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Science-Related Homework Help Physics Topic started by: darkstar28 on May 9, 2013



Title: Wiring batteries in series and in parallel to get at least 133 volts and 500 amps?
Post by: darkstar28 on May 9, 2013
It's for a hobby experiment. I've been successful at getting 48 volts and 195 amps by connecting 4 12 volt 195 amp big rig batteries in series. I have a total of 8 batteries to work with and can try to get more. The resistance I'm working with is 0.265. Is it possible to wire them both in series and in parallel to get at least 133 volts and 500 amps? If so, what would the connections be?


Title: Wiring batteries in series and in parallel to get at least 133 volts and 500 amps?
Post by: Nurnin on May 9, 2013
"If so, what would the connections be?" Very very dangerous.

As the amount of current needed to kill a human is on the order of 50 milliamperes, 500 amps would cook you if you ever touched it the wrong way.

However, to answer your question: putting power sources together in series adds the voltages together, but does not change the current. Adding them together in parallel adds the current, but not the voltages. You would need to do both to get the voltage and current you desire.


Title: Wiring batteries in series and in parallel to get at least 133 volts and 500 amps?
Post by: fewtew on May 9, 2013
just add batteries until it blows up in your face


Title: Wiring batteries in series and in parallel to get at least 133 volts and 500 amps?
Post by: Ikkou on May 9, 2013
This is very dangerous for a hobby, I would suggest you look at the theory but don't realise it in practise.  You are talking about 66kW of power there which could easily kill you if applied in the wrong spot, or kill someone else.  Permenant injury is a real possibility too if some of the connections cant take the power, you may end up with molten metal on you.

Theory wise you cant really get 8 12V batteries up to anything higher than ~96V without additional circuitry.  The voltages add in series while the currents add in parallel.  So the maximum voltage you can get with just the batteries and basic wiring is 96V, with the current being the rated current for one of those batteries.  The maximum current you can get with 8 batteries is 8* the max rated current for the batteries with the voltage of the parallel circuit equal to 12V.  You might be able to get more current but don't exceed the manufacturer's maximum current ratings.

Combinations of series and parallel wirings will yield different currents and voltages.  Make sure you have the same number in series for each parallel connection though (e.g. 2 parallel connections of 4 series batteries each etc)

So to get ~133V you would need 11 batteries in series (133/12V = 11.08 batteries, will actually  give 132V but the batteries wont exactly be 12V each in reality) the current I would say three banks, which will give you more than 500A (195A * 3 banks =  585A) in theory but you can limit the current that the batteries provide.

So 33 batteries total to to accomplish that in theory but don't do it in reality ever, its way too dangerous and can kill you and others.


Title: Wiring batteries in series and in parallel to get at least 133 volts and 500 amps?
Post by: smileylady6770 on May 9, 2013
To get 133V you'd need 11 batteries in series, which will give you 195A@132V.

To get 500A you need 3 of these strings of these paralleled together... so 33 batteries total for 132V@585A. (Actually, the  fully-charged voltage will be closer to 140V.)

But... be very, very careful. That's some serious energy you're working with there, a dead short will melt a misplaced socket wrench almost instantly (not to mention catch on fire), while the voltage itself can be lethal.

There was a Monster Garage episode where they built an electric dragracer out of a '62 Bel-Air and a pair of crane motors powered by an array of 28V lithium power cells. Link below.


Title: Wiring batteries in series and in parallel to get at least 133 volts and 500 amps?
Post by: rin615 on May 9, 2013
A car battery is 12.6 volts (the cells are about 2.1 V each so the actual voltage is about 12.6V at full charge).

Put eleven 12 volt batteries in series and you'll have 138.6 volts when they're fully charged. If they're 500 cold cranking amps batteries, you'll have 500 amps for about 30 seconds. After a ~20 minutes recovery, you might have it again.

If you need more current, parallel another 11 batteries in there.

Be really careful. Not only can this kill, but the batteries can explode.
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Cold cranking amps (CCA) is the amount of current a battery can provide at 0°F (?18°C). The rating is defined as the current a lead-acid battery at that temperature can deliver for 30 seconds and maintain at least 1.2 volts per cell (7.2 volts for a 12-volt battery). It is a more demanding test than those at higher temperatures.
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