XTAR VP4 verses OPUS BT C3100

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Tacoboy
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XTAR VP4 verses OPUS BT C3100

I want to order a battery charger in the next day or two and want something that can tell me the realistic capacity of the Li-ion battery (like the 26550).
I’m buying some flashlights and 26650 batteries for an outdoorsman for Christmas and I want to make sure the batteries I buy are in good working order.
So I guess I could get for a charger like the XTAR VP4 or OPUS C3100.
But I really know very little about chargers, can anyone point out the practical features that might make me decide one over the other?

eas
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If you want something that will give you a good mesaurement of lithium ion capacity, I’m pretty sure that the VP4 won’t do it. There are some lithium chargers that will give you the total amount of current used to charge a cell, which will actually give a reason estimate of capacity for Li-ion’s, provided they are in good shape, but i don’t think the VP4 even does that.

The best way is to do a discharge test. The Opus can discharge test Li-ion cells, as can the Liitokala. I think people have squeezed 26650 cells into the Opus, but I’m not sure.

RMM
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The VP4 does not do capacity measurements.  

The Opus will fit (2) 26650s in it, you just have to be careful not to bump the charger or else they will pop out.

The Opus' measurements aren't particularly accurate, but they can give you a good idea whether your cells are getting old and a relative idea of how two cells compare.  I'd say that at the lower charge/discharge levels its accuracy is probably off around 5-10%.  It is also a relatively fast charger and it has a lot of cool options--unrivaled at the price point.  The fan is loud and prone to failure, but it is easy to fix/replace.  It is a cool charger but I wouldn't gift it to anybody that doesn't like to tinker with things until they fix the fan issue.  My copy (v2.1) also only charges to around 4.15v, but that isn't as big of a deal breaker to me as the fan is.  

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Tacoboy
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RMM wrote:

The VP4 does not do capacity measurements.  

The Opus will fit (2) 26650s in it, you just have to be careful not to bump the charger or else they will pop out.

The Opus’ measurements aren’t particularly accurate, but they can give you a good idea whether your cells are getting old and a relative idea of how two cells compare.  I’d say that at the lower charge/discharge levels its accuracy is probably off around 5-10%.  It is also a relatively fast charger and it has a lot of cool options—unrivaled at the price point.  The fan is loud and prone to failure, but it is easy to fix/replace.  It is a cool charger but I wouldn’t gift it to anybody that doesn’t like to tinker with things until they fix the fan issue.  My copy (v2.1) also only charges to around 4.15v, but that isn’t as big of a deal breaker to me as the fan is.  

I’m buying flashlights and batteries for the outdoorsman, but the charger is for me to tinker with.
Once I know batteries are in good working order, I’ll give him the flashlight and batteries and a simple generic charger.

NightSpy
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My Opus was the most expensive charger I ever bought and I really don’t think it is the best. XTAR seems to really excel at good reliable every day chargers. The Opus has been a lot of work, and the reliability is dubious. The only use I have for the Opus is testing capacity for my NiMh and LiIon cells. I’ve done that and now the unit is idle. And I’m waiting for the replacement fan which is on a slow boat as I type this.

Tacoboy
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The main reason I bought the Opus was to get the mAh capacity, but all I ever seem to get is 4 dashes (- – - -)?

flydiver
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My Opus works fine. Based on experience with tiny little fans I did a preventative lube on it. The charger and fan work fine, if a little whiny.
FWIW I also have an Accucel-6 hobby charger. It’ll do more ‘things’, but for single cell NiMh and Li-on testing charging the Opus has just about taken over all that work.

BTW-the AC-6 ALSO has a tiny fan and it’s ALSO semi-crap, needing lube on a regular basis. I warned people in the purchase thread that this absolutely would be an issue. ALL fans THAT tiny and cheap are not very good.

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kuoh
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Same here, I’ve had no issues with charging or testing any of my batteries in the Opus. Even the still original fan runs fine, though as most have noted, it’s quite whiney. Luckily, now that it’s winter and the house is colder, it doesn’t run near as much. I’ll probably put it on top of one of those cheap laptop coolers eventually if the noise starts to bother me. Also, contrary to some of the other posters here, my Xtar VP1 is the charger that sits idle the most. Although it’s display is nice, it is the only charger I have that under charges. I only use it if the other chargers are busy, even then I have to take the charged cells out of the Xtar and top them off on another charger. I don’t know what the VP4 goes for now, but the Opus is still available for under $40 I believe. If cost is primary and the VP4 is cheaper, then go for it. If it’s the same, then I’d still opt for the Opus, despit the complaints.

