SONY VTC4/5 Specs - Let's Dispell the Misinformation

[DeadbeatJeff]

So, I'm sure many of you have heard of the "wonders" of SONY VTC4/5 batts, and likely have seen the chart below, which is being circulated in B&Ms, and across the internets via many platforms and networks.



If you have, you likely saw it out of context, and were told that these batts can do amazing things, like 100a 8sec bursts. Maybe you were told this by someone claiming that a 0.04Ω build or lower is perfectly fine... so long as you have these batteries. However, the chart above is not talking about single, unprotected VTC4 cells.

SONY VTC batts were never meant to be used individually. They were never meant to be seen by consumers. They are designed to be used in battery packs for high-power applications. The chart above is discussing battery packs with protection circuits.

The full PDF from SONY can be viewed here: See section 7.2.4.3, found in 7.2.4 SONY VTC4 Specs

These batteries, as individual unprotected cells, are not rated for the drains outlined in that chart. The specs are 30a continuous, 60a pulse, making the absolute lowest "safe" build 0.10Ω ± 0.02Ω, with a sensible build's being above 0.18Ω ±0.02Ω (differential to allow for the tolerances of these meters).

I'm just putting this here for posterity and future reference, 'cause I'm tired of typing the same thing every few days.

I'll also throw in a link to an online Ohm's Law calculator.
Online Conversion - Ohm's Law Calculator

 

[Baditude]

This is old news to myself. I've been saying the same thing here. I've posted in my blog, Deeper Understanding of Mod Batteries that the manufacturer never meant for these batteries to be used as single cells like we use them in our mods. Like you said, they were designed to function in a battery pack with its own protection circuitry.

There's the controversial subject of continuous discharge rating vs the pulse discharge rating. IMHO, the pulse rating is redundant and gives a false sense of security to those who are using o.2 ohm or less builds. These batteries should only be used for a resistance of 0.2 ohms and higher.

The continuous discharge rating is the standard spec recognized by all battery manufacturers. The pulse rating is not universally accepted and each manufacturer has a different definition of what it is. Which is why we shouldn't rely on any pulse rating.

Any failure, mechanical or electronic, that fires the mod will operate in the 'continuous' mode. If your setup relies on a pulse rating, it's instantly over spec.

If your amp draw is safely in the continuous discharge range, your coil could act almost like a fuse and burn out before the battery is stressed. If you are running the battery at the edge of it's limits (pulse discharge rate), there is no margin of safety.

You're preaching to the choir, Jeff. Vape safe.

 

[DeadbeatJeff]

Well, I hear that, and I acknowledge that the continuous will be safe even in the event of autofire. I just felt that I had to give the 0.1 as the ABSOLUTE lowest... or risk people's tuning out by default.

There is this culture of super-subohmers these days that thinks a VTC cell can basically do anything, backed up (at least they say so) by a certain high-energy youtube guru.

I just needed to finally put it on paper, so to speak, so I can save time in the future and so people can find the actual info when they search.

 

[dr g]

Actually that chart does refer to a single cell. However you are right that it does not certify the batteries safe for that time and that operation.

That chart gives a guideline for the operation of the cutoff circuit. Sony considers anything over 30A to be overdischarging and should trip the cutoff circuit. The time given is a guideline for that circuit to operate, but of course the "<" means what is actually "safe" could be anywhere LESS than those numbers, ostensibly including effectively 0. A lot will depend on ambient conditions, cell condition, etc.

 

[DeadbeatJeff]

Section 7.2.4 is titled "Protection Circuit", and the subtitle is "The protection circuit shall be installed in the battery pack or the charger"

Certainly speaking of a device or configuration with an additional protection circuit, seemingly in multiple-battery configurations.

 

[dr g]

Section 7.2.4 is titled "Protection Circuit", and the subtitle is "The protection circuit shall be installed in the battery pack or the charger"

Certainly speaking of a device or configuration with an additional protection circuit, seemingly in multiple-battery configurations.

View attachment 368208

Right, usually packs run in series so the max output current is the same as that for one cell. Regardless, there is no minimum specified, so while the 30A figure may be overly cautious on parallel configurations, the minimum is set by the performance of one cell.

 

[DeadbeatJeff]

Ah I see.

I'd been misreading the second and third notes in 7.2.4.3

So what exactly is the significance of these numbers for us?

 

[dr g]

Ah I see.

I'd been misreading the second and third notes in 7.2.4.3

So what exactly is the significance of these numbers for us?

