L322 Diesel V8 3.6 2008 Battery is over charging

Too high voltage 15,6 V and higher, replaced alternator, swap engnie control module, cables to alternator checked and are good.
Alternator command value in the ECU set to about 16V
Question how the ECU generates this value for the alternator?
I am not only one with this issue, I found on the other forum old thread but no solution.

tasts said:

Too high voltage 15,6 V and higher, replaced alternator, swap engnie control module, cables to alternator checked and are good.
Alternator command value in the ECU set to about 16V
Question how the ECU generates this value for the alternator?
I am not only one with this issue, I found on the other forum old thread but no solution.

Click to expand...

16 to 18 volts after starting is not unusual in some modern cars, it should drop progressively to about 13.8 volts but it could take while to do this depending on the state of the battery

After start voltage is low and rise up too high 15,6 - 17 V (no drop below 15,6 V)

tasts said:

After start voltage is low and rise up too high 15,6 - 17 V (no drop below 15,6 V)

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How long does it take to drop to 15.6 volts?
Have you checked the earth strap from engine to chassis?

Time voltage drop without rule, sometimes never drop. Earth strap was damage, low rew engine at starting, now earth strap new engine starting very well but too high voltage issue still present.

tasts said:

Time voltage drop without rule, sometimes never drop. Earth strap was damage, low rew engine at starting, now earth strap new engine starting very well but too high voltage issue still present.

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I don't have enough detailed knowledge to delve further but if the earth strap was damaged, it's likely that the system of regulation has also been damaged. Do you have diagnostics?

Diagnostic is engine control module send comand high voltage to alternator but I do not know why.

Does your car have auto start/stop? It's perfectly normal to see 17 or even 18 volts on a modern car.
How old is the battery and what is the voltage if you leave the engine off for an hour?
The car might be requesting a high voltage to compensate for a tired battery

Usually if a battery starts to lose its capacity the stop start is turned of by the cars ecu.
A high and constant output could point to a duff battery and or connections.
I would have the batteries capacity tested also.

No start/ stop
Battery replaced
I found also on this forum
https://www.landyzone.co.uk/land-rover/4-4-v8-high-voltage-boiling-battery-17v.290711/page-2
Other engine but the same issue

tasts said:

No start/ stop
Battery replaced
I found also on this forum
https://www.landyzone.co.uk/land-rover/4-4-v8-high-voltage-boiling-battery-17v.290711/page-2
Other engine but the same issue

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As you had a faulty earth strap, as I said it's likely there is damage somewhere to the regulator circuitry. It's complicated on modern cars. As the engine control module is requesting high voltage, you have to find out what the engine control module uses to generate the high voltage request.
For example, if the engine control module is not seeing the correct battery voltage due to a bad connection, bad earth or a component failure, it will I suspect stick at high voltage.
You could try putting a jump lead from the alternator to battery negative.

Engine control module seeing high voltage but comand alternator to high voltage. All connection to alternator checked many times and are ok, jump lead also used.

tasts said:

Engine control module seeing high voltage but comand alternator to high voltage. All connection to alternator checked many times and are ok, jump lead also used.

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In that case it sounds like a component failure in the ECM
If the earth strap from engine to chassis failed, the alternator regulation would likely be disabled. In that situation, an alternator can output uncontrolled high voltages. As I say I do not know the specifics of the system on your car, so what I say is speculative based on my working on alternators and regulators from a simpler era.

ECM failure it was also my idea but after swapped nothing change.I hope someone who has the same issue help me solve this puzzle. Logical diagnostics useless. On the two forums I found similar case but no answer.

tasts said:

ECM failure it was also my idea but after swapped nothing change.I hope someone who has the same issue help me solve this puzzle. Logical diagnostics useless. On the two forums I found similar case but no answer.

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I'd need detailed schematics to go any deeper but if you swapped the ECM with no change, it's back to a bad connection I'd bet. A matter of testing individual wires for continuity.

tasts said:

No start/ stop
Battery replaced
I found also on this forum
https://www.landyzone.co.uk/land-rover/4-4-v8-high-voltage-boiling-battery-17v.290711/page-2
Other engine but the same issue

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Is the replacement battery exactly the same as the original OEM spec battery?

Do you need to tell these cars that a battery has been replaced?

kermit_rr said:

Do you need to tell these cars that a battery has been replaced?

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That is also a possibility. Insane levels of complication IMO

I have to check is needed battery reset information, no BMS in this vehicle and I do not thought about this. It could help.

tasts said:

I have to check is needed battery reset information, no BMS in this vehicle and I do not thought about this. It could help.

Click to expand...

You also need to be sure that the replacement battery is the correct type and capacity. For example it may not be possible to replace a lead calcium battery with an AGM type or a GEL battery.