12v DC question.

Calahonda52

Want to run a 150 watt fan heater in the car to reduce the amount of frost in the mornings.

150/12 is 12.5 Amps.

The plan is to run a cable about 12 feet from garage to car.

I have a 20 Amp charger connected to a spare 70 Amp hour battery in garage and fan heater is running off it.

With the fan heater running, the voltage at the fan is 9 v, 12.8 v at the battery.

Do I need to increase the cable size to reduce the voltage drop?
Will the voltage drop damage the fan or over heat the cable?
Will the charger keep up with the draw from the battery?
ie 12.5 amps out 20 Amps in, with 70 Ah in the battery?
Thanks

adrian92

Calahonda52 wrote: »

Want to run a 150 watt fan heater in the car to reduce the amount of frost in the mornings.

150/12 is 12.5 Amps.

The plan is to run a cable about 12 feet from garage to car.

I have a 20 Amp charger connected to a spare 70 Amp hour battery in garage and fan heater is running off it.

With the fan heater running, the voltage at the fan is 9 v, 12.8 v at the battery.

Do I need to increase the cable size to reduce the voltage drop?
Will the voltage drop damage the fan or over heat the cable?
Will the charger keep up with the draw from the battery?
ie 12.5 amps out 20 Amps in, with 70 Ah in the battery?
Thanks

1. Yes
2. Low voltage likely to reduce life of fan motor
3 probably

Just my thoughts. Others will possibly correct me.

Just a thought - perhaps there may be easier (non-electrical) methods to achieve your objective?

Calahonda52

adrian92 wrote: »

Just a thought - perhaps there may be easier (non-electrical) methods to achieve your objective?

I agree, however the car is a 99 1.2L corsa and the heater does not click in for about two miles, our son leaves at 6 am so no brownies from neighbors for hard revving in the dark.:)

Driveway is north facing, shaded so the water defrosting methods leaves ice for us when we go out

2011

I would be concerned about leaving any type of heater running all night. It could be a fire hazard. If you are going to do this why not use a mains voltage fan heater? It would be so much easier. If you really want to go the 12 volt route use a 12 volt power supply unit. There is no need for the added complica of a battery and battery charger.

Like most people just pour hot water on the windscreen, problem solved instantly.

Risteard81

2011 wrote: »

Like most people just pour hot water on the windscreen, problem solved instantly.

You're actually better to pour cold water over it, as this is stilll warmer than the ice and will melt it. Hot water is liable to crack the windscreen due to the sudden change in temperature.

coylemj

Instead of pouring boiling water directly on the screen, pour a kettle of boiling water into a bucket of cold water, then slowly pour that bucket of (warm) water over the windscreen, the additional volume of water will help to warm up the windscreen inside and out, then you won't get the windscreen instantly fogging up when you sit in and start breathing warm moist air on to it.

Calahonda52

2011 wrote: »

I would be concerned about leaving any type of heater running all night. It could be a fire hazard. If you are going to do this why not use a mains voltage fan heater? It would be so much easier. If you really want to go the 12 volt route use a 12 volt power supply unit. There is no need for the added complica of a battery and battery charger.

Like most people just pour hot water on the windscreen, problem solved instantly.

I have the 20 amp charger, 20 amp power supply is big bucks.
This also allows me to eventually fit a cigarette lighter socket with a cover in the front bumper and use it to plug in the 12v feed. Better than a dangling lead.

Its not on all night, have a GSM relay with on snd off texts preloaded in Web text.

gctest50

a block heater should be safer/easier

this sorta thing :

http://www.amazon.com/ZeroStart-3200003-Lower-Radiator-Hose/dp/B0065V4MLG/?s=automotive&ie=UTF8&qid=1422027553&sr=1-2&keywords=block+heater+240v

brightspark

Get one of these next time they come around.

https://www.aldi.ie/en/specialbuys/sunday-9-november/products-detail-page/p/car-windscreen-cover-1/reminder.html

Bruthal

Calahonda52 wrote: »

I agree, however the car is a 99 1.2L corsa and the heater does not click in for about two miles, our son leaves at 6 am so no brownies from neighbors for hard revving in the dark.:)

Driveway is north facing, shaded so the water defrosting methods leaves ice for us when we go out

Leaving the car ticking over will get the heating working in the car. No need for revving at all. That is what i do on frosty mornings. Only takes a few minutes.

