Prado 2.8 Aux Battery Setup

[brogers Advanced Member Find all posts View Profile Close brogers]

You'll also note if you look at the wiring schematics they show all electrical devices being connected to their appropriate earth points in the earth loom. You'll find if you look at that earth point in the rear that it will also have the earth loom connected to it.

https://www.hkbelect.com/uploads/pro...th%20point.gif

Brake lines, fuel lines are tubes, not solid copper and your assuming there is another earth return to share the current. In the cases quoted devices were grounded to metal work that was only grounded through the lines, it was assumed the body work would make a good conductor, it didn't!

Yes corrosion caused by stray currents, stray currents are usually caused by people
using the chassis/body work as an earth return!

The body is earthed to prevent difference of potentials and stray currents occurring, not to allow it to be used as an earth return. Earthing the body also allows it to act as an earth screen to reduce RF problems.

As I wrote if it was ok to use the body as a conductor you wouldn't have the earth loom!

Enough said if you wish to use the cars metal work as a conductor to save a few dollars then whatever floats your boat, I prefer to pay a bit more and do it right the first time for maximum reliability and to avoid possible hassles later.

Thanks LeighW, I am much clearer about cables for my soon to be designed and installed auxiliary battery. I'll run a positive AND negative cable (as I did last time and it worked fine)...I just wanted to check.
Now...at the risk of asking another question that may start an avalanche...... I was thinking of using a tinned copper, marine quality cable....to reduce corrosion in the cable....is that a reasonable idea or just a plain waste?

[drivesafe Senior Member Find all posts View Profile Close drivesafe]

Hi brogers, it would be a slight increase in cost and tinned cable is usually stiffer to work with, but you would not gain anything from it’s use as you would also not loose anything, other than above, if you did use it.

It is simply your choice.

Most vehicle wiring is sealed in one form or another but this is more to do with the high tech communications used in most modern vehicles.

With dual battery cabling, the most likely place you will get potential problems from corrosion, is at the rear Anderson plug and in this case, even tinned wiring would be susceptible.

[krypto Avid PP Poster! Find all posts View Profile Close krypto]

With dual battery cabling, the most likely place you will get potential problems from corrosion, is at the rear Anderson plug and in this case, even tinned wiring would be susceptible.

I've noticed this and I've had to replace the Anderson plug, is there a reason for the corrosion

[drivesafe Senior Member Find all posts View Profile Close drivesafe]

Hi krypton, and not sure why the terminals corrode.

I have an Anderson plug at the rear, which gets it’s share of mug and such but I have never needed to do anything more than hose it out.

I have another under the bonnet and it has to be replaces because one of the terminals is corroded????????

[LeighW Avid PP Poster! Find all posts View Profile Close LeighW]

Interesting point about anderson plugs, the quality of the plug may have something to
do with it.

Generally in electronics true silver connections tends to go black (tarnish) rather than corrode.

I would image the main problem with the anderson "type" connectors is the silver plate is very thin and wears quickly allowing the copper plate, I'm assuming its copper plate as they don't appear to be solid copper to green up?

Pitty they don't gold plate them but I imagine to make them plate robust enough would make them to expensive.

[mjrandom Out of control poster! Find all posts View Profile Close mjrandom]

We replaced the wiring in a mates camper year before last. The camper was local but probably all sorts for parts. The wiring was a mess and the copper strands covered in verdigris the entire length of the cable. Resistance was higher than new clean wire. Camper didn't look abused but the insulation was clearly poor quality.

I use tinned cable simply because that is what my supplier sells but I have noticed verdigris inside the first bit of cable with natural copper that I used years ago. Haven't noticed any extra stiffness and I doubt you would with a quality multi strand cable.

If the cost isn't heinous go tinned.

I have noticed a huge variance in quality between genuine Anderson plugs and some of the copies. Connectors corrode quickly and the plastic falls apart and suffers embrittlement quickly. Genuine plugs are cheap and in my experience are a better product.

[drivesafe Senior Member Find all posts View Profile Close drivesafe]

I only use genuine USA made SMH or Anderson plugs ( Same company ) and I suspect the plug under the bonnet may have been contaminated with some form of chemical.

And mjrandom, you are right about only using the genuine article. There are a number of Anderson Plug knockoffs and they all seem to have very weak springs and/or much smaller contact areas, and as you posted, crap plastic housings.

