New batteries/mod problem?

[ghostrider1971]

Hi guys,

I've got two new Fogstar 3500mah batteries. I have charged them twice. Once using a D2 charger and the second time through the mod USB (RX2/3).

I'm just slightly curious after a "full" charge, using both options, the mod says the batteries are only 90% charged - this happened both times.

Both batteries have only been charged together.

Any suggestions, please?

[VapingBad]

Do you have a volt metre, 90% charge would be around 4.1 V, if they are around 4.2 V then the mod is faulty.

A quick google and those batteries seem to only be 10 A continuous discharge rate, personally I wouldn't vape with them and all my old 10 A batteries have gone into power banks now, they should be OK below 30 W per cell in a regulated mod if their spec is honest and I wouldn't put them near a mech mod at all, but there are so many far better batteries about.

[ghostrider1971]

VapingBad - thank you for the reply. When I fire the mod using a Cleito at 40w, the voltage on the RX2/3 shows as 4.1v (Sorry - I have no expertise in these things...)

I have only used the batteries in the RX2/3 with a Nautilus @ 9w (Yeah, strange choice...!) and a Cleito @ 40w max.

What would be your first choice battery recommendation, please? I have Samsung 25-r's I use in my other mods

[VapingBad]

25Rs are great for the majority of users, I think Sony VTC5A are top of the heap ATM for grunt, but 25R is probably the best value in puff per £.

[buggritt]

Agree with your advice VapingBad, but remember only a few years ago we were happily using mechs with lower rated batteries. That's all we had. At full charge, not using a super sub ohm coil, you're only drawing around 5 amps.
I only use 10 amp batteries, as they are at a higher mah.

[jtc]

TBH I've always read that apart from a DNA device it is wise to stay away from direct USB charging but with multiple batteries

[DaveJ]

Dec 8, 2016 8:03:11 GMT jtc said:

TBH I've always read that apart from a DNA device it is wise to stay away from direct USB charging but with multiple batteries

Yes - for SERIES cell configurations (*), that's my understanding too.

It's a little different iffn the mod (*) has the batts in parallel - especially if it's a parallel mod that will run on either one or two batteries. (which most likely means the battery sled has 'em permanently wired together and therefore any onboard charging MUST be balanced - and easy to test with a multimeter).

At least, that's as far as I understand it.

Dual Parallel regulated mods are rather thin on the ground though.


* For regulated mods...

[ukwarrior]

Dec 6, 2016 11:26:06 GMT ghostrider1971 said:

VapingBad - thank you for the reply. When I fire the mod using a Cleito at 40w, the voltage on the RX2/3 shows as 4.1v (Sorry - I have no expertise in these things...)

I have only used the batteries in the RX2/3 with a Nautilus @ 9w (Yeah, strange choice...!) and a Cleito @ 40w max.

What would be your first choice battery recommendation, please? I have Samsung 25-r's I use in my other mods

If you wanted to buy from Fogstar again (I do know Fogstar is quite highly regarded), the LG HE4 is the cheapest option at the moment- £4.15 for one battery, £4.07 for 2 ETC. The 25R is slightly more expensive, but not by much. 

For 2500MAH, 20A cells, I get either 25R's or HE4's, whichever is cheapest. Both will serve you well and work great in your RX 2/3. 

You could also go for one of the 3000MAH, 20A cells, such as the LG HG2, or the Samsung 30Q (This is actually rated at 15A by Samsung, which is still higher than the 10A of your current cells, but Mooch has rated them as a good 20A CDR cell). 

If you are only planning on using the mod at 40W max though, even the 10A batteries will be fine, as long as they are 10A under the wrap. You would be drawing up to around 7.16A in dual 18650 config, even less in triple 18650 config.  
I am pretty sure that particular vendor wouldn't lie though, but am unsure which battery is being used. 

[VapingBad]

Battery drain in regulated mods is higher than most people think, I am doing a little personal project using python script to turn a DNA 75 into a battery tester ATM I will be able to show that in a week or so, but will share this graph I made last night. The lines are cut off on the left because even the best batteries cannot supply those currents at those voltages. Batteries like the 30Q I tested the lines would need the same again removing from the start of the line as I measured over a volt sag at 75 W, but at best they will sag 0.75 V making the usable mAh about 1140, 25Rs are better at these powers despite having a lower mAh rating the one I tested was gave longer runtime at 75 W. The sag means you need more current to be able to get the watts and the runtime will be lower as they will sage below the low cut-off point. This is 2.75 V on a DNA 75 under load, but have been seeing some mods going as low as 2.5 V.

Wattage per cell: green 25 W, blue 50 W, Red 75 W


I am not even going to look at 100 W per cell, too scary, but you can see the pattern and where the line would be.

[ukwarrior]

Dec 9, 2016 11:43:32 GMT VapingBad said:

Battery drain in regulated mods is higher than most people think, I am doing a little personal project using python script to turn a DNA 75 into a battery tester ATM I will be able to show that in a week or so, but will share this graph I made last night. The lines are cut off on the left because even the best batteries cannot supply those currents at those voltages. Batteries like the 30Q I tested the lines would need the same again removing from the start of the line as I measured over a volt sag at 75 W, but at best they will sag 0.75 V making the usable mAh about 1140, 25Rs are better at these powers despite having a lower mAh rating the one I tested was gave longer runtime at 75 W. The sag means you need more current to be able to get the watts and the runtime will be lower as they will sage below the low cut-off point. This is 2.75 V on a DNA 75 under load, but have been seeing some mods going as low as 2.5 V.

