# MES RM3 heaters on eBay



## Zappo (Sep 1, 2011)

I just stumbled across these on eBay if anyone is interested. He says he has about 30 of them. They were apparently removed from new Thinks. It looks like the pack cables have been cut off flush, which bothers me a little. I'm getting a couple anyway. Gotta be better than the Kat tank heaters I'm currently using. Comes with a much better pump too. Now I just need to find a source for the mating connectors.

http://www.ebay.com/itm/181028809831?_trksid=p5197.c0.m619


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## rwaudio (May 22, 2008)

Zappo said:


> I just stumbled across these on eBay if anyone is interested. He says he has about 30 of them. They were apparently removed from new Thinks. It looks like the pack cables have been cut off flush, which bothers me a little. I'm getting a couple anyway. Gotta be better than the Kat tank heaters I'm currently using. Comes with a much better pump too. Now I just need to find a source for the mating connectors.
> 
> http://www.ebay.com/itm/181028809831?_trksid=p5197.c0.m619


I bought a couple of those as well, same feelings about my Kats heater, he's had an add on evtradingpost for a little while now. I'm pretty sure the HV wiring won't be too hard to replace, the wires will be soldered or bolted to something. The LV connector might be difficult to find, but a simple alternative is just a quick connect (of suitable size) with some heatshrink around it.
(please note the connector linked to is just a guess on the sizing, I will be measuring and ordering appropriate connectors when the heaters arrive).
http://www.digikey.ca/product-detail/en/42067-1/A27745CT-ND/456833

Metricmind also has these "surplus" heaters/pumps for sale, but theirs come with HV wiring still attached and you can buy the mating connectors however it will set you back $466 with connectors.


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## Zappo (Sep 1, 2011)

rwaudio said:


> Metricmind also has these "surplus" heaters/pumps for sale, but theirs come with HV wiring still attached and you can buy the mating connectors however it will set you back $466 with connectors.


Yeah, for that much difference in price, I'm sure I can do something about the connectors. It also looks like these come with a Bosch pump that is being sold for almost $200 elsewhere.


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## Electroddy (Dec 29, 2009)

Zappo said:


> I just stumbled across these on eBay if anyone is interested. He says he has about 30 of them. They were apparently removed from new Thinks. It looks like the pack cables have been cut off flush, which bothers me a little. I'm getting a couple anyway. Gotta be better than the Kat tank heaters I'm currently using. Comes with a much better pump too. Now I just need to find a source for the mating connectors.
> 
> http://www.ebay.com/itm/181028809831?_trksid=p5197.c0.m619




Just looking at the connector on these, it almost looks like the three wire connector for a Franklin Electric water well pump. If you do buy one, take it to your local pump installer/repair guy. It may be that he has the cable in stock. I used to install and repair pumps.


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## DIYguy (Sep 18, 2008)

Just wondering if the control electronics are included inside this beast. . . or is there a separate controller??


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## Huub3 (Aug 16, 2009)

Hello,

may I ask what your feeling wrt the Kat's heaters is. We do not have such devices over here (Europe), but I was thinking about using an industrial water heating rod for my heater (two in series to be precise), so interested to learn what make you think negative about these tank heaters.

Thanks a lot,


Huub


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## dtbaker (Jan 5, 2008)

DIYguy said:


> Just wondering if the control electronics are included inside this beast. . . or is there a separate controller??



details read like the temp control/switch/relay is internal. The specs on min/max pack voltage were a little sketchy, hoping they will work well with 120-156vDC

anybody know for sure?


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## rwaudio (May 22, 2008)

dtbaker said:


> details read like the temp control/switch/relay is internal. The specs on min/max pack voltage were a little sketchy, hoping they will work well with 120-156vDC
> 
> anybody know for sure?


The electronics are built in, it's a complete stand alone unit. The voltage range that that seller has is only 200-450v.


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## dtbaker (Jan 5, 2008)

rwaudio said:


> The electronics are built in, it's a complete stand alone unit. The voltage range that that seller has is only 200-450v.


oh crap, I hope I can cancel the order I just placed. I need for somewhere between 120-156v builds....


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## Ace_bridger (Nov 22, 2011)

I'm looking at getting one these too and am running a pack of 150V. I was hoping that it would run at 150V, despite being rated higher, but just chuck out less heat...thoughts?


