Physics - electricity problem

chapz

chapz

Active member
hey guys, so i have an assignment for my engineering class and i need some help!

the question is

If you had an old car that needed a 6V battery to drive the starter motor, could you use a 12V battery with a transformer to get the necessary output voltage?
 
gah i knew it had to do with this. i found it weird how were studying AC and question dealing with batteries comes up.... thanks a lot!
 
hahahah

well i live in quebec so we have cegep here.

we have

5 years of high school

2 years of cegep

4+years of university .... and so on

this class is one of 3 final science classes in cegep (2nd year, 4th semester) so its the same level of difficulty as a university class, so dont feel too dumb! haha
 
You could put a resistor in series with the stater motor. If the resistor and motor have the same resistance then the voltage will be split between the two (i.e. 6V p.d over each). This is assuming that the starter motor has a (roughly) constant resistance in startup. A potential problem is that resistors are normally small (so have a small thermal mass) but there will be quite a large current going through at start up so it will heat up very quickly (and maybe burn out).
Alternatively; if you assignment allows you to be practical/use common sense, go and get a 6V motor bike battery (not as common as 12V but definitely available).
You can make/buy a DC-DC inverter/transformer combo that will step up/down DC voltage to DC voltage but they normally wouldn't be capable of driving a load like a stater motor as they can't handle much current.
By the way if the car is an old 6V system it probably has a positive earthing, while modern car systems are negative earthed.
 
i have no knowledge on this at all; but i know in a pinch, you can tape AA to D's or C's etc. and transfer a charge -- would that be possible here?
 
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