Alternator \ battery problems (Diesel ZTT)

le-sabre · 3rd September 2018, 11:31

OK, Had the "Battery charge" error come up a few days ago. After checking it out it does seem like it's overcharging as i'm getting 14.5v -14.7 volts while running.
So after some discussion I changed the regulator as it sits on top and can be got at without a big job. I guess it's been done before as the alternator didn't have the familiar black cover on the back but this did make the regulator easy to swap over. Did that and no difference !! damn it , I'm now looking at £400+ to get it ordered and a new alternator fitted.

However, i'm now seeing that an incorrect battery can cause overcharging ?? and I have had a new battery only a couple of weeks ago. Could this be my problem and if so what is the correct battery ? I fitted an 096 75Ah battery which seems to work ok ( well it started the car which is more than the old one did anyway). Someone mentioned a 90Ah ? that seems very high but if that's what it should be then so-be-it.

Can anyone give me a definitive spec on the correct battery ? what was fitted from new ?

trikey · 3rd September 2018, 12:02

14.5 -14.7 sounds fine to me.

le-sabre · 3rd September 2018, 12:07

Now I am confused :-) I've been advised that is a bit too high really but i'm open to advice either way.
So why would I be getting the charge fault and the battery icon permanently lit up ?

MSS · 3rd September 2018, 12:13

I would say the information you have been given is incorrect.

A charging voltage of 14.5 to 14.7 with the car running does not indicate overcharging but 14.7 is at the top end of the acceptable charging voltage with a fully charged battery.

The charge error state should not come on with a charging voltage of 14.7v. The error probably indicates an intermittent non-charging or a wiring fault. Did you check the state of the slip rings when replacing the regulator?

A smaller or larger car battery will not lead to overcharging.

The correct battery size for a diesel is the 096 or a 100. These types would normally have a capacity of of 70 to 78 Ah.

It should not cost £400+ for an alternator replacement. Buy a 125A CDT second-hand Valeo from a breakers for around £50, spend £100 on a complete rebuild by an auto electrician and no more than £120 for fitting at an independent or one of the traders on the forum.

le-sabre · 3rd September 2018, 12:17

I have to say that I didn't go any further than replacing the regulator\bush assembly.
What should I be looking for on the slip rings ( I assume the slip rings are the part the bushes are against ? )

COLVERT · 3rd September 2018, 13:25

Correct. The slip rings are two brass bands side by side.

Ideally they should be flat and smooth and show no signs of burning.

Did the brushes you removed look very badly worn compared to the new ones ??

Worn brushes will only just touch the slip rings and this low pressure will cause arcing and burning of the rings rendering them useless.

le-sabre · 3rd September 2018, 14:17

The bushes looked not too bad actually, I will go back and double check the slip rings now though.
Thanks for the advice.

Mickyboy · 3rd September 2018, 16:01

14.7 V when cold is perfectly acceptable as you will notice when plugged in on T4 the ECM helps regulate the charge rate and increases the charge rate when cold, once the engine is out to temperature and reaches circa 77 degrees, then the ECM reduces the charge rate to circa 14.2 Vlots
Mick

Mike Noc · 4th September 2018, 08:12

Quote:

Originally Posted by le-sabre

Now I am confused :-) So why would I be getting the charge fault and the battery icon permanently lit up ?

Damage to the wiring can bring up the charge warning - trace the control wires back from the alternator and check for any damage.

COLVERT · 5th September 2018, 10:26

Quote:

Originally Posted by Mickyboy

14.7 V when cold is perfectly acceptable as you will notice when plugged in on T4 the ECM helps regulate the charge rate and increases the charge rate when cold, once the engine is out to temperature and reaches circa 77 degrees, then the ECM reduces the charge rate to circa 14.2 Vlots
Mick

I believe you mean the in-built regulator in the alternator don't you and not the ECM.---The engine temperature has no input here.---

3rd September 2018, 11:31	#1
le-sabre Regular poster MG ZT-T Join Date: May 2014 Location: WARWICKSHIRE Posts: 83 Thanks: 21 Thanked 4 Times in 4 Posts	Alternator \ battery problems (Diesel ZTT) OK, Had the "Battery charge" error come up a few days ago. After checking it out it does seem like it's overcharging as i'm getting 14.5v -14.7 volts while running. So after some discussion I changed the regulator as it sits on top and can be got at without a big job. I guess it's been done before as the alternator didn't have the familiar black cover on the back but this did make the regulator easy to swap over. Did that and no difference !! damn it , I'm now looking at £400+ to get it ordered and a new alternator fitted. However, i'm now seeing that an incorrect battery can cause overcharging ?? and I have had a new battery only a couple of weeks ago. Could this be my problem and if so what is the correct battery ? I fitted an 096 75Ah battery which seems to work ok ( well it started the car which is more than the old one did anyway). Someone mentioned a 90Ah ? that seems very high but if that's what it should be then so-be-it. Can anyone give me a definitive spec on the correct battery ? what was fitted from new ? __________________ [SIGPIC]ZT-T CDTi 135+ Ski Blue, Climate control, sunroof, rain sensor, headlamp washer, parking sensors, Xenon, Blue Alcantera/leather, 18" Gridspoke This vehicle was the 1st ZT-T in Ski Blue (code: JHI) to be made out of 3 Ski Blue ZT-Ts & the only diesel ZT-T in Ski Blue. This vehicle was the 7,369th ZT-T to run off the production line, out of 8,249 This vehicle was the 2,352nd ZT-T CDTi + (135) to be made out of 2,795

3rd September 2018, 12:02	#2
trikey Premium Trader Rover 75 Join Date: Nov 2010 Location: Devon Posts: 33,767 Thanks: 8,837 Thanked 14,831 Times in 8,030 Posts	14.5 -14.7 sounds fine to me. __________________ Lest we forget..