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## electricmini (Oct 21, 2008)

Ace_bridger said:


> I'm looking at getting one these too and am running a pack of 150V. I was hoping that it would run at 150V, despite being rated higher, but just chuck out less heat...thoughts?


Well, since it's actually got a PIC micro inside (according to the info on Victor's website [metricmind] ), and since I use PICs all the time in work,
I'm sure it could be hacked! 

Running it on lower than normal voltage will probably just reduce the maximum heating power, since the unit PWM's the heater element to keep the power draw constant over the stated voltage range.

It might even be as simple as changine a couple of resistors on the pcb to
fool the PIC into thinking it's got a different pack voltage (**pure speculation**)

I wanna get my hands on one now...


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## dtbaker (Jan 5, 2008)

I am concerned that at lower voltage, it might pull more amps than internals are rated for.... if they made two different models, there are probably some significant differences?


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## DJBecker (Nov 3, 2010)

Electroddy said:


> Just looking at the connector on these, it almost looks like the three wire connector for a Franklin Electric water well pump. If you do buy one, take it to your local pump installer/repair guy. It may be that he has the cable in stock. I used to install and repair pumps.


I believe that it's a standard Bosch automotive connector. The two pin version is found on fuel injectors and thus is known as "fuel injector" connector. Three pin versions are found on various automotive sensors, such throttle position sensors, oxygen sensors and MAF sensors.


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## electricmini (Oct 21, 2008)

dtbaker said:


> I am concerned that at lower voltage, it might pull more amps than internals are rated for.... if they made two different models, there are probably some significant differences?


The heater element itself probably doesn't have much inductance, so
I don't think the PWM action will act like a switchmode power supply..
i.e. it can't draw more power at lower voltage (unless the firmware crashes)

unless you're concerned that it might increase it's _duty cycle_ to try to
maintain the 4kW rating? Surely MES would have designed it to use the
heater at 100% duty when the voltage is at minimum - doing otherwise they'd be paying for more heater than they need to


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## DIYguy (Sep 18, 2008)

I suspect it may be ok with anything over 100VDC. Take a look at the note on the schematic.


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## TEV (Nov 25, 2011)

DIYguy said:


> I suspect it may be ok with anything over 100VDC. Take a look at the note on the schematic.


Do you have a pin diagram for the plugs ?

Thank You


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## DIYguy (Sep 18, 2008)

TEV said:


> Do you have a pin diagram for the plugs ?
> 
> Thank You


Not exactly, but if you look at the schematic on this page, you will see the wire colours. That should help.


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## dtbaker (Jan 5, 2008)

electricmini said:


> The heater element itself probably doesn't have much inductance, so
> I don't think the PWM action will act like a switchmode power supply..
> i.e. it can't draw more power at lower voltage (unless the firmware crashes)
> 
> ...



so..... why would they offer two different models specifically labelled for 100-250v and the other for 200v-450v ? you don't think there is anything significantly different internally?


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## rwaudio (May 22, 2008)

dtbaker said:


> so..... why would they offer two different models specifically labelled for 100-250v and the other for 200v-450v ? you don't think there is anything significantly different internally?


I would agree there must be a difference if only the value of the resistor doing the heating. As mentioned before it would make sense that the system is at 100% duty cycle at the lowest input voltage. There is a chance it may simply work at reduced power.

4000w at 200v = 20A
R = 200/20 = 10ohms

At 100v that's 1000W 
At 150v that's 2250W

This is simply taking some wild guesses at how the system may have been designed, this also assumes that the control circuitry even operates at the lower voltage.

Based on the same assumptions the 100-250v version would use a 2.5ohm heater.


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## Zappo (Sep 1, 2011)

Okay everyone, I got two of these delivered today. I will fill you in on everything I know so far.

First, I would STRONGLY recommend NOT opening these if you can avoid it. I would try loosening the gland nut for the wire cord grip and trying to pull the wires up enough to make connection. You will see why as I fill in what I ran into.

In order to access the internal wiring, you need to remove the hose fittings. They are in VERY tight. I ended up needing to carefully hold it in a vise and use a 15/16" both end wrench to get them loose. The fittings have an o-ring but they also have a copper washer glued to the inside of the case.

Once I had it apart, I found that the electronics are all fully potted at the bottom of the unit. I ended up using butt splices to extend the two power and one ground wire. 

