Difference between Opus BT-C3400 & BT-C3100 v2.1?

You pretty much hit the nail on the head ‘RobertB’ concerning the C3100 v2.2 & the “3400”. No difference at all, just the model #’s.
Click on the link and it will explain the v2.1 & v2.2 difference, which was just two little items.

Have and Lii-500. Bought it just to check it out. IMO it’s not in the same league as the Opus. The Opus has a lot more capability and just flat works better. The Lii is a $20 charger, and amazing because of it, but it’s just not as good.

Both can charge and discharge and measure capacity. What are some important Opus capabilities that Lii-500 does not have? How does Opus work better?

I’m genuinely interested. I own products from both companies.

I also would like to hear your thoughts ‘flydiver’. I know which one of mine I use the most but I really have nothing sound to base that on. :wink:

I don’t have the Lii-500 but would have considered it for the price if it was a US merchant so the delivery wait wasn’t based on use of a calendar. A few things I noticed were… and I could be wrong, just throwing some things out there.

Only one bay status visible at a time
Max 1000mAh charge rate - and no fan but needs one less due to this
only two thermal sensors between banks 1/2 and 3/4

More flimsy spring contact rail, wider PCB opening and fewer soldered down attachment points, and

soldered down spring arrangement, and that solder looked poor on pictures I’ve seen

Another thing that struck me was barely any capacitors, one tiny electrolytic on the input but then only a

scattering of SMD ceramic. I don’t have one to scope but that seems like a tight budget omission.

No 3.7 / 4.2 / 4.35 selector switch

Old style open inductors - potential high freq noise source (yes I’m ignoring fan noise on BT-C3100)

Negatives about BT-C3100

Display zebra strip contact may go bad over years’ time. Display death = charger death, not reasonable to try to fix that beyond wiping the contacts and hoping for the best while any other discrete component besides main processor can be desoldered/replaced. Lii-500 is all soldered up display AFAICT.

25mm fan! Who needs to stack something on top of a BT-3100? No inherent need for it to be as short as possible. If only it were about 5mm, 10mm at most taller (original fan sits above the bottom plate of the housing so wasted space) to fit a 40mm fan, it could have been more reliable due to size AND lower RPM, and then had more room for airflow and case venting. With the right 40mm fan it could have been just about inaudible and last much longer.

… then again, I have a much better selection of higher flow to noise and current ratio 50mm fans but that’s large enough that it would require another level of customization to make it fit.

I looked at the SkyRC for $80.00 on a decent offer to compliment my two Opus chargers. Instead I purchased three replacement fans and used points to get them for £3 delivered :open_mouth:

I have posted these photos before in other threads here in BLF but since this Fan thing is again hot, I am sharing my mod that will not win a beauty contest yet fulfills my intention and experiment of a quieter fan, cooler operation, virtually no additional cost, and controlled by the charger’s own power for hands-free operation, just like the OEM fan. The fan is a 12vdc, .13A taken salvaged from a busted pc psu.

The fan sucks air from above, drawing fresh air from the atmosphere downward, passing through the batteries and cooling them in the cradle as the air pass through the rails, then go down below to cool the pcb, then exiting through the holes at the bottom of th the casing, all automatically controlled by the charger’s fan requirement as needed.

Note the holes drilled in the charger housing bottom.

The finished product:

For all intents and purposes, the current v2.2 OEM fans are already improved and good enough actually, but hey, we want to mod, don’t we?

Another negative for C3100 is that it uses PWM/pulse charging instead of constant current. Personally, I haven’t been able to find any proof that it harms Li-Ion batteries, but HKJ seems to think constant current is better.

It’s really weird that noone had the same kind of issues like me.
Even in other cases that the power supply was problematic, the results were different.

I read a article somewhere while googling pulse charging that it maybe better for the batteries. As the chemicals have time to balance out in between pulses. And stabilize before the next pulse hits. The electrolyte doesn’t get to do this with constant current.

Isn’t it preferred with nihm to pulse charge?