Its not so much that heating kicks in after 2 miles, it takes that time to heat the engine coolant. It is the coolant which provides the heat for the car heater/fan.

9v won't really damage fan motor or heater if go that route.

freddyuk

Save yourself all the hassle and get a remote car start kit. Simply start the car with heater on, remotely from the house, 5 minutes before you need to leave.

2011

Calahonda52 wrote: »

I have the 20 amp charger, 20 amp power supply is big bucks.
This also allows me to eventually fit a cigarette lighter socket with a cover in the front bumper and use it to plug in the 12v feed. Better than a dangling lead.

Power supply unit for small money:

http://www.cctvdi.com/epages/61203576.mobile/?ObjectPath=/Shops/61203576/Products/EN-PSU18CH15A&Locale=en_IE

This is still not a good idea.
What is the purpose of the spare battery?
What is wrong with warm water?

The lighter socket would have to be rated for outdoor use. Installation of same will devalue your car.

Its not on all night, have a GSM relay with on snd off texts preloaded in Web text.

Not reliable enough.

CountyHurler

I'm a bit confused as to why you are using a 12V DC fan.. This would be understandable if you were using it IN the car... but you say you are running a cable from a battery to the car, so why not use a plug in (240V) fan instead, and put it on a timer, if that is the way you want to go?

Kevin McCloud

CountyHurler wrote: »

I'm a bit confused as to why you are using a 12V DC fan.. This would be understandable if you were using it IN the car... but you say you are running a cable from a battery to the car, so why not use a plug in (240V) fan instead, and put it on a timer, if that is the way you want to go?

What are the regulations of using a 240v fan heater in a car?

Kevin McCloud

I have to stress the point that introducing a mains cable into a car can be potentially dangerous.

Bruthal

Kevin McCloud wrote: »

I have to stress the point that introducing a mains cable into a car can be potentially dangerous.

Especially if it needs an extension lead:pac:

2011

Kevin McCloud wrote: »

I have to stress the point that introducing a mains cable into a car can be potentially dangerous.

What is the danger?
People use mains voltage vacuum cleaners to clean thier car all the time.

What are the regulations of using a 240v fan heater in a car?

ET101:2008 would apply, just the same as it does with a house.
Consideration should be given as to how to provide mechanical protection to the cable.

Kevin McCloud

2011 wrote: »

What is the danger?
People use mains voltage vacuum cleaners to clean thier car all the time.

Hoovering a car usually utilities the hoover externally on the ground and only the suction hose inside the car, that is going off topic.
Suggesting the op puts a mains fan heater into the car brings the potential hazzard as a mains lead must enter the car.

2011

Kevin McCloud wrote: »

Suggesting the op puts a mains fan heater into the car brings the potential hazzard as a mains lead must enter the car.

...and the hazard is?

Kevin McCloud

2011 wrote: »

...and the hazard is?

Mains lead getting damaged, potentially lethal.

2011

Kevin McCloud wrote: »

Mains lead getting damaged, potentially lethal.

You mean like using an electric lawn mower?

Normal practice is to protect cables from mechanical damage if a concern exists.
This can be achieved by using an armoured cable such as a CY cable.

Mains cables are used in many harsh environments even though the voltage is potentially lethal.
It is not an issue when the correct equipment is selected and it is properly installed.

gctest50

you could add a j1772 connector setup like Nissan LEAF etc


https://evconnectors.com/electric-vehicle-chargers-and-accessories/Type-1-Electric-Vehicle-Charging-Cables-and-Sockets/j1772-16-amp-socket-Inlet-dsi-ev16s-nc


house and car (fire) insurance may not be so happy though

.

Calahonda52

Kevin McCloud wrote: »

I have to stress the point that introducing a mains cable into a car can be potentially dangerous.

Thank you.:)

What I was looking for was suggestion on cable sizes for DC in the situation I described.
There are loads of ideas on You tube for doing it different ways, using hairdryers and such like.
All I was about was cable sizes

Bruthal

Kevin McCloud wrote: »

Mains lead getting damaged, potentially lethal.

Yea, but in real life, more likely driving the car will be lethal.

So will cutting the grass with electric lawnmower. Or drilling with electric drill.

But in reality, extremely unlikely to be a problem, let alone lethal.

Bruthal

2011 wrote: »

...and the hazard is?

