Jumpstart from the car

When my bike's battery goes dead after a cold night, I charge it with my spare laptop charger. It is rated for 19V, but when attached to the battery, the voltage goes down to 6, 7, 8 V and so on. I know it is charged if the battery voltage remains to 13V if charger is unplugged.

:blast

Don't ever take a PbAc battery above 15V otherwise you will generate hydrogen and possibly cause an explosion. The Laptop 19V charger sits at a lower potential because it is running in a constant current mode (i.e. about 3A and is current limited). The battery will suck as much current as possible in a discharged mode which will outstrip the demand of the charger - hence the lower voltage. The potential will rise as the battery is slowly charging as the demand decreases. If you take the charger off before it gets beyond 14V you may be ok as the voltage will exponentially increase beyond this point as the nascent current required for trickle charging maybe significantly lower that the current available from the charger.

Get a proper charger or even a power supply that you can regulate the voltage to simulate a charge cycle.
 
jump start it by all means, not a problem however id would't take the jump leads off for a while and before you do turn on everything on on the bike to absorb the surge from the alternator. its been mentioned in a earlyer post it can spike the ecu.

Hman
 
jump start it by all means, not a problem however id would't take the jump leads off for a while and before you do turn on everything on on the bike to absorb the surge from the alternator. its been mentioned in a earlyer post it can spike the ecu.

Hman

Bollocks
 
I hate to butt in but there are a few guys struggling with Ohms law here. A battery / bike will draw the current it needs from the supplying vehicle. You won't / can't feed too many amps in. It is possible' on occasion, to 'spike' an ecu - especially if the non-start vehicle has a dud battery that won't act as any kind of suppressor. This is why many modern jump lead sets have surge limiters built in. For that reason, it's probably best to not start the supplying vehicle when jumping a bike so as to reduce the voltage and supply impedance slightly. If your car battery won't start a bike without its engine running then I suggest you go and buy a car battery first:thumb

On the subject of wrecking a GS charging system, remember that the alternator is basically the same as a polo or golf internally so it's pretty robust in motorcycle terms. If your alternator goes up in smoke, you've connected the leads back to front and blown the diode pack :tears

HTH

Dick

Got this far down the thread before finding someone who echoes my own feeling:

Battery chargers are fitted with current-limiting circuits - to stop a potential difference of 14v suddenly causing a huge current to course into a flat battery ( I hadn't realised that commercial jump leads had similar).

So - I would be very careful not to bang a good battery onto one that was absolutely flat (I don't mean one that is attempting to turn then engine - it obviously has a bit of charge left)

I used to know someone who made up his own heavy-duty jumpleads from Aluminium welding cable............. perhaps not such a good idea now?

Al :)
 
:blast

Don't ever take a PbAc battery above 15V otherwise you will generate hydrogen and possibly cause an explosion. The Laptop 19V charger sits at a lower potential because it is running in a constant current mode (i.e. about 3A and is current limited). The battery will suck as much current as possible in a discharged mode which will outstrip the demand of the charger - hence the lower voltage. The potential will rise as the battery is slowly charging as the demand decreases. If you take the charger off before it gets beyond 14V you may be ok as the voltage will exponentially increase beyond this point as the nascent current required for trickle charging maybe significantly lower that the current available from the charger.

Get a proper charger or even a power supply that you can regulate the voltage to simulate a charge cycle.


I have a gel battery and I constantly check it for getting hot or something; during charging, the voltmeter is connected and I can see the voltage across the battery leads.
 
little help please

this is happening to me right now , my lights are on but its just not enoughe juice in battery to start the bike :( i managed to get my hands on battery charger, its got 12 v output, 1 black and 1 red lead coming out of it , i just dunno where to attach them on the bike , can any1 help me out please .
 
this is happening to me right now , my lights are on but its just not enoughe juice in battery to start the bike :( i managed to get my hands on battery charger, its got 12 v output, 1 black and 1 red lead coming out of it , i just dunno where to attach them on the bike , can any1 help me out please .


Red cable goes to +ve, black cable to -ve.

Connect up cables to battery before switching on at mains.

If Charger has normal/boost switch - leave on "normal".

Al :)
 
thank you so much for quick reply ,i dont have any means to reach the battery itself , i thought i could attach 1 of the lead on the round metal nod on the engine and the other 1 on somewhere else , just not sure where :( or do i have to expose the battery ??
 
thank you so much for quick reply ,i dont have any means to reach the battery itself , i thought i could attach 1 of the lead on the round metal nod on the engine and the other 1 on somewhere else , just not sure where :( or do i have to expose the battery ??
remove the starter cover and if you want to charge the battery, use the connection to the lighter: brown is - and the other one (don't remember the colour) is +; anyway, the brown is (-), that's for sure.

if you want to jump start it from a car, connect the minus cable to the engine's pipes where they come out of the cylinder heads and the plus wire to the starter's thick wire, it's only one in there, can't miss it.
 
get a push start use 2nd or 3rd gear and save yourself from fecking about with something you are not sure of :thumb2
 
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thank you all for your responses, i did try to push but i`m a small guy so that didnt really worked, i removed the starters cover and i think its charging now , well at least thts what i think, we`ll see soon enoughe
 


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