Xtar VP2 or Opus BT-C3100

Batteries and Chargers Chargers
1

Having read many threads. I think these are the two in the finals. Argument is welcome. Below is my perception from reading all those threads. I may easily have got some things wrong. From lack of proper understanding, or just getting confused with all the reading.

VP2:

+

  • Seems to be the most versatile if you have no interest in non-Lithium chemistries (I don't need a charger for that - I have one).
  • It takes long protected 18650 and CR123.
  • Apparently very accurate and excellent analysis capabilities.
  • Up to 1A charge current.
  • Will physically accept CR123 cells but I am not sure it has a way to provide the proper voltage.

-

  • Has 2 slots and costs more than the Opus BT-C3100
  • Half the maximum charging current of the Opus BT-C3100
  • With an adapter, this would NOT be suitable for charging C and D NiMh cells. Not really a negative - just a neutral point for completeness.

Opus BT-C3100:

+

  • 4 slots
  • Cheaper than VP2 with twice the slots and twice the max charging current in 2 slots.
  • Takes larger diameter batteries in two slots.
  • With an adapter, this would be suitable for charging C and D NiMh cells. With higher current than my existing NiMh charger.

-

  • Shipping with V2 firmware, but that has not fixed all the problems
    • Power supply is being upgraded but still seems too small for full rated charging current because of peak demand pulses from charger.
    • I believe I have seen reports of one slot overcharging batteries.
    • Charging voltage switches accessible only by opening the case. What were they thinking? Yes it lowers build cost, but?
    • No identified way to apply a firmware upgrade in the field or other methods.
  • Hardware issues with excessive current pulses exceeding the capability of the power supply. May require an upgraded unit to perform properly.
  • Will not accept CR123 ? - not positive - from what I gather there are two parameters; ability to physically accept the cell and suitable voltage.
  • Annoying approach to cooling fan operation. Instead of on and off it should be always on and use variable speed control.
  • Apparently not as intuitive or extensive functions/controls as VP2.
  • It will not physically allow some protected 18650 cells.

My inclination at this point: VP2. If the Opus unit was at firmware release 3 and hardware release 2; I would go that way (after seeing tests).

2

The VP2 is a charger only, no analyzation capabilities what so ever. I have a VP1 and don’t use it anymore now that I have the BT-C3100, unless I’m in a real hurry and need to charge more than 4 cells at the same time. As for not being able to upgrade the firmware, that applies to both units, if not the majority of chargers on the market. And the VP2 may seem more intuitive, but that’s because it only has a single button to control chraging current. Other than the voltage switch being on the inside, which is unimportant for some, the Opus would seem to offer more capability and flexibility. Say you wanted to charge a 10440 and 18650 at the same time, the VP2 would have to charge both at the lowest rate unless you want to risk damaging the smaller cell. The Opus would allow you to charge each at it’s optimal rate and test the actual cell capacity. I’ve done analyzation runs with 10440, 14500 and 18650 cells at the same time. With the GB pricing still available, I wouldn’t opt for a VP2. Heck if I could trade/sell in my VP1 for a decent price, I’d use the proceeds for another Opus. If you’re on a budget but still want a charger analyzer, you might also consider a LiitoKala Lii-260, though I’m not fond of using it as it gets the cells much hotter than the Opus, since it doesn’t have a fan.

KuoH

3

I own both a VP1 and a BT-C3100. I don’t have a need to support anything other than NiMh and standard 4.2V Li-Ion cells. My big objection to the VP1 is that it only has two slots, and really cannot tell you much useful about the cells being charged. Keep in mind that only 2 slots on BT-C3100 can charge at 2 amps. I also have an SP2. I find that two slots just aren’t enough, and if you are charging ~3000mAh cells, the I4 is painfully slow with all 4 slots in use. Most of my lights use 3x18650’s, so a two bay charger is a Nuisance.

The fan noise I regard as red herring. If you aren’t in the same room with it, you aren’t going to hear it. From the complaints, you’d think it was a 120db Siren going off. It isn’t. The power supply issue is real, unresolved it can make the reported charging mAh grossly inaccurate. For $11 you can buy a 12V/6A supply on eBay, and then that issue is ancient history. Plan B is to install a 200,000mfd low ESR cap across the output of the existing power supply. My point is that the power supply issue can be addressed fairly easily if you care. The Power supply issue does NOT cause the reported discharge capacity to be inaccurate.

At $50 including the 6 amp ‘brick’ supply I bought, I think the BT-C3100 is still a great deal.