While it was apart, I took a look at the wire colors for the control plug. The +12 Volt control is the center pin (brown wire). The pin closest to the outside of the case is the fault out line (blue wire). The pin to the inside of the case is ground (black wire). I found that 1/8" quick connect female crimp on terminals fit these and the two on the Bosch pump very well. The pump is clearly marked which terminal is positive. 

Going back together wasn't easy. Everything is very tight. It was even harder because one of the copper washers came loose. I didn't want to glue it keep it in place so I just fought it for a while.

I have it all back together and going into the truck. I probably won't have the time to get it finished mounted and wired until Wednesday or Thursday now (long hours at work). I will let everyone know how it goes. Wish me luck. Since I want to run this on either the pack or 240 VAC (like I did with the Kat tank heaters), I will run the AC through a bridge rectifier big enough to handle the heater current.


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## rwaudio (May 22, 2008)

Zappo said:


> Okay everyone, I got two of these delivered today. I will fill you in on everything I know so far.
> 
> First, I would STRONGLY recommend NOT opening these if you can avoid it. I would try loosening the gland nut for the wire cord grip and trying to pull the wires up enough to make connection. You will see why as I fill in what I ran into.
> 
> ...


Great info! (I had planned to take mine apart)

Is it clear why there are three larger wires? What appears to be two black and a red in the ebay photo's?

To deal with the AC thing I'm going to leave a Kats heater in the loop which eliminates most of the complex wiring DPDT relay etc. I simply need a standard AC relay of suitable voltage/current to turn the kats heater on (and the pump/interior fan)


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## TEV (Nov 25, 2011)

Great work, but where are the pictures ?
You do know that we are addicted to pictures, don't you ?


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## Zappo (Sep 1, 2011)

rwaudio said:


> Great info! (I had planned to take mine apart)
> 
> Is it clear why there are three larger wires? What appears to be two black and a red in the ebay photo's?
> 
> To deal with the AC thing I'm going to leave a Kats heater in the loop which eliminates most of the complex wiring DPDT relay etc. I simply need a standard AC relay of suitable voltage/current to turn the kats heater on (and the pump/interior fan)


The one black wire goes directly to the case as a ground. I'm sure you can determine which one it is by checking for continuity to the hose connections, since everything else is covered with the plastic shell.

I thought about keeping the Kat heaters for the AC but I already have the other working and I'd need to buy another Kat to replace the one I burned up.


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## Zappo (Sep 1, 2011)

TEV said:


> Great work, but where are the pictures ?
> You do know that we are addicted to pictures, don't you ?


I thought about that, but I was doing this at work (during my lunch break, of course ). I always forget that my "crackberry" has a built in camera.


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## rwaudio (May 22, 2008)

The heaters arrived today, and thanks to Zappo's advice I didn't take mine apart. So I'll share some pictures to show how much wire there is to work with.

The power wires are roughly 10awg so that's what I used to extend them. Strip the insulation just above the seal after removing the nut on the gland. Solder on the wire (crimping would be tricky but possible if you are careful using uninsulated connectors + heat shrink) heat shrink the wires, put the nut back on) Literally a 10 minute job including finding some wire.


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## Zappo (Sep 1, 2011)

It works!

I didn't get enough time to finish it tonight but I got power to it. The pump is extremely quiet. The 12 volt control works just like it should. It draws about 13 amps at 300 volts. It took a while to start putting out heat. It took about 15 minutes to take the outlet water temp from around 35 degrees F to about 100 degrees. That is probably because I have a pretty large holding tank (about 3 gallons).

One thing that surprised me about the design of these things. It is completely open between the inlet and outlet. It looks like the inlet flow is slightly guided downward but it mainly relies on convection flow. That is why it is critical that these are mounted vertically.

I hope I get home in time tomorrow to finish this up so I can drive it again. Over the last month or so, I really got used to driving this. It's just not much fun driving with a frozen windshield . Okay, so it's more just that I'm too much of a wuss to drive a car with no heat.


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## dtbaker (Jan 5, 2008)

rwaudio said:


> The power wires are roughly 10awg so that's what I used to extend them.


nice work.... and what pack voltage will you be running this at? you have a 250v+ traction pack?


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## Zappo (Sep 1, 2011)

Great work! Looks very professional too.


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## rwaudio (May 22, 2008)

dtbaker said:


> nice work.... and what pack voltage will you be running this at? you have a 250v+ traction pack?


I will have a 94S pack, bit over 300v it should work well.



Zappo said:


> Great work! Looks very professional too.


