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Eberspacher heater


JohnHT

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Further to the problem from dmorgan27 in January, I have the opposite problem in that the Eberspacher heater works OK on hook-up but this weekend it wouldn't fire up at all on diesel until I ran the van engine. When we bought our Pioneer Frobisher (a variant of the Autocruise Starblazer) new in 2006 we had a second leisure battery fitted as an article in MMM pointed out that the heater drained the battery quickly. Both batteries are 135AH capacity. The batteries were charged up overnight before leaving home. Surely I should get more than 4 1/2 years from the batteries?
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Hi John and welcome to the madhouse!

 

Problems with Eberspachers in motorhomes are by no means unusual and invariably they end up being battery related - often insufficient charging rate rather than duff batteries.

That said, judging by the experience of many of us you have not done badly to get over 4 years out of a pair of leisure batteries?

Do you have a digital multimeter and, with respect, do you know how to use it? Many of us keep one in the van and wouldn't leave home without it!

Have you checked the at rest battery voltages, both together and individually? 12.8 is fully charged and under 12.5 is not good?

Have you checked that the van's own battery charger is charging when on ehu? Around 13.8 volts usually?

Have you checked that the batteries are actually charging properly via the alternator? Around 14.2 volts is usual?

Have a look at the fuses close to the battery for poor or loose connections?

Then check at the split charging relays which are probably located just under the front of the bonnet in front of the battery - most Autocruise are - right where all the rain and road dirt can get in - as they often get dirty and corroded and fail to make contact.

As the alternator only charges the leisure batteries at about 10 amps you do need to do a lot of miles to fully recharge two large batteries.

 

I'm not sure but it is possible that your van is so wired that the Eberspacher works off the engine battery when the engine is running and off the leisure batteries only when then engine is off - which might also explain why it works when the engine is running?

 

 

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My understanding of diesel-heater technology is that these appliances need a a hefty 'whack' of voltage to fire-up. For a motorhome standing 'idle', this fire-up voltage would normally come from the leisure battery.

 

When a motorhome is on EHU or has its motor running, as Tracker explains, the available voltage will normally be at least 13.8V or 14V respectively. However, off EHU or with the vehicle's motor stopped, the available voltage at the heater may be much lower once voltage drop is taken into account and/or the charge in the leisure battery has reduced.

 

For a diesel-fuelled heater it's imperative that the wiring that connects the heater to the battery is suitably robust and as short as practicable. If relatively skinny wiring has been used, together with a long cable run, even if the battery is in perfect condition and fully charged initially , the voltage at the heater may be significantly below the 12.8V Tracker mentions.

 

If a battery is not fully charged to begin with, or age has reduced its ability to hold charge, or the motorhome user is exploiting the battery for other 'domestic' uses (eg. running a TV via an inverter), or the heater itself needs a bit of TLC, then the voltage available at the heater may be insufficient to fire it up.

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I have the similar Starblazer from the same year. Assuming that it is identical in all but cosmetics ......From my experience:-

 

Low voltage will cause the Eber to fail to fire up. I think that it is anything below about 11 volts. measured at the Eber. heater control box at the time of ignition.

 

The fact that it will fire up when the engine is running suggests strongly that this is the case because the Eber is then getting it's voltage indirectly from the alternator.

 

From the Sargent control panel you can watch the leisure battery voltage as the Eber fires up and will see a voltage drop which will be a good guide.

 

Although you can use the Sargent control panel to switch to using the van's engine battery for the habitation area this *will not* switch the Eber on to the engine battery. The Eber will *always* run off the leisure battery.

 

Discussion with other Starblazer owners has pointed to the wiring from the leisure battery to the Eber fitted by Autocruise, being below the specification required from Eberspacher and this could lead to low voltage at the Eber control unit but having run yours successfully for nearly five years, I doubt that that is worth considering as a cause.

 

The main drain on batteries when the Eber runs is at start up when the glow plug is heating. Once the heater is actually running on diesel I doubt that it is using any more power than a gas heater with the blown air system running

 

I apologise if this is all stuff that you know about and hasn't answered your question but to do that, I think that it is quite possible for batteries to last less than five years. I had to replace the 110 amp leisure in my Starblazer when it was about three years old. I fitted two 113amps.

 

hth

 

Harvey

 

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Many thanks to Tracker, Derek Uzzell and Harvey for the information and advice. I have checked some of the voltages mentioned but not when the engine is running nor have I checked the split charge relays - jobs for tomorrow!

 

John.

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I had a good morning checking voltages and was surprised to find little difference between the readings of both batteries, as the second battery is in the garage - some 9 feet from the other! Generally the voltages were 0.5 to 1 volt below Tracker's figures. When I checked the split charge relays, the contacts for both relays and the two 20 amp fuses were corroded. I have the van on hook up now and will check the voltages again tomorrow.

Again, many thanks to all for the help in this matter.

