Charger talk

[acrosteve]

Well, after reading this thread. http://www.candlepowerforums.com/vb/showthread.php?264618-Why-buy-a-Maha-MH-C9000

I am convinced that I need a MH-C9000.

That would allow me to retire my MQN06U and the CH15MN Energizer quick charger that I rarley use out of fear of damaging my eneloops.


But anyway, i think I will be getting into the 18650's soon and wonder if there is a charger comparable to the C9000 that would hand the Li-Ions? It does not seem so, but I thought possibly.

No, I do have a couple of chargers geared towards my RC trucks. I have a Duratrax Inellipeak that will do all types, but there is no balance plug on it. For my Lipo's I use my Duratrax Onyx 235 that can charge and balance up to 6s packs.

So other than getting a C9000 for my MiMH, and a Xtar WP6 II for the Li-Ions, what are my choices for around $50 each.

This thread is worth including. http://www.lygte-info.dk/info/indexBatteriesAndChargers UK.html

 

[45/70]

Hi acro. The most important requirement of a Li-Ion charger, is that it use a proper charging algorithm. This promotes both long cell life, as well as a needed safety factor when dealing with Li-Ion cells.

The reason you don't see any chargers with similar features as the C9000 for charging Li-Ion cells, is that 90% of these features are not necessary to charge and maintain them. In fact, some of the features that the Maha offers for maintaining NiCd and NiMh cells, such as "refresh", "cycle", and "break-in", would simply add wear to the cells with zero benefit.

Maintaining Li-Ion cells is pretty simple, charge them up at an acceptable rate with a decent charger, don't overcharge them, use them, don't over discharge them, and when storing them, preferably store them about half charged, or a bit less, in a cool environment. That's pretty much all the maintenance there is. Of course a means to measure the voltage of the cells, such as a reasonably accurate DMM, or voltmeter, is pretty much a requirement to accomplish this.

I'm not familiar with the Duratrax chargers that you have, but I would imagine that you could use them to charge your Li-Ion cells, if you came up with a way to hold your cells and hook them up. It isn't really necessary to charge Li-Ion cells in series. Hobby chargers are setup this way because most battery packs are welded together, and you have no other choice but to charge them in series, with the balancing leads. For flashlight/torch cells, that are "loose", as an alternative, you can hook the cells up in parallel and charge them that way. No balancing leads needed. Try a CPF search for "parallel charging Li-Ions", or something to that effect, to get more details.

Also, modern cylindrical Li-Ion cells of LiCo or LiMn chemistry can be charged exactly the same as LiPo cells, ie. at 4.20 Volts. Just be sure to follow the recommended charge rate for the cells, as cylindrical Li-Ion cells usually have a maximum charge rate of 1C, or less.

If you search the Forum for "hobby charger", you should find many threads dealing with using this type of charger to charge your Li-Ion cells. Also, ideas as to how to fabricate a charging cradle you can place the cells in for charging, or how to use magnets instead, as well as other ideas as to how to use a hobby charger for charging your cells.

Always play it safe and make sure all settings are correct before using a hobby charger to charge Li-Ion cells. More Li-Ion cells have gone when charged in a hobby charger than any other kind, usually, due to improper settings.

On a final note, if you haven't already, I highly recommend that you read through the relevant threads in the "Threads of interest" and "Smoke and Fire" threads located at the top of this Forum, if you are unfamiliar with the use and care of Li-Ion cells, regardless of which chemistry you use. Also, the Li-Ion sections found at Battery University are often referenced here on the Forum and are an excellent source of information, not only pertaining to various Li-Ion chemistry cells, but other types of rechargeable cells, as well.

Dave

 

[acrosteve]

Great. Thanks for the info. I will definitely check out some threads.

The duratrax chargers are fully programmable and have Li Ion modes as well as LiPo. I am very capable of making a cradle and being able to charge them in parallel is very possible.


I see the definite advantage of charging the NiMH on separate channels like the C9000 will do. But cince that is not an issue for the Li-Ion batteries, there would be no advantage of something like the Xtar WP6 II, since I already have some very capable chargers - I think. That would let me put more $$$ towards my new light.




Duratrax 235
Specifications
AC input: 110V 60Hz–240V 50Hz, 50W
DC input: 11-15V, 70W
Battery types: 1-10 NiCd or NiMH (1.2-12.0V) 1-4 LiPo, LiIon or LiFe (3.7-14.8V)
Battery capacity range: 50-9900mAh
Fast charge current: 0.1-8.0A linear, adjustable (4C limit for lithiums; 5A limit w/AC input)
Fast charge termination:Peak detection (NiCd/MH cells) cc/cv (lithium cells)
Fast charge safety timer: off-300 minutes
NiCd/MH peak sensitivity: 3-20mV, adjustable
NiCd/MH trickle current: 1/20 fast charge setting (auto mode) or 0-250 mA (manual set)
Lithium balancing accuracy: 5mV per cell
Lithium balancing adapters (2): ElectriFly & FlightPower/Thunder Power
Controls: 4 push buttons
Battery memories: 10
Display type: 2x8 reversed, backlit LCD
Data Displayed: input, output and peak voltage (packs), balancing voltages (cells) & charge current, capacity and time.





