Citroen c5 x7 importance of good battery.

[poppychops]

Have had my c5 x7 2.0 hdi auto executive for 2 yrs now and have constantly had i numerous issues which have ALL gone since getting a new battery.
upon starting the relays clicked behind the dashboard.
Economy mode displayed every time i got in the car.
Constant depolution fault messages.
Tyre sensor error messages.
unable to move electric seats without engine running.
sometimes radio would not work.
car was slow to start but never failed not to.
car cut out at junctions.
constant fault messages
gearbox used to make a massive bang when moving from drive to reverse.
So since having a new battery fitted i have had NO issues what so ever and the car is 100% reliable.

The car has been at garages for some of the numerous faults mentioned above (fuel pressure relay,cps,wiring loom etc) but the battery was never mentioned as the cause of the problem so if you are having any of the above issues see if you could "borrow" a battery before buying one and see if it makes a difference.

[GiveMeABreak]

Welcome to the forum.

Yes, it has been well-documented here on the forum in numerous posts that a poor battery is the cause of a lot of electrical problems and especially on the C5. It is the one thing many people don't bother with checking and think will last forever, forgetting they have a finite duty cycle!

[EDC5]

I was also suffering with the immediate economy mode message, thankfully not any of the other issues you had (touch wood) and a new battery has appeared to have solved that one; for how long I don't know. I get the impression that the old battery off my C5 could probably go on to give many years of good service on a less electrically fussy car

[GiveMeABreak]

Very likely it will Elis! And that point is very important in that simply having an operational battery that works to start the car is not always enough for the car to function correctly.

[EDC5]

True! although I wish Citroen would engineer their electronics to work between 11v and 15v would make everything a lot easier.

[Hell Razor5543]

The French can be a bit picky. Give then 100 barrels of the finest produce from the Champagne region and they are happy. Tell them you added one glass per barrel of the finest English sparkling white wine and they will start revolting!

[Xantippa]

This is so true. With my previous C5 X7 I had two faulty batteries (Snadzjer AGM and normal Bosch) that caused constant economy mode - and I thought there was something wrong with the car. After getting Exide AGM-battery, there hasn't been any problems. The car started fine even in the finnish winter with those faulty batteries.

[poppychops]

Apparently the cold cranking amps (CCA) are critical when purchasing a battery.

[GiveMeABreak]

Yes I have a Bosch S6 AGM and I constantly have the dreaded economy mode whether even when fully charged - I also have the Battery Charge Status Unit - and although the car will start all the time, I really don't think it is designed to work well with this car (unless you have Start Stop tech.). ECD5 also mentioned about the alternator charging rate - and that my not be suitable for the AGM battery. But I'm not replacing it now as it cost quite a bit and TBH I can cope with the odd minute of power it gives me after engine off, plus there's enough to move the seat forward and back whenever I get in and out the car - so that will do me.

As for the CCA - it is well over that needed for the car - although my X7 will only allow you to input 3 battery levels in the BSI / BCSU when replacing it - so again, depending on the type of battery selected, this may affect how it charges and monitors what it thinks should be the correct settings!

[white exec]

Always worth fitting the largest battery that will physically fit, and the best CCA you can lay hands on.
Agree that Citroen appear to have created a significant problem for themselves with an intolerance by the electronics of dips in system voltage.

The problem is aggravated on a diesel by (a) anything up to 80A being taken by glowplugs as soon as IGN is fully switched on, and (b) cranking starter-motor current is very high. Both these demands can hit the battery simultaneously, maybe pushing battery voltage down to 10 or so. Only good batteries, decently connected, will provide adequately. You are right, though, a wider voltage operating range would have been helpful.

One other important factor could be the state of the battery terminal connectors. Over many years, PSA have fitted crimped-on battery connectors, which can over time relax their grip on the thin multicores inside, and allow oxidation of the cores and connector through ageing and weathering. This results in some electrical resistance at this spot, which heats up each time the car is started or has to handle a very high charging current. The heat produced goes unnoticed, and accelerates the oxidation/ageing process.

