Do 2 batteries increase Amperage?

[Topwater Elvis]

if they are in series it doubles your voltage
if they are parallel it doubles your amperage

Considering this thread is about a regulated power device, battery orientation parallel/series makes no difference in battery amp draw (input), or amp output.

 

[ScottP]

Considering this thread is about a regulated power device, battery orientation parallel/series makes no difference in battery amp draw (input), or amp output.

Correct.

Which is why what I said in my first post of this thread is the same regardless of battery configuration:

Max Watts per battery = Max Battery Amp * 3
Max Watts total = Max Watts per battery * number of batteries.
So in this case:
15A * 3 = 45W max per battery
45W * 2 = 90 W max total.

 

[Nate5700]

I have a question, being largely naive to the specifics of modern vaping hardware. Are there actually regulated mods out there that parallel batteries? I'd be cautious of any that do, for the reason I indicated in my previous post

 

[untar]

Are there actually regulated mods out there that parallel batteries?

Every multiple battery DNA75/75C mod should be such a creature, eg Lost Vape Paranormal 75C.

High power real world applications rarely follow what you've been taught, power tools, e bikes, electric cars all use a combination of series and parallel batteries.

 

[ScottP]

I have a question, being largely naive to the specifics of modern vaping hardware. Are there actually regulated mods out there that parallel batteries? I'd be cautious of any that do, for the reason I indicated in my previous post

There are some yes. Most notably any DNA 75 watt or less mods that are dual battery are parallel configs. So all of the Lost Vapes Therion and Paranormal mods using the DNA 75/75C, the HCigar VT 75D, etc. No reported issues with any of them. I think the DNA board may have protections in place to prevent voltage bleed from one battery to the other though.

 

[ScottP]

Every multiple battery DNA75/75C mod should be such a creature, eg Lost Vape Paranormal 75C.

High power real world applications rarely follow what you've been taught, power tools, e bikes, electric cars all use a combination of series and parallel batteries.

LOL could you imagine if electric cars could only use series batteries? You would back out of the driveway and it would be time to recharge.

 

[untar]

I think the DNA board may have protections in place to prevent voltage bleed from one battery to the other though.

Nope. Gotta be careful. Reverse battery protection also only works with the 1st battery you insert.
There's just one battery connection on the 75/75c boards to connect your "pack". Everything outside of that has to come from the manufacturer/modder.

 

[Nate5700]

High power real world applications rarely follow what you've been taught, power tools, e bikes, electric cars all use a combination of series and parallel batteries.

Interesting. The series batteries with the regulator I guess was more a lab safety rule, the laws of electricity certainly don't require it. Modern power electronics I'd guess can mitigate issues with paralleling batteries, I'm just not a power electronics expert. I definitely wouldn't try it in a mech though.

 

[ScottP]

Nope. Gotta be careful. Reverse battery protection also only works with the 1st battery you insert.
There's just one battery connection on the 75/75c boards to connect your "pack". Everything outside of that has to come from the manufacturer/modder.

I am not talking about reverse battery protection. As Nate mentioned earlier, batteries can have a variance in their internal resistance. In parallel battery configs this can cause the batteries to drain unevenly, and if the voltage difference between the batteries becomes too great, it can cause voltage to feed from one battery to the other. (Think charging one battery using the other battery, while inside the mod) This can build up current in the wires/connectors between the batteries and build up heat.

Protected cells can help alleviate this issue as long as the voltage difference doesn't become too great. Using "married" batteries can also help.

 

[Rossum]

I am not talking about reverse battery protection. As Nate mentioned earlier, batteries can have a variance in their internal resistance. In parallel battery configs this can cause the batteries to drain unevenly, and if the voltage difference between the batteries becomes too great, it can cause voltage to feed from one battery to the other.

Eh? When two batteries (or any other elements of a circuit) are in parallel, they are at intrinsically at the same voltage (neglecting any voltage drop in the conductors that connect them in parallel).

Now does not mean that the current each of them supplies will be equal. If there is a difference in internal resistance between the two cells, then the one with lower internal resistance will supply more of the current. But they will be at the same voltage regardless.

 

[Rossum]

The correct statement would be:

If they are in series it doubles your voltage, but capacity (mAh) will not double
If they are parallel it doubles your capacity (mAh) but voltage will not double

In either case, two batteries can (in principle) supply double the power.

Power = voltage * current.

So it doesn't matter whether you double the voltage or you double the current; in either case, you get twice the power.

 

[Rossum]

LOL could you imagine if electric cars could only use series batteries? You would back out of the driveway and it would be time to recharge.

