How do I make a 12v UPS??

headstrong said:
I want to run a wireless AP which uses 12v @ 1 amp.....I used my multimeter and it confirms what gnome said about my AC/DC running at 16 volts instead of 12....

From what I understand the AP will only draw the amperage that it needs and so it shuldnt receive the full charge and blow itself up....right?
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the ac/dc is probably the cheepie type that kinda runs amok when no load is placed on it..same as most cellphone chargers.

when you apply a load they will stabilise to their rated voltage.
if you plug the ac/dc into the wall, and probe with your multimeter at the jack plug, with no device connected, then you WILL register a significantly higher voltage.
 
BiteMe said:
the ac/dc is probably the cheepie type that kinda runs amok when no load is placed on it..same as most cellphone chargers.

when you apply a load they will stabilise to their rated voltage.
if you plug the ac/dc into the wall, and probe with your multimeter at the jack plug, with no device connected, then you WILL register a significantly higher voltage.
Click to expand...


that explains it then...

OK so the general consenses if I were to connect a 12v car battery to my 12v wireless AP would be that my AP would be safe????
 
BiteMe said:
yes...it will be perfectly ok.
:-)
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Great thanks alot guys

Ok next thing.....how would I attach a battery charger to the setup? I want to keep the battery on float charge aswell as connected to the AP so when the power goes off my AP stays running....??????
 
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No worries.

Do you get problems with your WRT resetting its settings after power failures ?
 
My WRT54gl is running tomoto firmware and doesn't seem to reset at all.....
 
BiteMe said:
that is blatantly wrong.
your amps needs to be either the same or higher..the device will draw the amps it needs to operate. like a big tank, you only take what you need.

volts, however, can be though of as "pushed" into the device. and too many volts will damage it.

where did you get your info from? a chappies wrapper?
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:Dbite me fo saying this but i stand with my answer:mad:

let me shed some light for you ok
Amps is the load
voltage is the river.
Now you can have 1000 v on a line and you will not shock,its the amperage that burns you alive

A 1000v line with a low amps cant kill you but a 1000v with 14amps will,theorectically:D

voltage needs to carry amps in a line which then does the work of your device,I am correct or was i away to long away from tertiary education
 
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dablakmark8 said:
A 1000v line with a low amps cant kill you but a 1000v with 14amps will,theorectically:D
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No, not quite. Remember, V = IR. When one shocks, it is the amps that kill you, but the amount of amps drawn depends on the resistance placed over the potential difference (or voltage), thus the resistance your body will offer. The amps drawn is dependent on both the load (resistance) and the potential difference (voltage).

However, placing a router on a car battery can be a bad idea, because as someone said, it really runs at a couple of V higher than 12V. That means that placing the router (that has a constant resistance) on a higher voltage, will draw more amps, and those higher amps might kill the router. That make sense to anyone? :o
 
dablakmark8 said:
:Dbite me fo saying this but i stand with my answer:mad:

let me shed some light for you ok
Amps is the load
voltage is the river.
Now you can have 1000 v on a line and you will not shock,its the amperage that burns you alive

A 1000v line with a low amps cant kill you but a 1000v with 14amps will,theorectically:D

voltage needs to carry amps in a line which then does the work of your device,I am correct or was i away to long away from tertiary education
Click to expand...

You are leaving out resistance... Volts, amps and resistance are related.
 
yes i know but in theory if there was only that which i said.
I just wanted biteme tounderstand that i am not a moegoe that chews chappies all day...only sometimes...lol
 
dablakmark8 said:
yes i know but in theory if there was only that which i said.
I just wanted biteme tounderstand that i am not a moegoe that chews chappies all day...only sometimes...lol
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hey, i dont know you so cant judge, thats why io asked about the chappies.

anyway, even if i know you or not you are wrong. :-) hehehe

ok, put it into language you understand.
12v courtesy light in the car interior...lets say it draw 12w to operate, so that is 1amp.
and it is running off a 65+Amphr battery
notice the lack of smoke...because the device (lamp) will only draw 1amp from the battery.

notebooks...ac/dc adapters....19v@60 watt= ~3amp.
now, take a 4 or 5 amp ac/dc (like the old p4 desktop cpu laptops had) and voila...the things works fine.

amp=capabilty to supply...
i refuse to post a link to wiki. :-)
 
There is no way of winning with you,but lets say you right,and leave it as that.....
I am maybe a bit rusty,but i worked many years in modifying car electronics and not once did i burn any car wiring...lol
 
BiteMe said:
hey, i dont know you so cant judge, thats why io asked about the chappies.

anyway, even if i know you or not you are wrong. :-) hehehe

ok, put it into language you understand.
12v courtesy light in the car interior...lets say it draw 12w to operate, so that is 1amp.
and it is running off a 65+Amphr battery
notice the lack of smoke...because the device (lamp) will only draw 1amp from the battery.

notebooks...ac/dc adapters....19v@60 watt= ~3amp.
now, take a 4 or 5 amp ac/dc (like the old p4 desktop cpu laptops had) and voila...the things works fine.

amp=capabilty to supply...
i refuse to post a link to wiki. :-)
Click to expand...
say its a perfect world and there is no resistance,and all the other mattajalas.
I still stick with that 1000v-no shock thingie;)
 
I've decided to use a 12v 7aH battery...nice and cheap compared to a ups ..about R130

So now I need a charger.....Am I correct in assuming that the charger and the AP is need to b connected to the battery in parrallel????? So if the power fails then my AP stays on?
 
dablakmark8 said:
I am maybe a bit rusty,but i worked many years in modifying car electronics and not once did i burn any car wiring...lol
Click to expand...

yeah, i figured that out already:-) which is why you asked this morning if the relay had numbers on it..i take it you were looking for 84 and 86 etc as per bosch.

anyways, i dont mean no harm, just ignore me when i whine.
 
Can I use my ac/dc transformer which came with the AP to charge the 12v 7aH battery and run the AP at the same time?
 
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