removing voltage regulator from diesel heater

[Harry Bloomfield]

But it wont start the machine though. What size is your battery that you start your Webasco with may I ask? Cold cranking or leisure battery type?

It's an 80 amp hour.

 

[magicmushroom666]

Just connect the battery right next to the heater temporarily to see if the cable is your only problem. They do pull a very large current at startup, so no chance of 0.75mm working well. I have mine running from a power supply, and had to get a 20A unit for it to start sucessfully.
Also make sure you dont have a 24V unit by mistake, then it would always report low voltage. I seem to remember there was a way to change that through the controller somehow.

 

[AstonHill]

The Eberspacher heater did have a low voltage cut out, I would think most do, as to battery voltage, I have in resent years had to revise my thoughts on damage to batteries due to over discharge. It does depend on type of lead acid, for a traction battery or absorbed glass mat or valve regulated lead acid they seem to survive deep cycling far better than the vehicle start battery,

Our man from the battery shed says that these new jell absorbed glass matts are all the rage now. But double the money of the older type of LAB.

Note; with my car battery that I discharge to 4/5 volts I soon charge it up again stright after. Is this OK? as I read hear the longer you leave discharged the battery the harder the solfur on the plates become

to get the high amps to start an engine yet keep the battery small, the way the spongy lead is held on the plates allows it to fall off with deep cycling, the leisure battery is a hybrid, not as bad as a vehicle start battery for loosing the material, but worse than a traction battery.

So a cold cranking battery has thicker plates and in turn more space between each plate and thus easyer for the sulfer to drop off?

However load will drop the voltage on a traction battery much more than with a vehicle start battery, so where a battery needs to do both, a leisure battery needs to be 1.5 times the size of a vehicle start battery where used for duel tasks, like in a motor home.

And what do you recon to this diesel heater in question wanting to draw 12 amps just to power the glow plug. cold cranking battery better then leisure battery?

So question is how long and what size is the cable used battery to heater? Is this causing the volt drop, what size battery is being used, 40 Ah is minimum size for a caravan "A721.55.3.2 Capacity" and I would say in the main smallest used is 90 Ah, I would use smaller I have two 35 Ah AGM batteries for the mobility scooter and likely they would be OK where there is normally a mains supply, but would need a smart charger so stop over charging.

My leisure battery is 110amp/hr. But dose not hold 12v well

 

[AstonHill]

You have replied while I was writing, Volt drop calculator here clearly you need to know amps, and it does not do 0.75, but I used 1 mm and 5 amp at 20 meters and got 3.7 volts which would be enough to cause problems.

Is this something to do with ohms law or something?

Sorry I got maths wrong! wont be cutting cable after all

 

[AstonHill]

It's an 80 amp hour.

Are you using the car battery or you have leisure battery?

 

[Harry Bloomfield]

Are you using the car battery or you have leisure battery?

My car is fitted, with an 80amp hour battery, which power both car, and Webasto.

 

[robinbanks]

What do you think? Do you think it will give me 3mm2 wire with out putting to much resistance up?

I think nearly every time you post you demonstrate another limitation to your understanding that impedes you with regards to doing electrical work safely and sensibly. Thankfully we're only dealing with 12v here

When you halve the length of a wire you halve the end to end resistance. When you join two identical cores in parallel you also halve the resistance end to end. Taking a 2 core 0.75mm2 10m cable and cutting it in half and twice joining two cores together will make a 1.5mm2 two core 5m system that is a quarter of the resistance of the original 10m run. It does not generate a 3mm2 cable unless you join all 4 cores together, but you aren't doing that because you have positive and negative. It does not put the resistance up to shorten a wire or make it fatter; this has already been mentioned.

We do not have "live" as a term of reference in DC; please start calling things their proper names when talking with others or you will generate confusion

 

[ericmark]

At 110 Ah it should be OK, there is some where a chart giving the resistance of the cables and how to work out volt drop including temperature correction factors, it is rather complex, using square roots etc.

But the simple on line calculators are good enough for what you want.

Try with battery very close first, so you know if volt drop or something else.

