Battery Musing: Can charging at 2A, often called "zip" charging, damage our batteries?

[Mooch]

More mods are being released with the ability to charge their series-connected batteries at two amps via USB. Could this high charging rate damage any of the batteries we use, especially 18650's?

No.

Why not? Because the batteries are actually only being charged at about 0.7A to 1.1A, at the most.

The 5V at the USB port must be boosted up to the charging voltage, either 8.4V or 12.6V, for 2S and 3S battery setups (respectively). When the voltage is boosted up the available current must drop down because Watts In = Watts Out (minus a bit because the circuit isn't 100% efficient). Let's look at some numbers:

5V at 2A at the USB port = 10W of power into the voltage boost circuitry of the mod.

10W x 90% efficiency of the voltage boost circuitry = 9W available at the output of the boost circuit, going to the batteries.

9W / 8.4V for charging 2S battery setups = 1.07A
9W / 12.6V for charging 3S battery setups = 0.71A

So we have about 0.7A-1.1A of charging current available, depending on whether it's a 3-battery or 2-battery series mod.

But this assumes that the USB voltage has stayed at 5.0V after traveling through the USB cable. This voltage can easily drop to 4.5V due to low quality USB chargers and the tiny, higher resistance, wires in a lot of cables. This voltage drop lowers the charging current. Let's calculate how:

Assuming a drop to 4.5V at 2A at the USB port = 9W of charging power into the voltage boost circuitry of the mod.

9W x 90% efficiency of the voltage boost circuitry = 8.1W available at the output of the boost circuit, going to the batteries.

8.1W / 8.4V for charging 2S battery setups = 0.96A
8.1W / 12.6V for charging 3S battery setups = 0.64A

So we could have charging current levels as low as about 0.6A-1A if we're not using a good USB charger and cable capable of delivering a full 2A with very little voltage drop.

The bottom line?
There's no need to worry about damaging your batteries with 2A "zip" charging. You're only charging a 2-battery mod at 1.1A, at the most. You're only charging a 3-battery mod at 0.7A, at the most. It's probably lower.

I strongly recommend using a 3A charger and a heavy wire gauge USB cable to keep the USB voltage as close to 5V as possible. The more the voltage drops on the way to the mod, the longer the charging will take.

 

[DaveP]

Good info, Mooch.

If anyone wonders about how much current they are actually pushing through a USB charge, this is a good tool to monitor voltage and amperage through a USB port. I've had mine for over a year and it's easy to use. You just plug it into your USB source and then plug your mod into the output port. The output displays voltage delivered and current draw from the device on the output port.

It's $12 well spent if you need to check your USB power supply or the device you are charging. I found out that one of my 5 port 2.1A wall warts couldn't supply advertised rated current and the other one could. One would drive my XTAR VC4 charger to its rated 1A and the other would only allow it to charge at .375 and .5A depending on the number of batteries in the bays. This device showed me why.

https://www.amazon.com/AboveTEK-AUT...=8-1-spell&keywords=abovetek+usb+curent+meter

 

[Mactavish]

More mods are being released with the ability to charge their series-connected batteries at two amps via USB. Could this high charging rate damage any of the batteries we use, especially 18650's?

No.

Why not? Because the batteries are actually only being charged at about 0.7A to 1.1A, at the most.

The 5V at the USB port must be boosted up to the charging voltage, either 8.4V or 12.6V, for 2S and 3S battery setups (respectively). When the voltage is boosted up the available current must drop down because Watts In = Watts Out (minus a bit because the circuit isn't 100% efficient). Let's look at some numbers:

5V at 2A at the USB port = 10W of power into the voltage boost circuitry of the mod.

10W x 90% efficiency of the voltage boost circuitry = 9W available at the output of the boost circuit, going to the batteries.

9W / 8.4V for charging 2S battery setups = 1.07A
9W / 12.6V for charging 3S battery setups = 0.71A

So we have about 0.7A-1.1A of charging current available, depending on whether it's a 3-battery or 2-battery series mod.

