OR…in laymans terms…just connect the red to the red if you don’t want your electrics melted…possibly that makes life simple for the simple readers.
I bought a tipper non runner from the auction a while ago straight from the council…took it home,turned and reconnected the battery the correct way round,and voila.instant fix…ive no idea why the truck could have been sold as scrap/non runner as its not like the council to get things wrong?
ahh DD999…could it be that a pound or two changed hands to make it a non runner and it was not meant for you to buy!! I had to take ex police grandads,rover3500,council vans to Carlisle auctionmart in the 80s and a few pounds allegedly found their way intae my colleages back pockets as we stopped at the old moss for coffee and certain folks would enquire about the vehicles 
JIMBO47:
ahh DD999…could it be that a pound or two changed hands to make it a non runner and it was not meant for you to buy!! I had to take ex police grandads,rover3500,council vans to Carlisle auctionmart in the 80s and a few pounds allegedly found their way intae my colleages back pockets as we stopped at the old moss for coffee and certain folks would enquire about the vehicles
well it was me that bought it,and I buy plenty,so nuff said about the backhanders… 
my mate does repo work,and its 100 bung for a ecu after they repo a car im wanting…the punter don’t know as its taken away and that’s the last he sees of it,…the auction see it come in as a non runner…the finance co don’t now anything as it sells for whatever it sells for.( which is not a lot as being a non runner you have to factor in the price of an engine at least)…it gets bought and removed from auction as a non runner,1 ecu plugged in within 5 mins and hey presto,its a runner…just a perk of knowing who you know… 
Own Account Driver:
Conor:
Can’t understand how that could possibly happen just because he put the jump leads on one battery. Makes no sense.Because 24v is greater than 12v therefore the batteries will try to force themselves towards an equilibrium voltage and in the process a large amount of current will flow through any wires or conductive material connecting them - see every day’s a school day , even for such well qualified sorts.
Nope, doesn’t work like that. Its all about the potential difference and 0V reference levels. You make the mistake of many people and assuming that 0 volts is always referenced to the same level, i.e ground. It isn’t. 0V DOES NOT MEAN GROUND. “0V” is merely a term for a reference voltage level that all other voltage levels we’re measuring against use. Next mistake is always thinking that when you’re measuring voltage with a meter you’re measuring it in reference to ground, you’re not. When you measure voltage with a volt meter what you’re actually measuring is potential difference, the difference between the levels of the points you connect the test probes to. This is important when it comes to 24V systems on trucks using two batteries connected in series and connecting a 12V jump battery to either battery.
Two 12V batteries connected in series as they would in a truck. TPA is the negative terminal of the first battery that is usually connected to the chassis, TPB is the jump cable between the positive terminal of the first battery and the negative of the second battery and TPC is connected to the positive of the second battery.
TPA -Battery 1+ TPB -Battery 2+ TPC
Put a volt meter across TPA and TPB and you’ll measure 12V because the potential difference across the battery is 12V.
Put a volt meter across TPB and TPC and you’ll measure 12V because the potential difference across the battery is 12V.
The difference between Battery 1 and Battery 2 is that because the negative terminal of battery 2 is connected to the positive of battery one then the negative voltage level of battery 2 is at 12V (referenced to the chassis/battery 1 negative terminal), not 0V which is where you’re going wrong. When using the chassis connected to battery 1 terminal as the reference 0V you will see 24V on the positive terminal of battery 2 however the potential difference across battery 2 is still only 12V.
What that means is that you can have a jump battery for 12V, put it across Battery 2 even though you measure 24V between TPA and TPC and it’ll be just fine because the potential difference across battery 2 is 12V, the same as the jump battery.
Did you enjoy your day at school?
Conor:
Own Account Driver:
Conor:
Can’t understand how that could possibly happen just because he put the jump leads on one battery. Makes no sense.Because 24v is greater than 12v therefore the batteries will try to force themselves towards an equilibrium voltage and in the process a large amount of current will flow through any wires or conductive material connecting them - see every day’s a school day , even for such well qualified sorts.
Nope, doesn’t work like that. Its all about the potential difference and 0V reference levels. You make the mistake of many people and assuming that 0 volts is always referenced to the same level, i.e ground. It isn’t. 0V DOES NOT MEAN GROUND. “0V” is merely a term for a reference voltage level that all other voltage levels we’re measuring against use. Next mistake is always thinking that when you’re measuring voltage with a meter you’re measuring it in reference to ground, you’re not. When you measure voltage with a volt meter what you’re actually measuring is potential difference, the difference between the levels of the points you connect the test probes to. This is important when it comes to 24V systems on trucks using two batteries connected in series and connecting a 12V jump battery to either battery.
