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Thread: On-Line auto electrical info

  1. #61
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    cuppabillytea is offline Loud Mouthed Rat Bag Gold Subscriber
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    Quote Originally Posted by Homestar View Post
    Depends on your Land Rover Billy. I don't think it would be viable to do it, but potentially doable in some older vehicles with a bit of work. Starter, alternator and distributor would be the hardest parts I think.

    What sort of long term gains you'd get I don't know. Unless the contact areas stay continually damp I wouldn't have thought you'd have the same issues long term as a Ship would suffer.

    Easiest way is to not take it in the drink - leave it in the car park - you've got a Tugboat for playing in the wet stuff.
    Yes. Most marine systems are 48 V so you'd have to do every single component yourself. This would make it ridiculously complicated.

    Quote Originally Posted by bee utey View Post
    Most of the corrosion on a land Rover occurs due to small local corrosion cells wherever water can linger for hours after a dunking. Put a splot of mud on a clean steel or ally surface and keep it in the damp and shade and see what happens. Stray currents from operation will be the smallest contributors to corrosion, with the possible exception of aluminium alloy radiators. I once had an old rust bucket where the door lamp switch was screwed to a tiny patch of sound metal surrounded by a much larger patch of rusted metal. I don't know if this effect was due to stray current or the plating on the switch but the effect was strictly local.

    On a Land Rover, the best defence against corrosion between a steel and ally component is to thoroughy seal the join against water ingress or just make sure it dries out very quickly after dunking. Steel engine mounts on a cast ally block don't tend to rust out because the heat of the engine dries the joint out quite quickly.
    I tend to agree with you here. There are differences in potential across tiny areas in all metals, enough to let even a small droplet of water create an electrolytic corrosion cell.
    Cheers, Billy.
    Keeping it simple is complicated.

  2. #62
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    Dual Battery Circuit Safety Part 1

    Hi folks and my apologies for taking so long to get something going in the thread but I’m working 7 days a week, trying to keep order delivery times down.


    But in the last month or so, I have had a number of situations brought to my attention, where people have either purchased an “expert designed” dual battery kit or had a dual battery system installed by a “professional”, and have end up with a death trap.


    While most of the gear I supply Land Rover owners, is in kit form, and therefore is designed to be a safe as possible, but since the introduction of the latest versions of my isolators, I am supplying a lot more isolators to people with other makes of vehicles, and quite a few of these people already have had systems fitted and either want to upgrade their isolator or are planning on fitting their own set up because I do not have a vehicle specific kit for them.


    What is happening, when people are purchasing one of my isolators, to make sure they are getting the best isolator for what they want to achieve, I will often ask them about their current or intended setup. This is where I am hearing about the down and outright death traps being supplied or fitted by self proclaimed “experts”.


    The problem comes from people, who have no idea what they are selling, but they are giving “professional” advice about how a dual battery setup should be equipped. Again, this is info from people who have no genuine auto electrical knowledge, particularly when it comes to auto electrical SAFETY requirements.


    Almost every component used in any dual battery setup has operational characteristics that most people are unaware of, especially safety perimeters that MUST be factored in when designing a dual battery setup.


    The most common error, and the most dangerous one, is the use of totally inappropriate sized fuses and circuit breakers.


    Here is an example.


    There is an individual who has a book out on requirements for setting up for RV use, which covers all manor of RV subjects, including electrical “advice”. In the advertising used to promote his book, he displays a diagram of a basic dual battery wiring setup.


    In his diagram he uses 6B&S cable to run from the tow vehicle to the house battery in the caravan and this is a good choice.


    He recommends the use of 50 amp Anderson Power Connectors to connect the cable between the tow vehicle and the caravan, and again, a good choice.


    He shows fuses being used near the batteries at each end of the cable, which is the correct safety requirement for this type of auto electrical setup.


    Then it all goes pear shaped because he recommends using 100 amp fuses at each end of the cable.


    While there is a lot more to it, which I will cover in more detail in a later post, but surely commonsense ( not auto electrical knowledge ) would dictate that if you are using a 50 amp rated Anderson plug, then the maximum current rate of the circuit protection device for the same circuit should be no more than 50 amps, not 100 amps.


    6B&S cabling is rated at a maximum continuos current of 105 amps BUT, this is in open air, which the cabling is not, when run through a vehicle.


