Using car alternator to heat water

[ThePortLion]

Hi

I am an automation engineer, so i have a fair electrical understanding but it's limited so bear with me.

I have a motor which runs (over belts) a vacuum pump at roughly 1300rpm. It runs for a little over 2 hours a day.

The idea was to put an ordinary car alternator on the belts and
use it to charge a car battery and in turn heat water using
a 12V 1.2kw element.

The question is 1) Could it work?
2) If so, how much water could I heat in the time it runs for? (approx 75 - 80degrees required)

Thanks in advance

 

[telectrix]

for that load at 12v your current would be 100A. think thats a bit excessive for a car alternator.

 

[ThePortLion]

What spec element would suit?

 

[telectrix]

wouldn't like to use more than 240watts. trhat would take forever to heat the water. there are heaters deigned for car use with a smoke lighter plug on. you just immerse them in your cup of water. as there is a lot less water in a cup than in a kettle, that may solve your problem

 

[ThePortLion]

Thanks for your help, much appreciated.

I would be talking about heating 50 litres of water.

What about using a high output alternator?

Would the battery go flat very quickly?

 

[Graeme Harrold]

What are you trying to achieve???

A basic fundemental law of physics is the "conservation of energy", what you are proposing is adding a load to an existing machine, using a friction drive (v belt, frictional loss) to run an alternator (frictional losses in bearings). In essence you will be loosing power in all of the additional components, plus adding to the load on the initial motor (reducing life span, exceeding its load rating etc...) to get hot water. Plug the element directly into your initial power supply, sit back relax, watch the vaccume pump do its thing while drinking your tea from your efficient boiler...........

 

[telectrix]

50litres. thats 11 gallons in english. that's 176 mugs of tea. bloody 'ell. hope you've got adequate bogs. honestly, though , i think heating that amount of water from any 12volt source is a no goer. a 4kW PV system would do better, only about 15k, better still buy a 3kwatt tea urn.

 

[ThePortLion]

Thanks for the help