Minimum battery voltage for starting?

[oregonjake]

The other day, Miss Bugly had a hard time starting. She finally did, but not like in the past. The next day when I went to my local parts store for more SeaFoam, she refused to start and had to be bump-started. When got home, I put the charger on her and found she was taking almost 9 amps in charge. My question is, what is minimum voltage below which the bike will crank but not fire?

Yes I am going to do another charge test tomorrow but I would like to know minimum voltage requirements if possible. Thanks.

PS; dry battery (Optima) or new generation AGM or similar?

[posplayr]

10.76439571V is the absolute minimum. Feel better knowing?

[roeme]

Dunno, I'd say when the bike cranks, it'll fire as well.

I could be mistaken though, as I'm kick-starting mine all the time anyway.

[tkent02]

I can start mine with a 9v transistor radio battery. But it has a kickstarter and points ignition. You probably don't have that on your 1100. So you probably need the 10.76439571v as Posplayr mentioned.

[Brendan W]

The way I look at it the voltage is not as important as you might think. It's an indicator of battery state.
Energy is what cranks the bike and if the battery has a high internal resistance as soon as the starter draws current the voltage will fall off the scale.
A bad analogy perhaps but what pressure do you need to water the lawn ? Any pressure will do if the flowrate is high enough but no pressure on earth will water it through a pinhole.
You will see various rules of thumb about voltage not falling below 'x' during cranking etc. Some bikes are in better health than others and will start more easily.
9 A is a lot. Too much imho for a 14Ah battery and will warp plates if they aren't already

[phydeauxmutt]

Some accurate answers here, and some just a bit misleading, but most were pretty close.

Posplayr is probably right, but none of my meters is quite that accurate. I have always looked for "more than 10 volts" as my cut-off point. Since your bike does not have a kick starter, the condition of your battery is VERY important. The load imposed by the starter is usually rather constant. The condition of the battery, however, degrades with time, and cannot supply enough current to spin the starter adequately. As the starter draws from the battery, the voltage drops. When the battery is not strong enough to maintain at least 10 volts, there is not enough power left to run the ignition system.

Brendan W also brought up another point: a 9-amp charge is WAY too much for your battery. That alone might be killing it. The standard charge rate for any lead-acid battery is 1/10 of its capacity. You have a 14 amp-hour battery, the max charge should be 1.4 amps, but a 1.5 amp charger is not going to kill it. Even a 2 amp charger won't do much damage, but I would not go much more than that.

Replacement? A dry battery might be OK, but don't go for exotic stuff like lithium. Smaller, lighter, yeah, but they require a different charge profile than what our bikes can provide. AGM (absorbed glass mat) is the current (pardon the pun) favorite. Note that it is a construction style, not a brand name. AGM batteries can be found for less than $50 on the internet or about $80 in your local stores. They will usually come "fully-charged, ready to use", but I would still put it on a trickle charge overnight to make sure it is topped off.

[oregonjake]

Thanks posplayr, I thought it was 10.76439572 volts.

[mmattockx]

The other day, Miss Bugly had a hard time starting. She finally did, but not like in the past. The next day when I went to my local parts store for more SeaFoam, she refused to start and had to be bump-started. When got home, I put the charger on her and found she was taking almost 9 amps in charge. My question is, what is minimum voltage below which the bike will crank but not fire?

Yes I am going to do another charge test tomorrow but I would like to know minimum voltage requirements if possible. Thanks.

PS; dry battery (Optima) or new generation AGM or similar?

A fully charged battery will show 12.8V or so with no load and this makes no difference at all. The important thing is what voltage and current it can supply under a heavy load such as running the starter. There is pretty much no way to check static voltage and know how the battery will respond under load.

On another note, hitting that battery with 9A charge current is asking for trouble. Watch your fluid levels and temperature of the battery with that kind of input current.

10.76439571V is the absolute minimum. Feel better knowing?

Always the man with the precision answer!


Mark

[oregonjake]

Thanks for all the input (pun intended) and the recommendations on battery type. As soon as the showers clear I am going to do a complete charging test (again) just to verify charging output/rate is within factory specs. Battery load test is also warranted today. With that said, the fact that the headlight stays on during cranking, will that extra load put extra stress on the battery at starting, and if so, is there a (recommended) method to put a switch inline with the headlight to be able to turn it off when I start her, and would that help lessen the load on the battery and extend its useful life?