I think the main takeaway is that the cells are not intended to discharge over 30A and protection circuits should cut off any discharge over 30A.

 

[DeadbeatJeff]

And those times/drains are just to account for potential momentary fluctuations in current during operation, when implementing the fuses/protections?

 

[dr g]

And those times/drains are just to account for potential momentary fluctuations in current during operation, when implementing the fuses/protections?

I think it just means the fuse should trip quicker if there is greater discharge current, because it will go thermal faster!

 

[67Tele]

Thanks y'all!
Every day I learn something new on ECF that saves me money, stress, and potentially body parts.

 

[wonkeypickle]

Any failure, mechanical or electronic, that fires the mod will operate in the 'continuous' mode. If your setup relies on a pulse rating, it's instantly over spec.

and trust me, don't think it can't happen to you. My authentic stingray has a copper button assembly, and once dirty it decided to get stuck, leaving my mod in auto fire until i screwed off the button. luckily i keep my builds right about .2, leaving me headroom still.

 

[beckdg]

Good info here. Glad to see this info discussed including and beyond just a baditude battery introduction standard pamphlet. I would also like to add a beware of the continuous rating psa. I fear we're not long off the times when all lithium cells follow the ways of lipo specs where all specs are simply a proprietary number manufactured to sell cells regardless of their performance limits. I think one advantage we have is accountability because big name corporations like Sony and Samsung actually put their names on their cells. Being big targets they have a lot to lose and they're easy to locate in stark contrast with the former.

 

[Baditude]

Good info here. Glad to see this info discussed including and beyond just a baditude battery introduction standard pamphlet. I would also like to add a beware of the continuous rating psa. I fear we're not long off the times when all lithium cells follow the ways of lipo specs where all specs are simply a proprietary number manufactured to sell cells regardless of their performance limits. I think one advantage we have is accountability because big name corporations like Sony and Samsung actually put their names on their cells. Being big targets they have a lot to lose and they're easy to locate in stark contrast with the former.

Oh, like how Efest and EH advertise their batteries as a 35 amp battery, but in reality its a 20 amp battery? That reality is in the present.

 

[granolaboy]

Right, usually packs run in series so the max output current is the same as that for one cell. Regardless, there is no minimum specified, so while the 30A figure may be overly cautious on parallel configurations, the minimum is set by the performance of one cell.

a 2ah battery pack isn't very useful...my electric scooter uses a 40ah battery pack.

Usually battery packs are assembled in parallel banks, then the banks are connected in series. Then you either have a battery management system (BMS) built into the pack that manages balancing of the cell banks (you charge with a bulk charger), or you use a balance charger that connects to each bank and does the same job.

 

[beckdg]

Oh, like how Efest and EH advertise their batteries as a 35 amp battery, but in reality its a 20 amp battery? That reality is in the present.

With lipo... an honest seller... you can expect to safely peak almost half of the continuous rating ... and that's few and far between... and these are the trusted sellers that have a forum presence and are willing to all but spell out such sad truths for you. The efest of lipos... maxamps... rates their lipos @ continuous rating 4 paralleled packs wouldn't be safe (be safe meaning survive the first attempt in tact phusically) to peak at.

I understand what you're saying but when an honest seller offers a pack with warranty support rated over 200 amps continuous and won't warranty it if it's discharged at 30 amps continuous it's a whole different ball game. The unscrupulous have pushed that market beyond comprehension. For crying out loud I've seen countless disagreements on what different manufacturers consider continuous to be... and how that's manipulated by retailers and resellers.

It's the dark side of battery tech...

 

[dr g]

a 2ah battery pack isn't very useful...my electric scooter uses a 40ah battery pack.

Usually battery packs are assembled in parallel banks, then the banks are connected in series. Then you either have a battery management system (BMS) built into the pack that manages balancing of the cell banks (you charge with a bulk charger), or you use a balance charger that connects to each bank and does the same job.

Then again power tools are one of the most common if not the most common application of high drain 18650 battery packs which are all as far as I have ever seen single string.

 

[CRW78]

Which leaves the question, what battery to use from .04-.09?

 

[DeadbeatJeff]

Which leaves the question, what battery to use from .04-.09?

SONY US26650VT - 50a continuous

but the sag is so bad that you might as well be higher.

Some are claiming that the IMREN 26650s are 60a continuous, but I've yet to see any documentation, except for a couple eBay descriptions. I'm thinking they are the same as MNKEs - 20/60 - but I don't really know.

 

[CRW78]

I love the longevity of the 26650, but for hard hitting, prefer the 18650.