A clue to whether this is going on is to feel the connectors with your hand during/immediately after prolonged cranking, particularly if starting isn't immediate. If there is any sensation of warmth there, the connection needs renewing. It is best to cut off and replace the OE connectors with good brass clamps, having thoroughly cleaned the copper strands back to bright metal. Plenty of brass clamps around, even at H*lf*rds.

Also worth checking out (and cleaning up) earth connections for engine unit that could cause a system voltage drop when starting.

[EDC5]

Yep, when you turn on the ignition you have the glow plugs and the suspension pump running, and then with the cranking the current draw is big. I fitted a Yuasa 5096, that has 80Ah rather than the usual 74 or 77Ah battery of the 096 sized battery.

In this case I think capacity is more important than CCA as from my brief investigations it appears the state of charge (SoC) of the battery is primarily determined by the resting voltage of the battery. Therefore the higher capacity battery will have a higher resting voltage fending off the dreaded economy mode for a few more mins.

[Richard_C]

Agree with all of the above, my X7 battery went from OK-ish but odd error messages one day to stone dead the next. It does lots even after you switch off - ac flaps motor shut, alarm sensors, locking, flashing indicators, follow me home lights, all low drain or short term but it must add up.

The only thing I would add to the sound advice on battery terminals is if problems continue find the other end of the earthing strap and check it out. Often one bit goes to somewhere on the block or bell housing which can get loose, the other to a bolt on the bodywork which can easily get damp/corroded/horrid. The - has to carry just as many amps as the +.

[white exec]

Yes, the Ah figure for a battery is its theoretical 'capacity' - a 70Ah battery will do something like deliver 7A for 10h, or 3.5A for 20h. This linear mathematical relationship only holds good for middle-of-the-road currents, though.

For very small currents, like a car sitting on standby (likely less than 50mA), the battery will keep on delivering for hours (days, weeks, even months...) far beyond the mathematical calculation.

At the other end of the scale, a current pull of 70A on the same battery will not hold up for 1h, but less. As the current increases further, the time available falls off even quicker. At a cranking 350A, you certainly will not get a continuous 0.2 of an hour (12 mins) - as we all know!

Now, whether the battery is 70, 75 or 80Ah doesn't make a lot of difference to what is available in the way of prolonged cranking/difficult starting. The difference in power storage is fairly insignificant for these high-current moments. (Where the higher figure does help is for the low-current situations: standing by, parking lights, etc. For extreme long-duration, low-current use - eg in caravans and boats - there are Leisure batteries available. These not only tolerate being completely discharged better than normal car batteries, but also are available at 140-200Ah capacity! They will not, however, survive vehicle-starting usage.)

For prolonged cranking, winter starts, difficult starts, it's the CCA (cold cranking amperage) figure that counts. A battery that can provide 800CCA will "hold up" far better when it's being asked to provide 350A of cranking and glow-plugging than one which is only rated at 600CCA. CCA is the measure of muscle.

[EDC5]

The capacity is usually quoted at the 20Hr rate meaning that 100Ah battery can draw 5 amps for 20 hours. However a 50Ah battery will not give 5 amps for 10 hours.

Re the capacity vs CCA. Obviously the CCA needs to be high enough to start the car even in the cold but my motivation for getting a higher capacity over CCA was to manipulate the battery SoC calculation the car is using to determine the economy mode threshold.

[C5_Jack]

I would point out it is not only Citroen which has problems with relatively dead battery.
Having own an Audi A6, as soon as the battery was a bit tired after 3-4 years, the cat would behave strangely.
In the owners manual they recommended changing the battery every 3 years.

The only two cars and one truck which didn't care about the battery health is my wife's Honda Civic, which is 12 years old and changed the battery once this winter, my old Toyota pickup (it had two batteries) and my Caterham 21.

Jack