Very little I'd say.

ted1

Just get a deicer spray for 1.50 in dealz.

CJ Haughey

A mains fan heater in a car as suggested in post 4 should be avoided. Reading through the manual of my heater it would be a recipe for disaster.

2011

CJ Haughey wrote: »

A mains fan heater in a car as suggested in post 4 should be avoided. Reading through the manual of my heater it would be a recipe for disaster.

This could be due to an issue that does not apply to all mains voltage fan heaters and / or all cars. Perhaps this also applies to some 12VDC heaters too
It is impossible to say unless more information is provided.

Post 4 does not suggest ignoring manufacturers guidelines / recommendations etc...

Bruthal

CJ Haughey wrote: »

A mains fan heater in a car as suggested in post 4 should be avoided. Reading through the manual of my heater it would be a recipe for disaster.

Everything we do daily is a recipe for possible disaster. Unless you hide in a padded bunker 365 a year.

freddyuk

Calahonda52 wrote: »

Thank you.:)

What I was looking for was suggestion on cable sizes for DC in the situation I described.
There are loads of ideas on You tube for doing it different ways, using hairdryers and such like.
All I was about was cable sizes

I think the problem is most cannot quite understand your logic. If you are going to the trouble of going out in the morning and fixing up a mains fan heater for 15 minutes then you may as well start the car finish your cup of tea and in 3-5 minutes the screen is clear so drive off.
Not very green but then neither is a fan heater which will heat the car as well as the screen so less effective.
Worrying about the correct cable size seems such a faff when it is not needed.?
Sorry if I missed the point but I am "pragmatic"

adrian92

Calahonda,

To answer your specific question:

As I said in my first response - yes - you will indeed need to increase the cable size - if this is your desired method of solving the problem.

9 volt terminal voltage at the fan heater (with output voltage of 12 v) operating definately indicates that larger cable size would be needed.

More information would be required in order to advise what cable size you wish to use.

Hope this addresses your specific question

CJ Haughey

Bruthal wrote: »

Everything we do daily is a recipe for possible disaster. Unless you hide in a padded bunker 365 a year.

Hiding in a padded bunker can be also a disaster, what is your point here?

10-10-20

Clearly, trying to heat the cabin is the least efficient method. It's thermally very lossy and you'll loose any built-up heat when the car's fan-blower comes on (as it won't be pre-warmed).
Considering the options presented, I'd consider the screen cover the most efficicent and possibly effective method, seconded by the block heater if you really want to expend energy on this. If the block is warmed the car will be more efficient from start-up and you'll have a supply of warm air from the blower to clear the window quickly. Hence you're getting dual usage for your input of energy.
Plus, the block heater appears to be mains powered so you won't run as many risks with the charger circuit failing and the battery being flattened. Then fit an IP65 commando socket and a safety device (to prevent drive-off's with the plug engaged) and you have a better setup (IMHO).

Grounding then is going to be the next concern, but I'm sure that you would get tips on that from the many RV forums!

Bruthal

Its likely just starting the car is more efficient than electrically powering a block heater. Takes little time to defrost a window with a started car.

How efficient is the production of the electricity used for heaters?

2011

CJ Haughey wrote: »

Hiding in a padded bunker can be also a disaster, what is your point here?

I am going to hazard a guess that Bruthal's point is that nothing in this world is without some degree risk (no matter how small). So if you are going to make a statement such as "Reading through the manual of my heater it would be a recipe for disaster" that it should be elaborated on. That way other posters can see if the degree of risk of installing a mains powered heater in a car likely to be greater than that of remaining in a padded bunker.

10-10-20

10-10-20 wrote: »

Grounding then is going to be the next concern, but I'm sure that you would get tips on that from the many RV forums!

Earth it to the DC ground, safest course provided you have installed circuit protection. I've had mains semi-hard-wired in a vehicle for years, and a hellova lotta more battery capacity and electronics than your average motor.

I just use the wood burner to defrost the windows myself. :P
Plenty others I know use electric fires.

Calahonda52

Calahonda52 wrote: »

Driveway is north facing, shaded so the water defrosting methods leaves ice for us when we go out

Carpet.

Man of Aran

As Sir Liamalot suggests, something along the lines of this should sort it.
Throw a few sods of turf and rake embers lightly the night before, should be cosy still at dawn.:p