Battery problem?

[Downlands]

Hi

Went for drive yesterday (car is a 2007 R400 Duratec) and having stopped for a break, my car failed to start. Battery was flat. After a jumpstart, all was ok and I got home. 

I charged the battery up last night and all has been ok today although I did notice for the first time the ignition warning light coming on.

I’ve checked voltages on the battery when engine is running. At tick over, it’s 12.5v and when rpm exceeds 2k, voltage increases to 14.5v ish.

Not sure whether I have an alternator or a battery that’s on the way out.

Would be interested to hear if anyone can shed some light on this?

Thanks

Tim

[Jonathan Kay]

What type of battery? How old?

Is it a type that you can check the fluid levels and top up if needed?

At tick over, it’s 12.5v and when rpm exceeds 2k, voltage increases to 14.5v ish.

The reading at higher speed is OK (I recommend 3,000 rpm). Minimum desirable voltage at idle is often quoted as 12.6 V but that's probably OK. Does it go higher if you blip the engine and then let it return to idle and measure again?

Could you add another measurement: the minimum voltage seen during cranking.

I did notice for the first time the ignition warning light coming on.

On when you switch on the ignition and off as soon as it starts? Has the behaviour changed?

...

Even though it started when jumped I'd still check all of the relevant cables, including earths, and connections.

And the alternator belt tension and condition.

Jonathan

[anthonym]

Alternator.

[Downlands]

Hi Jonathan

Battery is a Banner Starting Bull. I believe it’s a 530 34 although it’s difficult to tell as the markings have rubbed off. It’s a least 3yrs old as that is how long I’ve had the car.

Yes, if I blip the throttle, the voltage rises and drops again.

I wasn’t able to measure the crank voltage as the car starts instantly.

The ignition warning light comes on when I turn ignition on and then disappears when the engine starts. It does however fade in when the engine is rev’d and fades away at idle.

I don’t know whether this is coincidental but until this morning, the car has ‘juddered’ around 2.5k rpm which was fine when accelerating through 2.5k but a pain in traffic. Since I fully charged the battery last night, the car has driven very smoothly today.

Thanks

Tim

[Jonathan Kay]

Battery

Check the fluid levels and top up if necessary.

I wasn’t able to measure the crank voltage as the car starts instantly.

!!! :-)

With a digital multimeter it's usually possible to see a transient value. This gives the voltage under load and it's possible to detect deterioration well before the unloaded voltage starts to fade.

Jonathan

[Jonathan Kay]

Charging

Discussion of R400s, pulley sizes, charging at idle and the effects of blipping.

...

It does however fade in when the engine is rev’d and fades away at idle.

That is not normal.

... if I blip the throttle, the voltage rises and drops again.

But does it settle down at the new idle at a higher voltage than at the idle before blipping?

...

I'd check those wires and connections in detail, including visual inspection and wiggling, disconnection and reconnection.

And the belt as above.

But after excluding those we might be homing in on the alternator, and particularly the electronics pack. These are surprisingly repairable at local electricians or the agent. And if you repair rather than replace you know that it will fit and won't need modifications to the wiring.

What sort is it?

Jonathan

[anthonym]

Borrow an alternator to test, and get a permanent voltage display gizmo.. someone will be along with a linky momentarily, I gave in and got one, brilliant bit of kit after various alternator strandings. You can see as it passes through all the stages Jonathan mentions, but always. Battery will be 53034, though mine is currently (!) 53030 and I think the difference is the breather tube outlet side. Edit WRONG the difference is the pos and neg are on opposite sides

Do just check the B+ is not disintegrated beneath its cover where it connects to the alternator ; that cost me an un-necessary new alternator somewhere in France. Likewise that the D isn’t fried in the last few inches to where it connects.

Anthony

[anthonym]

dup

[Downlands]

Thanks Jonathan.

I forgot to mention I checked the battery fluid levels. Not sure what the correct levels of the cells should be but they weren’t identical although there wasn’t much in it.

Will follow your advice and investigate further. 

Thanks

Tim

[Jonathan Kay]

In the absence of any specific instructions for the battery the plates should be just covered with fluid.

Jonathan

[Downlands]

Hi Anthony,

Thanks for the advice..... will double check the connector.

Tim

[anthonym]

Welcome.. to add insult to injury I had had TWO new alternators shipped out, and there was nothing wrong with the original. So, three working alternators. The problem was the disintegrating (in progress) B+ passed inspection, but not test with a meter in the usual manner, it was only on physical disconnection of the connector that showed up the problem. That fading in and out warning light is in my humble opinion, the clue to it being the alternator, unless a connector - and if you have connector problems already, probability rises, if you do not, then it falls away and suggests the alternator. The battery when fully charged solving the running quality again suggests it is the battery not being charged, rather than a fault with itself iyswim. The 5303x Banners are tough little beasts and three years is a bit early to fail, which typically is at a Winter’s end when it won’t hold a decent charge.

Not to distract you from all Jonathan’s suggested diagnostic processes, as I am of course passing « go » without going round the board.

And I have since replaced my entire engine loom because of connection failures, so I am an outlier. Which is not unusual ;-)

Anthony

[auyt]

Had the same issue yesterday with flat battery mine was simpler than yours I left the lights on after leaving home in Fog. Made for an expensive Breakfast Fitted motor bike battery and drove home

I use a Full River HC20 AGM very impressed with it but if you flatten one they take about 48 hours to charge.

[anthonym]

Funnily enough that’s why I fitted LED daylight running lights, to save my battery.

[Downlands]

Thanks All for help and advice, I’ll investigate further.

I do wonder if it is the Alternator because now I come to think about it, the day the battery was flat was a hot day and I kept getting stuck in traffic so the radiator fan was running a lot. Maybe that and having the DRL’s on all the time was drawing more juice than the alternator could provide at idle, which eventually ran the battery down.

Tim

[Nigel Riches]

Hi Tim.

Have you checked the excitation voltage at the alternator, is it within a small amount of the battery volts? 

Could be a case of insufficient excitation.

Or, the other side of the conversation, check the alternator output voltage at the output terminal, with the "charge" light fully extinguished, (2k-3k rpm) should be in the order of 14 volts, if this is good, check the volts at the battery +ve post, if not within a few squidgions of a volt, check the resistance of the wire from alternator to battery, should be zilch resistance over that distance, if you find  some resistance, make up a suitable jumper ( same gauge and length) to replace the "in car" wire and try again. Hopefully you can sort this problem.

There are some really good battery chargers on the market these days, not the old full wave rectifier and a capacitor if you are lucky, I revived my wife's VW Golf battery, stop / start technology, AGM construction, with a Ctek MXS-5 charger, can be used as a charger conditioner, whilst the car is idle for a prolonged periods. Recommended.

Hope some of this helps.

Nigel.