Thank you, once the nut comes off there is just enough wire to work with.


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## TEV (Nov 25, 2011)

" RM3 is an electric fluid heater, powered by current supplied from traction batteries. It is controlled
by a PWM circuit which keeps the power constant over the voltage range.
It also includes a safety thermostat, a thermal fuse, a control device detecting fluid flow interruption
and an output to signal faults and malfunctions.


RM4 includes in a single package a fluid heater RM3, a circulation pump type MR 2-20-600
(in option: MR 2-25-900 or MR 2-30-1200).
Glycol expansion tank: 1.5 liters."

So, those RM3 will need a " Glycol expansion tank " , right ?


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## TEV (Nov 25, 2011)

Do we really need the ground wire ? (the extra black wire) 
I saw some pictures with this RM3 with only 2 wire coming out of that port. The same for the RM4.

I also think that an SB50 Anderson connector will be great for the HV connection.


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## Ace_bridger (Nov 22, 2011)

Can anyone see a reason why these heaters wouldn't work with 144V pack (150V to 146V ish)?


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## TEV (Nov 25, 2011)

Ace_bridger said:


> Can anyone see a reason why these heaters wouldn't work with 144V pack (150V to 146V ish)?


The inside electronics may be too smart and won't start the heater if the voltage is too hi or too low.

Maybe someone can tap the battery pack for 150v for a few seconds and see what happens.


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## TEV (Nov 25, 2011)

if someone else drawn the short straw (wires cut very short ) like me , here we go :


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## TEV (Nov 25, 2011)

I didn't have enough time to finish.

To be continued


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## TEV (Nov 25, 2011)

Anybody find the part number for the connectors yet ?


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## Zappo (Sep 1, 2011)

Very well done TEV. The 2nd one I bought has real short wires. I hadn't thought about cutting down the threads. I've already pulled it apart now or I would have copied your idea on that. 

The ground wire is not needed for it to function. I tried it without and everything worked fine. I did end up hooking it up. I was hoping it would take care of another problem but it didn't. I have the heat set up to be enabled with a remote controlled relay. That worked very well with the Kat heaters. With this thing, it turns everything on but won't shut the relay back off unless I hold the remote transmitter right up to the receiver. I'm guessing the PWM circuit on these things must put out a lot of RF noise.

I still don't know what the proper connectors are but both the pump and heater control worked really well with individual 1/8" quick connects and a little heat shrink tubing. The connectors are exactly like the standard 1/4" quick connects only narrower. I'm not sure where to get them normally. We have a large selection where I work and have never used these for anything else I'm aware of.

This heater is working very well and I was able to clean up the overall installation quite a bit over the Kat heaters. I am able to run it on 240 VAC house power when its parked. I just ran the power through a bridge rectifier. Next step will be to try to insulate everything a bit better. It definitely stays on longer when I'm driving than when it is parked.


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## TEV (Nov 25, 2011)

Zappo said:


> Very well done TEV. The 2nd one I bought has real short wires. I hadn't thought about cutting down the threads. I've already pulled it apart now or I would have copied your idea on that.
> 
> The ground wire is not needed for it to function. I tried it without and everything worked fine. I did end up hooking it up. I was hoping it would take care of another problem but it didn't. I have the heat set up to be enabled with a remote controlled relay. That worked very well with the Kat heaters. With this thing, it turns everything on but won't shut the relay back off unless I hold the remote transmitter right up to the receiver. I'm guessing the PWM circuit on these things must put out a lot of RF noise.
> 
> ...


I am very interested how do they look inside, can you post some pictures with the one you pulled apart ?


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## Zappo (Sep 1, 2011)

TEV said:


> I am very interested how do they look inside, can you post some pictures with the one you pulled apart ?


I'll try to post some pictures tomorrow. I was just going to point you to a picture I found online the other day but I can't seem to locate it again.


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## Zappo (Sep 1, 2011)

Here are a few pictures of an open one.


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## TEV (Nov 25, 2011)

Zappo said:


> Here are a few pictures of an open one.



Thank You, so basically we can cut that plastic fitting flush with the cover.


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## TEV (Nov 25, 2011)

TEV said:


> " RM3 is an electric fluid heater, powered by current supplied from traction batteries. It is controlled
> by a PWM circuit which keeps the power constant over the voltage range.
> It also includes a safety thermostat, a thermal fuse, a control device detecting fluid flow interruption
> and an output to signal faults and malfunctions.
> ...