    A number of cable manufacturers have DERATING tables on their websites, making it pretty easy to work out safe maximum current capacities of deferent cable sizes, including 6B&S. The maximum safe continuos current for 6B&S should be based at around 80 amps.


    While 50 amp Anderson plugs are called just that, 50 amp, but in the right circumstances, a 50 amp Anderson plus can safely carry a continuos current load of 95 amps. More on this later.


    Here is where the real danger lays. Few people working in this industry have never bothered to look up the operating specs for the standard automotive fuses or circuit breakers, and this has lead to grossly higher current rated fuses and circuit breakers ( CB ) being commonly used where they should not be used.


    First off, the current marked on an automotive fuse or CB is what that fuse or CB is designed to carry for at least 4 hours. But to be able to carry it’s marked rate for 4 hours, it needs to carry higher currents for shorter times.


    On average, automotive fuses and CBs will carry 125% to 135% of their marked rate for around 30 minutes and much higher currents for shorter periods.


    This means that the 6B&S cable in the diagram could carry 135 amps for 30 minutes without causing the fuse to go open circuit ( to blow ), which means, for 30 minutes, the cable could be carrying around a 75% high current than the cable can safely handle.


    Now to the specs for a 50 amp Anderson plug. The maximum continuos safe current for a 50 amp Anderson plug is 95 amps, but this is at 25C, but with 6B&S cable connected to the Anderson plug and with the cable carrying it’s maximum safe current limit of 80 amps, the cable will be quite WARM at that current rate and will cause the Anderson plug to run at a higher temperature.


    The cabling and plug are going to be closer to 50C, which brings the Anderson plug’s safe maximum current rate down to around 75 amps.


    So with the maximum safe current for the 50 amp Anderson plug being around 75 amps and the 100 amp fuse not likely to go open circuit with currents under 135 amps, you risk having currents nearly double the safe maximum being carried through the Anderson plug for around 30 minutes.


    NOTE, until recently, a well known Australian supplier of dual battery gear also recommended 100 amp fuses in similar setups????


    When setting up a dual battery system using 6B&S cabling, the maximum current rating for in-line fuse or circuit breaker protection is 60 amps, not 100 amps. To improve the safety of my dual battery systems, I prefer 50 amp Auto Resetting Circuit Breakers, but I will cover this in a later post.


    While I would not classify the misinformation in the diagram as amounting to being a death trap, it is exceedingly dangerous. In my next post I will show how companies, who are nothing more than Box Sellers, are putting people’s lives at risk by selling much more dangerous setups.

  3. #63
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    Hi Tim,
    This is a great thread and I am reading it with much interest. As a retired auto workshop owner I used to see this stuff all of the time and would shake my head in disbelief at times.
    Many thanks for sharing your knowledge.
    Les

  4. #64
    DiscoMick Guest
    Thanks for that. It's very helpful to an amateur like me.
    Looks like my auto electrician did the right thing by fitting 60 amp fuses.

  5. #65
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    Dual Battery Circuit Safety Part 2

    Once again, this post is about warning people about how dangerous Dual Battery Systems ( DBS ) can be, if people deal with “self-proclaimed experts” who really have no idea what they are selling.


    Now this is not about trying to get people to buy from my business rather that buy from some other DBS supplier. I have not supplied separate bits a pieces for DBS setups for quite a few years now. The primary reason for this post is to give people a heads up on what is safe when looking for DBS components, when people are setting up their own systems.


    Some time back I was on a Pajero forum where one of the members had just watched a video on a supplier’s website that was promoted as being the “correct” way to carry out a DBS setup. The member stated that this was a great video for anyone wanting to learn how to fit a DBS. The problem is that anyone how follows the “advice” given in this video could quite simple end up burning their vehicle to the ground.


    First off, they recommend using 8B&S ( 7.9mm2 ) cable for a DBS setup, and while 8B&S will work, it will take at least 50% more driving time to recharge a battery over the drive time required when using 6B&S (13.5mm2 ) cable.


    They then fit an in-line fuse near the cranking battery and they recommend using an 80 amp fuse to protect the 8B&S cabling. The MAXIMUM current rating for any fuse or CB intended to protect 8B&S in a DBS is just 40 amps. While I have already covered how much of a danger this poses, but this is not the worst of it.


