Battery Vehicle battery as a power source

[Drummo1995]

If I use a vehicle battery connected to jumper cables, which is then connected to the heating element of a kettle, which is then placed in play sand, in a metal container, will the sand then heat up?

 

[UKMeterman]

If you want something that is safe and less hassle than the kettle then try someihing like Arcol, 27Ω 25W Aluminium Chassis Mount Resistor HS25F 27R F ±1% | RS - https://uk.rs-online.com/web/p/chassis-mount-resistors/1860145?gb=s this will dissupate 5W, the same kind of heat as a sidelamp on a car and comes with wires ready attached. get it bolted to a small bit of metal say a couple of inches across after a few minutres I would expect a decent themal night site to see it from miles! To make 12V batteries safe you must have an inline fuse such as H7335 | iMaXX Fuse Holder | RS - https://uk.rs-online.com/web/p/fuse-holders/2884498 (holder) and a fuse such as 0287003.PXCN | Littelfuse 3A Purple Blade Car Fuse, 32V dc | RS - https://uk.rs-online.com/web/p/car-fuses/7874142 If you short out a car battery it will melt the offending item, probably cause a fire and the car battery may explode. RS have trade counters across the country and also do mail order.

 

[Drummo1995]

If you want something that is safe and less hassle than the kettle then try someihing like Arcol, 27Ω 25W Aluminium Chassis Mount Resistor HS25F 27R F ±1% | RS - https://uk.rs-online.com/web/p/chassis-mount-resistors/1860145?gb=s this will dissupate 5W, the same kind of heat as a sidelamp on a car and comes with wires ready attached. get it bolted to a small bit of metal say a couple of inches across after a few minutres I would expect a decent themal night site to see it from miles! To make 12V batteries safe you must have an inline fuse such as H7335 | iMaXX Fuse Holder | RS - https://uk.rs-online.com/web/p/fuse-holders/2884498 (holder) and a fuse such as 0287003.PXCN | Littelfuse 3A Purple Blade Car Fuse, 32V dc | RS - https://uk.rs-online.com/web/p/car-fuses/7874142 If you short out a car battery it will melt the offending item, probably cause a fire and the car battery may explode. RS have trade counters across the country and also do mail order.

Thankyou, will I have to attach anything to the chassis mount resistor? And how long can I run it on a 12 v battery before the battery dies

 

[mainline]

Thankyou, will I have to attach anything to the chassis mount resistor? And how long can I run it on a 12 v battery before the battery dies

View: https://www.youtube.com/watch?v=9mAmg0D5ArY

 

[Avo Mk8]

Thankyou, will I have to attach anything to the chassis mount resistor? And how long can I run it on a 12 v battery before the battery dies

It would be a good idea to attach the resistor to a small piece of metal, as advised in the post you responded to, but from the spec. the resistor is capable of dissipating 9W without a heatsink, so it shouldn't come to any harm if you don't.

How long it will run depends on the battery you use, and how healthy and charged it is. Your battery will likely be labelled with its capacity in Ampere hours (Ah). So as an example, if it was a 100Ah battery, it could supply 100Amps for 1 hour, or 1 Amp for 100 hours, or 2 Amps for 100/2= 50 hours etc. The suggested resistor would take (roughly) 0.5A, so the 100Ah battery would last 100/0.5=200 hours.

 

[UKMeterman]

The big question is how big do you want your target and how hot do you want your target?

 

[Simon47]

Your battery will likely be labelled with its capacity in Ampere hours (Ah). So as an example, if it was a 100Ah battery, it could supply 100Amps for 1 hour, or 1 Amp for 100 hours, or 2 Amps for 100/2= 50 hours etc.

It doesn't actually work like that.
For a vehicle SLI (starter, lights, ignition) battery, as well as a nominal AHr rating, it has a CCA, cold cranking amps, rating which indicates it's ability to turn the engine over.

For the AHr rating, this will be specified at a particular rate - the faster you discharge, the lower the apparent AHr capacity. Back when I worked in IT, it could be really obvious how much adding batteries would disproportionately increase runtime. E.g. adding two battery packs (trebling capacity) could result in a 5-fold increase in runtime.
Pulling a few 10s of W from a large vehicle battery will result in a very long run time.

But, of course, unless you've a dual battery setup (as on FFR, fitted for radio, vehicles) then you'll be wanting to keep enough charge to start the vehicle.