Wattage per cell: green 25 W, blue 50 W, Red 75 W


I am not even going to look at 100 W per cell, too scary, but you can see the pattern and where the line would be.

That will be very interesting to see the results of, and I look forward to them wether they give good results for most vapers, or the opposite. I can already see at 75W the high amp load. 

I do not have advanced testing equipment, but I have noticed with most of my single cell mods I get better life with a 25R vs a higher capacity 30Q. I can only assume this is due to voltage under load giving me a weak battery message earlier. 1140 MAH doesn't sound much, but I can believe that in our use of said batteries. 

On my DNA75 I do have the cutoff set to 2.75V, which with the batteries I use is within their specification, as is 2.5V but that is the very end of the cycle and any lower would not be good. 

Which mods have you come across that do take batteries this low under load? As I can see how amp levels would be much higher than people assume when the voltage is this low in a regulated mod. 

I think mods that offer 200W+ on 2 18650's are pushing things much too far safety wise, 100W per cell is asking very much from an 18650. 

[VapingBad]

ukwarrior those point were the first point at which they sagged to 2.75, just for a split second ant the end of a 3 second puff. The test script I have written just uses a DNA 75 with a large coils just under 0.5 ohm and I use a couple of old PC fans to keep it cool. It is different from other tests in that if use pulses of constant load (puff at x watts for y seconds) rather than constant amps until it can only do 90% of the required power it increase the puff time taking about the same amount of energy as a vaper would do in the real world. Like the soft limiting DNAs have or limp home mode some engines have. It also pauses if the board temp goes over a configurable limit and has around 10 setting you can change to adjust how it tests. It is work in progress, but I should post it in the next week with test results for 4 batteries at 3 vaping pattens. The script will be available to anyone with a DNA 75 and EScribe, here is a quick teaser screen shot of the end of a 30Q test.

[mikedidthis]

Ben from Fogstar has been in touch as he is having issues accessing the forum.

In the mean time you if you have any issues, he is more than happy to help. You can email him at: [e-mail]

[Roofer]

Hand on heart, I am not one to give a supplier a bad name. Through a link I purchased 2 x 18650 3500 mah batteries. They are not my 'go to' daily batteries after putting them through various charge cycles. The usage time is terrible and I have put them to one side as a 'mistake'.

The battery wraps look cool, but that's it.

I haven't even contacted Fogstar with my thoughts, but due to this thread I thought it best to chip in.

Sorry to offend FS, but as I said, not for me again.

[ukwarrior]

Dec 9, 2016 15:03:31 GMT VapingBad said:

ukwarrior those point were the first point at which they sagged to 2.75, just for a split second ant the end of a 3 second puff. The test script I have written just uses a DNA 75 with a large coils just under 0.5 ohm and I use a couple of old PC fans to keep it cool. It is different from other tests in that if use pulses of constant load (puff at x watts for y seconds) rather than constant amps until it can only do 90% of the required power it increase the puff time taking about the same amount of energy as a vaper would do in the real world. Like the soft limiting DNAs have or limp home mode some engines have. It also pauses if the board temp goes over a configurable limit and has around 10 setting you can change to adjust how it tests. It is work in progress, but I should post it in the next week with test results for 4 batteries at 3 vaping pattens. The script will be available to anyone with a DNA 75 and EScribe, here is a quick teaser screen shot of the end of a 30Q test.

OK, that does sound good from your explanation, as it will reflect the amp load a vaper will be using in real life scenarios. 
I do have a DNA75, and Escribe, so it will be cool once it is available to be able to do these tests, and that anyone with a DNA75 and Escribe will also be able to. 

I noticed from the first graph you posted, even with the high amp load, the main thing was the calculation for amp load with a regulated mod still applied- in the 75W example 75/2.5=30, then divided by an efficiency of 85%=35.29A. It will definitely ease my mind in knowing that calculations for my regulated devices are correct, and also be very handy when explaining to people how to calculate for a regulated mod, as it seems many people mistakenly calculate their batteries amp load using resistance still. 

I understand this still effects what is output to your atomizer by the board, but not the amp load on your battery/batteries, this is dependant on watts and voltage. 

Thanks for doing this, it will help a lot of us out . 

[VapingBad]

ukwarrior The sag is related to load and internal resistance, you can make a guess with IR, but when you are really pushing a battery the sag increases with time. Here is the sag on a 25R 3 second puffs 75 W (88.2 W from the battery), the is first just at the end of where it can supply full power (just before it dips below the mod cut-off 2.75) and the sag is increasing with time, do this on a longer puff and it is quite dramatic. The second is where the sag crosses the line during the puff so it starts at full power then tails off. The third is where the sage is hitting the limit for the whole puff so can't do full power, but you can see from the power (green line) than power is reducing and because V is more or less constant current supply must be reducing. So there is no linear maths formula to predict this.


Black line = battery V, Green = vape power, Yellow = last puff energy in mWh, Blue = lst puff duration

Because the battery is at a lower voltage the board needs more current to meet it's power requirement, in the graph I did in post #8 0.5 V sag was a bit lower than the lowest I saw at 75 W (88.2 W at the battery) so I removed the values higher than 3.7 V as the best batteries at 4.2 V would sag to 3.7 V as soon as you took that load. Then the current would be 88.2/3.7 current 88.2/4.2.