    Then they show how to install and wire up an auxiliary battery in the rear cargo area of a vehicle. They install the battery and then wire it up to the cabling coming from the front of the of the vehicle. The cabling is simply connected to the auxiliary with no in-line protection. No fuse or CB.


    This is utter lunacy, and could easily lead to a vehicle being being burnt to the ground if a short occurs any where in the cabling.


    To demonstrate just how little they know about this field, later in the video, they recommend fitting a 20 amp DC/DC device, which if they had fitted the appropriate size cabling in the first place, would have been a waste of time.


    But they then actually make it a total waste of time and money by stating that you now run cabling from the rear mounted auxiliary battery to a battery in a caravan, and the DC/DC device will charge both batteries.


    Had they bothered to read the DC/DC manufacturer’s installation instruction, no matter what brand the DC/DC device is, all DC/DC manufacturers specifically state that the DC/DC device MUST BE fitted as close as possible to the battery being charged by that device.


    With their setup, the auxiliary battery will take many, MANY hours of driving to fully charge it, if it is in a low state, and because of the thin cable combined with how far away the DC/DC device is located from the caravan battery, the caravan battery will NEVER be fully charged, regardless of how much driving you might do.


    The problem with the “expert” advice given in this and the previous DBS setup, the “experts” based the use of the over current rated safety devices on them being able to go open circuit in the advent of a short circuit occurring and yes, in this type of event, they both would go open circuit ( actually in the second example, only the cranking battery would be protected from a short circuit event ).


    But if either of these “self-proclaimed experts” had any real knowledge of how DBSs work, they would know that the greatest potential danger for a DBS comes from current overload, not short circuits. And the reason for this is because there a cranking battery and alternator at one end of the cabling and an auxiliary battery at the other end of the cabling.


    This setup means there is a high current supply potential at both ends of the setup but the greatest danger comes from the auxiliary battery.


    The danger arises if the auxiliary battery drops a cell and shorts internally. This will not cause a dead short but it can cause a very high current draw.


    This current draw is basically going to be the same, regardless of the thickness of the cable, but the thicker the cable, the longer the cable takes to heat up.


    In the first post, where 6B&S cabling and a 100 amp is used, the fuse may or may not go open circuit before cable’s insulation ignites, but in this second setup, where they have used an 80 fuse to protect 8B&S cabling, because of the thinner cabling, the cabling will heat more quickly and has a much greater potential of the insulation igniting before the fuse ever blows.


    The setup they are promoting is an out and out death trap and their advice amounts to instructing unsuspecting people on how to fit a suicide kit to their vehicles.

  6. #66
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    Dual Battery Circuit Safety Part 3

    OK folks, this thread is about an area of Dual Battery Systems ( DBS ) where fires do occur when “experts” have carried out the installation of substandard wiring and protection.


    It is commonplace to find the power cabling use to charge the house battery in many caravans and camper trailers is way to thin. Many RV manufacturers use 8B&S ( 7.9mm2 ) cabling and some even use 6mm AUTO ( 4.5mm2 ) WIRING to charge the house battery in their caravans or camper trailers.


    Many RV manufacturers elect to use this thinner cabling because it fits into the terminals of 7 and 12 pin trailer plugs ( more on this later ).


    While the obvious problem is that the house battery is just not going to charge properly, if at all, with this size cabling, but there is a major risk of fires occurring and they do occur, because these same manufacturers will often use the wrong size fuse or Circuit Breaker ( CB ) to protect this under sized cabling.


    It is just as commonplace to find these same manufacturers have use a 50 amp CB to protect 6mm AUTO cabling, and as already covered in the two previous posts, but in this type of set, particularly in caravans, regularly results if fires occurring because a battery has failed or there has been a bank of batteries fit, and the first time theses batteries are in a low state and are being charge while driving, the large current load simply overwhelms the thin wiring and causes it’s insulation to over heat and ignite.


    This type of situation is not just limited to caravan or camper trailer wiring.


    You may have your Land Rover set up with a DBS and decide to buy a caravan or camper trailer. If your Land Rover has already been wired up with an Anderson plug at the rear, based on info supplied on this form, then you are probably set up properly and safely.


    But what regularly occurs is if you are not fully wired up to provide power to your new caravan or camper trailer, you may take the “advice” from the caravan supplier and go to their auto electrician to get your Land Rover wired up for electric brakes and additional wiring for powering your new caravan.