3rd September 2018, 12:07	#3
le-sabre Regular poster MG ZT-T Join Date: May 2014 Location: WARWICKSHIRE Posts: 83 Thanks: 21 Thanked 4 Times in 4 Posts	Now I am confused :-) I've been advised that is a bit too high really but i'm open to advice either way. So why would I be getting the charge fault and the battery icon permanently lit up ? __________________ [SIGPIC]ZT-T CDTi 135+ Ski Blue, Climate control, sunroof, rain sensor, headlamp washer, parking sensors, Xenon, Blue Alcantera/leather, 18" Gridspoke This vehicle was the 1st ZT-T in Ski Blue (code: JHI) to be made out of 3 Ski Blue ZT-Ts & the only diesel ZT-T in Ski Blue. This vehicle was the 7,369th ZT-T to run off the production line, out of 8,249 This vehicle was the 2,352nd ZT-T CDTi + (135) to be made out of 2,795

3rd September 2018, 12:17	#5
le-sabre Regular poster MG ZT-T Join Date: May 2014 Location: WARWICKSHIRE Posts: 83 Thanks: 21 Thanked 4 Times in 4 Posts	I have to say that I didn't go any further than replacing the regulator\bush assembly. What should I be looking for on the slip rings ( I assume the slip rings are the part the bushes are against ? ) __________________ [SIGPIC]ZT-T CDTi 135+ Ski Blue, Climate control, sunroof, rain sensor, headlamp washer, parking sensors, Xenon, Blue Alcantera/leather, 18" Gridspoke This vehicle was the 1st ZT-T in Ski Blue (code: JHI) to be made out of 3 Ski Blue ZT-Ts & the only diesel ZT-T in Ski Blue. This vehicle was the 7,369th ZT-T to run off the production line, out of 8,249 This vehicle was the 2,352nd ZT-T CDTi + (135) to be made out of 2,795

3rd September 2018, 14:17	#7
le-sabre Regular poster MG ZT-T Join Date: May 2014 Location: WARWICKSHIRE Posts: 83 Thanks: 21 Thanked 4 Times in 4 Posts	The bushes looked not too bad actually, I will go back and double check the slip rings now though. Thanks for the advice. __________________ [SIGPIC]ZT-T CDTi 135+ Ski Blue, Climate control, sunroof, rain sensor, headlamp washer, parking sensors, Xenon, Blue Alcantera/leather, 18" Gridspoke This vehicle was the 1st ZT-T in Ski Blue (code: JHI) to be made out of 3 Ski Blue ZT-Ts & the only diesel ZT-T in Ski Blue. This vehicle was the 7,369th ZT-T to run off the production line, out of 8,249 This vehicle was the 2,352nd ZT-T CDTi + (135) to be made out of 2,795

3rd September 2018, 12:13	#4
MSS This is my second home Rover 75CDT, Jaguar XF-S 3.0V6, V'xhall Omega V6 Estate, Twintop 1.8VVT, Astra Estate and Corsa 1.2 Join Date: Dec 2007 Location: Suffolk Posts: 7,085 Thanks: 283 Thanked 624 Times in 440 Posts	I would say the information you have been given is incorrect. A charging voltage of 14.5 to 14.7 with the car running does not indicate overcharging but 14.7 is at the top end of the acceptable charging voltage with a fully charged battery. The charge error state should not come on with a charging voltage of 14.7v. The error probably indicates an intermittent non-charging or a wiring fault. Did you check the state of the slip rings when replacing the regulator? A smaller or larger car battery will not lead to overcharging. The correct battery size for a diesel is the 096 or a 100. These types would normally have a capacity of of 70 to 78 Ah. It should not cost £400+ for an alternator replacement. Buy a 125A CDT second-hand Valeo from a breakers for around £50, spend £100 on a complete rebuild by an auto electrician and no more than £120 for fitting at an independent or one of the traders on the forum.

3rd September 2018, 13:25	#6
COLVERT This is my second home R75 Saloon. Join Date: Feb 2009 Location: France/or Devon. Posts: 14,003 Thanks: 3,851 Thanked 2,167 Times in 1,816 Posts	Correct. The slip rings are two brass bands side by side. Ideally they should be flat and smooth and show no signs of burning. Did the brushes you removed look very badly worn compared to the new ones ?? Worn brushes will only just touch the slip rings and this low pressure will cause arcing and burning of the rings rendering them useless.

3rd September 2018, 16:01	#8
Mickyboy SERVICING AND DEALER DIAGNOSTICS MG ZT CDTI 135 + & MGZT CDTI AUTO 160 & ROVER 75 TOURER CDTI 160 TROPHY YELLOW Join Date: Aug 2013 Location: Hernebay Posts: 4,331 Thanks: 818 Thanked 2,414 Times in 1,141 Posts	14.7 V when cold is perfectly acceptable as you will notice when plugged in on T4 the ECM helps regulate the charge rate and increases the charge rate when cold, once the engine is out to temperature and reaches circa 77 degrees, then the ECM reduces the charge rate to circa 14.2 Vlots Mick __________________ [SIGPIC][/SIGPIC] T4 Owner Jobs done : new UBP, Spy hole mod, Rear hub(wheel bearing),plenum cleaned and emptied, Inline thermostat fitted,Full service, In car Digital tv/DVD Bluetooth Satnav etc, Replaced UBP, Restored headlights,Fixed airbag connection.replaced HP pump,replaced rear light seals,changed intercooler O rings. Jobs to do: ,replace drivers lock,.[/SIZE]