Help with a Rover 45 Auto from year 2000

[LarryH57]

Like some members on here,  I have cars as well as an MV.

(I have edited this question - see last post on 9th Nov)

My year 2000 Rover 45 had a new battery fitted earlier in the year but I forgot to disconect it when the vehicle was laid up

Now it is completely flat. If I recharge it, and use the car, will it charge from use and still retain the charge and work properly?

Edited November 9, 2023 by LarryH57

[teletech]

A lead acid battery is sustaining damage any time it's under about 80% charge, that damage accelerates as the charge nears zero, so you've lost some capacity and remaining service life, but the odds are good that it will recover enough to be serviceable in it's application.

If you have a battery desulfator or desulfating charger that will help bring it back and if you charge it and discharge it a few times that will help it's capacity recover as well.

[ruxy]

You say it is completedly flat  -  but how flat  ,  if it's between  10.5 volt  and 11.5 volt then it will probably not turn the engine especially if it is a older battery but should recover unless it is ancient , these voltages are considered 'flat battery' but if it has been supporting engine management or if there is a wiring / parasitic drain - then the voltage could get much lower , run down to this state - you could get damaged elements & / or sulphation & never get recovery to it's original capacity.  A lot depends , if it's a premium (like 5 year warranty not 3 years)brand /type then it will withstand lack of a trickle charger better.  Voltage is not the only consideration.  I use a analyser/charger/desulphater by RING (Halfrauds sell for about £80).  You can check your voltage % and also your CCA as a % of the stated total battery capacity.  A laid up vehicle with battery disconected - I check every 1 or 2 months & if the capacity is off 100% , then I use a Lidl  'Ultimate' charger for a few days (this is also a limited desulphater).  Years ago - I used a tiny Draper trickle charger or a  Draper BC 1  Intelligent charger - set to a  Venner time switch , actually a pair coupled to give a short weekly boost.  This procedure - I have had long life-spans ,  a Continental Tudor  (Exide)  on a Citroen Picasso lasted over 14 years until I wrecked it with what you have done.

[andym]

There's no definitive answer to this as it depends on a number of factors, not least the make and type of battery.  The only real thing to do is take the advice given above and see what happens.

Andy

[LarryH57]

The answer from myself is,  my battery is junk now and won't hold a charge, and for the sake of the cost of a nice takeaway for me and the family and a few beers (just for me) I bought a replacement. On my Lwt I have a battery cut- out  key which is great, as it slightly helps prevent vehicle theft  - but cuts off the battery every time I am not using it, and is far more convenient than disconnecting the battery on my classic car.

A more pressing problem for my Rover 45, 1.6L automatic is that it has a temporary fault, in the' message' that gets sent to the gearbox on fast roads that tells it to change down, so its unnerving to be doing say 50mph and the auto box changes down to say 3rd gear or even 2nd temporarily, but when I slow down it then corrects itself and works again. It did it once on a trip to London. It is not the gearbox but the method by which it is controlled and a friendly garage not looking to fleece me suggested, the speed sensors on the vehicle, and possible a gearbox oil change.

Rimmer online sells such parts but suggests I find the part number, as does the garage who suggests I speak to Rimmer, so I am going round in circles. I need someone who has a proper service manual for a 1.6l auto - I guess a few inches thick as they used to be and not like the Haynes Manual  for the Rover 45 & MG ZS

The speed sensors for an auto are said to be one on the front wheel and another on the rear but I dont know which side.

Edited November 9, 2023 by LarryH57