    This is exactly what happened to two of my customers.


    The auto electricians in both cases, ran 6mm AUTO ( 4.5mm2 ) cable ( read wire ) from the auxiliary battery to the rear of their D4s, not just for the electric brakes, but also for power to the caravan, which means for charging the house batteries in the caravan.


    In both cases, the auto electricians had fitted 50 amp auto resetting circuit breaker to “protect” the 6mm AUTO cable.


    Both vehicles ended up with fires occurring in the engine bay.


    Armed with the info supplied in these three posts, you should be able to protect your vehicles, and yourselves, from potentially dangerous Dual Battery Systems.


    I will cover the use of Anderson plugs verses trailer plugs in the next post.

  7. #67
    DiscoMick Guest
    So what size wire would you recommend? You've got me worried now.

  8. #68
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    Hi Mike and sorry mate I missed your post.

    What is the intended use of the wire/cable you want to know about?

    Is it for a dual battery setup or for other use?

  9. #69
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    Dual Battery Circuit Safety Part 4

    There are two types of Anderson plugs, genuine Anderson plugs, and copies.


    Genuine Anderson plugs are branded with either ANDERSON POWER CONNECTORS or SMH ( which stands for Southern Machinery Holding, the original parent company of Anderson Power Connectors ).


    Any other branding indicates a non genuine copy, and while this may not seem important, there is a huge difference between the genuine and copies, both in current handling capabilities and safety.


    First and foremost, the size of the terminals can vary greatly between the genuine and copies. It would surprise most people if they saw how much narrower non genuine terminals are when placed beside the real McCoy terminals.


    It is not unusual to see as much as a third difference in width size between the genuine Anderson terminals and copies. This means at least a third less contact area and that means a much lower current carrying capacity when using copies.


    Genuine Anderson plugs can carry as much 95 amps with safety, but most copy plugs are lucky to be able to carry their so called 50 amp rating. This is often demonstrated when you come across a melted Anderson plug and they are never genuine Anderson plugs.


    It pays to be careful when buying Anderson plugs because it is now commonplace to see ads where they state “Anderson like plugs” or similar claims and note, there are some very well know auto electrical brands with their own copies and they are no where near as good as the genuine Anderson plugs.


    Now to substituting trailer plugs for high current applications, instead of using Anderson plugs.


    First major difference between genuine Anderson plug terminals and trailer plug terminals is that genuine Anderson plug terminals are specifically designed for what the industry calls “hot make and break” connections. This means they can be connected and disconnected while high currents are applied to the circuit.


    Anderson plugs can carry out 250 “hot make and break” connections at 50 amps.


    While the large terminals on a 12 pin trailer plug can carry 35 amps, they should never have a “hot make and break” connection. Doing so can causes arcing to occur and while Anderson plugs can tolerate this, trailer plugs can not and continually doing so with trailer plugs can very quickly damage their terminals. This can, over time, dramatically reduce the current carrying capacity of trailer plugs.


    Another problem with trying to use trailer plugs for carrying high current loads, is the fact that their terminals are easily tarnished and tarnished terminals can cause both a reduction in current carrying capacity but tarnished terminals can also create resistance in the contact area, which can result in high temperatures being generated in the trailer plug.

    NOTE, trailer plugs are not designed to tolerate heat.



    Also a problem with trailer plugs is the more you plug and unplug them the weaker the contact pressure between the male and female terminal becomes, again, causing a reduction it the current carrying capacity.


    With genuine Anderson terminals, both the above problems are pretty well eliminated because Anderson plug terminals are spring loaded so that they self-clean every time you plug and unplug, plus they maintain a constant contact pressure over the lifespan of the Anderson plug.


    So it pays to use the right connector for the desired requirement and Anderson plugs are now the industry’s preferred connector for dual battery connections between the tow vehicle and caravans and camper trailers.


    BTW, next time you have been camping, and you have used a fair bit of your house battery capacity, when you get back on the road, after you have been driving for just 15 to 20 minutes, try pulling over and going back to your Anderson plugs.


    You may be very surprised to feel just how warm they can get. NOTE, they should not be that hot that you can not handle them, but they can be quite hot. If they are that hot that you can not handle them, you have a problem that needs to be addressed.


  10. #70
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    can we get a quick article why slow charging a battery is batter than fast charging?

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