G'day.

Gots a problem with the KLX....

Battery sits on 11.5 volts (after sitting for 2 months) and 13.5 after a charge and still doesn't even turn over. I know if I jump started it from the car, it would fire up, but what's the voltage supposed to be?

Ideally, I'm after the 'resting' voltage, as well as running voltage (around 2k rpm).

Reason I ask is, I gots a good MotoBat battery (which I hear are the bees knees), and I'm surprised it's potentially toast already.....if so, I'll have to check the charging system, but I'm hoping it's just the battery.

1999 model, if that helps. Thanks, Rob.

 

Even though it reads 13.5V and so is fully charged, it may have developed internal resistance from sitting discharged for some time (so called sulfatation phenomena). So when trying to crank the engine, its voltage would drop below what is necessary to turn it over at a sufficent spped.

Only way to tell would be to try with a known good battery.

Another possibility is for a marginal ground on the engine case (or another connection problem). These can be visually assessed in most cases.

 

A quick check to determine if it is the battery or connections is to measure the voltage across the battery when cranking the engine over. If it drops below 10 volts, you have a battery problem.

Ride on
Brewster

 

Well technically each cell is 2.1 volts which combine for a total voltage of 12.6 volts... but it could be a little higher or lower depending on a lot of things. 13.5 sounds somewhat high.

However

Though you can measure the voltage of the battery to get an idea of whats going on... its almost a useless measurement. In fact the only real purpose for voltage measurement is for individual cell voltage measurement for the purpose of finding a weak / dead cell.

You need to do a Load Test by using a battery load tester, basically this device test the voltage while passing a set amount of current from the battery. Without this test its hard to know if your battery is good, weak, or whatever.

Batteries can measure a strong voltage, and still be completely junk once you attempt to draw current from them.

The most important thing about lead batteries is they sulfate when their charge falls below 80%. Any of the best batteries that are left to sit for lets say, 1 month at discharge, will basically be wrecked and junk. Sometimes you can desulfate them but not always. I've destroyed brand new batteries by being neglectful and doing this very thing.

Also your battery is AGM so if it gets overcharged its possible to wreck it almost instantly.

Edit: People often mention various ways to do this or that with a battery in order to test it...
Not many people mention that Autozone and many other auto places test your batteries and alternators for free, so that's one way of not having to mess with any thing other than bringing them your battery.

 

A good, fully charged battery can sit for 6-12 months before it needs a charge. Colder temps allow the longest shelf life as it slows the chemical reaction in a battery. A fully charged battery won't freeze until you get below -77°F (-67°C). If you put the bike away and the battery was at 11.5V and sat for 2 months, you may have lost it to sulfation. The 13.5V you see now is just a surface charge. Put some load on it (hit the starter). The voltage will drop, but shouldn't dip below 10V. It should then bounce back. Give it a few hours and taking a reading.

100% Charged: 12.7V
75% Charged: 12.5V
65% Charged: 12.4V
50% Charged: 12.3V
25% Charged: 12.0V
0% Charged: 11.7V

If you just gave it a quick blip on the starter, it should bounce back up to 12.7V. There are ways to "try" to recover a sulfated battery, but the time and energy isn't worth having a battery that can't be trusted.

For you, watch the battery voltage while hitting the starter. My bet is that the DC voltage collapses while under load.

 

Also, make sure your getting your reading after letting the battery rest for a couple of hours.

 

I have a desulfator, but I have never used it to save a completely destroyed battery. From what I was told if you have a battery that sat discharged for roughly a month, it can take almost 2 months of time on the desulfator to restore it; plus I would have to discharge it as the sulfator topped it off every day or so - not worth my effort.

I just throw my batteries on the sulfator from time to time when I notice the rest charge after normal operation starts to dip below my satisfaction, this way I can get them back up to the nominal 12.6v ... since all batteries sulfate over time.

 

I wouldn't bother with the desulfator if it sat for just 2 months unless the battery was already in question. Like I said, you can let them sit for 6-12 months (disconnected) without any ill effects. The pulsing of a desulfator can negatively impact the life of a good battery that just needs a charge. Use it only when you really need to. Sulfation comes with abuse and time. The most you are gonna get out of a VRLA is 5 years in a perfect environment kept under a perfect charge regimen.

I just tested out 4 batteries I had on charge last night. #1 & #2 came out of a battery back up in an office environment. #3 came out of backup kept in a perfect environment in a datacenter, #4 came out of my kids razor scooter. Which one's are still good?



Video link: VID-20130203-000052_zpsbbab824d.mp4 Video by lotrat | Photobucket

 

Those office UPS's always take a poop because everybody neglects them... and when they actually are needed they have been bad for months it seems. :-)

I'm not saying everyone should desulfate their batteries Lotrat... but I will continue to do so since I know what I'm doing. I'm not using the desulfater to bring them up to charge; just to literally desulfate them. Batteries tend to lose their rest voltage over the years from the light sulfate that hardens, its gradual but eventually when I start taking rest voltages on my vehicle batteries they will be down to about 12.4 volts... at that point I just desulfate them for a bit to get the rest voltage back up.

Ive had lead acid batteries last 10 years easy.

 

Lotrat, was that a brake/turn filament (rather than park) you were using as the load?
The 12.25 failing showed just how important the load test is. Who d'a thunk it?