Duratrax Intellipeak.

DTXP4170
Input Voltage:11-15V
DC Battery Types,
# of cells:1-10 Nickel-Cadmium cells (1.2-12.0V NiCd)
1-10 Nickel-Metal Hydride cells (1.2-12.0V NiMH)
1-4 Lithium-lon or Lithium-Polymer cells (3.6-14.8V Li-lon/LiPo)
Battery capacity range:100-9900mAh
Fast charge current:0.1-8.0A (1C max for Li-lon/Po)
Fast charge methods:linear, reflex, impulse and 4-step
Fast charge termination😛eak detection for NiCd and NiMH "constant current / constant voltage" for Li-lon / LiPo optional thermal cutoff for all battery types
Peak sensitivity:0-25mV adjustable
Trickle charge current:0-500mA (n/a for Li-lon / LiPo)
Discharge current:0.1-10.0A adjustable
Dishcharge cut-off voltage:0.1-1.1V per cell NiCd & NiMH 2.5-3.7V per cell Li-lon / LiPo
Temperature cut-off range:50-132°F (10-56°C)
Cycle count one to ten cycles (n/a for Li-lon / LiPo)
Cycle cooloff delay:1-30 minutes adjustable
Battery memories:10
Display type:8 line, 21-character LCD (168 characters max)
Graphical displays:Graphs charge and discharge voltage curves

 

[45/70]

Steve, I would say that with the right adaptation, charging cradle setup, or whatever you come up with, that your Duratrax chargers should work very well.

The 8A capability is a big plus. If you do go the parallel charging route for your Li-Ion cells, keep in mind that the current required will be the same as if the cells you parallel, are one big cell, for example four 2000mAh 18650 LiCo cells will in effect be one 8000mAh 4.2 volt cell, as the charger sees it.

I never really had any problems using my Dynam Supermate DC6, which is only 5A, or 50 Watts (whichever comes first). Last week I picked up an iCharger 106B+, which is 10A/250 Watt, so I don't ever see having any problem now, as far as charging batteries/cells for my lights anyway. In fact, I'm considering setting up the Dynam with a more or less attached power supply and charging cradle, for a more portable solution, and of course as a backup, as well.

One more note about parallel charging Li-Ion cells, just in case you don't come across it, never charge cells with a voltage differential of more than +/- 0.5 Volt (maximum spread), preferably much less, and always adjust the charge rate to suit the smallest cell that is in parallel. ie. maximum charge rate = maximum charge rate of the smallest cell x the number of cells that are in parallel. I personally, avoid this last part entirely, by only charging like cells.

And again, read up as much as you can on the subject, rather than just going by what I'm telling you. I don't want to hear about how Steve's house burned down because 45/70 said so and so.😱🙂

Dave

 

[acrosteve]

I did see the 0.5 differential issue, but did not really see a recommended solution. Say I have a cradle of sorts that allows for parallel charging. If I put the batteries in the cradle(including any that are outside the differential recommendation), would they equalize in a short amount of time, or would I have to manually discharge or charge any in question to get them to within 0.5v?

 

[45/70]

The problem with paralleling Li-Ion cells with a voltage differential greater then 0.5 Volt, is that the rapid inrush of current that can take place between Li-Ion cells, could cause overheating of the cell(s) and possible "thermal runaway" ie. a "vent with flame" incident.

The solution is to charge the cells that have a lower voltage up until they are at a similar voltage (pertaining to LiCo Li-Ion cells, this means a similar state of charge) separately, before attempting to charge in parallel with the other cells.

In reality, for cells to have a voltage differential of 0.5 Volt, we're talking about nearly discharged cells and fully charged cells, or discharged cells and nearly fully charged cells. This is because the voltage range between a fully charged LiCo Li-Ion cell (4.2 volts OC) and a fully discharged cell (3.6 Volts OC) is only 0.6 Volt. You're not likely to be trying to charge cells that are in such a different state of charge very often. That said, I personally prefer that the cells differ by no more than 0.1 volt of each other (maximum spread) before charging cells in parallel.

Dave

 

[acrosteve]

Thanks for all the info.

In the end, I think I am going to get a TK40 and not worry about anything except my AA Eneloops. Just seems so much simpler, and the light is top notch.