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Battery holding charge issue....

Guys thanks for help advice. One thing I forgot to mention is voltage charge sometimes reverts back to normal being tested today with AC on at 14.1 volts.

Bottom line I’m thinking the alternator is charging right and yet most time times not.

Planning to visit the auto electricians next week for get to the bottom of this issue.
 
Lead acid batteries have a huge problem with leaving them discharged, i.e. at a low voltages, under 11V. Sulfatation occurs while at low voltage. The sulfate crystals end up on the bottom inside the battery and create a shortcut inside a cell. However it is a slow process so if your battery gets discharged and you recharge it immediately, no harm will be done. That might explain why some of us see this more as a problem then others, it is just a matter of how long the battery remains discharged.
One bad cell in a battery can ruin its performance. The internal resistance will go up and the starting current will be drastically reduced. If you have a 24V starting system, there are 12 cells in series, 6 from each battery so a single bad cell in any one battery ruins the starting performance. And vice versa, it will inhibit charging.
About the problem at hand, I tend to agree with Firewout and many others. Even a small alternator will end up charging batteries as long as it delivers more current than the vehicle requires and you drive it long enough. 80A is a lot. The best way to check is to measure with a voltmeter : alternator output voltage and all individual battery terminal voltages once the vehicle is started. There shouldn't be a big difference between any of them at any time and the voltage should rise towards 14,2V or 14,5V. If not all voltages are more or less equal, check cabling and relay contacts, urgently. Worse case, these kind of faults may cause fire.
If the alternator charges intermittently, this points in the same direction.
The alternator has an S terminal. It opens a ground circuit as soon as the alternator starts working. If this is used to drive the relay that connects the third battery, you avoid discharging this battery while starting. Unless you have very thick cables running to the rear battery, that would be much safer.
 
My third battery in the back connects to the charging circuit via a relay which operates 10 secs (adjustable) after turning on the ign. This avoids any cranking current being drawn from it.
 
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Guys today finally got round to getting the alternator out. It appeared to have a weak Diode set fitted last time. Perhaps not as good as was on the alternator from stock.
 

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With luck, the store had newly arrived heavy duty ones so looked twice as beefy as the one taken off. Whilst fitting this the vehicles two 90 amp front batteries are being charged overnight and will have wait till tomorrow to see it all finished and tested.
 

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Guys after a few days of testing everything looks good now. The alternator is charging well all three batteries. The only thing that needs investigating further is how much power draw my Engel 40 liter has leaving it on every day from the 100 amp car battery. On the net is says 2.5 amps per hour that seems a lot!!
Does anyone have any idea?

Thanks
 
What you are looking for Dervis is the energy use of your fridge. That will be expressed in Ah (ampère hours) at 12V. You can compare that to your battery's capacity of 100Ah. Looking at the Engel datasheets, the 2,5A that you mention is the current draw of your fridge when it's running. Mutiply it by 12V and you get the power draw. To convert power or current to energy or running time you will need to know how much of the time your fridge is running. Mine is a Waeco 30l, it runs 30% time unless the car is parked in the sun or we have just bought some hot six-packs. So 30% of an hour x 2,5 A = 0,75Ah. Now you can compare it to your battery size. Remember that the effective capacity of a lead acid battery usually is only half the rated capacity (50%DOD).
 
Peter running the fridge for 12 hours over night the reading of my gauge was 13.3v to start and 12.4v after. So roughly looking at 0.9-1.0v. Would this be 2.0v per day?
Trying to get an idea of the limitations of my setup and roughly should I turn the fridge off if not using it / driving the vehicle everyday?

Thanks
 
Guys today finally got round to getting the alternator out. It appeared to have a weak Diode set fitted last time. Perhaps not as good as was on the alternator from stock.
Is the new rectifier a Toyota part? They are almost the cost of a complete alternator. Sorry I might have misled you at the beginning due to my haste in replying. Should have known better as I work in electrical engineering
 
Is the new rectifier a Toyota part? They are almost the cost of a complete alternator. Sorry I might have misled you at the beginning due to my haste in replying. Should have known better as I work in electrical engineering

I doubt it TBH Mick, a generic one not sure of the make. Easier to repair here in Cyprus than ordering one from overseas. This setup is temporary now as if I’m in Cyprus for next season will probably be transitioning into a trailer / caravan set up with solar and taking out the fridge & accessories.

