Alternator Overload

[jims-terrano]

Is it possible to overload an alternator by using a second battery.

The truck has been mis behaving slightly this week and I just can’t put my finger on it. Tonight I picked a friend up and drove to the pub. Came out of the pub and started after about an hour or so but engine was running rough kept sort of dieing and abs light kept coming on. After about ten seconds or so it was fine. Also I’ve noticed the reverse camera has started flickering to the extent it flashes now and have read on the internet that the cameras are sensitive to voltage.
I’ve had a battery for a good two years or so but noticed recently voltage when engine running was 12. Something volts and the camera was fine. Since changing the battery I’ve noticed volts hover around 13.8 whilst driving and the camera has started to flash. Split charge relay should only kick in when engine running.

Think tomorrow I’m goign to pull the fuse between the charge circuit so that it isolates the second battery to see if that makes any difference.

Besides replacing second battery I have fitted a stock air filter and gave mat a spray with switch cleaner. Also stuck some veg oil in with the fuel but not a high concentration.

 

[solarman216]

Not really, but if something is shorting yes it will bring the battery voltage down to the point of rough running due to lack of voltage the the control systems, this will not harm the alternator in the short term but long term is not good, easy method is stick a volt meter on it, if the voltage when running is less than 12v then something is wrong, Rick

 

[Lazy-Ferret]

In my experience, alternators are very much either good, or bad, not intermittent.

Bad things are basically, over voltage, as the regulator has gone, or half/no output because the diodes have gone.

You do get reduced output, because the rings are worn, or the electrical joins inside have become bad, but that tends to create excessive heat in that area, and it will burn out fairly quickly so the alternator will then be totally dead. You would also see a reduced voltage when the engine was running, or the alternator/charging light on the dash board would be on.

If the switching relay that brings the second battery in was to be playing up, and switching it on and off it could cause issues the the Alternator, but it would still create one of the above issues. As you are reading 13.8volts, it sounds like it is fine.

The main issue with the second battery is having enough charge left over from the alternator after charging the first battery, plus running the car (lights/wipers/heater/etc) to actually charge it up. What tends to happen is the first battery gets charged from the alternator, then when the voltage is high enough to switch in the split charge relay, the first battery is the one actually charging the second battery, until they both get to the same voltage. So in fact, the second battery does actually run the first battery down initially, then the alternator is charging both at the same time.

None of those things though should really cause the engine to play up, you are in the world of flat batteries and that sort of thing.

First things first, check your battery wires, make sure you are getting good connections, as a faulty connection would make electrical noise, that would upset the cameras.

Is the camera a wireless one?

 

[jims-terrano]

Will see what today brings. I have a voltmeter permanently in circuit, similar type to yours Clive.
I’ve had the occasional maximum of around 14 to 14.2 volts.

Been thinking about it over night, wonder if the maf didn’t like been cleaned.

 

[Davey Boy]

Jim
I'd do as Clive suggested and check your battery terminals and VSR are nipped-up first.
I do this as often as the bonnet is up.
I am still surprised at the way they can work loose with voltage traffic.
Give them a protective lube (I use chain grease, it sprays on then sets),for the winter while you're at it.
Mine reads 14.2 at the second battery by the way
Hopefully it's any easy fix for you whatever it may be.:thumb2

 

[macabethiel]

Alternator Overload Question.

My experience with Alternators over the years has been that as has been said previously they either work or they don't. If it starts to put out AC output into the battery it will usually show a fault on your dashboard in the form of a Red Battery light or other similar e.g.Ign Light.

Car designers usually put higher output alternators on some model such as my old r3mR as a result of more electrical gizmos. Hand in hand with that usually goes a higher capacity battery.

As I recall your recent battery was described by you as bulging - this would to me indicate serious overcharging due a short in the battery itself. Many years ago I was driving a brand new Opel on trade plates when when the vehicle started to splutter, I had to stop and the engine stalled. When I tried to restart it it was completely dead. It turned out that the battery had catastrophic failure causing the plates to short out inside. The battery casing was very hot and smelt. The mechanic fitted a new battery and all was okay.

If you replace a standard vehicle battery with a larger amp battery without upgrading the alternator this does not cause any problems though long term if the battery demand is high it may be unable to sustain a fully charged status.

On more modern vehicles if you upgrade the battery capacity you have to carry out a software update to suit - this allows the alternator to up the amp output accordingly. This is due to the complex voltage control systems required to prevent engine & gearbox ECU failure due to the voltage being too high.

On early Mercs circa 1990 they used an OVP relay (overload voltage protection) to do this. When the OVP relays faulted it would cause misfires and often the engine would just cut out as there was no current to the ECU. They now use a voltage control module to do this.

As regards voltage in the charging circuits I monitor mine with a cheap plug in digital volt meter. see link below.
https://www.ebay.co.uk/itm/Digital-...157057&hash=item48783957b4:g:X2sAAOSwmtJXXAKW

On start up the voltage reaches around 14.1 volts this is quite normal. If I switch off and plug it into the 12 v permanent supply socket the voltage will slowly drop from around 12.7 volts to 12.3 volts. If I leave it plugged in overnight the voltage will remain as 12.2 or 12.3 volts - indicating a good battery.

I have no experience of having two batteries with a relay. It might be that as your leisure battery was failing your alternator would have been maxing out on output - could this lead to overcharging of your main vehicle battery ?

I would start by isolating the second battery and doing some voltage checks on the main vehicle battery just in case it is failing. Hope this helps.

 

[jims-terrano]

So today the ABS light flashed a little on startup at lunchtime. I removed the fuse in the feed to the second battery. Hasn’t really made much difference the voltage on my voltmeter hovers between low 13. Something and 14.2 on full revs driving.
I’m now thinking this isn’t to do with the second battery or alternator. I won’t be able to do anymore now until sunday.

Incidentally this is a different battery not the leisure battery that had bulging sides.
I also have fuses everywhere in my wiring so I’m confident if there was a short it would have blown a fuse.
Battery terminals seem nice and tight as do the cables as they were my first thoughts too. I always keep battery terminals coated in grease as well.

 

[macabethiel]

Full Revs Voltage

Hasn’t really made much difference the voltage on my voltmeter hovers between low 13. Something and 14.2 on full revs driving.
l.

I might have misunderstood but if the voltage is showing over 14.0 volts for a long period that to me would indicate either a discharged battery or a failing battery as after say 6 miles or 20 minutes run I would expect the voltage to drop to around 13.7 volts or less once it has charged up.

At present we only use our newer jeep once a week or less. I connect the C-Tek every 3 weeks or so to charge it up fully. When I disconnect the charger and move the vehicle onto the driveaway the voltage will show say 14.1 volts for less than a minute it will then drop back to around 13.7 before I switch off.

Our older Jeep (WJ) is used daily so shorty after start up the voltage drops back to around 13.7 volts as most of the journeys are at least 10 miles, even when it is dark so lights are on this does not change much except that the voltage when we switch off will usually be 12.2 volts as against 12.3.

Not sure if this is of any help or not now I have read it back to myself !

 

[Blocky10]

Could we be experiencing a bad earth here?

 

[kitchenman]

Long shot, belt tension?