How True Balancing Got Started

When we founded True Balancing we didn’t have a background in batteries or in battery management electronics – which turned out to be an advantage. Continue reading to find out why.

We first encountered out-of-balance batteries when we were working on a new product that was powered by a lithium-ion battery. The client had purchased a pallet of batteries that had been sitting in a warehouse for about year with no maintenance charging.

We connected one of the batteries to a prototype of the product and tried to power it on, and the BMS flashed a warning signal indicating bad battery. The same thing happened with two more batteries.

Rather than just telling the client they had to buy new batteries, Eric brought one the batteries back to his lab and analyzed it. He found that the battery had self-discharged to a low SOC and the individual cells had self-discharged at different rates, leaving the battery in a very out-of-balance condition. The battery was in a condition that the BMS couldn’t correct. It wouldn’t even try to charge the battery. It just flashed a signal indicating bad battery. However, none of the individual cells were dead; every one of them could hold a charge. The cells just had very different states of charge. This is a classic example of an out-of-balance battery.

A bit of research revealed that what we experienced wasn’t unique – that out-of-balance is a major problem in the battery industry.

Designing a Better Balancing Technology

That got us thinking. Is there way to design a balancing system that would allow a battery to recover from this state? Or, better yet, prevent the battery from ever getting into such an out-of-balance state? We decided to take a stab at it.

This is when not having a background in batteries or battery management proved to be a blessing. Rather than looking at existing balancing technologies and trying to figure out how to improve on them, we started with a completely clean slate. We started from first principles thinking about how we would design the ideal system for keeping batteries balanced.

We set six design goals:

1. Balancing current can be as high as needed to keep any battery balanced (or restore any unbalanced battery to a balanced condition)
2. Very efficient (when balancing is active, absolute minimum amount of energy is drained from the battery)
3. Low cost
4. Design for manufacturability (use common electronic components that are readily available from multiple sources)
5. Design for system integration (can be easily integrated with any BMS and any battery)
6. Design for safety and reliability (must comply with relevant regulatory standards).

Starting with these design goals, we developed True Balancing. And serendipitously (yes, I used a thesaurus), the circuit architecture of True Balancing happens to have all of the elements needed for impedance measurement.

As we continued to improve the technology, we encountered specific out-of-balance patterns in batteries that had been in real world use which inspired the development of Positive Balancing