 

John

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JohnHT - 2011-05-04 3:51 PM

 

I had a good morning checking voltages and was surprised to find little difference between the readings of both batteries, as the second battery is in the garage - some 9 feet from the other! Generally the voltages were 0.5 to 1 volt below Tracker's figures. When I checked the split charge relays, the contacts for both relays and the two 20 amp fuses were corroded. I have the van on hook up now and will check the voltages again tomorrow.

Again, many thanks to all for the help in this matter.

 

John

 

You need to be careful when checking battery voltage as a simple one-shot reading may give a false impression.

 

Let's assume you are employing a charger that can maximise a battery's charge (and your motorhome's on-board charger may, or may not, be able to do this). 'Bench charge' (ie. the battery will have been removed from the vehicle, or disconnected from anything that might take current) the battery until it's evident it won't accept further charging, then disconnect the charger and let the battery 'settle' for, say, 24 hours. As Tracker advises, a voltage reading taken at the battery terminals should then show 12.7v (or above) if the charge-state is 100%. Below 12.7v the charge-state figures are 12.5v/75%, 12.4v/50%, 12.2v/25%, 12v (or below)/Discharged.

 

It's vital before taking a voltage-reading to allow plenty of 'settling' time (4 hours minimum - more if the battery is old) after charging has ceased: also, if a voltage-reading is to be taken with the battery in situ and connected to the motorhome's electrical system, you should ensure that the battery is not feeding current to anything. Many modern fridges, electrical drain valves, digital control-panels, etc. will take leisure-battery current unless action is taken to prevent this - and any current 'drain' occurring when a voltage-reading is taken will affect the read-out.

 

Even an apparently satisfactory voltage-reading may not always indicate that the battery is up to scratch. I remember a forum member following the above procedure, the voltage-reading looked fine and the battery semed to be holding charge. However, as soon as even a small 'load' was applied to the battery, the charge very rapidly drained away. In that instance the battery was plainly faulty, but it just shows that you need to be careful.

 

There's a comment on page 165 of June 2011's MMM about a 10-months-old leisure battery faillng and three separate tests not revealing a problem. I well recall arriving at a tyre/battery-fitting firm having managed to start my car only after charging its elderly, and clearly on its last legs, battery overnight and being told by a keen young fitter that his voltage reading (taken immediately after I'd driven there) indicated that the battery was OK.

 

 

 

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Thanks Derek. I checked the battery voltage this morning after 24 hours on hook up then disconnected the supply before starting the heater. The voltage indicated on the Sargent panel was 13.3v and it fell to 12.2v by the time the heater had fired up - much as Harvey had suggested.

I'll now put each battery on bench charge in turn as you suggest. That should decide whether I need to renew them before the Newbury show!

 

Regards,

John.

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Thanks Derek. I checked the battery voltage this morning after 24 hours on hook up then disconnected the supply before starting the heater. The voltage indicated on the Sargent panel was 13.3v and it fell to 12.2v by the time the heater had fired up - much as Harvey had suggested.

I'll now put each battery on bench charge in turn as you suggest. That should decide whether I need to renew them before the Newbury show!

 

Regards,

John.

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If all the fuses and connections are OK and the battery has sufficient electrolyte it does suggest that the batteries are - to use the technical term - knackered!

 

The one certain way to tell is by checkingthe specific gravity of the electrolyte with a hydrometer - if you have one - and if the cells have individual caps or access?

 

This tells you how -

 

http://www.reuk.co.uk/Battery-Specific-Gravity.htm

 

The show might be a good place to replace them if you need to as there are usually offers, or if you need them sooner Tayna Batteries in Abergele are usually very good with competitive prices and quick delivery.

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It's too many decades since I used a hydrometer but you're right; it's the most positive way to determine battery condition. As an apprentice, I used to replace the separators in the cells of the car batteries of my bosses mates! Lack of practice dulls the brain!
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JohnHT - 2011-05-05 8:57 PM

 

It's too many decades since I used a hydrometer but you're right; it's the most positive way to determine battery condition. As an apprentice, I used to replace the separators in the cells of the car batteries of my bosses mates! Lack of practice dulls the brain!

 

I wasn't sure to start with - but I'm glad that you know what you are doing before you start messing with batteries and acid - we all had to learn but no need to treat you like a beginner any more - sorry - just was not sure!

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Your advice has been invaluable and much appreciated. As I said, it is so long ago that I dabbled with batteries and the dangers of accidental short circuit or spilled acid shouldn't be treated lightly. So, fresh reminders and memory joggers save a lot of potential trouble.

John

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  • 3 weeks later...

Hi guys.

Just back from Newbury show. I managed to get the old batteries up to half charge (SG 1220) and, with the split charge relay cleaned up, the Eberspacher started up. However I followed your advice and now have two new batteries, bought at a fair price

Again, thanks one and all for your help.

 

John. :-D

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