The advice on 9 amp charging rate is appreciated, I did not know that. It seems the battery suffered no ill effects and after charging she started immediately. Battery did not heat up during charging and voltage test after charging showed a standing rate of 12.7 volts. I have not checked standing voltage yet today but will post results later.

[posplayr]

In the battery world charging rate is scaled by battery capacity. A very safe charge rate that is almost independent of technology is C/10. For a 14 amp-hr battery that is 1.4 amps. (i.e. 14 amp-hr/10=1.4 amps)For lead acid battery that corresponds to low 13's charging voltage. By the time you get over 14V you are charging at 3-4 amps and C/5 and beyond.

[posplayr]

A fully charged battery will show 12.8V or so with no load and this makes no difference at all. The important thing is what voltage and current it can supply under a heavy load such as running the starter. There is pretty much no way to check static voltage and know how the battery will respond under load.

Absolutely, indicated internal resistance is a direct measure of state of charge and the indicated internal resistance refers to how much the terminal voltage drops when you put on a known load.

My main issue with using the starter as a load (to measure battery SOC/internal resistance) is that the starter can draw high current for a variety reasons due to bad brushes or armature shorts that would pull the battery down lower that you would expect making you suspect the battery when teh starter is the issue.

The Quick Tests is designed around a typical electrical load based on lights which will not exceed the typical 10 amps you will have with the headlamp and tail lights on. Also 10 amps is over 2/3C load and is plenty to test the battery SOC in a typical operational range. If you turn on the ignition and with lights on and teh battery stays above 12V (down from about 12.8) you have a good battery and a good SOC.

On the other hand using a bad stater to do a battery load test you could have all types of consternation about bad batteries even if you just bought a new one. You cant go wrong using the electrical load from lights, you can definitely draw the wrong conclusion from using a starter for a load test.

[oregonjake]

So, did I do some damage that I cannot see/measure? My consternation level is rising, I may have to sit quietly for a while in the dark...

[posplayr]

Thanks for all the input (pun intended) and the recommendations on battery type. As soon as the showers clear I am going to do a complete charging test (again) just to verify charging output/rate is within factory specs. Battery load test is also warranted today. With that said, the fact that the headlight stays on during cranking, will that extra load put extra stress on the battery at starting, and if so, is there a (recommended) method to put a switch inline with the headlight to be able to turn it off when I start her, and would that help lessen the load on the battery and extend its useful life?

The advice on 9 amp charging rate is appreciated, I did not know that. It seems the battery suffered no ill effects and after charging she started immediately. Battery did not heat up during charging and voltage test after charging showed a standing rate of 12.7 volts. I have not checked standing voltage yet today but will post results later.

If you just did a Quick Test most of these things that you are learning would fall by the way side as the test is designed to eliminate the vast majority of the ambiguities.

[posplayr]

So, did I do some damage that I cannot see/measure? My consternation level is rising, I may have to sit quietly for a while in the dark...

Normally overcharging is associated with splattering electrolyte and overheating of the battery. If it has not been mentioned enough times yet a battery load tests is what tell you if teh battery is damaged.

If you beat the hell out of it with a 9Amp charge rate and it will not stay about 11V with a standard load it is history.

Read the link on battery SOC in the quick test link. It might me "illuminating".

[Gorminrider]

When I look at the Suzuki manuals, it seems they avoid much discussion of battery voltage...

Battery did not heat up during charging and voltage test after charging showed a standing rate of 12.7 volts. I have not checked standing voltage yet today but will post results later.

it's pointless to check the voltage of a "resting battery" until it's rested.... overnight is best. ..because the "surface charge" of a "just-off-charging" is ephemeral. I'd be very suprised to see your battery with 12.7 volts after a rest if it won't start your bike. But I wouldn't strain to see it if it doesn't....

Nowhere are used batteries discussed as viable, yet few people have brand new ones.... it seems to me pretty obvious that old batteries have less capacity. They don't take full charge anymore and so, it follows, "battery resting voltage" drops too. But a motorcycle can go along quite well for a long time with a battery that is not brand new; that does not exibit 12.65 volts at rest...