Not really. There's only one manufacturer of electric cars that uses puny cylindrical cells like we do (Tesla).

Have a look at VW's "GTE" drivetrain. It's common in a number of models in Europe, and can be found in the A3 e-tron in the US. It's a PHEV with that has an all electric range of ~20 miles. The 8.8 kWh battery consists of 96 large, prismatic li-ion cells in series; nothing paralleled at all.

With appropriate software, it is possible to monitor all 96 individual cell voltages. What's interesting is that the charge controller considers the battery "full" when the cells are right around 4.00-4.01V, and "empty" when they are just below 3.6V (3.56-3.58V). Needless to say, they are not running this battery very hard. Not a huge surprise, I suppose, considering they warranty the battery for 8 years.

 

[Nate5700]

Eh? When two batteries (or any other elements of a circuit) are in parallel, they are at intrinsically at the same voltage (neglecting any voltage drop in the conductors that connect them in parallel).

The way we modelled batteries in circuits problems was as a source in series with the battery's internal resistance. So you're correct that the battery terminals will be at the same voltage, but there can be variation on the source voltage, eg the voltage that the battery "wants to" supply. If there's a difference current can flow through the internal resistance of the battery backwards through the source. Same as if the battery was on a charger.

Of course that's just the theoretical model and what's going on in the battery is more complicated. But current can flow from one into the other.

 

[Rossum]

The way we modelled batteries in circuits problems was as a source in series with the battery's internal resistance. So you're correct that the battery terminals will be at the same voltage, but there can be variation on the source voltage, eg the voltage that the battery "wants to" supply. If there's a difference current can flow through the internal resistance of the battery backwards through the source. Same as if the battery was on a charger.

Of course that's just the theoretical model and what's going on in the battery is more complicated. But current can flow from one into the other.

Absolutely, current can flow from one to the other. But that doesn't change the fact that they will be at the same voltage.

 

[Nate5700]

Absolutely, current can flow from one to the other. But that doesn't change the fact that they will be at the same voltage.

I think we're on the same page, I was just trying to clarify what I think Scott was trying to say.

 

[untar]

I am not talking about reverse battery protection.

I know, I just added that to the mix as a further consequence of only having a single battery connection on the board (well, one for (+) and one for (-) but that doesn't change anything).
The DNA75/75c don't see what's going on between multiple batteries so anything requiring circuitry there won't work, including balance charging, "bleed" prevention, individual battery charge state and reverse polarity protection. To the board there's just one battery.

 

[Rossum]

The DNA75/75c don't see what's going on between multiple batteries so anything requiring circuitry there won't work, including balance charging,

Parallel li-ions essentially balance themselves.

 

[classwife]

Merged duplicate threads

 

[Ionori]

It wouldn't double the discharge rate of the battery but current will split between the two batteries if they are in parallel. So if each battery supplied 15 amps it would give you 30 amps total.

I wouldn't recommend it though. There can be variations of the internal resistance of the batteries among other factors, so you can't guarantee that current will split equally between batteries in parallel. What we were taught in electrical engineering school was to always put batteries in series and use a regulator.

There's an even better reason not to use batteries in parallel when vaping - the catastrophic short circuit that will happen if you insert one of the batteries the wrong way around.

 

[BeginnerOfVaping]

Did the math for you.

WATTAGE PER SINGLE BATTERY on REGULATED MOD:
(Wattage doubles using 2 batteries/triples using 3 batteries)

Up to 45W:

Samsung 18650 30Q, 3000 mah 15 amp CDR

Sony 18650VTC6 3000mAh 15 amp CDR

Up to 60W:

LG 18650HG2 3000mah 20 amp CDR

LG 18650HE4 2500 mah 20 amp CDR

Samsung 18650-25R, 2500 mah 20 amp CDR

Sanyo UR18650NSX, 2500 mah 20 amp CDR

Sony 18650VTC5, 2600 mah 20 amp CDR

Sony 18650VTC4, 2100 mah 23 amp CDR

AW 18650 3000 mah 20 amp CDR

Up to 75W:

LG 18650 HD4 2100 mah 25 amp CDR

LG 18650 HD2 2000 mah 25 amp CDR

Samsung 18650-24S, 2500 mah 25 amp CDR

Sony 18650VTC5A, 2500 mah 25 amp CDR

Up to 90W:

LG18650HB6 1500mah 30 amp CDR

LG18650HB2 1500mAh 30 amp CDR

LG18650HB4 1500mAh 30 amp CDR

Samsung 18650-20S 2000mah 30 amp CDR

Thank you! Really appreciate it