Thanks
 
Well Gervin, that's only part of story. After a charge, at first your voltage will drop really fast from 14,5V to 12,8V, even with very low load. After that you can use this graph to get an estimate of the state of charge. Note that these points are measured at no load, which is may not be what you did, your fridge might have been running. The voltage is influenced by the load too.

1596299338117.png

One thing that you could do is make a note of the voltage, say every hour. Assuming your energy requirements are constant (fridge running same number of minutes per hour) you will see that the voltage drop during the first hour is bigger than the one during the last hour (if you started with a full battery). That will allow you to extrapolate more accurately.

If you want a good view on your energy consumption out of your battery, consider a coulomb counter. It will count how many ampère-hours you used and you can compare that to your battery's capacity. They come with voltage, ampère and ampère-hour displays. You won't need to get up at night every hour. An additional advantage is that you will get a good idea of how your battery ages : the voltage of an aged battery will be lower at the same DoD.
 
1596301568008.png

Sorry guys, pasted the wrong graph, here is a better one.
 
Thanks peter that’s idea I’m more serious about looking into because when I start the truck all the charge is being send to the fridge battery.

Also considering to plug in to the mains electric from the truck to the fridge whist it’s parked up and try this out next week. This takes the hassle and load of the battery and don’t have to be too concerned if the trucks driven often enough.
 
maybe a Ctek charger would be the solution ? V is a pretty crude way of measuring battery capacity. A battery should be at rest -neither being charged or discharged - for at lest 1 hour before measuring voltage will give an accurate reading.The rate of discharge also affects a batteries capacity Peukert's law - Wikipedia - [Leaving Land Cruiser Club]
 
Guys after a long drive home the fridge gauge was reading 13.1v and so decided to plug the Engel into the mains for power. Only thing kinda new to me was that had to unplug the 12v lead. Kinda a hassle unknown to me. Guess both leads are designed that way as mains power cannot be detected to override the 12v system?

Giving this a go to see how this works out and test the condition the all batteries this way.
 
First some facts to work from for those (with respect) little or no electrical savvy, and whilst aimed at the stock Land Cruiser 80, this pretty much is the same for any typical car.

When you purchase a battery from a local store it is not fully charged, sure it was fully charged when it left the factory perhaps three or four months ago but by the time it reaches your local shop it has lost some of that charge, so may be at 90% or less? This will depend on shelf time, battery technology, brand, construction etc, so the ageing process has started.

The 12 volt battery is not a 12 volts= battery, it is 12.6+ volts. This is because each cell is a little over 2.1+ volts so X this by 6 =12.6+.

True battery voltage can only be tested by either leaving the battery to stand for a few hours with nothing connected to it, or switch on the headlights for a few minutes and then switch off and then test, this will remove the surface or false reading you will get and reflect the batteries true voltage, but whilst that gives you a good idea the battery may be in good condition it does not guarantee that it is! The voltage may be there to show the multimeter 12+ volts but if there is an internal short inside the battery casing the voltage will drop to nothing once a load such as the starter is placed on it, the cells all need to work together, this is why the 'Green Eye' on many batteries is pretty much useless as it is taking it's specific gravity reading from one cell, the other five could be dead! Again aimed at the 80, after leaving the lights on you cannot test the batteries unless they are disconnected from each other, otherwise this will give you a false reading.

Years ago the connections between individual battery cells were exposed so it was easy to check the connections as the links were easily checked, that has gone. Something else that has all but gone was a way to add water and check the specific gravity (true charge) with a hydrometer to confirm an individual cells condition. This is why the typical battery has less life, we used to check them and add water when we tightened the V belt driving the dynamo and fan... also now gone.

