# Thread: On-Line auto electrical info

1. I recently got genuine Anderson plugs from this mob on ebay.
I thought the value and service pretty good.
Don.

2. ## SoC - Battery State of Charge

Originally Posted by Eevo
can we get a quick article why slow charging a battery is batter than fast charging?
Hi Eevo, before going into charging details I think it might be useful to explain what SoC means.

SoC, stands for State of Charge, but there is also the reverse abbreviation and this is DoD. DoD stands for depth of discharge.

SoC indicates the amount of usable battery capacity reminding in a given battery, whereas DoD indicates the amount of battery capacity already discharge from that same battery.

For simplicity, I will only use SoC in my articles as a means of giving measurements relating to battery capacity. I will post up a charter a little further down, showing what the SoC measurement stands for in a battery but there's a lot more to it than just straight out voltage equals existing capacity.

Ah or ampere hours marked on a battery, roughly indicate the amount of hours you can draw a one amp load from a battery.

In theory, if you have a 100Ah battery and you apply a one amp load to that battery, say a 12W globe ( which will have roughly a 1 amp draw ), then that globe should glow for 100 hours.

In reality, the amount of usable ampere hours is controlled by a number of factors. Factors like the age of the battery, how well the battery has been maintained and so on.

Now to confuse the issue.

The SoC measurement of a battery is an indication of the State of Charge of the battery’s capacity that can be charged, and I will try to explain.

As above, age and condition of a battery will have a bearing on the actual amount of a battery’s original capacity that is still usable. When you measure the voltage to determine the SoC of the battery, you will only be measuring the SoC of this usable capacity.

For example, if you have a 100Ah battery that is partially sulphated ( I will cover the sulphation in more detail in the next article ) and you actually only have say 80Ah of usable capacity. If the battery is fully charged, and you get a 12.7v voltage reading, which indicates an SoC of 100%, in this case it does not mean you have 100% of the original 100Ah fully charged, you only have 100% of the 80Ah now available that is full charged.

The problem is that from the SoC measurement, you have no idea that you only have 80Ah available, and in this case, your 12w globe will only run for 80 hours.

You will need something that is capable of measuring current in and out as well as the voltage, and be able to analyse this data, to be able to get an accurate capacity indication. I am not going to cover that here.

So a simple voltage reading is not a reliable indication of the true available capacity of a battery, but in most RV applications, it will give you the info you need.

SPECIAL NOTE. There are two different types of voltage measurement used to determine the SoC of a battery. This article is based on using the voltage measured from a battery that is in use. There is also OPEN CIRCUIT VOLTAGE READINGS, where the battery must site in a No-Charger/No-Load state for at least 24 hours, before the voltage reading is taken.

OPEN CIRCUIT VOLTAGE READINGS are far more prone to erroneous results and are pretty useless while on holidays, when you need to have the battery sit around used for 24 hours, just to see how available capacity there is.

The chart below is comparatively accurate when measuring any form of lead acid battery. OPEN CIRCUIT VOLTAGE READINGS are battery specific, which means you have to have the correct OPEN CIRCUIT VOLTAGE Chart for the specific make and type of battery you are trying to monitor.

1 SoC Table.jpg

3. Great idea.

Might save some reinventing the wheel...

Auto Electrics - How to Use a Multimeter

Auto Electrics De-Mystified

Soldering

4. Hi folks and my sincere apologies for taking so long to post up info in this thread. I am just flat-out and no time has been available.

Owing to the amount of time I am now spending on the phone each and every day, fault finding and fixing dual battery electrical problems, I would be far better off posting up info and instructions in this thread, so people might be able to sort out problems for themselves, before they need to phone me.

NOTE, I am still going to be available to phone but hope this thread will still reduce the need to call me.

To give you an idea of what I have to address. Over the weekend, I received a number of call from a gent with a D4, who was having serious charging problems with his setup.

He and a mate with a Toyota Land Cruiser both have the same new caravan.

They are both having problems charging their auxiliary and house batteries, even after a 5 hour drive.

I go the D4 owner to take some voltage measurements with the motor idling.

He tells me he was getting 14.4 at the cranking battery and 14.4v at the rear plug ( not an anderson plug ).

So the caravan was connected and the voltage now drops to 12.7v at the trailer connector.

After some investigating, it turns out that his D4 dual battery WIRING was 6mm AUTO or 4.5mm2 twin, it should have been 6B&S or 13.5mm2.

The caravan wiring was even better as it was 4mm AUTO or 2.5mm2, again it should have been 6B&S or 13.5mm2.

