Block heater.
 

As the overnight temperatures start to tumble (it isn't even officially autumn yet) I think a block heater would make a lot of sense. This morning I drove my wife to her work, two miles there, two miles back, and the car didn't get up to even approaching operating temperature.
My question is, could I run a block heater off an auxiliary battery and inverter?
I would take the battery into the house during the day, and charge it from the mains, then return it to the garage at night, to run the block heater. I would require some sort of battery operated timer (run from the car battery to avoid having to constantly reset it), but that, the inverter and the block heater would be a permanent fixture on the car. I would just need to connect the battery to a plug on the car.
My garage is provided by the county, is remote from my flat, and has no provision for power.
What do you guys think? Any better suggestions? All ideas welcome.

That's a lot of power. Most block heaters are only 400 to 600 watts.
Do a warm air intake using exhaust heat or any of my fast warm up ideas.

If you are going to battery power it, might aswell go with a 12V heater.

Do some power calculations, and then determine the Ah of the battery. Look up lead acid battery weight and then ask yourself are you willing to transport that much lead to gain x £.


If you do decide to go that route, there are some neat internet enabled relays, then you could switch it on and off with your mobile phone.

My intention is only to use the block heater overnight, while the car is in the garage. I wouldn't need to carry it in the car. What I would need to do is carry it the 70 yards from the garage and up the 48 steps to my flat.
The mobile phone would work fine as I am up an hour before I use the car. Any longer for heating the block would need a timer, as 05:20 is the earliest I intend getting up!
A 50AH battery is big and heavy.

I really think you should consider insulating your engine bay as much as possible. Full grill block with a section you can open, belly pan and insulation around engine. Check out my album on my echo mods. You could maybe
do what your suggesting, but not with a 50ah battery.

The block heater is very light. And removing it would be a pain.

You stated that you do not have power where you park, so you would need to carry all the power in a battery.

To run it the whole night you need even more power, because heat loss is a function of delta T. The hotter the engine is the faster it loses heat. So switching it on just before starting your car is the energetically optimal way of doing it.

My thoughts were to switch the block heater on an hour before I need the car. It is in a garage, and because we are near the sea the outside temperature here seldom drops below 0°C. A 400 watt heater running on 12v would draw 34A. Leaving on an hour would need 34AH, hence a minimum of 50 AH battery. It would only be used for first trip of the morning, then on my return the battery would be taken into the house and charged up until the evening, when it would be reconnected to the car. The block heater would be fitted to the car and never removed.
An electronic timer, powered by the car battery would switch on the auxiliary battery/block heater an hour before I need the car.
I intend manufacturing a grill block, which for the 4 mile morning trip, would be closed completely, and opened up for my longer journeys.
There is insulation on the underside of the bonnet at present. Not very thick, but it is there. There is also a factory fitted undertray, which is reasonably full. For me to do any more is really beyond the tools and facilities I have access to.

It's good you have some protection already. You could let some reflective insulation in the existing under tray and some over top of the engine. I think it would help and be cheap and easy. As for your battery calculations, in theory you are right about the AH and amps required, but nothing is 100% efficient. Batteries are rated at a 20 hour rate. The 1 hour rate is about half that. Also, you don't want to discharge below half capacity or you will get very few cycles out of it. Do you already have a block heater in the car or do you have to buy one? The inverter will have a percentage of losses as well.

Just a note, this applies mainly to lead acid batteries. High-draw and deep cycles also hurt other chemistries, but not nearly as much. On the downside, most of the alternatives like lithium-based batteries would be fairly expensive.

I had been looking at using a deep draw battery. I don't have a block heater so would try and get a 12v one, if they are available, so I would not need the inverter.
The garage itself is fairly well insulated in that the door is the only outside surface and that faces away from the prevailing wind. The roof is a heavy concrete plinth, with a heated house on top of it.
This is a picture of my old car outside the garage, to give you an idea of the set up. I now have a new door without windows in it!

http://i.imgur.com/5hEukVz.jpg

Something else you may want to investigate as an alternative to a block heater is an oil pan pad heater. They are available for 12 volts and draw less power. You would need a fairly flat area on the oil pan. They heat a little slower but the lower power might allow you to use the battery you were thinking of. They do work pretty well since heat rises. They have their advantages and disadvantages compared to a coolant heater.

I guess you have never even considered a fuel-burning supplemental heater. But anyway, maybe insulating the engine compartment and getting a warmer air intake (eventually trying an adjustable one similar to what is used in small aircraft to prevent carburettor icing) would be the most cost-effective options for you.

OTOH if you decide to try a heating pad at the oil sump, the extra load on the alternator would be likely to help you reach the operating temperature quicker.

I don't think a sump heater would work as the Jazz has an in sump transmission with the casing all webs, etc.
Using supplemental heating in the garage is illegal and dangerous, owing to the houses immediately attached to the garage and lack of flue. I cannot run a generator to supply power for that very reason (not that that would be an efficient way of saving a few mpg).
Because it never gets really cold here and because my cold start trip is only 4 miles and 10 minutes duration, I don't feel I would gain much from getting the engine hotter, quicker, on the trip. Only real benefit would be if I could have it warm to start with.
Perhaps I will just have to live with it. At over 50 mpg UK at the moment, any gains I make may not be economically viable (never mind the humping of batteries and all that rigmarole).

I thought the original Mini and some old Citroën/Peugeot and Renault econoboxes with the "suitcase" engine were the only cars to feature this layout.

The transmission isn't actually in the sump (like the BMC engines) but attached to the end of the sump. This is the sump:
http://www.hondafitjazz.com/manual/A...3401KCAD01.PNG

And in Plan.

http://www.hondafitjazz.com/manual/A...3401KAJD03.PNG

Some of the jump packs have air compressor, light and invertors built in, mines not as heavy as a lead battery and useful for other things.

If it has an invertor built in you can use a cheap clock timer to turn it on and off. Don't need a battery charger either. You need to verify the watt draw of block heater to be sure the invertor has the capacity you need. You could always rig up an external invertor and use the 12v cable to power it instead of the 12v power outlet.

I take it I would just take the jump pack into the house, and plug that in to recharge it.

Yep, wouldn't need a battery charger, handy to have around, I use mine for lots of different things, I picked up a 12v fuel pump for $7 and use it to transfer fuel from boat tank to cars. Run a air compressor to pump lawn mower or wheel barrel tires. Power goes out can charge phones and the little LED light would probably run for a week.

Closest gas station is 10 miles, kids cars used to pretty much just go to school and back 4 miles each way, and fuel is cheaper where I work. Burn a gallon to go fill them up or fill the boat tank when filling my car and transfer it to my other cars.

DEWALT 2800 Peak Amp Jump Starter 1000-Watt Power Inverter with Digital Compressor-DXAEPS2 - The Home Depot

Thank one would do it, but pretty expensive.

Another thought if all you really want is 110v, a computer ups. Make sure you get one that you can turn the beeping off.