Flooded batteries are not a problem, but do need topping up from time to time. But vehicle batteries have thinner separators so easier for the active material to fall off, there is space at bottom of the battery to collect this, but once full it will short out plates, but before that point it will loose most of its capacity.

A battery once fully charged should stay above 12.6 volts for a day, a good battery will triggure a smart charger every few hours, wife's Jag with a 90 AH AGM once a day dropped below 12.8 volts, my Kia with flooded on last legs, would triggure charger every 10 minutes.

With a battery there are two resistances, internal and external, at cranking amps the battery could well be 9 volt, so old cars used a 9 volt ignition coil and a resistor the latter shorted out when cranking.

 

[AstonHill]

My car is fitted, with an 80amp hour battery, which power both car, and Webasto.

So we go back to what our friend erricmandodar states about car starting battery needed as opposed to leisure batteries

 

[DetlefSchmitz]

Just one remark: Dunning–Kruger effect

 

[Harry Bloomfield]

The more you learn, the more you realise how much there is to be learned.

 

[SUNRAY]

Has no-one worked out the volt drop? I can't be bothered to trawl through all of this thread.

0.75mm² wire is (from memory) ~ 25mΩ/m so 10m = 25x10x2mΩ = 500mΩ or ½Ω.

Ohms law Volts = Resistance x Current = 12 x 0.5 = 6V drop.

So even with a 14V supply 14-6=8V

Personally for something which requires 12A running on such a low 12V I'd be aiming for a maximum volt drop of say 0.25V for consistant operation.

0.24V/12A = 0.02Ω or 20mΩ and for a 10m cable will be 20mΩ/10m = 2mΩ/m If my memory is correct that will be 16mm² at 2.5mΩ/m or 25mm² at 1.5mΩ/m.
I would not even consider anything less than 6mm² as a temporary botch.

You will also require good quality connectors, certainly not a cigarette lighter type of thing.

To put this into perspective, in my car I have 2 way radio kit mounted in the rear boot area and ran 10mm² from the battery top 30A fuse.

 

[AstonHill]

ok this thread is not going to answer my question on how to deactivate it
So rather then spend another 56 quid on a battery I think I will just send it back for a refund and forget about it!

 

[SUNRAY]

ok this thread is not going to answer my question on how to deactivate it
So rather then spend another 56 quid on a battery I think I will just send it back for a refund and forget about it!

WOULD IT NOT MAKE MORE SENSE TO ACTUALLY READ THE REPLIES THESE KIND PEOPLE
HAVE BOTHERED SPENDING THEIR TIME WRITING.

IF YOU REALLY WANT TO IGNORE OUR ADVICE, BY ALL MEANS,GO AHEAD AND BUGGER YOUR PERFECTLY GOOD MACHINE
AND RANDOMLY CHOP BITS OUT,
THE VERY BITS THAT ARE PUT IN THERE TO PROTECT YOUR SAFETY
AND YOUR PROPERTY.
IN FACT IF YOU CHOP ENOUGH BITS OUT IT WILL NEVER WORK AT ALL
BUT THAT IS NOT MY ADVICE OR THE ADVICE OF ANY OTHERS ON HERE
AND YOU ARE ON YOUR OWN

WE RALLIED TOGETHER AND HAVE GIVEN SOME EXCELLENT AND EXPERT ADVICE.

WE WILL HAVE A GOOD CHRISTMAS KNOWING WE HAVE DONE OUR USUAL GOOD DEEDS.​

 

[SUNRAY]

You know your problem dont you? Your just one of those jobs for the boys men, think he will make a livelihood out of bureaucracy. But in reality he dose not see the bigger piture as everyone looses in the end

You are obviously not aware of the advice I give on this site, I go out of my way to help those who come here for help and advice and sometimes I look for ways, let's describe as unorthodox or non standard, to get something working safely or to avoid major upheaval works.

As an example a lot of time and effort went into 7 pages of someone who did want help: https://www.diynot.com/diy/threads/2-way-lighting-switches-on-stairs.541693/page-7

So please don't confuse me which the 'jobs for the boys' brigade, that is not who I am.