Another thing that’s different that was noted in hjk review iwnthe opusndoes a cc/CV charge on nihm. I’ve noticed this as well. I like it does something different. He didn’t see any harm with it doing that. I’ve put equally drained batteries in this opus and the 2000? Nihm only version I have and they are done at the same time the. Strange two charging methods but finish at the same time

In a word….control. If I JUST wanted a drop in charger, I’d have kept my Xtar VC4 I think. Nice charger. I sold it to get the Lii-500. Seemed like a respectable analyzing charger that would combine the characteristics of the VC4 and the Opus. Well, sorta.

Lii-500 functions:
Charge/Fast Test/Normal Test - @ 300/500/700/1000
Supposedly it shows internal resistance. Maybe I have a funky unit but ALL of my batteries have the same IR, so that’s a completely useless function.
I have opened it up, inspected carefully and all components and soldering seem to be OK.
The ‘backwards’ way the batteries load is a pain, but not a deal breaker. Hard to get a full load in and out easily.

Opus Functions:
Charge/Discharge/Discharge-Refresh/Test/Quick Test (internal resistance) - @ 200/300/500/700/1000/1500/2000
The Quick Test (internal resistance) is functional on the Opus, not great, but semi-reliable and reproducible. It’s a crude stick to measure the battery health.

I got these chargers as ANALYZERS. I can control the Opus more finely and do some tests I can’t on the Lii, simple straight Discharge with more current options than the Lii being a big one.

Absolutely I use the Li-500, but mostly now just as a drop-in charger. If I want some detailed battery analysis I use the Opus.
I’m certainly not going to dispute HKJ but my previous best NiXX charger [ MAHA MH-C808M AA - AAA - C - D Battery Charger] that I’ve been using for over a decade (got top reviews in CP forums from Silverfox way back then) uses pulse. I hope the MAHA engineers are not completely out to lunch. I haven’t seen any problems with it in a decade+ of hard use. I still use it regularly. I also only have a couple li-on batteries smaller than 18650 so don’t see that as a problem. I think HKJ’s objection is for small batteries as the pulse is potentially too high.

If you just want to charge and occasionally get a reasonable idea how you batteries are, the Lii seems to be fine.
If you want more control and a finer analysis with more options I think the Opus takes the lead.

FWIW anecdotally I’ve seen more issues with Lii-500 failures than Opus here on BLF, but maybe I have a personal filter active :wink: . Opus mostly seems to get people bitching about the fan. :slight_smile:

Note/clarification - I think the MAHA uses PULSE charging, while the Opus uses PWM, not the same thing, but I’m not qualified to discuss the difference or the issues.

I’ve read the same, but apparently Opus doesn’t actually do pulse charging. It does PWM which is not the same…

This is strictly regarding Li-Ion chemistry, BTW.

[quote=Pete7874]

This is one of my main concern and I’m surprised it doesn’t get mentioned more. With those high pwm surges,2amps if I m not mistaken this charger is only useable with 18650 and other high capacity cells. So that would mean all those low current charge settings are completly useless except maybe for reviving dead cells. Also chargin aaa would not be recomended.

I have one on order and I am very much thinking of returning it when it arives. Maybe save up for the skyrc

PWM > high current pulses……harmful! Yes? No?

I know li-on is not li-poly, but in the RC world for a long time it was thought that charging lipos in excess of 1C was damaging. But a number of ‘battery gurus’ and at least one high end charger manufacturer FMA-Cellpro were charging at much higher levels. This was thought to be dangerous, stupid even. Now pretty much all RC chargers and li-polys are OK to charge at 1-5C, except maybe tiny ones.

Just to experiment I did some charging (hobby charger Accucel-6 and some others) at rates higher than 1C while I monitored them. The charge would start out high, then rapidly ramp down as the charge approached completion and at the end be essentially the same as the termination on a 1C charge rate. At no time ever did I get any cell that got hot or puffed, not even warm. Cell size didn’t seem to matter. It didn’t seem to hurt them at all.

OTOH, there are still people out there advocating charging at 1/2C for safety, reliability, and long term cell health, and say it with a profound conviction, as only men can do, that they, and they alone know the proper way to charge batteries. There seems to be nothing really to support that belief system.

I don’t KNOW it, but my strong suspicion is that in the myriad ways a cell can be abused and ultimately die, being charged with PWM is way way way down on the bottom of a very long list.

