Battery overcharging - Dash warning lights

[stephenusername]

Ford fiesta 1.4 2002 year.

battery warning light started lighting up on dash intermittently and when this happens the battery does not charge. Started getting worse and other lights stared lighting up, air bag, lost speedo/rev and mileage counter. When this happens under the dash to the right of the steering one of the back boxes starts to make a clicking noise. Took it to a auto electrician whom said the battery is overcharging at about 15v which according the other forums can cause the dash light problem. The auto electrician tested the wiring continuity between the battery, ECU & alternator. He then changed the alternator but still the same problem. The last thing he said which could be the cause is a faulty ECU. I sent the ECU of for testing and the ECU is fine. The car also has a brand new battery. Any suggestions will be appreciated.

[btmaldon]

What type of battery is on there? Hope its not a Lead Acid battery. That would cook with the Smart Charge system.

[Russ]

The smart charge system on fords will charge the battery at a higher voltage if the voltage on your battery is down. As the above post, is it a calcium battery on the car and how old is the battery as it may be on its way out!

http://www.valeoservice.com/data/master/webfile/2945759434DDE6E8714173.pdf

[Tdci-Peter]

6 hours ago, stephenusername said:

auto electrician tested the wiring continuity between the battery, ECU & alternator. He then changed the alternator

It seems unlikely that a 2002 Fiesta has smart charge. It is probably just the standard fixed voltage charge at 14.5v (about).

I hope the electrician properly tested the battery. If the system voltages are getting high enough to make modules malfunction, it is likely to be the battery or its wiring. New batteries can fail sometimes.

Any problems starting? Try turning max electrical load on (headlamps, demister, etc) for a minute or so, then starting the car.

 

 

[stephenusername]

I have a Bosch S3 battery. Cannot find what type of battery it is. This is the second battery I have just bought in 9months. The first I killed by the intermittent charging. The electrician checked the car with first the old battery and then the new battery once the new alternator was installed. I looks like it could be wiring.

[Russ]

1 hour ago, Tdci-Peter said:

It seems unlikely that a 2002 Fiesta has smart charge. It is probably just the standard fixed voltage charge at 14.5v (about).

I hope the electrician properly tested the battery. If the system voltages are getting high enough to make modules malfunction, it is likely to be the battery or its wiring. New batteries can fail sometimes.

Any problems starting? Try turning max electrical load on (headlamps, demister, etc) for a minute or so, then starting the car.

 

 

Ford have been using calcium batteries & smart charge since 1997 apparently although not sure if this will include the UK 

http://www.yuasa.co.uk/info/technical/silver-calcium-batteries/

[Tdci-Peter]

1 hour ago, Russ said:

Ford have been using calcium batteries & smart charge since 1997

I must admit, I had assumed that the smart charge came in later than that, and that my 2006 Focus did not have it! But a bit more research suggests that all Mk2 Focus, and possibly some Mk1, have this type of charge system. Learnt something there, thanks for that!

One reason for my assumption is that, whenever I have monitored it, my car reads about 14.2 to 14.6v with engine running. (I have in-car voltage monitoring, though the display is usually switched another channel. I will watch it a bit more, now)

But the Fiesta 4th generation covers 1995 to 2003, so it may not have had it. You would have to look at the alternator plug, or a wiring diagram, to find out.

1 hour ago, stephenusername said:

I have a Bosch S3 battery

I don't think the Bosch S3 is "silver calcium". The S5 claims to be a calcium silver alloy, and it is what I have. I have not checked the S4. The difference is not that great, they are all lead-acid, including Calcium, Silver-Calcium, AGM, EFB, and SLA or VRLA types. Manufacturers claims vary. But there are small but potentially important differences in charge voltage & temperature characteristics.

Back to the subject of voltage monitoring, a plug in meter may be a very useful thing to have, if there is any suspicion about the charge system. Being able to monitor it while driving, as the engine warms up and the battery gets back to full charge would be useful. Something like this: http://www.ebay.co.uk/itm/LED-Car-Auto-Battery-Electric-Cigarette-Lighter-Voltmeter-Voltage-Meter-Tester-/271523172388?hash=item3f380ad024:g:VxIAAOSwuTxWBTW4

One problem with these devices is they do not monitor battery terminal voltage The car system voltage at the cigar lighter could be 0.5v (or more) different to the battery, depending on the various electrical loads. But at least it does give some idea of what is happening, and will show trends or changes.

 

[stephenusername]

Hi Peter,

Thanks for your advise. I will look into the monitor

Stephen

 

[jeebowhite]

Bosch S range are Silver Calcium, but have differing CCA's and capacities.

[Kim tagawa]

My car is ford fiesta st 2007 I have changed alternator new battery checked wiring but still brings the battery light on dash board hence saying is over charging ,what  could be the problemo

[Tdci-Peter]

18 hours ago, Kim tagawa said:

I have changed alternator new battery checked wiring but still brings the battery light on dash board

Since you have changed or checked everything apart from the ECU, you need to double or treble check wiring and alternator type, before you are left with just the ECU.

Using Forscan or another really comprehensive Ford specific diagnostic system to read the error code(s) that will undoubtedly be present if the light is on, might reveal a clue. I am not altogether optimistic that it will solve the problem, but it might just narrow it down.

Ensure the new alternator is the right type. There are variants, and they do get mixed up sometimes.

Looking for intermittent or poor connections in wiring takes a lot more work than a quick look or multimeter check. Wires can fail inside the insulation, this usually shows as a slightly weak or bendy bit in the wire, but when bound in a harness this is very hard to locate. In the heavy earth & power cables, looking for voltage drops from one end to the other while the alternator is delivering current is a good check. (Don't forget the big engine earth cable!)

Monitoring system voltage and voltage drops with various loads (from minimum to everything on) and at various rpm can help, though it can also be quite confusing, especially with smart charge & the ECU starts altering the voltage. Repeating these tests & looking for any inconsistent results may give a clue.

The smart charge connector on the alternator may be one wire (LIN bus) or 3 wire (older smart charge). Following these wires through to the ECU might find a break in one, or a bad connection.

Sadly, there may be no easy fix. I have spent many, many hours hunting down bad wiring in my career, and it is not much fun, but can be worth it when the system starts working again!