I have a mikita 12 volt and when I charge it it wont hold charge.

check your charger with a multimeter and make sure that its putting out at least 13.8 volts

A typical, fully charged & unloaded 12 volt lead acid battery should indicate about 12.6 V. Check the voltage / percent charge chart below:

Volts - Charge
11.7 - 10%
11.9 - 20%
12.1 - 30%
12.25 - 40%
12.35 - 50%
12.45 - 60%
12.5 - 70%
12.6 - 100

A fully charged that is only about 12V indicates a a problem with the battery - dead / shorted cells, etc. You can always remove the battery and have it tested at Autozone or similar auto parts stores if you're unsure. From the info you've provided - my guess is that the battery is "done"

I hope this was helpful - good luck!

engine running what is the battery voltage.if around 11 volts and 12 volts it is not charging. around 13.5 volts it is charging.alternator give to pcm the volt charge then the pcm send a ground to cluster to turn off charging light

I'm not sure if you have all of the info you need to go forward with this.
The battery may be rated for 800 amps but could have less than 12 volts if the alternator is not charging it.
It could have a dead cell which would keep it from holding a charge.
You would need to check the charge of the battery with a volt meter, then see if the alternator is charging at 14 volts when the engine is running. The battery should be at least 12 volts with the engine off.
The problem could be in the wiring from the key switch or dash gauges back to the alternator.

New altenators will put out up to 14.7 volts. When they put out less than 12.0 it's time to replace them. Batteries should hold at least 12.0 volts, they wont hold much more than that.12.6 maybe.
If they will not hold at least 12 then they need replaced. Batteries go bad because one of the cells inside will not take a charge anymore.

HAVE THE ALTERNOTATOR CHECKED TO SEE IF ITS PUTTING OUT ENOUGH VOLTAGE SHOULD BE OVER 14 DC NOTHING 12 V. OR UNDER DC VOLTS

Have you put a meter across the battery to check its charging? I would expect to get 13.5 volts plus if the charging sytem is working.
It sounds like you have done all the good checks, but what about the battery itself? A failing battery can drag the charging sytem down. I would charge it up and ask a shop to load check it, or keep it off the bike and monitor if its holding charge for a few days. If it drops below 12 volts, it had it.

You need a new battery, their life is around 5 years, or if you leave them discharged for a while they start to loose capabilty to hold charge.

Hi,

You should be able to get over 12 volts from the charging system of the lawnmower. I would think once it is running, you should get 12.8 to just over 13 volts dc to adequately charge your battery. If you have less then 12 v power output from your chargiing system, well then the charging system is not working properly.

Of course, if the battery is defective and wont hold a charge, you can test that be taking the battery out of the machine and checking the voltage. It should be 12 volts or slightly better. If you let it sit overnight and it drops substantially, well it is likely not holding a charge and draining internally. If it does not have 12 volts to begin with and your charging system is ok, well then it is likely defective.

Also, you can use the glass hydrometer made for batteries to draw up some fluiid and check against the colour scale.

Each cell on a battery is 2 volts, so 2 volts times 6 cells is 12 volts. So if one cell is bad, then they all become bad as the battery needs a total of 12 volts to operate.

Some gargages will test your battery for free if you buy the new battery from them.

HI. you may have a battery drain issue that is sapping your battery overnight.

Here is the procedure I use to isolate a battery drain. Remove negative battery cable from the battery. Using a 12-volt test light, hook one end to the negative battery post the other end to the negative battery cable you just disconnected. The test light will glow or "light" if there is a drain. If the "light or glow" is faint, that is probably normal draw for the clock or computer. If the "light or glow" is bright, then there is a large drain. That should be corrected. Now start removing and replacing the fuses one by one until the light goes out; that one will be the circuit with the drain. Remember to hold in the button in the door jam for the interior lights.