Next, if 12.6 volts is a fully charged battery then 6.3 volts is not a half charged battery, it is a dead battery, and it was dead at 7,8.9 and even 10 volts, if your battery is managing 11 volts there may be enough to crank and start the engine depending on: Electrical connections/condition of engine/condition of starter/engine temperature/environment temperature/age of engine oil and so forth, so you can see anything less than a decently charged battery and it may not start. Also note that voltage on a weak battery will be pulled down by the glow plug circuit (12 valve) or heater matrix (24 valve) models before you have even cranked the engine.

The 80 with it's batteries connected in parallel when the engine is off presents another problem, if one battery fails it will draw down the other so a dead battery on one side of the circuit will leave you with two dead batteries, hence again the reason to test them individually.

Now to the charging circuit.

When the two 80 batteries are believed to be fully charged and in good condition as is the engine etc, you crank the engine and it starts, you have taken a significant amount of power from the batteries which is now to be replaced by the alternator, if you drive say five minutes down the road to the shops and switch off that power may not be replaced why? Because it depends if you sat in traffic/you were on a motorway/was the heater on. the AC. the latest stereo etc. It is funny how the two journey types differ and yet neither have recharged the battery to it's pre start condition.

An 80 alternator only charges up to a specific RPM circa 6000? So 1000 engine rpm will equate to say 3000 alternator rpm (pulley ratio), so driving at a speed that keeps the engine at 2000 rpm means the alternator (now at 6000 rpm) is maxed out. So a five minute drive at 70 miles an hour will not yield much more charge than an engine at 1500 rpm driving through town. When the five minute journey is complete you do a bit of shopping and come out and restart and return home. Those batteries will not have had enough time to become fully charged. Remember I said believed to be fully charged, well it is unlikely they were, the battery voltage will have already been pulled down by simple things like temperature, remember they like 25*C, and now we can add in typical week in the life of your 80, you went to the shops to or three times, perhaps started and stopped the engine two or three times in town, perhaps started it to move it out of the way of another car on the drive? Perhaps even jump started your neighbours Land Rover :) and then parked it up with the alarm set and stereo and clock memory adding some parasitic drain on those batteries over a few days, so now it is easy to see how your batteries life can be shortened........because it/they is/are rarely if ever fully charged.

Something else which seems to be misunderstood.

A battery will only take as much amperage as it can depending on it's internal resistance, a low battery but in good condition might take 30 amps or more but only for a very short period of time, this soon reduces down to say 10 amps where it tends to hold for awhile and then will continue to reduce until less than 1 amp, that will take hours of driving to get it to that stage, again pointing out how difficult it is to get a battery to a fully charged condition, having a 100 amp or even a 500 amp alternator will not charge the battery any quicker, as long as the alternator can supply the current the battery needs then that is enough to get it charged, whilst it is amps that charge a battery, those amps need to be available for a sufficient amount of time for the battery to recoup a decent charge.

In a nutshell, a typical car battery lives it's life at around 80% - 85% % of it's fully charged condition, without the ability to check the cell gravity, or the water level we are no longer prompted to grab the battery charger and leave it on charge overnight, hence the need to maintain a decent charge on them, without that kind of maintenance, this is why typical battery life has fallen over the last few years.

regards

Dave
 
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I've bought motorcycle batteries in the past (a while ago mind) that were dry with the acid being supplied in 6 ampules, then poured into the individual cells and a one piece cap fitted onto the battery top to 'seal' the battery. This is the only battery I've ever bought that was supplied 'fully charged'. This method of supply is obviously not possible with the factory sealed AGM or Gel type batteries. The almost universal use of factory sealed batteries and the charging deficit scenario you mention in day to day use probably explains the appearance and widespread use of modern 'intelligent' maintenance chargers like Ctek's etc.
 
I don't work on motorbikes, but have seen my supplier with 6 and 12 volt dry batteries and yes they are supplied with mixed acid water bottles to be added by the purchaser, I have also purchased these bottles of acid to stretch the life of house solar batteries.

regards

Dave
 
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