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[Lomas]

I’m converting my Landrover to electric and encountered a small problem.  The round smiths heater needs converting to 100 volts or twelve volts. Not the motor but the heating element. Has anyone any bright ideas who may be able to do this. Remove the heating core and replace with a heating element. Tia.

[andrewR]

.... well, if you were to be able to buy a standard 240V fan heater of some kind, and safely splice the innards into the Smiths casing, and run it safely at 100V, then the heater elements will output about 17% of the heat that the heater would have done when used at 240 V. i.e. If you had a 1kW 240V heater element and run it at 100V, it will output about (100/240)^2 * 1kW which is about 173 W.

You might want to install (or perhaps if you buy and modify a fan heater it might have it already) a temperature cutoff switch of some kind, that stops it melting or going on fire if it gets too hot.

[ChrisJC]

An interesting problem! I suppose it depends how authentic you want it to look.

If 'inspired by' is OK, I would get some large heatsinks (with a lot of fins), cut them into annuli and attach power resistors to the back of each one. By tuning the resistor values, you can control heat output vs voltage.

Chris.

[Davidss]

I can't pretend I know about ALL options, but the 'standard' way of creating heat, additional heat in the case of modern clean burning diesel engines, or ALL heat in the case of EVs, is to use 12v PTC heaters. As they have been used in mainline diesel engined vehicles for several years they are available second-hand from crashed or other vehicles 'beyond economic repair'. Search in eBay.
In 4 seater cars, of mainly German origin, the forward seating area had heat from the engine, while the rear seating area had PTC derived heating.
For a Series style vehicle, it might be easier to use a flat heater box, not a round one.

PTC = Positive Temperature Coefficient, when the surrounding medium (air or liquid coolant) is cold the current draw is high, even very high, but as the surrounding medium warms so the 12v current demand drops rapidly. This is natural reaction, occurring without a sophisticated electronic control unit.

A specific EV example is a BMW i3, this has three elements in a tank filled with liquid medium. Each element has a different heat rating, so used in various combinations a variety of heat outputs can be derived. (Combinations being element 1 only, 1+2 only, 1+2+3, 1+3 only, 2+3 only). As part of a sophisticated machine the heated liquid can be used to deliver warmed air to the vehicle interior via a heater matrix, as well as warmed liquid to channels in the main battery pack, which is a battery of dry cells.
It being understood that an externally warmed battery can deliver more power over its cycle of use than a cold battery. This is so even when the heating energy is drawn from itself. A sophisticated BMS (Battery Management System) is required; not all EVs have such a system.

Regards.