Two 12V batteries connected in series as they would in a truck. TPA is the negative terminal of the first battery that is usually connected to the chassis, TPB is the jump cable between the positive terminal of the first battery and the negative of the second battery and TPC is connected to the positive of the second battery.
TPA -Battery 1+ TPB -Battery 2+ TPC
Put a volt meter across TPA and TPB and you’ll measure 12V because the potential difference across the battery is 12V.
Put a volt meter across TPB and TPC and you’ll measure 12V because the potential difference across the battery is 12V.The difference between Battery 1 and Battery 2 is that because the negative terminal of battery 2 is connected to the positive of battery one then the negative voltage level of battery 2 is at 12V (referenced to the chassis/battery 1 negative terminal), not 0V which is where you’re going wrong. When using the chassis connected to battery 1 terminal as the reference 0V you will see 24V on the positive terminal of battery 2 however the potential difference across battery 2 is still only 12V.
What that means is that you can have a jump battery for 12V, put it across Battery 2 even though you measure 24V between TPA and TPC and it’ll be just fine because the potential difference across battery 2 is 12V, the same as the jump battery.
Did you enjoy your day at school?
CBA to try and make head nor tail of that but, out in the real world, it happens all the time. Fitter connects crocodile clips across one battery only on the flat battery truck then plugs then other end into the 24v anderson socket on his service van and melted leads every time.
You can jump a 12v car off a truck by only connecting across one 12v battery in parallel safely without melting the leads which might be what you’re talking about (although I wouldn’t necessarily bet on it).
I was waiting to see if Bking responded in some BS perfect storm but also in the real world modern vehicles won’t tolerate the wrong polarity battery connection, even briefly, without considerable damage there is little protection designed in to protect against in reality. If the ignition is not on it might not be too bad but the amount of circuits still active with the ignition off has got bigger and bigger over the years. Not at all unusual for the vehicle to be an insurance write off. It’s a bit like flood damage where it’s a difficult job as nothing electrical can be assumed working in the aftermath - connecting the battery directly to the vehicle the wrong way round and connecting jump leads the wrong way round are obviously slightly differing scenarios.
norb:
Love your style OAD …Now that you have proven the king of kings he is wrong yet again…I see he no longer puts forward an argument ,just insults …He is now on google and will come back asking you to answer some random question which as nothing to do with this thread whatsoever
I reckon a max of 12 weeks before he’s back with his 40 years experience mechanic routine - well the textbook he’s using is forty years old I suppose. To be honest it’s a bit poor that apprentices are still using such old textbooks a lot of the basics are probably ok but like he’s got caught out with his insulated return a lot doesn’t reflect current standard practice.
Just in case he does come back with some more nonsense though he can tell Scania how they’ve got it all wrong :
So did the Iveco get repaired or torched?
You can jump a 12v car off a truck by only connecting across one 12v battery in parallel safely without melting the leads which might be what you’re talking about (although I wouldn’t necessarily bet on it).
That is exactly what is happening.
but also in the real world modern vehicles won’t tolerate the wrong polarity battery connection, even briefly, without considerable damage there is little protection designed in to protect against in reality.
They do tolerate it for brief periods.It happens all the time, I’ve even seen AA/RAC breakdown drivers connect them up the wrong way. One of the main reasons that modern cars now have the negative terminal completely covered by the battery lid, that lid is a pain in the arse to take off but there’s a flap to access the positive terminal with a jump point on the body for the negative lead is because of the number of people who were connecting jump leads the wrong way round. Modern cars have far more protection than old stuff like my Ford Capri had basically because of the sheer amount of computers in the things. You won’t have a good reputation for long if accidentally connecting jump leads the wrong way round fries the ECUs. Reverse polarity protection for an individual ECU costs pennies to put in place. This diode is rated at 70A and can survive a 15A reverse polarity drain and costs just £6.
If the ignition is not on it might not be too bad but the amount of circuits still active with the ignition off has got bigger and bigger over the years. Not at all unusual for the vehicle to be an insurance write off. It’s a bit like flood damage where it’s a difficult job as nothing electrical can be assumed working in the aftermath - connecting the battery directly to the vehicle the wrong way round and connecting jump leads the wrong way round are obviously slightly differing scenarios.
[/quote]
Conor:
Own Account Driver:
Conor:
Can’t understand how that could possibly happen just because he put the jump leads on one battery. Makes no sense.Because 24v is greater than 12v therefore the batteries will try to force themselves towards an equilibrium voltage and in the process a large amount of current will flow through any wires or conductive material connecting them - see every day’s a school day , even for such well qualified sorts.
