Bongo Fury

We have a problem with our Eberspacher D2 diesel heater. It works fine when on electric hookup and sometimes immediately after a long drive but, if on leisure battery only, it usually fails to start.
According to the manual the heater has an under voltage cutout and will not start if the battery voltage is below about 10.5V. I have put a meter across the supply (at the heater end rather than at the battery) and the voltage is dropping to about 11.3v (from 12.7) at start up. In theory this is sufficient but I guess could be within a margin of error on the voltage sensor. The heater has been checked by an Eberspacher service agent and is fine (and of course works fine when on hookup).
So the big question is - how do we get it to work when on battery only?
I wondered whether using an Elecsol dual purpose battery might help as it could be better suited to the high current draw that the heater requires at startup. I read a thread from a few years back that suggested using the van's starter battery to power the heater (something I am not keen to do).
Has anyone had similar problems? Any thoughts or suggestions gratefully received.
Shaun

Shaun_E wrote:We have a problem with our Eberspacher D2 diesel heater. It works fine when on electric hookup and sometimes immediately after a long drive but, if on leisure battery only, it usually fails to start.
According to the manual the heater has an under voltage cutout and will not start if the battery voltage is below about 10.5V. I have put a meter across the supply (at the heater end rather than at the battery) and the voltage is dropping to about 11.3v (from 12.7) at start up. In theory this is sufficient but I guess could be within a margin of error on the voltage sensor. The heater has been checked by an Eberspacher service agent and is fine (and of course works fine when on hookup).
So the big question is - how do we get it to work when on battery only?
I wondered whether using an Elecsol dual purpose battery might help as it could be better suited to the high current draw that the heater requires at startup. I read a thread from a few years back that suggested using the van's starter battery to power the heater (something I am not keen to do).
Has anyone had similar problems? Any thoughts or suggestions gratefully received.
Shaun

Personally, I think you are thinking along exactly the right lines (about high current draw dropping LB voltage too much for the cut-off). I was thinking of an Elecsol for similar reasons (I'm experimenting witha 12v electric blanket and thermostat), but in a recent debate the Energy Bull battery started to sound like it might eb a better battery than the Elecsol (have a search on here)

shaun

how old is your L/B ?, if it's getting on a bit perhaps a good bench charge from the mains may help, or perhaps a new one

mine fires up first time every time and my L/B is quite small at 75AH

only other thing i could suggset is to make sure all your eberspacher connections on the loom are tight and nice and clean, you never know !

MAZABON wrote:shaun

how old is your L/B ?, if it's getting on a bit perhaps a good bench charge from the mains may help, or perhaps a new one

mine fires up first time every time and my L/B is quite small at 75AH

only other thing i could suggset is to make sure all your eberspacher connections on the loom are tight and nice and clean, you never know !

I reckon that's a good point. My LB voltage was dropping under load and triggering the low voltage cutout on my experimental setup (triggers at 11.2V - your trigger sounds v. low). Even giving it a full mains charge didn't fix things. I suspect my LB is knackered. Also of course. you can get voltage drop across the wiring if it is too thin and/or the run is too long.

Thanks for the replies and it sounds like I am making sense
Battery is of unknown provenance as it was fitted as a replacement when we bought the van (due to the fitted one failing) but I suspect it wasn't new.
I have stuck my Optimate conditioner on it which should bring it up to fully charged and will try again this evening.
I'll have a read of the battery debate but looks like the dual purpose battery would be a reasonable thing to try.

Is the wiring from the battery to the heater well sized?

If its skinny it may be you are getting volt drop between the battery and the heater.

I you check the battery voltage as well as the at the heater you can see what the difference is.

If possible solder all the connections as well, crimp on ones don't always work that well and can corrode.

Charged the battery up and the heater starts with no problems.
Voltage drop between battery and heater is minimal as I checked the voltage at the heater end of the wire.
Looks like we just need to make sure we charge the battery fully before going away to any place without hook-up. If the battery doesn't last a weekend then we may have to buy a new one.
Thanks folks,
Shaun

The D2 draws about 3 amps during startup. The LB does sound a bit weak. I would start up the Eber with the engine running for a few minutes during heater startup if I was expecting a cold long weekend.

dandywarhol wrote:The D2 draws about 3 amps during startup. The LB does sound a bit weak. I would start up the Eber with the engine running for a few minutes during heater startup if I was expecting a cold long weekend.

I have had a similar problem with my set up and i have a new 110 ah battery, just changed the feed wiring from 3.5mm to 6mm now working a treat
also had problem with my fridge cutting in and out changed to 6mm wires and a marine type 12volt power socket now also O/K
so volt drop was the cause of all faults.