KuoH

flydiver wrote:
My Opus works fine.
wight
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kuoh wrote:
Same here, I’ve had no issues with charging or testing any of my batteries in the Opus. Even the still original fan runs fine, though as most have noted, it’s quite whiney. Luckily, now that it’s winter and the house is colder, it doesn’t run near as much. I’ll probably put it on top of one of those cheap laptop coolers eventually if the noise starts to bother me. Also, contrary to some of the other posters here, my Xtar VP1 is the charger that sits idle the most. Although it’s display is nice, it is the only charger I have that under charges. I only use it if the other chargers are busy, even then I have to take the charged cells out of the Xtar and top them off on another charger. I don’t know what the VP4 goes for now, but the Opus is still available for under $40 I believe. If cost is primary and the VP4 is cheaper, then go for it. If it’s the same, then I’d still opt for the Opus, despit the complaints.

KuoH

flydiver wrote:
My Opus works fine.
The VP4 simply won’t do what OP wants. [HKJ’s recent review actually showed that it’s much less capable than the VP2 – which I didn’t realize previously! That’s probably why HKJ hadn’t bothered to review the VP4 in the past.]

Still fine, still on a break. One day I’ll catch up with you folks! previous wight catchup Wink
list of my drivers & variants (A17DD, FET+1 stuff, WIP stuff, etc)

flydiver
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I do have mine sitting in a cool basement (low 60*F) and on top of a PC fan. Not sure it makes much difference in the Opus fan engagement. But then, when I am using it it’s often cycle testing 4x batteries so that’s a fair amount of heat to deal with, especially on discharge. My AC-6 fan kicks on with a single cell and 1A discharge. It is just about silent though (runs slower).

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NightSpy
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flydiver wrote:
My Opus works fine. Based on experience with tiny little fans I did a preventative lube on it. The charger and fan work fine, if a little whiny.
FWIW I also have an Accucel-6 hobby charger. It’ll do more ‘things’, but for single cell NiMh and Li-on testing charging the Opus has just about taken over all that work.

BTW-the AC-6 ALSO has a tiny fan and it’s ALSO semi-crap, needing lube on a regular basis. I warned people in the purchase thread that this absolutely would be an issue. ALL fans THAT tiny and cheap are not very good.

How close are the capacity readings between the Opus and the AC-6?

flydiver
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NightSpy wrote:
How close are the capacity readings between the Opus and the AC-6?

Maybe about 20% variation. Couldn’t tell you for sure which one is right, especially with NiMh since they tend to be all over the board depending on their history and abuse status.
Doing several cycles of the same battery in the Opus is generally netting me within 10% and sometime better than 2%. But that’s comparing apples to apples.

I’ll try doing a cycle on a Li-on in each unit. I can reference the AC-6 with a wattmeter to see if those 2 agree.

Philosophical note: I’ve been doing NiXX charging for over 15 years on a bunch of chargers, some not so hot, some very good. I’ve been doing lithium charging for over 6 years (radio controlled planes, now LED lights) with a number of chargers, most of them decent to very good. I see a number of people in this forum get disturbed that their charger does not charge a Li-on to 4.2v, maybe 4.15v.
First -that’s NORMAL. HJK has said it numerous times. It’s useless to try and get that ‘last’ 0.05v out of a Li-on, it’s an almost meaningless amount of useable current, and it’s better for the battery to be slightly undercharged in the long run anyway. Lighten up folks. Smile
Second – these really are semi-exact tools and devices. As long as they are doing a decent job, not exceeding charge and discharge limits, and doing it with reasonable accuracy and reliability, that’s just fine with me. It’s pretty useless to go OCD over 0.05v in charging anything. Nor are you likely to ever get any better than within 10% of the real capacity of a rechargeable battery. How do you REALLY know what the capacity is? By specs? We know how good a lot of those are. Wink The chargers are better used to gauge the general quality of the battery and track it’s performance over the long haul. These are not electronic micrometers for under $50.

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SIGShooter
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NightSpy wrote:
flydiver wrote:
My Opus works fine. Based on experience with tiny little fans I did a preventative lube on it. The charger and fan work fine, if a little whiny.
FWIW I also have an Accucel-6 hobby charger. It’ll do more ‘things’, but for single cell NiMh and Li-on testing charging the Opus has just about taken over all that work.

BTW-the AC-6 ALSO has a tiny fan and it’s ALSO semi-crap, needing lube on a regular basis. I warned people in the purchase thread that this absolutely would be an issue. ALL fans THAT tiny and cheap are not very good.

