Starting and charging
Generator Battery Charging System Repairs
A standby generator waits for weeks, then has to crank from its own battery. That battery stays ready only if the charger, the cables and the connections are doing their job. This page is the charging system as a whole. A battery that will not take or hold charge is the separate symptom page.
- Charger and battery separated
- Standby sets included
- No jump-start as a repair
- Onsite across Gauteng
While the set is waiting
How does a generator battery stay charged?
On most standby sets a dedicated charger feeds the start battery while the mains is present. The engine charging circuit, where one is fitted, only works once the engine is running. A set that sits does not keep its own battery charged by running.
Possible causes of a flat battery include a failed charger, a battery that will no longer accept charge, corroded terminals, a loose cable, a damaged lead, an isolator left open, or a charging voltage that is too low or too high. A controller alarm can be reporting any of those.
The visit measures charging voltage at the battery, then checks the charger, the cables and the battery itself. Replacing the battery because the charger is dead, or the charger because the battery is finished, is the mix-up this page is meant to avoid.
The charging path
Why does a generator battery keep going flat?
A flat battery is the result. The charging system is what should have prevented it between outages.
Generator battery charger faults
Trickle and standby chargers fail open, fail high, or show an alarm while the battery voltage quietly falls. The charger is tested, not assumed from a flat battery.
Charging voltage problems
Too little voltage leaves the battery flat. Too much can cook it. The reading is taken at the battery terminals with the charger connected.
Battery terminals and cabling
Corrosion, a loose clamp, a damaged cable or an isolator in the wrong position can look exactly like a dead charger.
Standby generator battery charging
The useful test is the state of the battery after the set has been standing, not only whether it cranks on the day of the visit.
Battery versus charger fault
A battery that will not hold a charge and a charger that is not supplying one are different parts. Both are measured before either is replaced.
How we diagnose generator charging problems
Voltage, the charger output, the connections and any controller alarm are recorded together. A jump-start only proves the engine can turn. It does not repair the charger.
Related Pages
Charging, starting and maintenance
Google reviews of ProService Generator Repairs
Google Review
They did a fantastic job overhauling my Firman generator. The mechanic was prompt, professional, and took the time to explain exactly how to maintain the battery properly.
Google Review
Excellent residential generator maintenance in Bryanston. They are quiet, efficient, and replaced our failing battery charger during load shedding.
Common Questions
Questions about generator battery charging
What is a generator battery charging system?
It is the charger, cables, terminals and battery that keep a standby set ready to crank. The engine alternator, if fitted, only charges while the engine runs.
Why does the battery go flat between outages?
Possible causes include a failed charger, a battery that no longer holds charge, corrosion, a loose cable, or an isolator that is open.
Is a flat battery always a bad battery?
No. A healthy battery goes flat if the charger has stopped. Both are tested.
The controller shows a charging alarm. What does that prove?
It proves the module is unhappy with the charging circuit. It does not name the failed part until the voltage and the wiring are checked.
Can I leave a jump pack connected as the charger?
No. A jump gets the engine turning once. The standby charger is what should hold the battery while the set waits.
Does this include the starter motor?
Only as far as the test shows the cranking problem is actually the battery supply. A click or a slow crank has its own starter page.
What should I send about the battery charger?
Whether it clicks, cranks slowly, or does nothing, plus any charger or controller alarm, and how long the set has been standing.
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
Tell us how the battery behaves
Say whether it is flat after standing, whether a charger alarm is on, and whether a jump-start is the only way it turns.
- Call
- 082 057 4605
- Message us on WhatsApp