Nope, doesn’t work like that. Its all about the potential difference and 0V reference levels. You make the mistake of many people and assuming that 0 volts is always referenced to the same level, i.e ground. It isn’t. 0V DOES NOT MEAN GROUND. “0V” is merely a term for a reference voltage level that all other voltage levels we’re measuring against use. Next mistake is always thinking that when you’re measuring voltage with a meter you’re measuring it in reference to ground, you’re not. When you measure voltage with a volt meter what you’re actually measuring is potential difference, the difference between the levels of the points you connect the test probes to. This is important when it comes to 24V systems on trucks using two batteries connected in series and connecting a 12V jump battery to either battery.
Two 12V batteries connected in series as they would in a truck. TPA is the negative terminal of the first battery that is usually connected to the chassis, TPB is the jump cable between the positive terminal of the first battery and the negative of the second battery and TPC is connected to the positive of the second battery.
TPA -Battery 1+ TPB -Battery 2+ TPC
Put a volt meter across TPA and TPB and you’ll measure 12V because the potential difference across the battery is 12V.
Put a volt meter across TPB and TPC and you’ll measure 12V because the potential difference across the battery is 12V.The difference between Battery 1 and Battery 2 is that because the negative terminal of battery 2 is connected to the positive of battery one then the negative voltage level of battery 2 is at 12V (referenced to the chassis/battery 1 negative terminal), not 0V which is where you’re going wrong. When using the chassis connected to battery 1 terminal as the reference 0V you will see 24V on the positive terminal of battery 2 however the potential difference across battery 2 is still only 12V.
What that means is that you can have a jump battery for 12V, put it across Battery 2 even though you measure 24V between TPA and TPC and it’ll be just fine because the potential difference across battery 2 is 12V, the same as the jump battery.
Did you enjoy your day at school?
And yet more twaddle and ■■■■■■■■ dressed up as technology.
Bking:
Conor:
Own Account Driver:
Conor:
Can’t understand how that could possibly happen just because he put the jump leads on one battery. Makes no sense.Because 24v is greater than 12v therefore the batteries will try to force themselves towards an equilibrium voltage and in the process a large amount of current will flow through any wires or conductive material connecting them - see every day’s a school day , even for such well qualified sorts.
Nope, doesn’t work like that. Its all about the potential difference and 0V reference levels. You make the mistake of many people and assuming that 0 volts is always referenced to the same level, i.e ground. It isn’t. 0V DOES NOT MEAN GROUND. “0V” is merely a term for a reference voltage level that all other voltage levels we’re measuring against use. Next mistake is always thinking that when you’re measuring voltage with a meter you’re measuring it in reference to ground, you’re not. When you measure voltage with a volt meter what you’re actually measuring is potential difference, the difference between the levels of the points you connect the test probes to. This is important when it comes to 24V systems on trucks using two batteries connected in series and connecting a 12V jump battery to either battery.
Two 12V batteries connected in series as they would in a truck. TPA is the negative terminal of the first battery that is usually connected to the chassis, TPB is the jump cable between the positive terminal of the first battery and the negative of the second battery and TPC is connected to the positive of the second battery.
TPA -Battery 1+ TPB -Battery 2+ TPC
Put a volt meter across TPA and TPB and you’ll measure 12V because the potential difference across the battery is 12V.
Put a volt meter across TPB and TPC and you’ll measure 12V because the potential difference across the battery is 12V.The difference between Battery 1 and Battery 2 is that because the negative terminal of battery 2 is connected to the positive of battery one then the negative voltage level of battery 2 is at 12V (referenced to the chassis/battery 1 negative terminal), not 0V which is where you’re going wrong. When using the chassis connected to battery 1 terminal as the reference 0V you will see 24V on the positive terminal of battery 2 however the potential difference across battery 2 is still only 12V.
What that means is that you can have a jump battery for 12V, put it across Battery 2 even though you measure 24V between TPA and TPC and it’ll be just fine because the potential difference across battery 2 is 12V, the same as the jump battery.
Did you enjoy your day at school?
And yet more twaddle and [zb] dressed up as technology.
How do these ■■■■■■■■■ get away with this horse ■■■■?
dave docwra:
So did the Iveco get repaired or torched?
That’s what I was wondering…
Stralis’s have a small fuse on top of the batteries too, when this blows you have no power to the dash…
Beetie:
dave docwra:
So did the Iveco get repaired or torched?That’s what I was wondering…
Stralis’s have a small fuse on top of the batteries too, when this blows you have no power to the dash…
How do you have a “small” fuse on top of the batteries when you draw at least 600 amp for the starter motor?