How close are the capacity readings between the Opus and the AC-6?


I’m not flydiver but my AC-6 reads about 9% – 10% lower than my Opus.
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flydiver wrote:
NightSpy wrote:
How close are the capacity readings between the Opus and the AC-6?

Maybe about 20% variation. Couldn’t tell you for sure which one is right, especially with NiMh since they tend to be all over the board depending on their history and abuse status.
Doing several cycles of the same battery in the Opus is generally netting me within 10% and sometime better than 2%. But that’s comparing apples to apples.

I’ll try doing a cycle on a Li-on in each unit. I can reference the AC-6 with a wattmeter to see if those 2 agree.

Philosophical note: I’ve been doing NiXX charging for over 15 years on a bunch of chargers, some not so hot, some very good. I’ve been doing lithium charging for over 6 years (radio controlled planes, now LED lights) with a number of chargers, most of them decent to very good. I see a number of people in this forum get disturbed that their charger does not charge a Li-on to 4.2v, maybe 4.15v.
First -that’s NORMAL. HJK has said it numerous times. It’s useless to try and get that ‘last’ 0.05v out of a Li-on, it’s an almost meaningless amount of useable current, and it’s better for the battery to be slightly undercharged in the long run anyway. Lighten up folks. Smile
Second – these really are semi-exact tools and devices. As long as they are doing a decent job, not exceeding charge and discharge limits, and doing it with reasonable accuracy and reliability, that’s just fine with me. It’s pretty useless to go OCD over 0.05v in charging anything. Nor are you likely to ever get any better than within 10% of the real capacity of a rechargeable battery. How do you REALLY know what the capacity is? By specs? We know how good a lot of those are. Wink The chargers are better used to gauge the general quality of the battery and track it’s performance over the long haul. These are not electronic micrometers for under $50.

Did you race 1/10th scale 4wd offroad back in the NiCad days?
That last couple of percent did make the difference in winning or loosing Flat Stare
Sanyo was the bomb back in those days!

flydiver
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Just planes, no racing, no ultra high performance.
Since battery performance is related to temperature (higher is better up to a point) and NiCad high performance packs lose voltage FAST after a charge I can see where in that particular case it made a difference. Abuse ‘em or lose.
Interesting in the RC community that huge numbers of people have no clue how NiXX works or how to charge them anymore. They keep asking about setting cell counts, amperage/voltage, and how to balance them…. Silly 5 years ago people could barely deal with lipos. Now they can barely deal with NiXX.

For anyone just using rechargeable for fun and not having a yardstick to measure against you probably couldn’t tell.
For LED lights it’s the same, unless you are going to sit with a stopwatch and a super accurate voltmeter to measure each electron passing by. If that’s your thing, fine, but don’t make the rest of the people paranoid or think that’s the standard to go by.

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tatasal
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I have tried discharging a Panasonic NCR-B cell in both my iCharger 106B and Opus v2.1 and the difference between the two was 8 mAh. The Xtar VP2 was used to charge the Panasonic cell before each discharge session. Pictures of these result posted in one of the Opus threads here in BLF somewhere.

Edit: I have found the photos of the mah results:

! photo IMG_3932_zpsad830c18.jpg!
! photo ce3ef675-6377-43d2-9de9-26e16843a7c6_zps17f3dfd9.jpg!
! photo IMG_3941_zps91a14393.jpg!

However, Flydiver and I are in the same belief: to quote…..

First -that’s NORMAL. HJK has said it numerous times. It’s useless to try and get that ‘last’ 0.05v out of a Li-on, it’s an almost meaningless amount of useable current, and it’s better for the battery to be slightly undercharged in the long run anyway. Lighten up folks.

Second – these really are semi-exact tools and devices. As long as they are doing a decent job, not exceeding charge and discharge limits, and doing it with reasonable accuracy and reliability, that’s just fine with me. It’s pretty useless to go OCD over 0.05v in charging anything. Nor are you likely to ever get any better than within 10% of the real capacity of a rechargeable battery. How do you REALLY know what the capacity is? By specs? We know how good a lot of those are. Wink The chargers are better used to gauge the general quality of the battery and track it’s performance over the long haul. These are not electronic micrometers for under $50.

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flydiver wrote:

Maybe about 20% variation. Couldn’t tell you for sure which one is right, especially with NiMh since they tend to be all over the board depending on their history and abuse status.
Doing several cycles of the same battery in the Opus is generally netting me within 10% and sometime better than 2%. But that’s comparing apples to apples.

