MTD yard Machine lawnmower,17hp Briggs And Stratton engine. Runs for about 15 or 20 minutes and stalls. It will not start again until I recharge the battery over night. Then only runs again for 15 or 20 minutes. Could this be a problem with the charging system?

Yes it could be

check your battery 1st , then check the stator a/c output

• 10 or 16 Amps DC regulated for charging
battery
• Two black leads (C) from stator
• Yellow connector (D) with two pin
terminals
• Two yellow leads (E) to regulator-rectifier
(F)
• One red lead (B) from regulator-rectifier
to red connector output lead (A)
• 10 and 16 Amp systems use the same
stator, color coding and regulator-rectifier
• Alternator output is determined by the
flywheel alternator magnet size


The stator and regulator-rectifier are the same
for the 10 and 16 Amp systems. The system
output is determined by the flywheel magnet
size.
Test Alternator Output
1. Temporarily disconnect stator wire
harness from the regulator-rectifier.
2. Insert RED test lead (A, Figure 28) into the
V ω receptacle in the meter.
3. Insert BLACK test lead (B) into COM
receptacle.
4. Rotate selector to AC Volts position.
5. Insert RED (A) and BLACK (B) test lead
probes into output terminals (D & E) in
YELLOW connector (C). (Test clip leads
may be attached to either terminal).
6. With the engine running at 3600 rpm, the
output should be no less than:
• 20 volts - 10 Amp System
• 30 volts - 16 Amp System
7. If No or Low output is found, check for
bare wires or other defects. If wiring
defects are not found, replace the stator.
voltage depending on alternator type and magnet size

then check the regulator / rectifier , make sure it is grounded properly

make sure battery earth lead is good

i suspect loss of bat voltage is letting the afterfire solenoid close off the main jet

let me know model and type codes off engine & i will try help further

cheers