Holden Barina 1994 EV Build thread

[z_power]

Originally Posted by Astro

The element has a thermal switch mounted to the side of it. This cuts the power when the element reaches about 180C and turns it back on when the temperature drops below 140C.
Not sure if i should run the element at its equilibrium temperature of 205C or let the thermal switch cycle the element on and off.
Not sure which is best for long term reliability. Is running the element at 205C going to shorten its life or is the thermal switch going to fail as it is now switching 156v DC rather than 240v AC?

We're having -8 degC today and I'm tinkering with heater too so here's my .02:

- I didn't found any DC voltage rating of these small snap-switch thermostats so it's better to use em for controlling proper rated relay/contactor. After all you do need one for manual on-off control (hint: there're HV DC relays inside Prius battery boxes, I got two of ~100A and one 10A for less than $50)

- an element ripped from 230V 1500W heater connected to my 180V battery pack can reach ~1000W and it's only at a given fan speed; I guess it's "trapped" somewhere in transition region of resistance coefficient - see graph - so I'm awaiting package from U.S. witch cheap 110V ceramic space heater; 1000W doesn't feel like enough even in my small cabin

- here's nice YouTube find, you may skip to 4:28 for interesting part:

https://www.youtube.com/watch?v=n6U_BfM8h24#t=267

[Astro]

Originally Posted by z_power

...- an element ripped from 230V 1500W heater connected to my 180V battery pack can reach ~1000W and it's only at a given fan speed; I guess it's "trapped" somewhere in transition region of resistance coefficient - see graph - so I'm awaiting package from U.S. witch cheap 110V ceramic space heater; 1000W doesn't feel like enough even in my small cabin...

I would be very interested to hear how the 110V model compares. I had a quick look on eBay for the 110V heater elements but couldn't find any. This is surprising as the ceramic heaters themselves are very common and most would be made in china. I would have expected the elements to be available and quite cheap. Even searching for the heaters themselves from an overseas (110V) country didn't return many matches.

When using a hair dryer in our bathroom it only takes a few minutes to heat the bathroom. The hair dryer is a 2400W model but is normally only used on half output, 1200W. I was hoping that the ceramic heater would achieve the same for a car.

The heater in the linked video is a 110V model. The element looks identical to the one i have so it isn't that they are wired differently or anything like that. They must have different resistive values in the the ceramic sections of the element.

When i tested mine i had the element sitting with no fan blowing just like he did. I used 96V DC and it went up to 205C. I wouldn't want to try touching it through a couple of layers of paper towel.

[thingstodo]

Originally Posted by Astro

I had a quick look on eBay for the 110V heater elements but couldn't find any. This is surprising as the ceramic heaters themselves are very common and most would be made in china. I would have expected the elements to be available and quite cheap. Even searching for the heaters themselves from an overseas (110V) country didn't return many matches.

Here is a link to alibaba express for some 500 - 1000W units

110V PTC - Shop Cheap 110V PTC from China 110V PTC Suppliers at Tony Tang's store PTC heater on Aliexpress.com

One of these should be easy to mount.

Standard disclaimer - I am not associated with Tony Tang's store and have not used these products. They were literally the first ones that came up on my search of alibaba express.

[Astro]

I managed to get the power steering pump plumbed in.
It works great, unfortunately it is also quite loud.
Can only just be heard in the quiet cabin but outside the car it is rather noisy.
Sounds the same as the one in this video.

Loud

It will do for now but i may try a different model of pump later to see if there is a quieter version. The one i used came out of a Holden Astra. Looks the same as the one in the video.
I will have to look at more wrecking yards to see if i can locate a MR2 to see if their pumps are any quieter.
It isn't noisy in the cabin and so it may be just noisy outside with the bonnet up, will check that.
I may also be able to reduce it's volume by adding a pulsed signal rather than permanent 12v. The electrical connections to the pump are via two large gauge cables for 12V and ground and then 3 smaller gauge wires. One for diagnostic which isn't used in this application. One supplying 12v to the smarts of the pump and another input which varies the pump speed. Not sure if it is duty cycle or pulse rate that is used to vary the pump speed. In most descriptions i have seen this pulsed input is just given permanent 12v as well and the pump runs at full speed.
After a few seconds at full speed the pump throttles back to maybe 80% of full speed.
I assume this is because it is at full pressure.
As soon as the steering wheel moves it goes back to 100% of full speed again.
Stop moving the steering and after a few seconds it drops back to 80% or so.

Hopefully i can add a PWM or pulsed voltage to this input to reduce the pump to a much lower RPM. Without the motor in the front the steering seems super light.
Once the motor and controller are installed it may not be so light.

After dinner i will go and confirm the wire colours and what each function is so that there is a reference for anybody else who wants to use this pump in their conversion.

