How much voltage is needed to start a bike?

# Thread: How much voltage is needed to start a bike?

1. ## How much voltage is needed to start a bike?

What voltage does a battery need to have before it can reliably start a bike?

My poor SV is stranded while I juice up its battery...

2.

3. 12 is good

4. ## Beat me to it..

Originally Posted by Jayson
12 is good

Considering a motorcycle runs a 12 volt system ...12 is a good number...may be low as 10 if its not too cold...its more to do with amps then volts....

5. The way a battery works to generate the amps you need to start it means that if your rest voltage is much, if any, less than the high 11's then it probably won't start. It may crank over in a laboured hard fighting kind of way but at that point the battery voltage has been sucked down so far that it may not have enough for the onboard computer to supply to the spark coils for a decent pop.

If the battery is just sitting then it should be at least the high 11's. If it's on a charger then it's probably 80% when the voltage hits 13.5 or 13.6. But pull the charger and let it sit for 10 minutes and then check it again.

If it's low then your best bet is bump starting the bike instead of using the starter.

And if it's stranded then you have to ask yourself how it got that way. Either your battery is gone or the charging system is toast.

6. Resting voltage for a battery in good condition should be about 12.8, and it takes a while (1/2 hr.) to drop down to that after charging it. On charge it should reach 13.8 or so. Unfortunately, voltage is not a very good test of battery condition. It doesn't really tell the battery's ability to deliver enough starting current, but it is an indicator.

7. "idle" Voltage is a very poor indicator of battery strength. I'd say about 13 should be good. But real indicator is voltage under load.

8. well it got up to 12.3v when i pulled it off the charger and it started fine. I'm also charging/conditioning the battery now so tomorrow it'll be full.

Yes the real question is why did the battery die, i'm going to try to figure out how to test the charging system, and also see if there's a parasitic load when the bike is off.

Any advice would be welcome, i have a full multimeter but electrics isn't something I'm good at.

9. Moved to Tech where it should have been....

First of all, how old IS the battery? If it's only a couple of seasons old then how did you treat it over the winter(s)?

It's rare for a motorcycle battery to last more than 3 seasons. 4 is probably a miracle. If it's going dead from just sitting around or is labouring to crank the starter then it's probably past it's prime and needs to be replaced.

10. Originally Posted by TeeTee
It's rare for a motorcycle battery to last more than 3 seasons. 4 is probably a miracle. .

interesting, my 99 F4 still has the stock battery......

11. What Teetee said - if you have a battery that's lasted more than 3 years you're one of the lucky ones, go and buy a lottery ticket

If you have a multimeter, set it to DC volts in the 20 volt range. Start the bike and hold the meter probes on both poles of the battery, black to black (neg -ve) and red to red (pos +ve).

Rev the engine and the volts should climb - above 3000 rpm you should get around 13.5 volts and a bit more at 4 - 5000 revs. If this is what you get then the charging system looks fine. If the battery is still going flat overnight then it's time for a new one.

12. Originally Posted by lowlife
interesting, my 99 F4 still has the stock battery......
They you're certainly one of the attentive owners that takes care of their battery over the winters. Good on ya ! But at that age I'd be expecting trouble really soon.

13. An attentive owner, of just a pigheaded SOB that rides to work all year rain or shine.
My '00 VFR with all its nerdy electrical mods is still on the original battery.

To keep this on-topic my answer to the question is 0,0 volts.
You don't need any voltage to start a bike. All you need is either a small hill or big friend.

-Sandworm

14. The question that really should have been asked here is... why didn't you just jump start it? - instead of being "stranded" albeit I'm sure in a garage somewhere.

Turn the bike on, stick it in first, pull clutch in and run beside the bike or roll it downhill. Hop on and slam your butt on the seat as you pop the clutch.....

Sure it's harder on your battery to charge it this way but at least you get the bike going.

15. Originally Posted by TeeTee
First of all, how old IS the battery? If it's only a couple of seasons old then how did you treat it over the winter(s)?

It's rare for a motorcycle battery to last more than 3 seasons. 4 is probably a miracle. If it's going dead from just sitting around or is labouring to crank the starter then it's probably past it's prime and needs to be replaced.
It's 2.5 years old and I usually ride through the winter, except last year when i let it die.

I don't buy this "it should only last 4 years" business, my friend has 2 OEM batteries going on their 6 or 7th seasons and they run fine. Of course he treats his better than I do mine.

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