mick
Well-Known Member
If I run a 400W heater from a 17ah powerpack, nothing else connected, how long will I get? (Ditto 1200W.)
Battery stamina
- Thread starter mick
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sailinglegend420
Well-Known Member
About 4 minutes!!!!!
bobgosling
Well-Known Member
Watts are just Volts X Amps
400 Watts = 12 Volts X 33(ish) Amps
If your battery can give 17 Amps per Hour then it should also give 33 Amps in 0.51 hours
Of course, 33 amps is going to melt most cables anyway ....
400 Watts = 12 Volts X 33(ish) Amps
If your battery can give 17 Amps per Hour then it should also give 33 Amps in 0.51 hours
Of course, 33 amps is going to melt most cables anyway ....
sarabande
Well-Known Member
At that discharge rate, there will be more heat given off by the battery boiling than by the fan. There's a bit of a mismatch if you are talking 12v.
pvb
Well-Known Member
Only a few minutes...
The correct answer is only a few minutes. Your battery's 17Ah capacity will most likely be quoted at the 20hr rate. This means it'll supply 17Ah at a steady discharge over 20 hours (ie just under 1A discharge). If you try to take 33A (400W divided by 12V) out of it, it's capacity will be dramatically reduced. The actual reduction will depend on many factors, but you'll probably only get 15-20% of the theoretical 17Ah capacity - let's say 3Ah in round numbers. So the 33A current will flatten the battery in less than a tenth of an hour - around 5 minutes maybe.
The correct answer is only a few minutes. Your battery's 17Ah capacity will most likely be quoted at the 20hr rate. This means it'll supply 17Ah at a steady discharge over 20 hours (ie just under 1A discharge). If you try to take 33A (400W divided by 12V) out of it, it's capacity will be dramatically reduced. The actual reduction will depend on many factors, but you'll probably only get 15-20% of the theoretical 17Ah capacity - let's say 3Ah in round numbers. So the 33A current will flatten the battery in less than a tenth of an hour - around 5 minutes maybe.