But this assumes that the USB voltage has stayed at 5.0V after traveling through the USB cable. This voltage can easily drop to 4.5V due to low quality USB chargers and the tiny, higher resistance, wires in a lot of cables. This voltage drop lowers the charging current. Let's calculate how:

Assuming a drop to 4.5V at 2A at the USB port = 9W of charging power into the voltage boost circuitry of the mod.

9W x 90% efficiency of the voltage boost circuitry = 8.1W available at the output of the boost circuit, going to the batteries.

8.1W / 8.4V for charging 2S battery setups = 0.96A
8.1W / 12.6V for charging 3S battery setups = 0.64A

So we could have charging current levels as low as about 0.6A-1A if we're not using a good USB charger and cable capable of delivering a full 2A with very little voltage drop.

The bottom line?
There's no need to worry about damaging your batteries with 2A "zip" charging. You're only charging a 2-battery mod at 1.1A, at the most. You're only charging a 3-battery mod at 0.7A, at the most. It's probably lower.

I strongly recommend using a 3A charger and a heavy wire gauge USB cable to keep the USB voltage as close to 5V as possible. The more the voltage drops on the way to the mod, the longer the charging will take.

Is all the above true in regards to zip charging a Vaporshark DNA200 with its 900mAh LIPO battery? Reason I ask is I have set Escribe to show charging AMPS on the charge screen. With a 2.1 amp iPad wall charger and USB cords that test out being able to deliver a 2 amp charge, my Vaporshark screen shows 1.95 amps on its charge screen, and charges quickly.

And assuming one could get a true 2 amp charge rate, would it still be best for battery longevity to charge a FullyMax 900 mAh battery at 1 amp? I'm not sure what the charging specs are for the FullyMax 900 mAh battery. Is a 2 amp charge the recommended or acceptable charge rate, or 1 amp?

If my Vaporshark is actually getting near a 2 amp charge, I could use a 1 amp USB wall charger like an iPhone charger. It might take twice as long, but would be worth it if I could extend overall battery life.

 

[Dubminer]

Very interesting Mooch.What about zip charging a single battery mod? would that shorten the battery life?

 

[Mactavish]

Very interesting Mooch.What about zip charging a single battery mod? would that shorten the battery life?

Wondering the same as I preordered the new VS SwitchBox DNA75. It takes a single 18650 lithium battery. I usually charge these batteries in my Xtar VP2 external charger at .5 amps. If zip charging actually delivers 2 amps in this new mod, I'm concerned not only about battery longevity, but safety.

 

[Dubminer]

Wondering the same as I preordered the new VS SwitchBox DNA75. It takes a single 18650 lithium battery. I usually charge these batteries in my Xtar VP2 external charger at .5 amps. If zip charging actually delivers 2 amps in this new mod, I'm concerned not only about battery longevity, but safety.

Yes,exactly my thoughts as well.

 

[Mooch]

Very interesting Mooch.What about zip charging a single battery mod? would that shorten the battery life?

Not if the battery can handle regular 2A charging (or whatever rate they are using).

 

[Mooch]

Is all the above true in regards to zip charging a Vaporshark DNA200 with its 900mAh LIPO battery? Reason I ask is I have set Escribe to show charging AMPS on the charge screen. With a 2.1 amp iPad wall charger and USB cords that test out being able to deliver a 2 amp charge, my Vaporshark screen shows 1.95 amps on its charge screen, and charges quickly.

And assuming one could get a true 2 amp charge rate, would it still be best for battery longevity to charge a FullyMax 900 mAh battery at 1 amp? I'm not sure what the charging specs are for the FullyMax 900 mAh battery. Is a 2 amp charge the recommended or acceptable charge rate, or 1 amp?

If my Vaporshark is actually getting near a 2 amp charge, I could use a 1 amp USB wall charger like an iPhone charger. It might take twice as long, but would be worth it if I could extend overall battery life.

That 1.95A is the incoming current, before it is stepped up to 12.6V. If it was the actual battery current there would be 1.95A * 12.6V = 24.6W of charging power and we can't get that from a 12W USB charger block.

You can definitely use a lower power USB charger to limit the current even more though.

