NiMh battery chargers
 

Hi
Our club sails RC sailboats. A good many use NiMh battery packs (5 cell), some use AAA and others AA''s. Most everyone uses rechargeable in their transmitters also. Most of the newer folks are having a hard time finding a decent charger. It seems that most of the older chargers required setting the cell count, Mah rating, battery type as well as charge current. Most of those when set properly do a fine job of charging, 95-100 % charge ( 7.2-7.4 v immediately after removing from charger), they are warm (not hot at all) they completely shut off or go to a trickle charge when finished. In the last month or so I have bought (and returned) 3 different newer chargers for testing and found them all lacking in their ability to charge NiMh. They may do Lipo fine but not nickel. They are so called smart chargers which don't require setting anything but battery type and current. That would be great if they worked. They undercharge or overcharge. They are not consistent even doing that. There are loads of brands that appear to be the same type of charger (B6V2, B6V3, TB6, B6 and etc.)). My guess is some work but others use cheap components in their processing boards which accounts for the poor results.

Has anyone bought a charger lately that does a good job on NiMh? thx

Can't believe there are no answers. I can only guess most are flyers and don't use NiMh.

Flynow:

The problem is that few modelers use Nimh batteries these days and those that do have chargers that are many years old that do the job well. I suggest that you buy an older high quality charger. Quality brands you might look for include Schultze, Sirius, FMA, Great Planes and others. I think if you posted a “Want” add on this board or other hobbyist boards you would have great success. I bought 3 Schultze chargers that sold for $300 each when new, for $75 for all three through a ad on a hobbyist message board.


You might also consider Enloop Nimh batteries. They are much superior to traditional Nimh batteries in many respects, are easily purchased and specialized Enloop chargers readily available. I have switched to Enloops for most of my hobby applications as well as household applications. Impressive batteries!

Look for Enloops on Amazon or here:

http://www.electrodynam.com/

https://batteriesamerica.com/

My Supermate DC6 charges NiMH just fine. And it determines the cell count automatically. I've charged both 4 cell and 8 cell packs and it tells me what I have. It does set the charge rate to 1 Amp but that can easily be changed. And I've charged 800Mah to 2500Mah packs without a problem.
Note: I don't like to go above 1 Amp charge rate so if my 2500 Mah packs are really low it make take two times to charge them fully since the DC6 has a time limit. But that only happened once.
PS: It is really low cost. Much lower than the major brands.

I use a number of NiMh cells in cameras and flashlights, because the new cells have a high capacity, and specifically purchasing LSD (Low Self Discharge), they have decent shelf life. I find Tenergy has great LSD AA batteries. But I also use a charger with a temperature sensor, and it can also be set to the desired charge RATE. (Which is based on the cell mAh rating). One amp for a 2500 pack, might be on the low side. I typically use .5C, but higher rates can be used to). If your charger does not display the charging current, a decent DMM can be inserted in series with the pack, to observe the charge profile being accomplished. The charger must sense the negative voltage drop which occurs near full charge.. which requires the correct observation of a 5 milli-volt drop!! So at the higher currents, the drop is more pronounced, and easier to recognize. Sadly, some chargers measure the starting voltage of the pack, to guesstimate how many cells. If you start with a pack, which still has a significant charge (and multiple cells).. it can "guess wrong".. and cook your pack!! To further understand the issues, here is a very good article on the specifics for NiMh cell charging. NOT a simple task, or at least for many of the inexpensive chargers! A valuable read: (Being a new guy to RCU, it won't allow me to post the link, but if you search fo BU-408, you'll find it).

I still use some NiMH batteries from old RTF planes for different projects. I can charge with the included charger, but the paperwork says to recycle the batts for best performance. MY question is how to run the batts down without connecting them to the entire RTF system, which includes running the TX (which uses its own 8 AA cells)? Is it possible to run the batts down by connecting them to a small 12v light bulb? I think they'd blow a small 6v bulb. what do you think? Thanks!

Yes.
But, don't run the packs down to 0v. I forget what the minimum voltage is for NiMH, but to a Google search and don't go below that per cell.
The reason they might recommend that is because NiMH / NiCad can develop a "memory". But that's not typical.
E.G.: If you regularly run the pack down to 50%, and then recharge, after about 100 to 200 cycles, if you tried to run the pack down to below 50%, the pack may "die" when it gets to 50% instead of continuing.