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American Legion Rider
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22,174 Posts
Discussion Starter #1
How many times have we read or heard this about motorcycles that won't crank
or they just click or buzz?

Maybe this title will get the attention of the next person who swears they have a
fully charged battery therefore it cannot be the battery that is their problem.

Think about these numbers when it comes to battery voltage. So when you see
12v on that multimeter, think again about whether or not you have a fully charged
or good battery.

State of Charge..............Battery voltage
......100%..............................12.65+
......75%............................... 12.45
......50%................................12.30
......25%................................12.10
.......0%.................................11.90


Numbers are approximate and depend on multimeter accuracy as well.
Don't know if it would do any good to make this a "Sticky"??? But maybe
the title will work on it's own. Corrections can be made if needed.
 

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Retired twice: Navy and as a govt contractor
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13,310 Posts
But it has 12 volts and it is a 12 volt battery :)
 

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Premium Member
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7,984 Posts
Another error often made is with solar panels. A 50 watt panel will charge at 4 amps. 50 divided by 11. But to charge a volts battery usually needs about 14.5 amps. Now we only get 3.4 amps, and the panel needs to fave the sun, which they rarely do. That reduces the amps by about half, down to 1.7 amps which is close to a 1.5 amp battery tender.
My van cage eats .75 amps doing nothing, so I use a 1.5 amp tender. The tractor which has a slightly smaller battery, has the 50 watt panel and a regulator.

The important number for most of the bike problems is: The battery is half flat at around 12.2 to 12.3 volts. I use 12.25.
One fridge on my boat has an alarm that screams if it senses about 11.75 volts or less. Maybe bikes could use an alarm set at 12.25 volts.

A book called Living on 12 volts, has more info than most of us can digest.

UK
 

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Mod/Motorcyclist/ Trucker/ Deplorable
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1,213 Posts
Amp hours(ah) on the battery and volts is what determines where your at in where you are with the health of a battery. Old battery = less than labeled ah.

Kinda like having a mug of beer versus a shot of beer. Each one may be full to the top but how much juice in it is definable by it capacity.

Other thing...small batteries getting hooked to a cage to jump usually means finishing them off. Battery tenders and trickle chargers FTW.
 

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American Legion Rider
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22,174 Posts
Discussion Starter #5

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American Legion Rider
Joined
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22,174 Posts
Discussion Starter #7
Only if they read it .
I have not forgot how lost I was when I first found this site after being away from any form of computer for 15 years. So I do understand how some folks feel and understand not seeing the things other see as, "are you blind or something?". I don't know how to get folks to read. I sure wish I did but I don't. That's why we see the same questions over and over. And if I made this a Sticky I don't think that would help that much either. Although it might get a few. I did add tags that will get picked up by search engines. I'm hoping that might get a few more. I'm just doing to best I can with my limited knowledge and abilities. If y'all have any other suggests, bring it on. If I can implement them I will. But think way way back when you was a brand smacking noobie. What would get your attention, if anything. I do think we had better control when newbies had, for lack of better words, a probation period. Or where they could only get to one forum. Now any 12 year old kid that skipped school for the day can get in. Although they probably read.:D :D :D
 

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Premium Member
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7,984 Posts
Another piece of wisdom came from Wintr, who said to never charge a battery at more than 10% of its capacity.
Which shows I do read stuff now and then.

UK
 

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Premium Member
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5,518 Posts
Another piece of wisdom came from Wintr, who said to never charge a battery at more than 10% of its capacity.
Which shows I do read stuff now and then.

UK
Thanks for that; my advice is meant to be quick and simple to remember. A battery has a maximum charge rate, and for most lead-acid types, that is 1C, or the amount of current to charge it from empty to full in 1 hour - IOW, just remove the h from the Ah rating. This would be the quick charge rate, and you should watch it closely, so it doesn't boil; also, since the battery should never be truly empty, it won't be an hour before it approaches full. So for a quick charge, use the % charge values above, to estimate how long a quick charge will take to get to about 80% full, then drop to the safe rate until full (or the 'smart' in the charger does it for you). With flooded batteries, at the first sign of bubbles, you should reduce the charge rate; hard to determine with a sealed battery, so use the estimate. Also, the true value varies with construction, so if you really need a quick charge, try finding the value from the manufacture who makes the battery, but still keep an eye on it. The safest rate is about 1/10C for most batteries, but you should still check it frequently, if your charger doesn't have a 'smart' function, as even at this rate, the battery will reach its boiling point.

Also, just to be clear, the Voltage values listed are for a rested battery, that is, a short time after charge or discharge, so if you want to know the state of charge while charging, you have to disconnect the charger and wait several minutes for the surface charge to bleed off, then measure the Voltage.
 
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