New battery fitted system isn't charging , battery keeps going flat

You have it set on automatic or manual .. If it is set for automatic the charger will cycle on and off so the battery does not charge too much. If it is manual when battery reaches charged voltage, it is time to disconnect.

have the system checked for a draw as this will cause the battery to go flat. you don`t say but have you had the charging system checked.

if its a new battery it could be as simple as it wasn't charged when you purchased it, If it was charged and your mower isn't charging it, the power source to the battery from the mowers motor isn't working properly,, not knowing if its a 12 or 6 volt system you need to check the battery ,, see which one it is,, using a multimetter ( if its 12v ) check the battery after you charge it with an outside source ( battery charger) you would have a reading of 12-12.5 volts on a normal check,, then start the mower, and check the battery as its running,, you should get a reading of 13-13.5 volts minimum, if your not, the alternator or magneto isn't working properly, if you do show the increased voltage at the battery connections, then you need to clean the contacts since the charge isn't reaching the actual battery

My guess is that with the age of the battery it isn't able to hold a charge anymore which means you'll need to purchase a new battery. Your best bet for that will be to go through Sony or the website Dr. Battery.

Something is draining the battery, or either the alternator isn't putting out to keep the battery charged. A local shop can usually check it for free and let you know if it's the alternator. The other is a shortage somewhere which will be a pain to trace down.

first check if the battery is any good,, it maybe that its lived its life and you need to put a new one on the bike,,also check if this battery charger is realy charging the battery up,,the charger may be working but is the charge reaching the battery? to check if there is a drain just hook up a meeter if it reads a big drain when nothing is on then its the alarm using up the power but the charger should keep the battery toped up ok? i keep a solar sell of 2.5 watts hooked up to my bmw all the time and i never have had a flat battery yet!!! a charger may "over cook" the battery and that will kill it off very fast, all it needs is a stand by charge going into it thats only about 50ma 's and a battery's life is only about 2 to 3 years so if its older than this fit a new one to the bike

CHECK THE CONECTIONS TO THE ALTENATOR AS IT SOUNDS LIKE IT BIS NOT CHARGING THE BATTERY .

Check the whole connection in the hood for the charging system.

I had this exact same problem on a hipster 125, it was a faulty regulator module ( mounted under the seat) I also found a short circuit (somewhere) in the wiring loom between the regulator output and the chassis (probably what killed the regulator in the first place!) I cut and replaced the entire wire to save removing most of the loom and after testing reg to ensure it was dead i fitted a new one (about £60) bike charges and runs like a dream now even with fully lights approx 80% of the time. good luck

Sometimes when the battery keeps going dead like that, a component may be creating a current draw. you can do a simple current draw test with a fluke meter by setting the meter to read amps, make sure the test leads are in the proper portals on the fluke for an amp test, and disconnect one of the battery cables and connect the test leads in-line with the battery and cable. It would help to know you have a good fuse inside the fluke. They are easy to blow, and whatever you do, DO NOT try to start the unit with the meter hooked up for the amp draw test. That is how fuses are blown. With the key off, check for any amp draw. If there is, you can start unplugging components until the draw goes away. If there was no draw to begin with, you may have a stator coil (or alternantor, whichever it has) that is weak and can't keep up.