Charging fault
Generator Battery Not Charging
The battery is going flat, or it will not come back up after a start. That is the symptom. It is not yet proof that the charger has failed, and it is not the same job as rebuilding the whole charging system. Possible causes include a failed charger, a battery that will not accept charge, a loose or corroded connection, a blown protection device, the wrong charging voltage, a wiring fault, a controller alarm, a drain, or a break in the charging circuit.
- Symptom first
- Charger measured at the battery
- Jump-start is not the diagnosis
- Onsite across Gauteng
The battery will not recover
Why is my generator battery not charging?
Because something between the charger and the battery posts is open, or the battery itself will not take what the charger is offering. The meter decides which. A lamp on the charger is not that measurement.
A set that only starts after a jump has usually been standing with a charger that is not holding the battery. Once the engine is running it may seem fine, then it is flat again at the next outage. That pattern is a charging fault, not a one-off flat battery.
The broader repair of chargers, cables and isolators sits on the charging-system page. This page is for the complaint: the battery is not charging.
What the flat battery is telling you
Standing flat, jump-starts and charger alarms
Battery goes flat while the generator is standing
The engine is not running, so only the standby charger can hold the battery. If that supply is missing, the next outage finds a dead set.
Generator only starts after a jump-start
The starter and the engine may be fine. The battery was empty. The next test is why it emptied while the mains was on.
Battery charger alarm
The controller or the charger is flagging the circuit. The alarm is kept and compared with the voltage at the posts. It is not cleared as the repair.
Battery versus charging-system problem
A battery that collapses under a load test is a battery fault. A charger with no output, and a battery that still accepts charge, is a charger or wiring fault.
Why standby generator batteries fail
They age, they sulphate if they sit flat, and they fail after repeated deep discharges when the charger has already stopped. Age and a dead charger can arrive together.
How charging faults are tested
Voltage is read at rest, with the charger on, and while cranking if that is safe. Connections are inspected. Live booster leads across unknown wiring are not the test.
Related Pages
The charging system and other start faults
Google reviews of ProService Generator Repairs
Google Review
Fast battery replacements in Bryanston.
Google Review
They manage the generators for our retail complex in Allen's Nek flawlessly, recently performing a very quick battery replacement on our standby generator to prevent downtime.
Common Questions
Questions about a generator battery that is not charging
Why is my generator battery not charging?
The charger, the wiring or the battery is not completing the charge. Which of the three has failed is measured, not guessed from a flat battery.
It starts if I jump it, then dies next time. Is that the battery?
It might be. It is also the pattern of a charger that is not holding the battery while the set stands.
The charger light is on. Does that mean it is charging?
Not always. The voltage at the battery posts is the reading that matters.
Can corrosion stop a battery charging?
Yes. A green or white clamp can leave the charger working and the battery isolated from it.
Could something else be draining the battery?
Yes. A parasitic drain is one possible cause, checked after the charger output is known.
Is this the same as a generator that will not start?
No. No-start includes fuel, the starter and the controller. This page is specifically a battery that is not being charged.
Should I keep jump-starting it?
A jump proves it can turn once. It does not find the charger, the cable or the battery that will be flat at the next outage.
Still unsure what the fault is? Call or WhatsApp 082 057 4605 for onsite diagnosis.
Service Areas
Onsite visits across Gauteng
Technicians travel to the generator. These are the main Gauteng areas. Suburb pages sit under each region.
What to send before we attend
ProService Generator Repairs confirms an onsite visit from these details. Send what you have. A missing model number does not stop the booking.
- Location
- The suburb or site, so the visit can be booked in the right area.
- Make and model
- The generator brand and model, if they are known.
- kVA
- The size printed on the data plate.
- Fuel type
- Diesel, petrol, LPG, natural gas, or dual-fuel.
- Controller model
- The module name on the panel, when it is visible.
- Fault or alarm
- What the set does, and any text on the screen.
- Photos
- The generator, the data plate, and the controller or alarm. Send these on WhatsApp.
Book a Visit
Say when the battery goes flat
After standing, only after a start, or with a charger alarm on the screen. Those three are booked differently.
- Call
- 082 057 4605
- Message us on WhatsApp