Diesel Heater Voltage issue

revemike · Senior Member

Diesel Heater Voltage issue

Peter_n_Margaret · Guru

Measure the voltage at the heater, that is where it counts, not at the battery......
It is unlikely to be a battery problem and more likely to be voltage drop caused by cables that are too small.

Cheers,
Peter

Brenda and Alan · Guru

The simple answer is the voltage at the heater is to high as the heaters are designed to run off lead /acid type batteries. If you run your lithium bank to a max voltage of 13.8 your diesel heater will run fine. Had the same problem ourselves when charging the lithium bank to over 14 volts. Our heater is an Eberspacher and the controller has a max as well as a min voltage that it will run at.

Alan

ps I think your lithium at 90% charge would more likely be at 14+ volts so maybe check your voltage with a good multimeter.

-- Edited by Brenda and Alan on Friday 1st of June 2018 08:41:07 AM

-- Edited by Brenda and Alan on Friday 1st of June 2018 08:42:00 AM

Mike Harding · Guru

Putting two or three diodes in series with the positive supply to the unit will drop the applied voltage by one to two volts and may solve the problem.

You must ensure the diodes have a current rating sufficient for the application and install them in such a way that they have some airflow and are not pressed against other wires as they will become warm - if they become hot you need larger diodes and better cooling.

One of these may help:

https://www.jaycar.com.au/6a10-6a-1000v-diode/p/ZR1024

https://www.jaycar.com.au/diode-6a4-400v-6a-rectifier-r6-pack-10/p/ZR1044

PS. Ensure the diodes are the correct way around otherwise it won't work at all - no harm will be done but it won't work.

revemike · Senior Member

Thanks for these comments. I am almost certain the issue is high voltage. Mind you, the voltage at the Anderson plug where the heater gets its power from is only around 13.30v. I went into the supplier today and he had run into the same problem when using a Lithium at a Show. The voltage of that battery was 14+v so he was a little surprised I has having issues at 13.3v. He is going to send my step by step description to the manufacture and get some comments.

I am not an electrician but I will look for someone who can help with the diode suggestion.

dorian · Guru

Brenda and Alan wrote:
The simple answer is the voltage at the heater is to high as the heaters are designed to run off lead /acid type batteries. If you run your lithium bank to a max voltage of 13.8 your diesel heater will run fine. Had the same problem ourselves when charging the lithium bank to over 14 volts. Our heater is an Eberspacher and the controller has a max as well as a min voltage that it will run at.
Alan
ps I think your lithium at 90% charge would more likely be at 14+ volts so maybe check your voltage with a good multimeter.

The alternator charging voltage would be 14.1V - 14.5V. A diesel heater must be designed to accommodate that and more.

AIRTRONIC / AIRTRONIC M Technical description, installation, operation and maintenance instructions:

https://www.caravansplus.com.au/pdf/airtronicD2D4_technical.pdf

Lower voltage limit: An undervoltage protection in the controller switches off the heater when the voltage limit is reached.

10.5

Upper voltage limit: An uppervoltage protection in the controller switches off the heater when the voltage limit is reached.

16 volt

Mike Harding · Guru

revemike wrote:
I am not an electrician but I will look for someone who can help with the diode suggestion.

An electrician wouldn't know a diode if it dropped on his head.

Aus-Kiwi · Guru

Oh donât make it one of those threads !! Lol

Mike Harding · Guru

Aus-Kiwi wrote:
Oh donât make it one of those threads !! Lol

I just get fed up with electricians pretending they are "experts".

thomas01 · Senior Member

Now, now MH. Settle down.

Not all electricians are wire jerkers.

Anyhow, most of us don't have to pretend to be experts. We just are.

And that's my expert opinion!!!

Robert.

-- Edited by thomas01 on Friday 1st of June 2018 10:15:58 PM

Brenda and Alan · Guru

Dorian I know the eberspacher D2 is supposed to operate up to 16 volts, but ours fails to ignite if the voltage at controler is above 14.1 volts and it sets the 010 error code. Don't know why so onyt charge the lithium bank to 13.8 volts and have no problems any more.

Alan

revemike · Senior Member

I THINK I have sorted it.... another test tonight when the solar will not be adding amps will confirm.

Update: Test Results

Today, I checked the wiring and found that the connection to the pump was a little loose. I also altered the position of the pump to remove the upward angle away from the heater. The installation notes say that the pump should be positioned angled upward towards the heater. I have positioned it more in keeping with this requirement.

12volt standard battery

Turn on heater. At standby 12.67v

Fan on (only) 12.55v .33amps

With heat on 11.29 - 9.59amps

Pump ticking 11.35

Heat felt from vent 12.19v

12volt Lithium

Turn on heater. At standby 13.83v

Fan on. 13.64v

With heat pump working. 12.30v - 11.80v

Heat felt from vent. 13.37v

Note: The error message did not present this time. The battery was at around 90%SOC at the time of this test and the sun was shining on the solar panel.

Peter_n_Margaret · Guru

It is clear to me that the failure is low voltage.
The cable to the unit is too small and you are getting a lot of voltage drop.

Cheers,
Peter

grahamg · Senior Member

when these startup they draw a large current for a short period which will drop the voltage if the battery is on the way out or the cable too thin etc... once they start they only draw a small current.If you measure the battery voltage all appears to be ok unless you actually measure it when the high current occurs.

if i am aware the battery is a bit low, I will connect and and run the car until it starts and all is ok.

revemike · Senior Member

I made some alterations today that appear to have made a difference...

The attached photo shows the amount of cable I was able to discard from the heater installation today.

The heavy roll was from the power source end (connection to Anderson plug to 12v source). The smaller roll of wire, that is a very light gauge, was removed from the connection to the pump.

After removing the excess I tested the heater (with solar supplementing power) and the heater functioned perfectly. I will try it tonight when there is no supply from solar and see if the heater still functions (without the low voltage error).