Volv XC90 V8 2007- at 77000 miles i got a power system failure service urgent and when my mechanic tested voltage and it was 11v as charge rate and he told me the regulator is gone ,the battery then went flat . i got a new aftermarket Bosch regulator a couple of weeks later and it was replaced and it then gave a charge rate of 15.8v which i was advised it was too high and might damage other components , after a few months i then went to a volvo dealer and purchased a brand new alternator which they assured me was the 180amp( south africa ). i then removed the old one and put the two alternors side by side(please see attached ) and noticed they had different part number and the old one is made in Great Britain while new is made in hungary, i then proceeded to install the new alternator and at the same time charged my battery (100AH. 12.6V) with a lifespan of 57%, after first crank it started and ran smoothly but after a minute that light came back on again-power system failure service urgent - i swear i cud have kicked this car , mechanic then checked volatge charge and its at 13.5V constant, i am made to undrstand it should have a charge rate of at least 14V. can anyone please assist me as to how to rectify this or what should i do , i have just had it upto hear with this car, my mechanic suggested i change battery and get a new one and he thinks i will get the 14V charge rate , i do not want to keep throwing money away /

please please assist

 

if the battery is weak it will draw current and drop the voltage. 13.5V is typical of a system with a load -ie headlights on, blower going etc. Aside from finding the correct parts for your alternator, your mechanic may want to see if something is drawing too much current - bad cables, starter, an odd motor etc by removing fuses and relays.

 

What's the voltage on the LIN wire to the alternator? Could have a bad ECM.

 

dont know much about what LIN is will have to ask mechanic and probably get the car On Vida.

 

so you reckon if all is checked and seems not to be putting a load i should change battery and problem will be fixed?

 

Charging the battery will increase the voltage, but you don't need to buy a battery to get one that is charged. You can do that by running the car, or you could hook up a battery charger. It's perfectly normal for system voltage to be 13.5 volts sometimes. In fact, during cranking, it's probably 10 or 11. After the car has been operating for a few minutes on the highway, you would typically expect to see just over 14 volts.


If one of the battery cells gets shorted out, then the resting voltage of the battery will be about 10 volts instead of about 12. In that case a new battery will be necessary.


Batteries are cheap here in the USA, so it's not much of a penalty to change one here.

 

If its stuck at 13.5, there may be a problem with the ECM. That is the default charge voltage.

 

how can this be corrected if ECM is faulty

 

It would need to be replaced. I would first check the voltage on the LIN wire to the alternator.