6-Stage Battery Charging: how we taught a Su-Kam inverter to make batteries last longer
In a power-backup system, the battery is the most expensive part — and the first to die. So we built charging that nurses the battery, stage by stage. We called it DT-6S.
Anyone can push current into a battery. Charging it intelligently is a different craft.
Honestly, battery charging was the biggest challenge we won in our time. Lead-acid batteries are temperamental, and getting their charging right was a constant learning — we made design after design after design. This six-stage method, DT-6S, was the best of all of them, and we built it for our smaller inverter range, where battery life matters most to an ordinary household.
And here is the part people forget: it was software. Alongside inventing the pure sine wave inverter, the achievement I’m proudest of is the charging software we wrote for the charging section of our inverter-UPS. It controlled the charger so precisely that it improved both the backup you got and how long the battery lasted.
For most of the industry, charging was crude: pour power in until the battery is full. But a battery treated that way ages fast — plates sulphate, acid stratifies, performance fades. We wanted Su-Kam’s solar hybrid inverters to do the opposite: to charge in a way that actually extends the battery’s life. The result was DT-6S six-stage charging, and the claim we put on film was simple — it increases battery life by at least six months.
The six stages, one by one
Clean the plates first
High-voltage, low-current pulses break down the sulphate deposits that build up on the battery plates — restoring capacity, reducing internal resistance, and setting up a longer life.
Ease it awake
Charging begins gently, with low current and low voltage, so the battery’s temperature stays normal instead of spiking.
The main fill
Now it delivers high voltage at a pre-defined current for a full charge — the battery voltage rising gradually, but never tipping into overcharge.
Top it off, safely
Voltage is held constant while the current is gradually reduced, letting the battery reach a complete charge without the damage that overcharging causes.
The stage that protects life
The most important step for longevity: a controlled high voltage at constant current mixes the electrolyte — the sulphuric acid and water — preventing acid stratification and keeping the battery at peak performance.
Hold it there
Finally, periodic low-voltage, low-current charging maintains the battery’s charge level and keeps its temperature normal — ready for the next power cut.
This is the kind of engineering that never makes a headline but quietly defines a brand. We didn’t just sell an inverter; we built the intelligence that looked after the battery behind it.
The next challenge: teaching it
A technology this good is wasted if no one understands it. Six charging stages, electrolyte chemistry, desulphation — that is a lot to explain to a busy dealer or a first-time customer. So we faced the same challenge we always did: how do we teach our own people, our dealers and our customers? The answer, once again, was to put it on film — to show the six stages clearly, simply, so anyone could understand why a Su-Kam inverter looks after a battery better. That video is the one above.