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Robert, UK Qualified Car Technician
Category: Car
Satisfied Customers: 4708
Experience:  Fully qualified / self employed garage technician in the UK
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I own a Vauxhall corsa cdti. I want to charge the battery

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I own a Vauxhall corsa cdti.
I want to charge the battery and hace a ctek smart charger.
They advise leaving the battery in the car & charge as necessary as the charger will not affect the cars ecu,
chargers send out a pulse charge to disulphate the battery which is of high voltage so can this cause ecu problems?
If I remove or or disconnect the negative terminal the ecu will lose its learned values so driving will be different,fuel consumption higher etc will the ecu correct itself over prolonged driving?


To my knowledge i havent heard of smart chargers damaging ECU's.. if that was the case then it would be widely known by now and by brand of smart charger to avoid..normally smart chargers are used to keep the battery topped up when the car is going to be left unused for a length of time..and all the smart charger does is sense what voltage is in the battery and if if falls slightly the charger charges the battery until it reached the 12-13v and should shut down.... If you remove the negative terminal, which you dont have to really - then yes by doing so you will loose radio / clock,date etcs go back to default...but it shouldnt cause increase in consumption as per fuel.but the ecu will default to factory settings,bit like a system hard reset until the car is used over period of time,relearn..but it it isnt noticable or effect any stored faults or present fault codes "if car/spanner" light is on will be erased... i do hope this helps

Customer: replied 2 years ago.

Thanks for the informative answer,

approximately how much driving time is needed for the ecu to relearn?

Am pleased to hear that performance & fuel consumption is unaffected.

Should not have worried about the ecu resetting as few years ago the battery was changed at a kwikfit so the ecu would have reset I guess.

Thank you.


It normallly shouldnt take long..max 10miles id say maybe less..but normally if the battery is unhooked it shouldnt really effect settings on the ecu to be honest it will sort of reset it back to factory settings - like i say pretty much a hard reset...which is strange considering working on these cars or other vauxhalls for that matter a fair few times over the years..never had to reset the ecu diagnostically if thats what kwikfit done after a battery change on them or around that year......but apart from that using smart charger a good quaility one then you can hook it straight up without having to unhook the battery...

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