Battery Charger works but wont charge flat battery?

Battery Charger works but wont charge flat battery?

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Tampon

Original Poster:

4,637 posts

225 months

Friday 27th April 2012
quotequote all
I have a halfords battery charger, used it to keep a leisure battery topped up for a few years. I left the battery for a year or so and then the charger would not charge it. The test lights come up and say it is working just the two lights that say charging/ maintaining don;t light up.

I presumed I killed the battery by leaving it so long it won;t charge ( it was sealed )

I have now just taken the battery out of my bike, been standing for a few months and is dead so I decided to charge up ( had enough power in it to light the light but not turn the engine over a month ago ). Noticed the water was low so have tp it up with Distilled water and wacked it on the charger.

Now same thing is happening, charger switches on and make the noises but no lights on the charging/maintaining section. I have it on the right settings ( bike battery, not sealed )

I have just read here http://www.powerstream.com/how-to-use-a-battery-ch... that

"Also, if the battery is so low in voltage that the charger can't detect it, the charger won't turn on. In this case you need to bootstrap the battery by jumping it to another battery"

Does that mean if the battery is dead the charge won;t recognise it and won;t charge it ? seems silly to me.

If so what is the best option to do now ? jump start it off the car via jump leads and then leave the bike to run?

Tampon

Original Poster:

4,637 posts

225 months

Friday 27th April 2012
quotequote all
Borrowed time is fine, it is a £600 hack.

Do you have any idea about the charging, not charging thing ? Or how to get it to work ?


Tampon

Original Poster:

4,637 posts

225 months

Friday 27th April 2012
quotequote all
playalistic said:
Yep. Leave the bike running after jumping it or preferably go for a half hour run and then take it off to charge. Although I wouldn't hold much hope of this battery holding a charge for long now it has been nerfed.
Cheers, going for a run isn't really possible as it is sorn no MoT, that why I am trying to fix it for the spring summer. So it will sit there for 1 hr just tick over

Tampon

Original Poster:

4,637 posts

225 months

Friday 27th April 2012
quotequote all
Brillant, thankyou for that. If it doesn;t work I will try jump starting it and leave it running.

Tampon

Original Poster:

4,637 posts

225 months

Friday 27th April 2012
quotequote all
Right I went to get the jump leads. Not happening. Not there. Bugger.

idea

Got Heath Robinson about it and striped some cabling and made my own "jumpleads". Now hooked it up to the battery in the van for half and hour to see if it can put some voltage in the battery in that time then I will try it on the charger again.

If not the next move is to leave it hooked to the van battery and then hook up the charger in situ then try disconnecting the van battery to see if that works, but it is raining and I am running around in the rain with copper cabling hooked up to batterys with the wife on the phone on her lunch break asking me "are you sure?".

Yeahhhhhhhhhhhh it will be fine.hehe

So do you think half and hour will be long enough to put some charge in the little bike battery just hooked up the big one ( engine not running obviously)?

Tampon

Original Poster:

4,637 posts

225 months

Friday 27th April 2012
quotequote all
Right it worked a treat. Seem a small charge is what is needed in the battery for the charger to charge it. Seem to make a "battery charger" a redundant piece of kit if you need it most when the battery is flat !


Tampon

Original Poster:

4,637 posts

225 months

Friday 27th April 2012
quotequote all
£300 !!!!!

I will stick to my secondhand £10 jobbie and a bit of lateral thinking. That like 20 lapdances, 30 if you go at lunchtime wink

This one seem to "maintain", flicks between maintain and charging during the day, and if you switch it to bike setting it trickle charges a car battery as well.

Tampon

Original Poster:

4,637 posts

225 months

Friday 18th April 2014
quotequote all
TooMany2cvs said:
Problem is that a smart charger needs to "know" it's got the right type of battery attached before it'll start to charge, and it'll adjust the charging voltage/current to best charge the battery. If the battery's so flat that the charger doesn't "see" it, it won't charge it.

So you need a dumb charger that just blindly shoves out +14v whatever. Then make sure you don't leave it on for an extended period, because it WILL bugger the battery up...
It is 2 year s after the event but that is all you are doing when you fool the charger there is voltage in the battery. Turns the smart charger into something that kicks out a charge, leave it for a hour then disconnect, reconnect and bobs your uncle it reads the previous flat battery and charges it properly.