[Astro]

Ok, I checked the wiring and it is.

Heavy gauge wires
Red -> 12 volts (could be 30+ amps so if using a relay it needs to be a large one)
Brown -> Ground

Light gauge wires
Black -> 12 volts (most people connect this to the alternator energise wire)
Blue with white stripe -> Vehicle speed signal (connect to 12v for 100% pump output)
Brown with white stripe -> Might be diagnostic connection? (not required, leave unconnected)

The wires change colours after the first connector so double check them.
The colours i have listed are for the wires that go between the pump and the first connector.

Also the pump takes a several seconds to spin up. For a few seconds it makes no noise and then the noise ramps up to full volume in about 10 - 20 seconds.

Checked the noise level with the bonnet closed and it is still quite loud.
If i had an internal combustion engine running i probably wouldn't hear it but with the rest of the car making no sounds it seems quite loud.

[z_power]

Sorry for thread hijacking but I've got some good news to share - my heater saga came to happy ending

A mailman dropped a package at my place today...

I swapped 120V element in and THIS IS IT! Oh, i mean HEAT! It pulls between 8 and 11 amps from 180V battery, depending on fan speed (higher airflow = higher current); with ~2000W this feels like heater now - I mean you feel nice warm air from ducts even though it's -7degC tonight. With previous 230V element current could barely reach 5.5A which translates to ~1000W. It surely made a difference from "no heat at all" state and offered almost comfortable cabin temperature but only when driving in city traffic. As soon as I was on freeway it was getting a bit cold and windows got foggy :/ "Half power" position was of no practical use, now I use it most of the time.

I really recommend 120V elements in conversion with battery voltage <200V.

[Astro]

Originally Posted by z_power

Sorry for thread hijacking but I've got some good news to share - my heater saga came to happy ending ...

Hijack away. This is all good info.
The 120V heater you bought, what was its wattage rating of the appliance?
When you say half power do you mean you are switching off some of the rows of the element or only using half fan speed?
What temperature of snap-switch thermostat are you using?
I think i will now hold off until i source a 120V version.
Thanks for letting us know the good results.

[z_power]

CZ442WM is the model I've bought, it's tag plate says 120V, 1500W max. so I'm "overclocking" it a bit
I can switch on 2 or 4 rows, fan motor comes on automatic and its speed can be regulated with Soliton... pardon, simple PWM controller
Thermal switch rating was 130 or 140 C (I don't rememer...) and during kitchen table tests with previous setup connected to grid power it took ~5s of fan inactivity to switch off. I'll do some more testing in car today or tommorow, forgot to take my IR gun thermometer last time.

[BLSTIC]

Ever thought about using the original heater core and a resistance water heater? In your car it's an easy decision, but some cars with climate control may be a bit more sensitive about their heater controls

[Astro]

Originally Posted by BLSTIC

Ever thought about using the original heater core and a resistance water heater? In your car it's an easy decision, but some cars with climate control may be a bit more sensitive about their heater controls

Unless you have some sort of complex climate control that would require you stick with heated fluid then the ceramic heater element seems to me to be the better option.

Using a resistance water heater may be a bit easier because you don't have to make any changes inside the cabin but it has quite a few drawbacks.

You are dealing with near boiling water so you have to be mindful of the pressure that can be generated in the system and have some sort of safety valve. This is normally the radiator cap.

You need a reservoir of fluid to heat, this takes up space and adds weight.

The reservoir and all it's piping needs to be heavily insulated. The energy to heat that water didn't come for free like it does on an internal combustion engine so you don't want to lose any of it.

Then there is the heating delay, to bring up all the water in the system to a sufficient temperature will take many minutes.

You need to add a pump to circulate the water. Taking up more space and adding more weight.

Then the pump and heating element need to be controlled to maintain a controlled temperature and have some protection/detection set up in case of low or no fluid.

Also all these extras like the heating element, circulating pump, reservoir, etc start to add up to a significant cost.

All these issues disappear with a ceramic heater element.
They weigh next to nothing.
Are self regulating. (They have a positive temperature coefficient, the hotter they get the less current flows until they reach a natural equilibrium).
They heat up fast, maximum temperature achieved in seconds. Very handy for demisting a windscreen on a cold morning.
No fluids to worry about.
Take up almost no space, certainly no additional space. They replace the existing fluid heater core in the cabin which further reduces weight.
Are very cheap. Sourced from a cheap space heater and only requiring a relay to control turning them on and off.

The ceramic heater option can have some issues that need to be taken into consideration.
How difficult is it to access the cabin heater core. On some vehicles this may be embedded deep within the dashboard requiring significant effort to access.
Interfacing the element control relay to the dashboard controls.
Fabricating something to mount the heating element to.

But that's about it.