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Build a li-ion 36V battery pack charger with a Boost regulator


Well-Known Member
The current rating of a power supply is just that, a rating. It is designed to deliver that much current indefinitely under normal operating conditions. The actual current limit could be anywhere from 20% to 50% higher that its rating. Well beyond it's recommended power rating. Also, unless a power supply is specifically designed as a battery charger, it's current limit will usually be a hick-up type limit, where the output shuts down and restarts. Not the kind of current limit behavior you want for a battery charger.

For a battery charger, you want a controlled current limit that adjusts the power supplies output voltage to track the charge state of the battery. This means adding a current monitor error amplifier to the existing voltage regulation circuit.

The one charger per cell topology is good since it provides optimum efficiency while keeping the cells in balance, but it is also requires much more circuitry. Each output does need to be isolated from the input power, because each charger output is wired is series with its neighbors. You would also need at least 11 wires between the charger and the battery, since you need a connection between each cell in addition to the positive and negative end terminals. I would only recommend that type of charger if the power were very high. In your case, I would just let the protection IC you have chosen do the balancing.


New Member
Hi evaleto, I like this topic. I don't know whether you are success in this charger. Please let me know the success story. Thank you.

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