" domain blocked because of excessive spam.
Use another domain or send PM.

From: D Yuniskis on 16 Mar 2010 21:26

Hi Joerg,

Joerg wrote:
>> I recently came across one of these "emergency" devices
>> that stores energy *mechanically* -- no more dependence
>> on Li cells (going bad from lack of use). I need to
>> see what other offerings they have.
>
> I was (so far) rather disappointed by all this alternative stuff. It all
> broke in due course.

Yup. "Plastic". Designed to appeal as "impulse buys".

> Nothing beats the old 2-cell $2.99 flashlight. Ok,
> on the job I also carry a tiny MagLite Solitaire that needs only one
> AAA. That has saved the day quite a few times. PHUT .. *BOOM* ... "S..t!
> I can't see anything and somethin's glowing over here!" ... "Wait, I've
> got a li'l lamp"

I just want something for my bugout-bag that I can rely on
*without* having to worry that some component (e.g., a
battery *buried* inside the "emergency light") has died
because it's been in storage for 10 years... I *think*
this thing will work good as there are no "components"
that I'd have to worry about crapping out (just the little
DC "motor/generator" and a bunch of mechanical bits)

What good are emergency devices if you can't rely on
them in an emergency?? :>

From: Joerg on 16 Mar 2010 21:21

D Yuniskis wrote:
> Hi Joerg,
>
> Joerg wrote:

[...]

>> Nothing beats the old 2-cell $2.99 flashlight. Ok, on the job I also
>> carry a tiny MagLite Solitaire that needs only one AAA. That has saved
>> the day quite a few times. PHUT .. *BOOM* ... "S..t! I can't see
>> anything and somethin's glowing over here!" ... "Wait, I've got a li'l
>> lamp"
>
> I just want something for my bugout-bag that I can rely on
> *without* having to worry that some component (e.g., a
> battery *buried* inside the "emergency light") has died
> because it's been in storage for 10 years... I *think*
> this thing will work good as there are no "components"
> that I'd have to worry about crapping out (just the little
> DC "motor/generator" and a bunch of mechanical bits)
>
> What good are emergency devices if you can't rely on
> them in an emergency?? :>

That's what preventive maintenance is for :-)

Seriously, we religiously replace the smoke detector batteries twice a
year, my lab stuff is also done regularly, and so on. With flashlights
there are a few that always get exchanged when the regular-use one dims
out and their batteries get installed in the regular-use flashlight. So
there is a rotation scheme. Same with smoke detector batteries, they are
used up in the voltmeters, the radios I use for EMI work and so on. IOW
in gear where a low-bat situation is ok but used often enough that it
won't leak from old age. This way only depleted batteries are discarded,
nothing goes to waste.

--
Regards, Joerg

http://www.analogconsultants.com/

"gmail" domain blocked because of excessive spam.
Use another domain or send PM.

From: D Yuniskis on 16 Mar 2010 21:42

Joerg wrote:
>> I just want something for my bugout-bag that I can rely on
>> *without* having to worry that some component (e.g., a
>> battery *buried* inside the "emergency light") has died
>> because it's been in storage for 10 years... I *think*
>> this thing will work good as there are no "components"
>> that I'd have to worry about crapping out (just the little
>> DC "motor/generator" and a bunch of mechanical bits)
>>
>> What good are emergency devices if you can't rely on
>> them in an emergency?? :>
>
> That's what preventive maintenance is for :-)

Bug out bag isn't something that sits in a prominent
position in the house. I.e., you've got to go *looking*
for it. And, hopefully, *never* need it. (out of sight,
out of mind)

> Seriously, we religiously replace the smoke detector batteries twice a
> year, my lab stuff is also done regularly, and so on. With flashlights

Aside from smoke detectors, we don't use anything with
replaceable batteries, here. No, I take that back,
the remote control for TV, etc.

Smoke/CO/Heat detectors are AC+DC. I think the battery is
not used -- though tested once a minute? -- in normal
operation. Replace on New Year's eve.

Anything else with a battery tends to be rechargeable
(iPods, PDAs, etc.). And, those batteries are silly to
replace as I can often rescue a replacement for the
entire device instead of paying as much for a "new"
battery :-/

> there are a few that always get exchanged when the regular-use one dims
> out and their batteries get installed in the regular-use flashlight. So
> there is a rotation scheme. Same with smoke detector batteries, they are
> used up in the voltmeters, the radios I use for EMI work and so on. IOW
> in gear where a low-bat situation is ok but used often enough that it
> won't leak from old age. This way only depleted batteries are discarded,
> nothing goes to waste.

From: Joerg on 16 Mar 2010 21:36

D Yuniskis wrote:
> Joerg wrote:
>>> I just want something for my bugout-bag that I can rely on
>>> *without* having to worry that some component (e.g., a
>>> battery *buried* inside the "emergency light") has died
>>> because it's been in storage for 10 years... I *think*
>>> this thing will work good as there are no "components"
>>> that I'd have to worry about crapping out (just the little
>>> DC "motor/generator" and a bunch of mechanical bits)
>>>
>>> What good are emergency devices if you can't rely on
>>> them in an emergency?? :>
>>
>> That's what preventive maintenance is for :-)
>
> Bug out bag isn't something that sits in a prominent
> position in the house. I.e., you've got to go *looking*
> for it. And, hopefully, *never* need it. (out of sight,
> out of mind)
>

Ahm, what about the food items in there? Just imagine, you and your
family have successfully evacuated. Now dad does the manly thing and
starts the fire. Mom pulls out a can of Progresso, says 'Best before
1998' on there, puts in can opener ... *POOF* .. *SPLAT* ... a horrid
stench wafts through the area ... "Oh, maybe that's why the can was
bulging" :-)

[...]

--
Regards, Joerg

http://www.analogconsultants.com/

"gmail" domain blocked because of excessive spam.
Use another domain or send PM.