Need more amps to fire up heater

Discussion in 'Tech/Mech General' started by treeman, Sep 5, 2013.

  1. treeman

    treeman Read Only Funster

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    I am having trouble getting enough electricity to my Eberspacher D2 airtronic diesel heater to fire it up. I'm thinking it's the way the thing is wired that's causing the trouble as I've just installed a new LB and still problems.
    The heater is an add-on by a previous owner and it was wired straight to the back of the ZIG CF8 unit into the engine battery output connector. This explains why the previous owner told me the heater only worked with the engine running - i.e. as alternator was charging the battery so good voltage. I've tried connecting to the back of the LB connector on the Zig but not enough power to start it. I've set up a 44ah battery as close to the heater unit as I can and connected it up with a short length of wire and it starts and runs fine for hours so I'm guessing there is a power loss/drop over the 5 metre run from LB to Zig and the Zig takes some juice as well.
    Am I right in thinking the best thing to do is get some decent 2.5mm cable and run direct from LB to heater to get most power to heater? (I'll stick an in-line fuse in too).
     
  2. BwB

    BwB Funster Life Member

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    Direct to the leisure battery with heavy wires (and fuse) was how my D2 was wired on a previous van. So yes I would think you're right.

    They seem to take very little electric power when running but they do suck it up when initially starting from cold.
     
  3. Snowbird

    Snowbird Funster Life Member

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    If it was me I would leave it alone. They do take a lot of juice on startup as they have a glowplug inside. Its better to leave the engine running whilst it goes through the startup cycle, then once its running switch off the engine. Mine does the same and after watching how many amps it took to ignite it I left it alone.
     
  4. FULL TIMER

    FULL TIMER Read Only Funster

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    I would say that the problem is in the wire sizing, on the eberspacher there should be two red wires one thick one 65/0.30mm 4.50mm the thick one should have a 25 amp fuse and be connected directly to the leisure battery pos terminal, this is the main wire to the heater, and a thin one normally 2.0mm 28/0.30mm should be fused at 7.5 amp and this is just a live supply to whatever control switch you have. there should also be a thick brown wire again 65/0.30mm this should also be wired direct to battery neg terminal , the power supply must be continuous otherwise if the power is cut the heater will not be able to run the cooling down cycle causing an overheat lockout. I have fitted hundreds of these in Ambulances in the past and using this size wiring have never had a low voltage problem,
     
  5. FULL TIMER

    FULL TIMER Read Only Funster

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    Forgot to say, anyone having problems with either D2'S or D4's and in the Norfolk area you are more than welcome to give me a shout or visit,
     
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  6. TheBig1

    TheBig1 Funster Life Member

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    with a 5m cable run i would be inclined to increase to 6mm cable rather than 4.5mm due to the resistance in the wire. just common sense to over engineer applications where high initial current draw is expected
     
  7. treeman

    treeman Read Only Funster

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    Thanks for the replies - I'm learning more as things go along so please bear with me.

    Snowbird - I see your point, my desire to not use the vehicle battery is I'm worried I'll drain the vehicle battery if running just from that. Also like to not to have to start MH every time we want heat.

    Full Timer - I am new to all these wiring sizes but after some investigation I understand a bit about number of strands/area and diameter etc. I do have some 50/0.25mm sq wire to use but sounds like I'd better go to 65/0.30 or even go to 84/0.30 (although this seems very expensive in comparison to 65/0.30).

    As an aside, the installation had no return/negative wiring back to battery, just to a close negative earth on the MH. Would it be advisable to install a proper negative wire direct back to LB? Does this need to be same gauge?

    Thanks again for all responses - appreciated.
     
  8. FULL TIMER

    FULL TIMER Read Only Funster

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    the 65 strand wire should be fine even on a 5 m run it is slightly heavier than Eberspachers own wiring which is normally supplied as part of a 5m loom. I would take the earth/negative wire again using the 65 strand directly to the leisure battery if only to eliminate any poor connections to the body ie from heater or leisure battery,
     
    Last edited: Sep 6, 2013
  9. treeman

    treeman Read Only Funster

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    That sounds sensible approach. I'll order some 65/0.30 and get it all cabled in and see how I get on. Had a few problems with my Eberspacher last winter, before I left here in Dorset I spent £50 and 2 trips to my nearest dealer for him to tell me the ECU had blown! Ended up buying new ECU and servicing it myself which is rewarding when it all works when back together.
     
  10. FULL TIMER

    FULL TIMER Read Only Funster

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    To be honest apart from ECU'S going sometimes due to motor failure the most common problems I come across are overheat trip outs ( mainly due to ambulance staff blocking the hot air outlets or lint build up on the inlet side), if this happens enough times the heater will stay in a locked mode ie the heater starts up as normal but shuts down after 5 minutes, other than that it's just fail to start up in the allotted time this is normally due to either low voltage at the heater or the small gauze ( plug strainer)below the glowpin being blocked by carbon build up believe me it is very hard to see this build up but if the heater smokes a lot on start up this is normally why.
     
  11. mitzimad

    mitzimad Funster

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    i cant see why you need an earth return the resistance of any cable is going to be greater than that of the vehicle body
     
  12. treeman

    treeman Read Only Funster

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    That makes sense, I'll try just wiring the live to the LB first and see if it works ok.
    Only thing to note is vehicle is 27 years old so rust is in evidence and I've noticed a couple of problems with poor earths on rear lights for example so because of the sensitivity of the heater to inconsistent power levels it would be comforting to have a reliable negative earth back to battery.
     
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