How accurate are weighbridges

Public weigh bridges are normally certified for accuracy.

Rusty you are expecting too much.
That’s a 3 percent difference between the given and your measured weights – that accuracy is not too bad for weighing devices of that type.

I have been operating a weighbridge for local council for last 10 years. Although we are not acertified public weighbridge, we get people here weighing cars , trucks, trailers caravans etc for registration purposes without any knockbacks. Ours weighs up to 60 tonne in 20kg steps & is recalibrated every 12 mths by law and hasnt failed that in 10 years. So in answer to your question, I highly doubt that " your " weighbridge is inaccurate by said 100kg

That "weight certificate"..was that from a weigh bridge or from the manufacturer.

Was that "certificate" before or after accessories where fitted.

Gas bottles, water tanks full?

Even the choice of wheel and tyre can give a variation of 100Kg if it has 4 road wheels and 2 spares.

If you are using bathroom scales....hell they are more likley to eb dodgy than a weigh bridge.

cheers

I suspect the manufacturer has it weight BEFORE he puts in what he classes as extras like a battery, spare wheel etc.

Hi

When you say "allowed for water in tanks, allowed for fuel for jerry cans and generator"...did you guess the weight of these when you came up with estimated total ? If you weighed everything else (clothes, food, equipment etc) apart for these then they can be the only source of the extra weight (assuming WB super accurate)...though ..have you checked for stowaways in a cupboard :)

Cheers
Greg

Certified weigh bridges are very accurate. They can suffer problems, but these normally show up as fairly substantial differences in readings. Things like the bridge will not zero itself or will read in the minus.

Things that cause it are the likes of a bad load cell, crook electronic card, wiring or something caught between the weigh frame and the surrounding structure.

As said, weights and measures bring in weights and test the bridge for accuracy.

Make sure you weigh everything. On a van that big, water will probably weigh 190 kg and gas 16 kg, so half your payload is gone already.

You may have to shed some weight or relocate it.
On the side, I just pulled 25kg out of my van to get under ATM. I had to transfer some of this weight to the vehicle as the things I pulled out were essentials.

What, may I ask do you hope to tow it with?

Unless the weighbridge ticket delivered with the van was within a day of delivery then it was probably done when it was first towable before any "extras" were fitted and usually a bare van without bedding, soft coverings, gas bottles, spare wheels. Friends were in that exact situation last year, van even packed with the basic necessities was way over weight. The only way to get it back to the supposedly as built tare weight was to remove the mattress, gas bottles, curtains seat cushions, boot lid, rear bar etc etc.
The manufacturers response was they were all "extra's" even the innerspring mattress as foam was standard and the seat cushions and curtains etc made up for the fitted awning!
As others have said weighbridges by law have to be accurate especially if they are charging customers like transfer stations etc.

As others have said, a certified weighbridge will be quite accurate and the weighbridge operator will be able to tell you to within XX Kilos. Many large weighbridges only weigh in 10 Kg increments.

I suggest your problem is much earlier. What it Tare configuration for your van? Were any customer options added after the tare was obtained? Manufacturers are motivated to tell you the best possible figures and without knowing the tare baseline, totalling in the bits and things you added is pretty vague.

I take it you did not weigh the van on the way home from the dealers/seller when you first picked it up?

Iza

It seems you need to return to the manufacturer to find out why their figures are wrong rather than hoping it is the weighbridge. Your real payload is apparently way too light for an off road van going on long trips. If it is true that they did not include basics like mattresses, spare wheels and awning in the TARE you have a worse problem. Depending on the certification of your chassis and suspension it may be possible for you to get an engineer's certificate to change the compliance plate to a higher ATM. Otherwise you appear to have a case for being sold a product that is "unfit for purpose." John

I work for a company which operates a number of certified weighbridges, that easily weigh in over 50 000T each year and 50 000T out. Quite a large amount of the material we receive has been dispatched from places with a weighbridge, hence we have a comparison of net weight loaded and unloaded.
These are typically 42 to 80T gross loads(single triaxles semis to double road trains and everything in between)
Differences of 200kg are possible and but are at the extreme end of what we observe in practise despite these weighbridges being certified each year. We don't worry about variances up to 200kg, unless we think it is consistent.
100kg is not unreasonable variance, especially you don't know at what stage of "completion" the manufacturer weighed the van (did it include bedding, the fridge etc).

i might suggest that any off road van with a tare of 3000kgs when loaded even lightly for a trip will exceed their 3500kgs max towing for most of the vehicles in Australia except for the American imports of the like of Chev, Ford and Dodge. The weigh bridge is not out, the vans are just getting too heavy and our tow vehicles are not big enough.
Just another observation is that most of the Kedron, Bushtracker etc vans of around 20' plus that are being towed with a top load boat are far exceeding their max weight capacity.

Cheers

Merv

Thanks to all those that have replied. This is truly the best forum out there
It seems as though I need to find out what the manufacturer included in his Tare weight

I think there should be an industry standard here and will contact RVM Australia to get the current standard and suggest changes

Maybe I missed something in the conversation, but wouldn't it be easier to just take out everything you have added and go and get it weighed again? That way you know what it actually weighs, no more speculation.