I don't know the FullyMax's recommended charging rate but it's probably close to 1A. It can certainly handle the 0.7A it gets in the VS DNA200.

 

[Mooch]

Wondering the same as I preordered the new VS SwitchBox DNA75. It takes a single 18650 lithium battery. I usually charge these batteries in my Xtar VP2 external charger at .5 amps. If zip charging actually delivers 2 amps in this new mod, I'm concerned not only about battery longevity, but safety.

You can use a 0.5A or 1A USB charging block to limit the current.

 

[Mactavish]

That 1.95A is the incoming current, before it is stepped up to 12.6V. If it was the actual battery current there would be 1.95A * 12.6V = 24.6W of charging power and we can't get that from a 12W USB charger block.

You can definitely use a lower power USB charger to limit the current even more though.

I don't know the FullyMax's recommended charging rate but it's probably close to 1A. It can certainly handle the 0.7A it gets in the VS DNA200.

Ok, then I guess I can rule out the 2 amp charger as a suspect with the two FullyMax 900 mAh batteries my friend had in both his Vaporshark and Volcano DNA200's, that showed zero voltage, would not charge via USB anymore and were BLOATED. I also doubt both charging boards are malfunctioning. The way he treats his gear, the only theory I have now is, he must have left them in his car and they overheated.

 

[Mooch]

Ok, then I guess I can rule out the 2 amp charger as a suspect with the two FullyMax 900 mAh batteries my friend had in both his Vaporshark and Volcano DNA200's, that showed zero voltage, would not charge via USB anymore and were BLOATED. I also doubt both charging boards are malfunctioning. The way he treats his gear, the only theory I have now is, he must have left them in his car and they overheated.

They aren't the most robust of batteries.
Hard use at high wattage could have caused that. The puffing is a classic sign.

 

[Mactavish]

They aren't the most robust of batteries.
Hard use at high wattage could have caused that. The puffing is a classic sign.

He's hard on everything, could break a steel ball!
I'll have to ask him the watts he uses. But I also know he leaves stuff in his car, and in the summer heat, temps in a closed car can get very high. I put in a new FullyMax and plugged it in, showed it as charging, so at least I know the charge circuit is good. I told him to properly dispose the bloated batteries.

 

[$hahin]

Hi Mooch

Not doubting your expertise here, since you pretty much taught me everything i know about batteries since I got into vaping, but will really appreciate if you could just clarify this for me.

As far as I know, current remains constant in a series circuit. According to your calculation, the current seems to get split between the batteries, or did I miss something?

I started charging my batteries via usb on my kbox 160 recently, as it charges much quicker than my d2. It seems to charge at least 3 times faster.

The spec of the mod says to charge at 5V and 1.5A. So I'm using a Samsung phone charger rated at 5V 2A. Which should be fine right? Seeing as current is pulled and not pushed, so my mod should only be drawing 1.5A right?

I'm using the hg2's, and since the battery spec says 1.5A is the standard charge current, I've only been charging via the mods usb now. I notice no significant increase in battery temperature compared to using the d2 charger. Actually, it seems as if the d2 makes the batteries ever so slightly warmer.

The thing that worries me is how fast my batteries charge via usb. Is it only the increase in temperature which reduces the battery cycle life? Or does charging at a higher current reduce battery longevity even if there's no significant increase in temperature?

To me it seems like my mod is charging the batteries using the full 1.5A, but from your calculations, it's actually charging at 1.1A.

Shouldn't current remain constant throughout a series circuit?

Apologies for all the questions, but thought it would be informative for all readers, so just figured it best if I was as comprehensive as possible.

One last thing. Twice, after charging via usb, I put the batteries in the d2 charger just to see if they were holding equal charge, and there was a very slight difference. The battery in the slot connected to the circuit board seems to be draining slightly quicker, but very slightly, I'd estimate only a 0.01V to 0.02V difference between the two batteries, as the one holding less charge catches up to the other within a matter of seconds. I just leave one battery in the charger slightly longer. I remove the batteries as soon as they reach 4.0V.

