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.
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).
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...