They need an expansion tank, or not ?


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## Zappo (Sep 1, 2011)

TEV said:


> They need an expansion tank, or not ?


If you go with a closed loop, you will need some kind of expansion tank (and a place to fill the system). I went with a separate vented tank below the level of the heater. Fluid is pumped to the heater, then to the heater core and returns to the holding tank. My original setup with the Kat pumps had a cheap submersible pump in the holding tank. I think it would probably work ok with just the pump on the heater but I am using both pumps. The cheap submersible acts as a primer pump.

Hope this helps.


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## TEV (Nov 25, 2011)

Thank You.


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## etischer (Jun 16, 2008)

I just picked up one of these heaters too. I had pretty good luck soldering extension wires. I meshed the two ends together, then wrapped a wire around the bundle to hold it together while I soldered. 










The big knot ends up being just barely larger than the diameter of the wire.


















I also found a plug for the Bosch pump, and heater signal in the fuel injection harness from my old ev motor. The heater control plug is off the air flow meter on a 1998-2001 VW Passat.


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## Huub3 (Aug 16, 2009)

etischer said:


> I just picked up one of these heaters too. I had pretty good luck soldering extension wires. I meshed the two ends together, then wrapped a wire around the bundle to hold it together while I soldered.
> 
> 
> 
> I also found a plug for the Bosch pump, and heater signal in the fuel injection harness from my old ev motor. The heater control plug is off the air flow meter on a 1998-2001 VW Passat.


Hi Eric,

nice work. Are you going to replace the heater core air heater, or is the water heater planned to be on top of your current system?

Regards,


Huub


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## etischer (Jun 16, 2008)

It will probably replace the heater core. The heater core works ok, it's just not very powerful (900 watts vs 4000). Another interesting issue is the heater core is before the AC evaporator in my car, so if I run both to demist the windshield it has the opposite effect. The heater core heats the moisture off the evaporator and really fogs up the windshield as soon as the AC compressor stops.

Mounting the fluid heater was the easy part, I'll have to see if I go through with the full install. The biggest pain is relocating my Linkpro which is currently occupying the location where the heater knob used to be. It would be so nice to have a functional heater knob though!



Huub3 said:


> Hi Eric,
> 
> nice work. Are you going to replace the heater core air heater, or is the water heater planned to be on top of your current system?
> 
> ...


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## TEV (Nov 25, 2011)

etischer said:


> I just picked up one of these heaters too. I had pretty good luck soldering extension wires. I meshed the two ends together, then wrapped a wire around the bundle to hold it together while I soldered.
> 
> 
> 
> ...


I am interested to find the plugs for my heater, what engine was in your passat ?


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## etischer (Jun 16, 2008)

it was a 1.8 turbo, the same plug is probably on an Audi A4.


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## TEV (Nov 25, 2011)

etischer said:


> it was a 1.8 turbo, the same plug is probably on an Audi A4.


Thank You.

P.S. I got my heater installed and it's working very nice.


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## a4x4kiwi (Mar 23, 2009)

Does anyone happen to have a spare heater (even with short wires)?

I am after an RM3 HV for my project BMW E30.

Email [email protected].

TIA.
Mal.


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## TEV (Nov 25, 2011)

I have one , but I am located in US.


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## Ace_bridger (Nov 22, 2011)

Try Skooler on here. He had one spare but in the UK.


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## Yukon_Shane (Jul 15, 2010)

Ace_bridger said:


> Can anyone see a reason why these heaters wouldn't work with 144V pack (150V to 146V ish)?


This is an old post but I thought I'd follow-up on this point because it doesn't look like it has been addressed yet. 

I bougth two of these units hoping that they would work with my 160V pack and just yesterday finally got around to testing one of them and it worked fine. As predicted the power use (and thuse heat production) is lower then rated at my lower voltage. I was reading approximately 17 amps out of my pack that was sitting at around 164V at the time so that's about 2,800 watts versus the rated 4,000 watts. Still that's probably plenty of heat for my application so I'm happy. 

Now I just have to find some way to mount the darn thing


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## Elegancec (May 23, 2012)

I have killed it.
I did a mismatch in the cables:
Com line +12V and ground to the +12V socket.
Result: Smoke.

Please do not the same fault, always check it twice against wrong polarity.
I guess it is non repairable and is directly prepared for the trash bin. Very stupid mistake.

Does anyone have a spare one?


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