So does that mean I don't have to bother using the d2 charger at all now? Most recently, I haven't been checking difference in charge between the two batteries using the d2, and have just been charging via usb. Perhaps I will check again soon.

Is charging till 4.0V good enough, or should I be charging to about 3.8V rather to improve cycle life, as I read on another website?

I have another mod which I also use, so I'm not really worried about batteries lasting me throughout the day. I usually go about 3 days using my kbox before I charge the batteries, so I'm more concerned about getting a good cycle life out of the batteries as opposed to how long they last me per charge.

Ok, sorry again for rambling on here and for all the questions. Awaiting your response in this regard.

 

[Mooch]

Hi Mooch

Not doubting your expertise here, since you pretty much taught me everything i know about batteries since I got into vaping, but will really appreciate if you could just clarify this for me.

As far as I know, current remains constant in a series circuit. According to your calculation, the current seems to get split between the batteries, or did I miss something?

Current is never split between batteries in a series circuit. By definition it must remain equal. The power is split though.

I started charging my batteries via usb on my kbox 160 recently, as it charges much quicker than my d2. It seems to charge at least 3 times faster.

The spec of the mod says to charge at 5V and 1.5A. So I'm using a Samsung phone charger rated at 5V 2A. Which should be fine right? Seeing as current is pulled and not pushed, so my mod should only be drawing 1.5A right?

Current is pushed IMHO, it's all just senantics though. The charging chip in the mod will only allow 1.5A to pass if that is its rating. Using a 2A charger, or higher, is better as it will run cooler.

I'm using the hg2's, and since the battery spec says 1.5A is the standard charge current, I've only been charging via the mods usb now. I notice no significant increase in battery temperature compared to using the d2 charger. Actually, it seems as if the d2 makes the batteries ever so slightly warmer.

The thing that worries me is how fast my batteries charge via usb. Is it only the increase in temperature which reduces the battery cycle life? Or does charging at a higher current reduce battery longevity even if there's no significant increase in temperature?

To me it seems like my mod is charging the batteries using the full 1.5A, but from your calculations, it's actually charging at 1.1A.

Shouldn't current remain constant throughout a series circuit?

Current may or may not remain constant in a series circuit. What the circuit does determnes that, not whether it's series or parallel.

Using a battery ages it. Increasing its temperature ages it. Warm/hot charging is worse than almost room temperature charging though.

Apologies for all the questions, but thought it would be informative for all readers, so just figured it best if I was as comprehensive as possible.

One last thing. Twice, after charging via usb, I put the batteries in the d2 charger just to see if they were holding equal charge, and there was a very slight difference. The battery in the slot connected to the circuit board seems to be draining slightly quicker, but very slightly, I'd estimate only a 0.01V to 0.02V difference between the two batteries, as the one holding less charge catches up to the other within a matter of seconds. I just leave one battery in the charger slightly longer. I remove the batteries as soon as they reach 4.0V.

So does that mean I don't have to bother using the d2 charger at all now? Most recently, I haven't been checking difference in charge between the two batteries using the d2, and have just been charging via usb. Perhaps I will check again soon.

Is charging till 4.0V good enough, or should I be charging to about 3.8V rather to improve cycle life, as I read on another website?

I don't know if your mod balances your batteries when charging. Charging externally balances them every time if you charge them fully. If you only charge to a lower voltage you can extend their life but they won't be balanced and their voltages can, and probably will, drift apart.

Using a charger is a terrible way to read voltages. Their accuracy is not good. Get a basic multimeter.

Charging only to 3.8V is crazy IMO. The increase in cycle life is negligible versus the big loss in capacity. Using 4.1V already gives significant gains in cycle life.

I have another mod which I also use, so I'm not really worried about batteries lasting me throughout the day. I usually go about 3 days using my kbox before I charge the batteries, so I'm more concerned about getting a good cycle life out of the batteries as opposed to how long they last me per charge.

Ok, sorry again for rambling on here and for all the questions. Awaiting your response in this regard.

Lots of questions there.

 

[$hahin]

Thanks Mooch, much appreciate the advice.