Charging a three-cell nickel-based battery pack with a Li-Ion charger [pdf]
24 points by theblazehen 2 days ago | 4 comments

kdklol 8 hours ago
I was recently searching for NiMH charging ICs, turns out they basically don't exist. Most devices which charge their NiMH batteries implement low CC charging, which is slow. It's a shame, because NiMH batteries do have their advantages (safety, ease of finding replacements, etc.) and can be recharged fairly quickly if the charger is smart enough.
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hnuser123456 6 hours ago
In the RC vehicle world, these things have been prevalent for about a decade now: https://www.amazon.com/Battery-Charger-Balance-Discharger-Ba...

I'm not sure what IC they use, but it uses a two-line text display and can switch between Lipo, LiFE, NiMH, NiCD, Pb, and a few other modes, and some of them allow adjustable cutoff voltage, max charge time, etc. That's just a cheap 80W model but there are 200W+ chargers that use the same interface.

There are also 18650 cell chargers that can also take NiMH AA/AAA and charge them at high currents, like this: https://www.amazon.com/NITECORE-UMS4-Intelligent-LumenTac-Or...

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cmbuck 6 hours ago
What do you mean by "they basically don't exist"? Solutions like the TI BQ25172 are designed exactly for this purpose.
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Liftyee 4 hours ago
I have done similar searches before. They do exist, but most dedicated ICs are targeted towards tightly-integrated cells or battery packs. The variety available is much smaller than for Li-ion batteries, and the ICs are more expensive.

It seems like commercial multi-cell battery chargers mostly use custom microcontrollers to achieve this, instead of multiple charging ASICs.

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