dead battery again

elevensies

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British Zeds
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Aug 24, 2024
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84
Location
North Lincolnshire
Model of Z
roadster 2.8 widebody
this time last year i replaced the battery, not this one has decided its had enough, 6.2v and my charger wont give it any more charge, so... im going to get another battery i used in my van as a leisure battery, hook that up to the bmw, then put my trickle charger on it. hopefully the battery will show above 8v for the trickle charger to do its work.
ctek charger, doesnt have recovery mode.

failing this, when i can drive again (2 months ish i guess) i will take battery back to shop and replace under warranty

dam thing
 

Pingu

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Dec 8, 2011
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I inherited one of these...


It is expensive (the cost of two batteries), but I've never had a battery that it won't charge, except a leisure battery off my son's boat.

I came back from holiday and the Range Rover battery was at 0.45v (yes, less than a volt), and it charged. It took an hour to accept charge (after some persuasion), but the current eventually rose to 10A after about 8 hours, then charged normally. The battery's little green light is on - which surprised me.

A 12v that is reading 6v wouldn't be a problem.
 

Pond

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British Zeds
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Dec 26, 2016
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Spaldingski, Lincs
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Z3 project
My Ctek only refuses to charge under around 3v, as that seems to be cut-off where it can't 'sense' it is attached to anything.

Charging a knackered battery is pointless anyway IMO. If one cell has gone it will never be any good again even if it will take the charge.
I was pleasantly surprised how cheap Z3 batteries are TBH. When my bodyshop killed my battery over the summer (by moving the car 6ft at a time every day for weeks without thinking about the battery) I needed a new one. Only £70 for a Yuasa. Bargain IMO.

My Ctek cost more!
 

ExMX5owner

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My Ctek only refuses to charge under around 3v, as that seems to be cut-off where it can't 'sense' it is attached to anything.
This I can attest too, If the battery is dead flat, your charger probably cant see it.. If you get a few volts into it with a trickle charger, the proper charger will kick off. Don't ask me how I know...:(. My work around is as follows, Plug in the real charger and connect it supposed dead battery, Nothing happens. then flash the terminals with a trickle charger to kick the proper one off... It worked for me.. On a side note anyone interested in cheap hardly used chargers PM me...=)).

Gone are the days when you could do light welding with a battery charger...:whistle:
 

elevensies

Zorg Legend
Supporter
British Zeds
Joined
Aug 24, 2024
Points
84
Location
North Lincolnshire
Model of Z
roadster 2.8 widebody
This I can attest too, If the battery is dead flat, your charger probably cant see it.. If you get a few volts into it with a trickle charger, the proper charger will kick off. Don't ask me how I know...:(. My work around is as follows, Plug in the real charger and connect it supposed dead battery, Nothing happens. then flash the terminals with a trickle charger to kick the proper one off... It worked for me.. On a side note anyone interested in cheap hardly used chargers PM me...=)).

Gone are the days when you could do light welding with a battery charger...:whistle:
sadly i no longer own a ''real'' charger, i wish i still had my old one as that would have done the trick.
my battery has a 5 year warranty so when im able to drive i will be taking it back for a exchange.
 

Pingu

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Points
145
sadly i no longer own a ''real'' charger, i wish i still had my old one as that would have done the trick.
my battery has a 5 year warranty so when im able to drive i will be taking it back for a exchange.
Some battery shops have a clever piece of kit that can tell if the battery has been allowed to discharge too low. This is considered by them to be out of warranty, and they won't replace.

Don't tell them that you let it go flat, and you may get away with it.

Good luck.
 
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