I am unaware of any 18650 cells (protected) that are longer than 70mm. Some of mine are near 70mm, but none are longer, and 70mm is the limit on the BT-C3100.

Having spent part of my life building commercial electronic equipment that was UL listed, I’d never even put switch on the unit to support anything other than NiMh and 4.20 volt Li-Ions. To much of a product liability issue. In fact I doubt you could get UL or ETL to approve such a device given the potential disasters that can occur from setting the switch improperly(and neither the Xtar chargers or the Opus Chargers bear either a UL or ETL label). The CE label says next to nothing about safety. The external power supply does carry the appropriate regulatory approvals. That’s strictly a product liability issue.

My thoughts

4

OK. I screwed up several things. For whatever reason I believed the VP2 had diagnostics. So, advantage Opus.

Intuitive: Null for both.

Cell length and improperly charging one of the 2A slots. I believe I have seen comments about that. But I can not find it. Information overload strikes again. Everything I can find looking now seems to support that slot size as enough.

There is also an in-progress thread on odd coincidences of statically unlikely identical readings from pairs of slots.

Fan noise. It is in the same room as I am. I have gone to considerable lengths to build a quiet PC. It is difficult to determine if it is running if you don't see flashing lights for drive activity. I actually spent appreciably more on the build than if I had ignored noise. From personal experience I would be driven crazy by a constantly varying speed on an external fan. Those little ones can be particularly nasty because of their likely sound spectrum.

Switch. I really have no idea if this is important. Do the two voltage options for Li deal with multiple chemistries or just variants of a single chemistry? I have not used anything but Ni batteries. I am considering a use for the iron based cells. I understand the comments on the standards groups. But if I need to access the switch I would consider it unacceptable. I believe (and I have not been very good at this) that the VP2 has a similar switch on the outside.

Firmware: Most vendors of many things will not support customer firmware updates. Sometimes it is an issue of cost to provide the access. Sometimes, it is just the urge to keep the capability from end users. Some times fear of the customer doing it wrong. Properly implemented and documented, with suitable disclaimers that should not be a serious issue and keep the parasitic lawyers off their backs.

At least a published company policy to return for firmware updates and an estimated cost. Who pays shipping, etc.? Does it have to go to China? Maybe they could pay an enthusiast or company here in the US to do it. A PC and the proper interface should be all that is needed.

I have a whole bunch of home automation controllers that have no real process for updating their hardware. Adopters, particularly early adopters, pay a large price for supporting them when they started. You have to buy a new device. They are not inexpensive.

The firmware is pretty much my biggest concern. With the current exception of needing some capacitors added, everything still flaky is probably a firmware issue. I know this is silly, but it almost feels like they do not own an oscilloscope.

How about one slot overcharging. Is that real?

I appreciate the feedback. And apologize for my lack of "correct". Information overload across weeks. No excuse; but it happened. I need to take notes.

5

Which slot is overcharging on the opus ?

6

The only thing that is a real problem for you is the fan, it is too noisy if you have to be in the same room and do other stuff.

Other than that the Opus works OK as it is, especially if you are in no hurry and only use the default current (500 mA) when charging. Then the issues with underpowered powerbrick goes away.

That said, I still prefer to use my Pila IBC to charge my 18650 Li-Ion batteries and my MAHA MH-C808M or my MAHA C9000 for my NiMH batteries. But in a pinch I could easily manage with only the Opus. The ability to easily (if slowly) check the capacity if Li-Ion batteries is great! That was the main reason I bought it. I have discarded quite a few batteries thanks to the Opus. No duds left!

7

I like the Opus for what it can do and its features.

I don't use it much due to the fan noise.

8

I recall one use had problems with the fourth slot. I don’t know of anyone else with this issue.

It sounds like the fan will drive you crazy. For me it varies. Sometimes I would rather just turn the fan off, other times I really don’t mind it.

The switch inside the Opus is an undocumented feature and should be treated as such. The termination voltage does not change. I don’t think the firmware accomodates it.

I wouldn’t expect firmware updates from Xtar let alone Opus.

9

What does the switch do? Do you have a link to any info on that (potentially including the termination voltage not changing)?

10

Voltage. 4.2, 4.35 and one other I think

Or are you asking in the sense if it doesnt change termination voltage then what does it do?

11

Correct, that’s what I’m asking.

12

Well, I only tested charging to 3.7V, and default 4.2V (4.35V was tested here).

The problem is Discharge is always to the same 2.8V instead of adjusting (I am sure I tested all three for discharge). So the switch only affects the charging termination voltage.