How to recharge a flat battery?

**shanks** · 20th January 2012, 19:45

Hey guys,

How can I recharge the batteries of my Hornet 250? I had a crash two months ago n whilst Im currently fixing the bike, the battery has gone flat.

Can I use the normal jumper leads of my car to the bike battery? I somehow doubt that since they are both different volts/amps I suppose?
Any advice?

Cheers

**Edbear** · 20th January 2012, 19:55

Put it on a trickle charger, pref under 5amps after checking fluid level if that is poss. Once charged, test with a multi-tester that it is showing 12-13v.

You may not be able to recover it after this time flat but hopefully will.

The bike and car should both be 12v so worth a try jump starting at first.

**Hopeful Bastard** · 20th January 2012, 19:56

I use my old mans Commercial Battery Charger hooked up through a Lightbulb which is then connected to my Battery. Works all the time for me.

Not recommended if you dont know what you doing.

**Virago** · 20th January 2012, 20:11

You can't charge a battery by simply hooking it up across another battery - the balanced float voltage will be below that needed to effect a charge. Unless of course you keep the engine running in the car...

You need to charge the battery properly. Unless something was drawing power on the bike, it's unlikely that it's been dragged down to 0V, so it should recover.

Don't be tempted to jump-start it and let the bike charge the battery, the regulator/rectifier isn't designed for that, and you have a good chance of frying it.

**Macontour** · 20th January 2012, 20:11

I am sure the bike will be 12 volts so a jump start off a car battery is no dramas as long as you connect negative(earth) connections first so as not to get a spark. Even better if the jumper leads are surge protected to protect the electrical systems of both vehicles from spikes.

Better though is a small or bike dedicated battery charger(trickle charger) that will charge at about half to one and a half amps.

Ensure taht the caps are off the battery if possible and do it ina well ventilated place as the Hydrogen gas produced is explosive.

Don't let the cells dry out.

**Macontour** · 20th January 2012, 20:12

I am sure the bike will be 12 volts so a jump start off a car battery is no dramas as long as you connect negative(earth) connections first so as not to get a spark. Even better if the jumper leads are surge protected to protect the electrical systems of both vehicles from spikes.

Better though is a small or bike dedicated battery charger(trickle charger) that will charge at about half to one and a half amps.

Ensure that the caps are off the battery if possible and do it ina well ventilated place as the Hydrogen gas produced is explosive.

Don't let the cells dry out.

Oops Sorry!!

**Tigadee** · 25th January 2012, 18:16

Originally Posted by Macontour

Better though is a small or bike dedicated battery charger(trickle charger) that will charge at about half to one and a half amps.

What about 2.5 amps? I have a charger already but not sure if it does MC batteries too...

**jellywrestler** · 25th January 2012, 18:41

Originally Posted by Macontour

I am sure the bike will be 12 volts so a jump start off a car battery is no dramas as long as you connect negative(earth) connections first so as not to get a spark.

whoa, bad bad advice you always connect the earth LAST when jump starting and disconnect the earth FIRST. The reason for this is if while connecting to the live terminal if you slip and hit earth it's not connected to another battery and won't short out, then when that's done you connect the earth one.

**bikaholic** · 25th January 2012, 18:48

There is an assumption here that both car and bike have a grounded negative.

**SMOKEU** · 25th January 2012, 19:09

Buy yourself a small battery charger. I bought one about 4 years ago for around $15. Mine even does 6V batteries as well as 12V. It's a 1A model.

**jellywrestler** · 25th January 2012, 20:28

Originally Posted by bikaholic

There is an assumption here that both car and bike have a grounded negative.

not in my comment i never mentioned which pole was earthed...
Been a sparky for 33 years and used to work on 4400ampere hour batteries so know how they work well.
there's often a spark when hooking up jumper leads which people don't expect it's normal and no harm if they jump a little and touch an earth when they're going for an earth but if they jump a little when going for the other and slip onto an earth when the other ends already connected you've got yourself a welder right there and then...

**bikaholic** · 25th January 2012, 20:55

Originally Posted by jellywrestler

not in my comment i never mentioned which pole was earthed...
Been a sparky for 33 years and used to work on 4400ampere hour batteries so know how they work well.
there's often a spark when hooking up jumper leads which people don't expect it's normal and no harm if they jump a little and touch an earth when they're going for an earth but if they jump a little when going for the other and slip onto an earth when the other ends already connected you've got yourself a welder right there and then...

whoa bad advice, none of the above posts have considered that a cars polarity may not be that of the bikes. There are some oddball cars out there, and 6 volt ones too. I hire sparkies and if they don't do as they are told they are gone.

**jellywrestler** · 25th January 2012, 21:16

Originally Posted by bikaholic

whoa bad advice, none of the above posts have considered that a cars polarity may not be that of the bikes. There are some oddball cars out there, and 6 volt ones too. I hire sparkies and if they don't do as they are told they are gone.

listen carefully i didn't mention polarity at all, i mentioned earth and not earthed
, if someone doesn't know red to red and black to black at each end like the cables are colour coded then they shouldn't even be around a job like that.+

**bikaholic** · 25th January 2012, 21:33

Originally Posted by jellywrestler

listen carefully i didn't mention polarity at all, i mentioned earth and not earthed
, if someone doesn't know red to red and black to black at each end like the cables are colour coded then they shouldn't even be around a job like that.+

Where have i indicated you mentioned polarity. And when a battery is positively earthed, the red lead goes to the frame, so it is not all about colour.

**Reckless** · 25th January 2012, 23:01

Originally Posted by shanks

Hey guys,

How can I recharge the batteries of my Hornet 250? I had a crash two months ago n whilst Im currently fixing the bike, the battery has gone flat.

Well my first thought is WTF a kiwi bloke that dont even know how to charge a battery jeepers??
Secondly your fixing a crashed bike that could hurt you with that sorta knowledge base??
Please get someone of experience to help you

And you two bloody hell LOL!!

Originally Posted by jellywrestler

whoa, bad bad advice you always connect the earth LAST when jump starting and disconnect the earth FIRST. The reason for this is if while connecting to the live terminal if you slip and hit earth it's not connected to another battery and won't short out, then when that's done you connect the earth one.

Originally Posted by bikaholic

There is an assumption here that both car and bike have a grounded negative.

Given the extent of the knowledge above and the nature of posts you two have provided??
Should have well confused the living fuck outa the kid that's for sure.

Made my night you 2 have LMAO.

ok seeing as how I've stirred up a hornets nest I better put up or shut up

here goes put simply I hope.

1 borrow/buy a 12v car or bike battery trickle charger
2 disconnect the battery. Earth lead first (negative or minus side) , then the positive (positive is the one with the plus next to it, should be coded red)
3 you might want to check water levels if required?? if its a sealed battery it will be ok
4 Correctly hook the battery up to the charger, plus to plus/red to red and minus to minus or black to black etc, then plug in and turn the charger on at the mains. Charge it overnight.
5 ensure you turn the mains supply to the charger off before disconnecting it from the battery once its charged. This is the most dangerous time for explosions from sparks when disconnecting the charger leads with gases around it from a freshly charged hot battery, so turn it off at the wall before you touch the connection leads.
6 Reinstall the battery hooking up the positive first then ground or earth/negative lead (usually black or Minus) last.

Jeepers that brings me back to the block coarse days

And seeing as how I've had a little giggle about you guys above I expect quite a few comments back, specially if I've missed anything LMAO!!!