I’ll try doing a cycle on a Li-on in each unit. I can reference the AC-6 with a wattmeter to see if those 2 agree.

Philosophical note: I’ve been doing NiXX charging for over 15 years on a bunch of chargers, some not so hot, some very good. I’ve been doing lithium charging for over 6 years (radio controlled planes, now LED lights) with a number of chargers, most of them decent to very good. I see a number of people in this forum get disturbed that their charger does not charge a Li-on to 4.2v, maybe 4.15v.
First -that’s NORMAL. HJK has said it numerous times. It’s useless to try and get that ‘last’ 0.05v out of a Li-on, it’s an almost meaningless amount of useable current, and it’s better for the battery to be slightly undercharged in the long run anyway. Lighten up folks. Smile
Second – these really are semi-exact tools and devices. As long as they are doing a decent job, not exceeding charge and discharge limits, and doing it with reasonable accuracy and reliability, that’s just fine with me. It’s pretty useless to go OCD over 0.05v in charging anything. Nor are you likely to ever get any better than within 10% of the real capacity of a rechargeable battery. How do you REALLY know what the capacity is? By specs? We know how good a lot of those are. Wink The chargers are better used to gauge the general quality of the battery and track it’s performance over the long haul. These are not electronic micrometers for under $50.

+1.
I own (presently) 5 different chargers and they vary a little here and there (plus/minus a few percent).
But that’s ok. I’m not gonna go OCD over a tenth of a volt! I’ve got more important things to worry about.

Lights out! That's when things get interesting...

flydiver
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This has gotten a bit off topic, but I did test the difference between the Accucel-6 and the Opus C3100 v.2.1.
Laptop pull, Samsung ICR18650-28A, therefore of unknown capacity and history.

Charged at 0.5A on AC-6 and then discharged to 3.0v 0.5A > 2735mA Recharged on AC-6, placed in Opus on Discharge 0.5A > 2527mA
208mA difference
FWIW the AC-6 saw it as 4.20v when full, the Opus as 4.22v, and a DMV as 4.19v.
When I check a lion charged on the Opus the DMV generally sees it around 4.17v.

Which is right? I don’t know, but I consider that amount of discrepancy to be of little concern.

Mostly what the AC-6 can do (besides charge my RC batteries which require balance) is charge a goodly number of things and charge faster if I want or need to. The voltage readings are not accurate when charging. You can get close only by setting the charge at a very low rate.
Unless you set up a jig it can only do a single cell.

The Opus can do 4 cells at a time. The voltage seems to be accurate while charging, so I know where it’s at in the process. For Li-on it charges as fast as I need it to. It can do a cycle without having to make it a 2 step process as the AC-6 does.

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When the chargers are done with discharge are you checking the claimed 3v with a single DMM? Might be that one device actually takes them to below 3v or not quite too 3v or some such which would add some or detract from the comparable capacities.

Photons Away
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Tacoboy - Must just say that the XTAR VP2 is a better charger than the XTAR VP4 just in case you may still be considering one of these.

flydiver
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It might but I’m not sure how much it matters unless you are being fussy about it. Most lithium simply go over the edge around the low 3’s and simply have no real workable capacity left. In addition it hammers the chemistry. I generally try to stay above 3.2v.

At a 0.5A discharge there is always rebound. The lower the draw the lower you can end up taking it down. Stock cut-off on the AC-6 is 3.0v, on the Opus they claim 2.8v. I can diddle the AC-6 by using NiXX setting if I want but didn’t for this case. I did not compare the actual end point recovery of both devices, but the recovery on the AC-6 was to 3.42v. I unfortunately did not measure the Opus.

For example, I have a Milwaukee Lion 18v tool pack I just opened today. 5-cells, 3 over 4v, and 2 at mid-3v. (kind of corroded inside-I think they got a bit wet). I individually charged up the lowest cell at 0.5A until full on the AC-6. Then I tried a discharge at 1.0A as I had hopes these might be higher output and would like to use them that way. The cut-off was 3v, the capacity used was 319mA and the rebound was all the way to 4.0v. In other words, it puked. There may be some low grade capacity in those cells but there sure is no punch. I’ll test them later with a lower draw to see if they might be powerbank candidates or other low draw device.

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Tacoboy
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Photons Away wrote:

Tacoboy – Must just say that the XTAR VP2 is a better charger than the XTAR VP4 just in case you may still be considering one of these.

My Opus BT-C3400 arrived on Wednesday (12/17).