There are several universal battery chargers on the market that can charge NiMH and various Lithium Ion batteries all in one package.
I have an earlier model of this one and it does my NiMH, NiCd, Li-Ion, and Li-Po batteries just fine. It does use a different set of contacts for recharging AA / AAA batteries though, but perhaps this is simply due to the necessities of form factor?
I'm curious how these devices are able to detect what kind of battery the user has put into the device? There's no setting or knob turned by the user - they simply place a battery in an it starts charging and it also knows when to stop. Often these battery chargers can be run off USB as the power source.
I'm thinking a device that can charge NiMH, Li-Ion, and even 12V lead-acid would be kinda neat to make.
I've never seen a charger that would do diff chemistries. Link, please.
If there was such a thing, I think it'd be a compromise of only doing least common denominator type and a waste of time.
NiCad, NiMH, LiPo, LiFe, LiOn, there's a lot.
Apply a small charging current to the cell and observe the voltage. It will rise quickly to the discharged voltage of the cell, which will indicate it's type.
Then apply full current and charge to about 15% higher .
Don't forget that even a "discharged" Li-Ion cell will read about 3V...
Ni-MH and NiCd are charged with constant-current, so if you provide CCCV-like supply 4.2V@50 mA for "a while", it should quickly get a Li-Ion cell to 3+ V, and won't bother the other chemistries. NiCd vs NiMH is harder, but they're basically compatible anyway. Li-Ion and LiPo are compatible. LiFe and NiZn might be problematic...
INTP:
I've never seen a charger that would do diff chemistries. Link, please.
If there was such a thing, I think it'd be a compromise of only doing least common denominator type and a waste of time.
NiCad, NiMH, LiPo, LiFe, LiOn, there's a lot.
They are readily available and there is no compromise. They have been around for as long if not longer than when LiPo's became readily available to Joe Public. They are very good chargers and the software is very involved. This is one I have for my RC Planes
This one detects the cell count of NiMh by voltage and LiPo's by the balance port. If charging LiFe unbalanced it asks if the detected cell count (by total voltage) is correct
I'm familiar with those chargers, but they require user input. OP showed one that's simply separated by physical circuit. It doesn't need to figure out what chemistry the battery is, it knows NiMHs go here, and it knows Lithiums go here.
Just another cheapo charger that uses voltage cutoff, can only charge NiMHs in pairs, so cap around 3v. Probably less since NiMHs don't change voltage much over their discharge.
What I meant by compromise for these chargers is that they use some lower current than what could actually be accommodated. Playing it safer for the sake of simplicity. Hobby chargers with proper settings or various 'speed chargers' push closer to the limit. But those speed chargers are specific to the type of battery that they charge.
What I meant by compromise for these chargers is that they use some lower current than what could actually be accommodated.
Heh. Thereby extending overall cell life, improving charging safety, and VASTLY simplifying design...
Yeah, I don't know how a charger could possibly detect maximum allowed charge rate, which is dependent on cell size as well as how "advanced" it is.
What they actually do is charge the battery with a fixed current . When the battery of fully changed there is a dip in the rate of change in battery voltage , that signals to turn the charger off .
MarkDerbyshire:
They are readily available and there is no compromise. They have been around for as long if not longer than when LiPo's became readily available to Joe Public. They are very good chargers and the software is very involved. This is one I have for my RC Planes
So you can plug any battery type, any chemistry, any capacity, any number of cells into the two wire connection for that charger and it will automatically work out the battery that is connected and charge it appropriatly ?
So given that my universal charger separates nickle and lithium batteries into separate circuit, that must mean that NiMH and NiCd batteries can be charged the same, while LiPo and Li-Ion can also be charged the same?
NiMH and NiCd batteries can be charged the same, while LiPo and Li-Ion can also be charged the same?
Yes, approximately. LiPo and LiIon are essentially identical except for packaging, and NiMH and NiCd are similar except that NiMH has about twice the capacity in the same size (and thus could be charged at double the rate), MIGHT have slightly different end-of-charge detection, and doesn't like "trickle charging."
You gain a lot of flexibility if you're not trying to charge "as quickly as possible."
In general, chargers are a lot smarter than they used to be back when your only choice was NiCd. I've wondered if NiCd could have worked a lot better if they had been able to build them with some level of smart charging assumed, rather than allowing for the dumb chargers that were available at the time...