EN-EL15 v. EN-EL15a v. EN-EL15b v. EN-EL15c?

[David H. Hartman]

Is it safe to use a Watson B-3410 7.0v 1800mAh 2.6Wh EN-EL15 replacement battery pack that came with my D800 as a throw in, in my D850. I was hesitant to use it with the D800 at first but others reported no problems with them. The Watson battery packs are sold by B&H Photo Video, NYC, NY USA.

Since I have two EN-EL15(s) and the EN-EL15b that came with my D850 I probably will never need to use the Watson in the D850. I'm wonder if it's safe in a pinch to use the Watson?

Dave

[I'm going to pack the Watson EN-EL15 replacement with the D800, outside the camera]

[Erik Lund]

The only risk is that it might suddenly loose power,,, third party batteries has a tendency to be unreliable in that regard. Really annoying if it was on a day you depended on it,,,

[Matthew Currie]

The Watson EN-EL15 that came with my D7100 in 2014 has lost about half its power over the years, wjhie the original Nikon one is down only a little.  But that's still enough for an emergency backup to throw in a pocket.  I think Watson is probably a little better than many third party batteries.

[David H. Hartman]

The Watson and my D800 are resting peacefully in a box where they will remain until I figure out what to do with the D800. These days I don't need a backup on my person. The one time I needed a backup I was stuck scrapping an HP5 cassette spool on the curb. The cassette fit so tightly I was afraid of damaging my week old F2. I heard my editor saying, "Does this guy know what he's doing?" He loved the work so I got many more jobs.

Yes, I took a job with only one camera and it was only one week old. Not too smart!

Dave

[Øivind Tøien]

I got 4 EN-EL15 (Li-Ion 20) and one EN-EL15b and both the MH-25 and MH-25a chargers (the latter came with the D500), which I use interchangeably and have not noticed any marked difference in the charging time. Both are rated for 8.4V/1.2A so that would not really be expected, although there is of course a possibility that the latter is smarter with respect to the reduced current output that is usually applied when approaching full charge.

What isn't mentioned is that the old  MH-25 charger will not in practice bring the new types (b,c at least) up to full capacity. You need the MH-25a for that.

Edit: I just checked my MH-25 and the EN-EL15b showed 100% just after being fully charged and voltage was 8.29V unloaded. This is quite reasonable for a battery charged to a cutoff at 4.2V per cell.

The first spare EN-EL15 for my D7100 stopped working after only 7 months - would not charge in the MH-25 and charged very little with a small Watson charger. It looked like one of the cells had gone bad - any of my attempts to revive it not to be mentioned here failed, so I put it aside and bought a new spare. This spring after it had been sitting in a safe place for several years, I thought I could just as well open it up to see if I could convert the casing to a spare power cable.

When I measured the cells, one was pretty much fully charged, while the bad cells was still at 2.5V, which my information searches at the time indicated was above the voltage (2.0V) where dendrites and shorts where likely to form and is considered unsafe. So I hooked that cell only up to a single cell Li-Ion charger designed for a smaller cell and endpoint 4.2V which is in the lower range for end point voltages, so currents should be very safe, and monitored the voltage as it charged. It finally reached very close to the voltage of the good cell. Apparently there is an internal voltage equalization that had a few mV difference in set point for the two cells, so at the end of the charging the good cell increased its voltage slightly. Temporarily closing the battery and inserting it in the mh-25 it would now charge for a short while, and worked normally in the cameras, so after running it though a normal discharge-charge cycle, and observing no significant drop in voltage of either cell over a few days, I decided it was working normally and re-glued it. It is currently dedicated to my battery grip. When I checked it now after sitting unused for several months it was at 92% charge and listed as new in the D500.

One could wonder why it went bad in the first place. Perhaps there could have been a glitch in the voltage equalization circuitry - possibly induced by a single recharge in the non-original dumb Watson charger although the latter does not quite make sense. I am still a bit careful where I store that battery - it will definitely be discarded if it shows a new failure again, but so far so good.