The most annoying part of this conversation was that both he and his mate had gone to the same auto electrician, who had “professionally” installed both systems, but not with one of my isolators. He had fitted Redarc VSRs.

The gent had rang me because he could not get help anywhere else and he and his mate were in the middle of nowhere, in WA.

On Monday, I get a call from a gent with an Amarok, who had bought one of my Amarok DBS kits, but because he was short of time before his trip, had had the kit “professionally” installed by a well known 4x4 outlet.

In his case, which is still being sorted, even after a long drive, his SC80 would shutdown after bing parked for just a few hours.

The voltage at the cranking battery was around 12v after the shutdown, the auxiliary battery was at 12.7v and there was no power at the Anderson plug once the SC80 had shut down. ????????????????

Even with the SC80 shut down, with 12.7v at the auxiliary battery, there should have been 12.7v at the Anderson plug.

The clowns ( professionals ) at the 4x4 outlet were supplied with a Ready-To-Fit complete kit but for some unknown reason, they have modified/altered the cabling?

So can I suggest that people with DBS problems, with mine systems or some other brand, please post up your problems here and then everybody can see what to avoid and how to fix these problems.

5. Geez you're more patient than I am. If it wasn't your system they had fitted or modified one of yours I hope you billed them appropriately for your time.

6. ## LONG TERM BATTERY MAINTENANCE

Hi folks and the most common enquiry I get is about problems relating to low cranking batteries and the error message “Low battery start engine” or the likes.

In the vast majority of these situations, the owner is the problem, not the batteries, not the vehicle and not my dual battery system.

I would guess 95% of the time, it is the use of the vehicle ( or lack of use ) that is the root course of this problem.

Regardless of you doing a LONG trip every month or so, short driving, as I have labelled it before, Shopping Trolley Syndrome, I have found is the prime cause of the early demise of cranking batteries, and many auxiliary batteries as well.

First to what occurs in the cranking battery in Shopping Trolley Syndrome situations.

When you first buy your new vehicle, it comes with a battery capable of supplying 100% of it’s designed capacity. NOTE this also applies when you change an old battery for a new one.

But as a Cranking battery, it rarely needs to supply more than a few percent of it’s capacity to start the motor.

You then do lots of short trips, and initially, you manage to replace “MOST” of the energy used each time you start your motor. But you never quite replace the total energy used when you started your motor.

Now the following is a very simplistic explanation of what occurs inside the battery.

Because you do not drive long enough to FULLY recharge the battery, a very, VERY small portion of the battery’s plate surface gets a scale building up, where the sulphuric acid solidifies ( sulphates ) on a minute area of the battery plate surface.

The area covered is now pretty well unusable ( or can not be charged ).

This sulfration can take years to build up to a point where it has any effect on the battery’s ability to start your motor. But over time, as more battery plate surface area becomes effected by the build up of sulfation, the performance of the battery, when starting a motor, will become sluggish.

At this point, the battery is probably still recoverable, but at this point, the amount of battery plate surface area being effected rapidly increases.

This rapid increase is caused by the fact that, while you still need the same amount of energy ( battery capacity ) to start the motor but as more area becomes unusable, you actually need to drive longer to allow the battery capacity used to start the motor, to be replaced.

Because you are still driving the same short trips, the mount of battery capacity being replaced is rapidly getting less and less with each trip.

You get the picture, and even with the periodical long trip, as the usable amount of the battery’s capacity is greatly diminished, you are only able to fully charge the small portion of battery’s capacity that is still usable.

In the initial stages of the sulfration, your battery voltage can still show a fully charged state, but this is only an indication of the state of charge of the USABLE portion of the battery’s capacity.

As the sulfration progresses, because you are using far more of what remains of the battery capacity while starting your motor and you are replacing far less while driving, even this remaining portion will now not be able to be fully charged, causing the voltage to drop in the battery, and this is when you begin getting “Low battery start engine” messages.

Once you start getting this messages, you should do something immediately to correct the problem causing the message ( see below ).

If you do nothing about the problem, in a very short time, the battery capacity and voltage level will drop to a point where you have a “flat battery” and you can no longer start your motor.

In many cases, by this stage, a cranking battery in this condition, is going to be hard to recover, if not impossible to recover.

As stated above, the sulfration of a battery can take quite a long time and it will take quite a long time to reverse the effects of sulfration, but in most cases, partial or full recovery can be achieved, but again it will take some time.

To try to reverse the effects of Sulfration, you need a 3 stage ( or more stages ) battery charger. It must have at least a BULK, ABSORPTION and a FLOAT mode.

