Li-Ion chargers with voltmeter?

Is it too challenging to incorporate a voltmeter in a Li-Ion charger like the La Crosse and Maha Ni-MH chargers, for example? It seems more convenient to have that feature in a Li-Ion charger over a Ni-MH charger because of the higher voltage and safety concerns. I would love a feature like this in the affordable chargers.

All hobby chargers display voltage while charging, so you might want to look in that direction. :)

I use the cheapest clone IMAX B6 from ebay and very satisfied with it. Cost less than $30 shipped for the set. You won't get only voltage display, but current and capacity as well.

You should test it at least once with a multimeter - it’s a well-known fact that B6 clones often ship in non-calibrated state (so they can potentially overcharge your batteries) (just saying)

I've researched the hobby charger option but it seemed a little hardcore for me considering I'd only be using it for li-ion batteries used in flashlights. So $30 even includes a power supply? If not, what do you use? I should be able to pick up a compatible adapter on ebay for under $10, correct? Are there battery charging bays/cradles that are available for this type of setup?

Depends on seller.

You can use any 11-18V AC adapter, e.g. laptop charger, AC adapter of a router, etc.

Even for $5 :slight_smile:

Sadly no, you’d have to McGyver one up yourself. I am using generic $5 dual-bay 18650 charger with electronics ripped out as a cradle, it has one drawback though - two cells are in parallel so charging e.g. 14500 and 18650 at once is not possible (well, it is, but very unrecommended).

Thanks for all of the answers, Shadowww. I think this setup might be more complicated that I'm hoping for. It's not that I'm incapable. I would just prefer something more simple, which is why I was curious about regular li-ion chargers and why none of them incorporate a voltmeter when it's standard on some of the mid to higher end Ni-MH chargers. I'm looking for a setup I could duplicate for my dad since I'm collecting flashlights for him. However, he doesn't have interest in the flashlights themselves but rather the purpose they're needed for. He's definitely capable of monitoring the voltage with a DMM but he just wants simple plug and play. That's why I'm now wondering if I need to switch him over to all Ni-MH. Too bad there isn't something like the La Crosse BC-700 for li-ion.

you can insert a voltmeter on your original charger, maybe adding a switch on/off, there are many types, digital(that worksfrom 3,3v), for digital for lipo packs that can read many cells, or old fashion if is for your dad xD

the cons is that cheap small voltmeters can wrong of 0,1v

Or something like this might work, that's why I ordered mine:

Gonna make a prototype charger monitor and if it works it might create some interesting gifts for friends and family. ;)

Looks interesting, but I wouldn't know where to begin. How complicated is a project like this? I have a friend who seems to have a fair understanding of electronics (he's done so much LED wiring/soldering for various projects, including Xbox controllers). Maybe it's something we could try out since he now has the flashlight gear because of me

I've got one too. I was planning to do the same. I don't think it's that hard to solder the + and - contacts inside the charger.

I guess what I don't understand is the concept of wiring this voltmeter to the charger and then it just works. Are you simply wiring it to the + and - of the bay so you're getting a readout for one particular battery?

That is correct. Simply connect the pin 1 to - and pin 2 to + of the charger, and it should show the voltage.

Once my voltmeter arrives I'll take some pictures and post them. It should be really simple.

I already have one voltmeter like that, but the one I have measures 2S-6S, meaning, only 2 to 6 batteries in series (while not charging).

Keep in mind that the one I linked above measures only 1 battery while charging. No cross-connecting nor series connecting anything to it while charging, unless you balance charge with hobby charger.


Take a look to my DIY at - very simple! It is only checker, but you will got an idea..... The only disadvantage is display blinkig (pausing between readings).

This usb charger will charge one battery at a time, but charge current can be selected as well as the voltage display you are interested in. Something to think about and simple to use.

Cottonpickers chargers are great but they are kind of overpriced… :confused:

I disagree. To each their own.

Cottonpickers' are hand made. For the basic model without display he's earning about $10. That is barely enough to cover his time spent soldering. Not to mention collecting, testing, assembling parts, testing finished product, sorting orders and shipping. And whatever else he spends time on while making those (electricity, gas, sandwich, chocolate, ...).

I'm seriously pondering the idea to make a few myself, to give away as complimentary chargers with gift flashlights.

Don't get me wrong, I'm a budgeteer. I'd never pay $17 for a charger that big/cheap/usb/insert_whatever_here. It's too expensive for me too.

But I'd build some. As a learning experience and tons'o'fun, it would be a time well spent. As a paid job, not.

So, it depends on your viewing point. Viewed as a maker, they are as cheap as they can get (which is too cheap). As a buyer, they are too expensive.


And from what I understand follow the correct CC/CV charging method unlike 100% of the cheap chargers.

ML-102 and Xtar MP1 are under 10$ and are very close to CC/CV method

If your not into hobby chargers just buy a cheap multi meter, you should have one any way for these lights and batteries.