As you said liion is not the same as lipo. My limited understanding is that lipo can handle way more current than liion.
A hobby charger still usses a cc cv curve even if you charge at higher rates. Do you use the opus for small cells? How do they handle the high current pulses? I would not want to charge my eneloop aaa in the opus.
How do older, recovered laptop cells handle the pwm. It is an analyzing charger after all so that would be my main use: analyzing questionable cells.
What is the use of having an 100mA charge setting if it still puts 2A pulses in the cell?

I haven’t found any problem that I can determine using the Opus for any cell, AAA and recovered laptop included. I usually don’t use it for AAA unless I’m analyzing though. I have a Lacrosse I tend to use for that. I dislike AAA, I think it’s a poor size, but a lot of things do use them.

I guess ultimately it’s a question of control and the hated fan vs. PWM, and what you are primarily going to do with it. Both have their compromises. Try to be clear what is important to you when you chose. I like control.

In terms of current handling, there are lots of BLF users that are battery abusers :smiling_imp: , looking for current output in a li-on that some of my older, larger (2200mA 3S) lipos can’t match.

If I could charge some of my cells quicker I would.

The imalent 4400mAh cell is currently getting hit with 2A and its brand new.

I’ve had no problem with different size nihm or the 20is laptopbpulls I now have 9 were new unused others used. Charges just fine cells don’t get warm or act any different then liito 100 or vc2 charging them. New or old havnt seen any capacity decrease that isn’t average for cycle life. If it does affect cells its is so tiny I’ve seen no difference in aging in cells cycle wise then before I got one. Used only w vc2 and liito li 100 for a long time. Hundreds and hundreds of charges on each. Like 24/7 they was a line of batteries waiting to be charged for several months they never got a break. I had to upgrade. And I’ve put the opus through at least a month straight non stop duty when I first got it. To get capacity. I did my own non scientific expiriment. There are 4 cells that have been paired together one set I kept in the vc2 and the other in the opus. After around 100+ more cycles they both sets had roughly the same degraded capacity. There is no way you could tell which one hae been charged by which. So the opus damaging cell life I havnt seen it. I have some NCR b that get charged almost daily with the opus with over 200 for sure. But just under 300 cycles. Still have 3300mah. At the standard 500mah setting takes 8 hours from 3.0 volt every charge. 2 amp on the 26650s.

I use a lot of cells. When I take my daughters to the park its the high school ball fields that has a park its completely dark I make a circle of lights and light the plat structure up. 15+ cells in a night easy when we go. And for a stretch we were going 5-6 nights a week before it got bitter cold 6 lights on turbo for 2-3 hours. Pkus the one im walking aroubd with and my spare clipped to me anf a duffle bag of extra lights and batteries. Theb the light my wife walks around with. From 18650 to 26650 single and series. And with heavy use I habnt seen a difference in capacity that the other batteries with the same exact cycles because they are matched. So whatever the difference its less then 1%

Yeah, I don’t think PWM kills cells, USERS kill cells most of the time. :wink:
I’ll bet keeping a cell fully charged in storage is worse for it long term than storing it at 50% and charging it every time with 2C+ and PWM. But, those kind of tests are not done in any kind of controlled manner and would take forever anyway.

My take, don’t worry about it. Pick the charger you think suits you objectives, use pattern, and budget the best.

Well, I ignored that in my post because I am open to the idea of modding, have a few parts lying around. It would be no big deal to me to tack on some capacitors across the battery rails. I looked up the datasheet for the regulator, at least the IC model # used on past revisions of BT-C3100, and it does allow for an output smoothing capacitor.

Heh, I hate vagueness in posts so I should elaborate. EUP3484 regulators (or just stamped “P3484”) are on each charging bank. A datasheet for that shows a typical app circuit with 22uF on the output, but goes on to elaborate with equations and alternates like tantalum or lower ESR electrolytic, so you could choose the capacitance and ESR to arrive at the ripple reduction you want. It’ll never be a purely linear charge, but at some point you could consider it shades of gray how little ripple there is.

However, I must confess that I have not reviewed the details of HKJ’s analysis, so I don’t know how bad the pulse is.

You might find that eventually it needs some capacitor attention anyway, as the generic little 220uF caps they have on each bank could be considered a “wear item” with a finite lifespan shorter than the otherwise viable life of the charger. I mean something is going to fail first (after the !@#$ fan) , and if it’s something you can fix for a couple bucks cost…