Speed in charging is NOT required, and a small charger is much better for your battery than a large charger. Any charger with a charge capacity up to about 10 amps for a single battery setup and up to 15 amps for two or more batteries will be fine.

A 5 to 7 amp charger will work well in the recovery of any battery. So don’t go buying a big charger, just to use for recovering and maintaining your batteries.

To try to recover a sulphated battery, connect your battery charger in the evening and let it run all night.

Many people will connect a battery charger and run it till it goes into FLOAT mode and then they remove the charger. While this will recharge the used capacity that can be charged, it does nothing for recovering lost capacity.

In the morning, disconnect the charger.

Repeat this process for as long as possible, and for badly sulphated batteries, it may take a week or two to get the battery back to a decent condition.

Also, with small battery chargers and a large battery or battery bank, your charger may stay in BULK and ABSORPTION mode for a few nights, but it will then fully charge the batteries eventually.

Each night, the amount of time a small charger is in BULK and ABSORPTION mode will get shorter and shorter then each night it will go into FLOAT mode by the next morning.

It is actually the length of time the charger is on that helps to S-L-O-W-L-Y reverse the effects of sulfration.

While the charger is on, regardless of which stage it is in, the chemical reaction the charger causes in the battery, very, VERY S-L-O-W-L-Y, dissolves the scale off the surface of the battery’s plates.

This progressively increases the battery’s capacity and in many cases, can bring a battery back to or near it’s original capacity.

This process should be carried out for a week or so, even when you are using the vehicle during the day.

If you are not driving the vehicle at all, still only charge overnight and turn the charger off during the day.

There are two reasons for this type of operation. First off, the effects of dissolving the scale reduce with the amount of time the charger is continually on, and after about 12 hours, there is little gained.

Plus by leaving the charger off for a period, like 12 hours, even if the vehicle is driven between charge cycles, the electrolyte in the battery will settle.

Regardless of the state of charge of a battery, most battery chargers, when first turned on, go straight to the BULK stage, and then analyse the battery’s actual state of charge.

The charger will then go to the appropriate charging mode required.

This initial BULK charge helps to stir up and mix the electrolyte properly, and correctly mixed electrolyte also helps to reduce the sulfration.

Once this initial recovery is carried out, it is recommended to do at least one overnight recovery charge cycle once or twice a month where vehicles are not used all the time and/or are continually used for short trips.

BTW, if you have an appropriate sized solar panel, this will do exactly the same thing, except it will automatically turn on in the morning ( sunup ) and and automatically turn off in the evening ( sundown ) and is idea for use on vehicles that are left unused for long periods of time.

7. Thanks Tim

I am guilty of shopping trolly charging. I was charging it overnight every 3-4 mths but this was not enough. The battery in the L322 failed recently prematurely.

I tried reviving it using a multi stage charger a few times without success. Voltage would quickly drop to below 11v.

After fitting a new battery I thought I would try drop fixing the old battery a few times to see if that removed the scale. Obviously, I wouldn’t drop it so hard to crack the case.

I then put it on the charger again and this time it took charge. After a month or so of sitting it’s still at 12.35v. Not bad but should put it on again.

Has the drop fix worked at removing the scale? Is it a possible last ditch option?

8. Originally Posted by rar110
Has the drop fix worked at removing the scale? Is it a possible last ditch option?
i'll get the fire extinguisher

9. Originally Posted by Mick_Marsh
Probably worthy of a book in itself but what about when a DC/DC charger is appropriate, and when it is not.
if your not stepping up or down 24/12 or 12/24 its not.

Weldings simple. drop the earth lead off and tie it away from the battery, that goes for all of your batteries, Isolator switches count and drop the earth point to your solar system as well.

in 90% of cases you dont actually need to do this as most people when welding clamp close to the weld, the current goes no where but between the tip and the welder earth. BUT.. what if... you're welding on the exhaust, the earth lead on the motor is shot, its earthing though the earth on the electronics and the handbrake cable (which is high resistance compared to the earth in the electronics so the grunt is taking its first path via the electronics) and because you've got a bit of an odd angle you accidentally short the shield of the mig to the chassis...

the current now goes down the chassis, into the body earth, into the electronics and handbrake cable up to the engine and back down the exhaust where you clamped it.

lets have a little fun and say you were positive earth welding because of the wire and welder you were using. What just happened to your electronigc?

10. Originally Posted by Eevo
i'll get the fire extinguisher
You always like drama.

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