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Since my old, dirt cheap battery charger broke down, I disassembled it and was surprised not to find any integrated circuit in it:

board of a simple battery charger

Obviously, I'm now looking for a replacement. Now, there are advanced battery chargers which advertise:

... provide longer lasting, better performing batteries ...

But I'd rather ask in this community: What are the specific advantages of the more expensive models? I guess they're limiting the charging current? But if they only inform me on fully charged batteries I'd rather stick to the cheap chargers.

I'm slightly unsure if this is the right place to ask such a question (it sounds like buying advice) -- let me know if not.

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  • \$\begingroup\$ One thing the newer chargers do is to vary the charge current according to the current state of charge of the battery and some will go to a “float” charge for the last 5 or 10%. \$\endgroup\$ – Solar Mike Jan 7 '18 at 19:48
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I'm assuming you only want to charge NiMh and/or NiCd based cells because that's what your old charger supports. If it supported Lithium based cells it would need to have more complex electronics.

The more expensive chargers often use a higher charging current for faster charging but this means that this current has to be switched off or lowered when the cells are full.

Cheap chargers like your old charger take much longer (10 - 14 hours) to fully charge the cells. These chargers simply charge with a small current which is allows continous charging meaning, it does not need to be switched off.

When NiMh and NiCd cells are fully charged but you still charge them, they get warm. That's not a problem at a low current (as is the case with the simple chargers) but it is a problem (the cells will overheat) at a large current. So fast-chargers need electronics to detect that a cell is full and stop fast-charging it.

If you can wait for your cells to charge, by all means get a slow / cheap charger.

If you cannot wait, get a fast charger.

You could also consider buying more cells and alternate sets using the slow / cheap charger and for the same money as a fast charger.

For cell lifetime in my experience the slow charging does put less stress on the cells so that should make them last longer.

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  • \$\begingroup\$ your assumptions on NiMh and NiCd are correct. Thanks for the comparison, +1. I'll wait a little more for other, possible answers before accepting. Thanks! \$\endgroup\$ – Sebastian Jan 7 '18 at 20:54
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    \$\begingroup\$ NiMH should not be charged after they are fully charged, even a slight current will cause permanent loss of capacity according the manufacturer's data. Allowable current is only of the order of self-discharge current. Of course that's not necessarily the cheap-*** charger maker's problem if it slowly wrecks your batteries. \$\endgroup\$ – Spehro Pefhany Jan 7 '18 at 21:55

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