Battery charger - Opus BT-C3400

[stuartv]

All my dive lights use 18650 Li-ion rechargeable batteries. They all came with "free" chargers and batteries. I had also bought the Tenergy charger + 2 battery pack from DGX and 6 Sanyo NCR 18650BF batteries from eBay.

The Tenergy batteries are spec'ed at 2600 mAh.

The Sanyo batteries are spec'ed at 3400 mAh.

I felt like the Tenergy charger has been doing an okay job, but I wanted something that would charge 4 batteries at a time. I also wanted an "intelligent" charger that will recondition the batteries when needed. I also wanted a charger that would charge at, at least, 1000 mA (charging 4 batteries simultaneously). I also was hoping to find one that will test the batteries and tell me their actual capacity.

I searched around here on SB and found a lot of posters saying that they use a Nitecore intelligent charger and are happy with it. I found a few posts recommending an Xtar charger. Neither of those companies has a charger that I could tell would actually test the batteries and tell me each battery's actual capacity. Plus, the Nitecore only charges 4 batteries at a time with a max rate of 500 mA.

I found, I think, one post mentioning the Opus BT-C3400, but only that the poster was getting it. No report on it after actually using it.

The Opus claims to charge 4 batteries simultaneously, with 1000 mA. And it has a mode for reconditioning batteries. And it has a mode to test actual battery capacity. All 4 slots are independent, so you can have 4 batteries in it and have each battery going through a different operation at the same time. 1 charging, 1 doing a charge/test cycle, 1 doing the recondition cycle, etc., all at the same time. It will also handle Ni-Mh AA batteries (and other sizes), which I use a lot of in my musical equipment. So, I bought one. $47, with 2-day shipping from a seller in Sacramento, CA, on eBay.

I received it on Monday and have used it to test/charge a pile of batteries now. And here are the results.

The Sanyo batteries (spec'ed at 3400) all tested over 3300. 2 were over 3400.

The Tenergy batteries (spec'ed at 2600) tested 1 at 2700+ and 1 at 2800+.

2 no-name, black/gold labeling, batteries that came with one of my lights were labeled as 4000 mAh. They tested at just over 1000. I left them going through a recondition cycle this morning to see if that makes any difference.

It will be comforting, in the future, to know I'm getting in the water with batteries that I can have some confidence in, because I've actually measured their true capacity. And to know when a battery is really dead and I can just throw it away.

All in all, I am very happy with the Opus BT-C3400 charger. For me, it was definitely worth the extra money over the less expensive Nitecore or Xtar chargers.

 

[stuartv]

A small update. I used this charger to also charge/test some Ni-MH AA batteries I have. In the first batch of 4, 3 of them tested at around 2600mAh. One only tested at a bit under 1100.

I took the 3 out and did the Charge Refresh mode on the one. That does something like 5 full charge discharge cycles or something. When finished, the battery tested at around 2600. Nice!

 

[scuba5150]

Thanks for the great information. I've recently switched to rechargeable batteries for my dive light and have found the world of rechargeable batteries and chargers to be confusing. The recharging unit you found sounded so good, I just ordered one myself. Thanks again.

 

[spoolin01]

These are great chargers, aren't they? They seem like the Li-Ion equivalent of the nice LaCrosse 4-channel NiMH intellichargers.

If you want more information, google the BT-C3100 which is apparently the same charger. There are some reports on the various generations of the charger over at candlepowerforums, and elsewhere.

I have the BT-C3100 v2.2, which can be had for $38 or so lately. It appears to have a bit better specs than the alternatives - higher charge and discharge currents, a separate display for each channel, wider range of battery sizes, and best of all, it charges both LiIon and NiMH/NiCd. One charger for almost all cylindrical rechargeables. You can get adapters so you can do D-cells as well.

I find it useful for matching batteries for capacity, and identifying those that have gone bad. I quickly found that the UltraFire 18650s I got were junk, or had become junk at some point shortly after purchase.

The capacity test results are going to be somewhat dependent on the discharge current selected, if you're trying to match specs or other reports. I've settled on 1A for Li-Ion batteries, since I mostly use those in flashlights, which typically draw 1A or more. From what I've read, Li-Ion don't typically benefit from refresh-cycling, and are best stored long-term at half-full. On the other hand, I kept my last laptop plugged in 24/7 for about 7 years, and the battery pack was still strong as new.

 

[sandanbob]

If you go to Budgetlightforum.com, you can find a lot of reviews (and, occasional group buys and other sales threads) on chargers, batteries, and lights. There aren't a lot of dive lights posted/reviewed, but there's a LOT of other information. Even some non-flashlight threads, such as budget knives.

Bob