Tuesday, 2 February 2016

How to deal with a flat battery

A flat battery has implications way beyond not being able to start your vehicle now a days and it always happens at the most inconvenient of times. Then the panic sets in because you have read somewhere that you cannot jump start it or believe that is the case because it states something in the hand book about going back to the main agent to get it looked at. The answer to that is you can. We have jumped it with no adverse affects having used a quick start charger for twenty seconds.

Battery under floor on passengers side (N.S)

Just recently we have had to jump start it again only I think it is time for a new battery. Which in its self means a bit of mucking about with a second battery if you have one just so you can remove the terminals without loosing the data from the vans memory. Who said progress was a good thing!.

 You can purchase data savers that attach to the battery leads or plug into the cigarette lighter. They are basic power packs which maintain a current to the digital systems in the van. What happens is the ECU looses the information stored in it. Which includes Idling, operating values and fault codes.

What are the most common causes of a flat battery technically known as discharged:

  • Alternator not charging at the correct output or faulty voltage regulator. In this case the alternator fails to meet the needs of the demands asked of battery. Causing a loss of charge over an extended period.
  • Short-circuit causing a continual demand on the battery over and above what is expected. At one time the most common cause of this was a badly fitted radio.
  • Alternator belt, ( Auxiliary drivebelt ) slipping due to stretching or damage ready to break. This is indicated by a squeal when you start the engine. At one time you could adjust the belt but these days it means replacement.
  • Battery connection/s loose and or corroded. This includes any earth straps. If it is a blue colour on the battery terminals it can be removed with boiling water and then a smear of petroleum jelly to stop it returning,( be careful not to short the battery when doing this).
  • Battery defective, This is when one of the cells becomes weak draining the charge from the remaining good cells. This shows it's self when there is a cold snap and is the most common cause of not being able to start you vehicle on a cold and frosty morning.

You should check all the above before making the decision to replace the battery. Sometimes it can be a combination of alternator and battery. It can also be the starter motor but the symptoms are slightly different. Do not confuse one with the other.

Changing the battery

What follows is for the 1.9 diesel engine model:

A simple way round this is if you have access to a spare car battery. You can make up a set of fly leads that you can attach to the battery terminals. If you have one of the older Vivaros you may find as we did that there are two redundant threaded posts on the cable termination attached to the battery. (The posts take a ten millimeter nut.) If that is the case you can use two yellow loop connections at one end of the fly leads and proper battery clamps on the other. If you use this method make sure that the connections are tight. If left loose they will make and break loosing the data. You also need to be careful not to touch the live to the earth or the body work. A way round this is to put the live connection in a thick plastic bag to stop this happening accidentally. 

Tools / Kit:

Spare battery, two 10 mm nuts plus washers. Fly leads to connect between batteries, 13 mm socket for battery clamp, 10 mm ring and C spanner for battery terminals, 12” socket extension, ratchet, T30 Torx for bolts holding floor plate covering battery.


  1. Open passenger door and remove the floor covering. Do not leave the keys in the ignition as the central locking may actuate locking you out.
  2. There will be a black plate with four T30 bolts. You only need to loosen them so the plate can slide sideways toward the off side (drivers side).
  3. With the battery exposed remove the battery clamp, it is held with a 13mm bolt to the front and base of the battery.
  4. Firmly attach fly leads one at a time. Starting with the spare posts on the vans battery. Then to the spare, do not do it the other way round as you may get a shock or make it spark by shorting it out.
  5. Now loosen the battery clamps and remove. Place the positive battery cable in the plastic bag.
  6. Push the cables out of the way and remove the old battery.
  7. Put new battery in place.
  8. Replace the battery cables and tighten.
  9. Remove the fly leads.
  10. Replace battery clamp.
  11. Check that it starts and runs as it should.
  12. Box it up.

Things do not always go this smoothly. If for some reason you didn't save the data. The memory can be reprogrammed. If it has lost this information you may experience surging, hesitation, erratic idle and inferior performance.

The following sequence will re-equip the ECU with the information it needs to run properly:

  • Start the engine and keep it as close to idle speed as possible until it reaches normal operating temperature.
  • Then run it for approximately two minutes at 1200 rpm.
  • Drive the vehicle in varying road conditions for five miles or for as long as it takes for the ECU to relearn.
A couple of notes:

If the alarm and immobilizer are on or off when you disconnected the battery they will return to that state when the battery is re-connected. If you have an OE radio the code will need resetting which you hope you have not lost!

The job is quite easy to do it is all the mucking about that makes it sound more difficult than it is. If you are doing this for the first time there is no rush. The only reason we site the Vauxhall version is because it is the make we work on.


Was it the right decision to change the battery? in this case it was. The main reason for us is the van is not used on a daily bases. A weak battery can go on for months before it shows there is a problem. The first sign is a cold snap. The second is you have to jump start it again the following day in which case change the battery. You can not keep jumping it as it will damage the digital systems and that is one big bill you do not need.  

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