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Can I use a lithium charge module on NiMh batteries? The charge module has 2 led, one for charging and one for full that I would really like to use with my NiMh batteries.

Bence Kaulics
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Andre Queen
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  • No, you cannot, you should not for your own safe. NiMh and Lithium batteries have different chemistries, different cell voltages and they require different charging methods/algorithms. – Bence Kaulics Jun 20 '16 at 08:20
  • Thank's, will do, will get some lithium batteries instead then! – Andre Queen Jun 20 '16 at 08:32
  • @BenceKaulics you might want to enter that as an answer. I'd upvote it. – Neil_UK Jun 20 '16 at 08:34
  • For a multiple of three NiMH connected in series compared to Li-Ion (3x1.2 V vs. 3.6 V), you can in some cases get away with it, but in all other cases you can not. If unsure (you ask here so hence unsure) - don't. Also, pride yourself with asking before setting something on fire. Your neighbours will thank you when your house isn't on fire. :-) – winny Jun 20 '16 at 09:11
  • This has always been an off-topic "usage" question but it is becoming increasingly evident that it needs to be closed as it keeps attracting people who abuse the answer form to post questions. And since it never belonged here in the first place there is no reason to keep it. – Chris Stratton Feb 08 '19 at 17:07

2 Answers2

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You should never charge one type of a battery with a charger designed for another type, because that could be truly dangerous.

The reason behind is that NiMh and lithium batteries have different chemistries, different cell voltages (1.2 V for NiMh and 3.7 V for lithium), so they require different charging methods/algorithms.

With an inappropriate charging you could damage the battery, which could cause capacity loss or fire (specially in case of lithium and LiPo cells).

Community
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Bence Kaulics
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  • Downvoted for being inaccurate. First of all, both Ni-Cads and NiMh chemistries are both magnitudes less 'dangerous" than Li-ION, and are also much more tolerant. While there are obviously chargers precisely tailored to those chemistries, charging them with home-brewed improvised power sources works. Often all that is needed is a resistor to taper the current to a level the battery can tolerate, which for a trickle charge is very easy. And nobody suggested the opposite case of using such a charger for Lithium chemistries. – Randy Dec 22 '18 at 22:21
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    @Randy. I won't start an argument about my answer with you because you are just clearly upset about your answer getting downvoted by someone else. – Bence Kaulics Dec 23 '18 at 09:59
  • Maybe true, but I am willing to listen. Note that I edited my original answer, realized I may not have been as clear as I could have in expressing the caveats involved. But I stand by the premise. Ni-Cad and NiMh are much sfer than Li-PO and Li-Ion cells, so with a little care to watch for excessive current a Lithium charger could be used for a the Nickle chemistries. Granted, its not ideal. But improvising is part of the craft, and as I pointed out already, many folks are on a budget. – Randy Dec 25 '18 at 00:27
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First, had you asked about doing the opposite (using an NiMH charger on a Lithium cell), the answer would have to be a resounding NO. NiMH is much more tolerant of ongoing "trickle" charge, and some chargers meant for these cells are simply current limiters that never really turn off, even after any "fully charged" LED turns on. In the case of a Lithium based battery, that ongoing current would at the very least ruin the battery, and at worst cause it to explode or catch fire.

But you are asking about the opposite case... using a Lithium charger on an NiMH cell, and here the answer is "maybe", but even under the best circumstance you likely would not like the result. At the very least you would have to determine that the maximum current output of your Lithium charger is still a safe charge level for the target NiMh cell. But understand that a Lithium based charger would attempt to supply current until the cell gets to approx 4.2V. Since an NiMh cell will never get to that voltage, the "charge" led will never indicate anything useful, and the current will never shut off. If that max current still amounts to only a "trickle charge" level, you MIGHT not harm the battery. But then consider that the typical voltage of an NiMH cell is much lower then the the maximum "over discharge" point for Lithium cells. SOME Lithium charge management ICs will actually shut down and go into a high impedance state seeing such a low voltage, to avoid possible additional damage to a cell it likely thinks is already "toast". Obviously in that case no charge will occur. You might actually have better luck trying to charge 3 NiMh cells in series with a single cell lithium charger.

Bottom line, its a reasonable experiment if you carefully monitor the current, voltage, and charging behavior in a safe environment. But again, I don't think you'll be happy with the result, even if it 'marginally" works.

Edit: Prompted by some reasonable concerns from others, I will point out that it is possible for any charger not specifically intended for a given battery or cell to output more current than what they will handle without damage. The risk of danger or fire is significantly lower with Ni-Cad or NiMH chemistry but you can still damage any battery or cell with excessive current. Therefore in addition to monitoring the current when attempting such an experiment, it is important to at least add a resistance capable of limiting worst case current to a level way below the battery's safe limit. If determining the battery's charge specifications or calculating a safe resistor value (resistance and power rating) is beyond your current level of understanding, than I must concur with some of the comments in saying that you should NOT attempt such an experiment.

Here is one informative article I found on charging NMh cells you might find interesting...

http://www.powerstream.com/NiMH.htm

Randy
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    Downvoted for saying it might be ok. It will not be ok. A safe trickle current for nimh would be 0.05C. A typical lithium charger will charge at 0.5C - 1C, so unless you're using a charger for a battery 10x smaller than the battery you have, you'll be in trouble. – BeB00 Dec 21 '18 at 06:57
  • Whatever @BeB00. I offered plenty of information for the OP to make an intelligent decision and adjustment to determine what is safe for his/her battery or cell pack. And since you DON'T know if the safe case you suggested applies, you're just going beyond your knowledge with this down vote and comment. FYI, improvising is part of the art of electronics, and its quite possible a simple resistor will make a Li_ION cell charger usable for a variety of Ni-XX chemistries. – Randy Dec 22 '18 at 22:26
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    "improvising is part of the art of electronics" - When you need to build a state machine with opamps, that's improvising. Charging batteries with entirely incompatible equipment isn't improvising, it's just stupid. You're giving the clearly inexperienced OP bad advice, and downvoting you is the correct course of action. The right thing to do is tell OP no, get a different battery or a different charger, which is exactly what happened. – BeB00 Dec 22 '18 at 23:41
  • @Beb00 Like I said... whatever. We completely disagree on improvising. You're free to vote as you wish, but you are simply wrong. Why improvise anything? Because for most people money doesn't grow on trees.Safety? Had the OP asked about charging Lithium cells with anything less than a proper charging circuit, I'd have answered accordingly. Going the other way can easily be made both compatible and safe very easily, with a 2¢ resistor. Ideal? NO. Usable? Compatible? Safe? YES! I've charged Ni-Cad and NiMh cells with similar improvisations for almost 50 years! It works! – Randy Dec 23 '18 at 00:20
  • @BeB00 - I do realize though that I did not sufficiently explain the need for a resistor, and have edited the post. – Randy Dec 23 '18 at 02:06
  • This answer is ridiculous - the Question is about using the wrong type of off-the-shelf charger, and the Answer is to wrap that up in a regime of monitoring current, voltage, temperature - as if someone who asks a question like this will have the wherewithal to do that. Downvoted. – Techydude Feb 09 '19 at 04:18