Hi Leigh, Anderson terminals are as you posted, silver coated copper.

[krypto Avid PP Poster! Find all posts View Profile Close krypto]

I only use genuine USA made SMH or Anderson plugs ( Same company ) and I suspect the plug under the bonnet may have been contaminated with some form of chemical.

And mjrandom, you are right about only using the genuine article. There are a number of Anderson Plug knockoffs and they all seem to have very weak springs and/or much smaller contact areas, and as you posted, crap plastic housings.

Hi Leigh, Anderson terminals are as you posted, silver coated copper.

The corroded plug was one of yours with not a lot of use, it was pretty well unusable

[drivesafe Senior Member Find all posts View Profile Close drivesafe]

Hi again krypton, did you notice any residue or the likes on the terminals?

BTW, keep an eye on the new one and if you have a problem again, let me know and I’ll send you replacement terminals.

[BenB Lurker Find all posts View Profile Close BenB]

Thanks all for the input you've helped me a lot!!
I have been researching the different isolators and am still undecided. What is the major advantages of spending more and going with something like the Traxide usi-160 or sb80 or projecta dbc100 or redarc sbi12d? Trying to keep cost down and will probably not have a winch in the near future.

[krypto Avid PP Poster! Find all posts View Profile Close krypto]

Hi again krypton, did you notice any residue or the likes on the terminals?

BTW, keep an eye on the new one and if you have a problem again, let me know and I’ll send you replacement terminals.

Thanks, I just put it down to wear and tear but was surprised. Actually thought the compressor was stuffed when I plugged it in.

[JohnC80 Junior Member Find all posts View Profile Close JohnC80]

Went for a decent drive on the weekend so ran some voltage tests. Used the 12v plug inside to measure with my multimeter. Before I left I measured the start battery at the terminals and it was 12.45v with nothing on. I turned the ignition on but had nothing else on (air-con etc) and tested the battery and the 12v plug. Both read 12.43v. Idled the car at 900rpm and the voltage sat at 13.68v for the battery and the 12v plug. Bought the revs up to 1,500 and 2,000rpm and the voltage sat at 13.72v for the battery and the 12v plug. I did these tests as I wanted to see if the 12v plug measured similar to the start battery.
Went for a drive for 2 & 1/2hrs testing the plug every 10mins. I tested with air off and air on. Only other things running was the stereo, iphone charging and the lights were on. Plug voltage measured from 13.68 to 13.73 for the entire trip. Revs were also noted and this didn’t seem to affect the volts. Once I turned the car off I let it settle for 30mins. Start battery tested at 12.85v with nothing on.
I decided to do this test as I was told that the volts would settle to low 13’s within an hr of driving the car. I did not see this. Obviously I wasn’t able to test amps but the brains trust will decide if this was a pointless exercise or not. Would be great to see what amps the alternator is producing during this time.

[LeadWings Member Find all posts View Profile Close LeadWings]

Went for a decent drive on the weekend so ran some voltage tests. Used the 12v plug inside to measure with my multimeter. Before I left I measured the start battery at the terminals and it was 12.45v with nothing on.

I have tested mine and it is the same - 12.4V when parked up, even after a long drive. I thought a fully charged battery should be 12.8V??

[drivesafe Senior Member Find all posts View Profile Close drivesafe]

Hi John and Leadwings, 12.4v has your battery at 80% SoC, and a fully charged cranking battery normally around 12.5v ( 90% SoC ) to 12.7v ( 100% SoC ).

While you might have expected a higher settled voltage than 12.4v after a long drive, there are other factors that will also effect the total charge of your cranking battery.

The most common cause of lower than fully charged cranking batteries after a long drive is how was the vehicle used in the week prior to that long drive.

If you continually do lots of short drives then your cranking battery will progressively loose its usable capacity.

I single long drive every so often can regain some of that lost capacity but if you know the bulk of your driving is always going to be lots of short drives ( the Shopping Trolley Syndrome ) then it will be very advantageous to give your cranking battery a long, low current charge every month or even more often if you have a mind to.

Most modern vehicle use causes this problem and either the periodical battery charge or, depending on situation, like the location of your vehicle during the day, a small solar panel can, over a period of just a few weeks, bring your battery back to a fully charged state at all times and get back most, if not all the lost capacity.

[mjrandom Out of control poster! Find all posts View Profile Close mjrandom]

...to 127v ( 100% SoC ).

1000%?????