Sofirn Q8 group buy (gb closed, but try PM to Sofirn for discount)

No, it was fine. They were all fully charged and at 4.2 volt.

People mix all different battery sizes in parallel setups.

It’s in series that you need all them to be identical.

Like with the BLF GT. You can put 4 identical 3500mah in one carrier and 4 identical 2000mah in the other carrier. This will work fine as the carriers are in parallel.

The 4 battaries in each carrier are in series, so those 4 need to be identical and matched up.

When batteries are in series the voltages can vary and the low voltage protection only sees the total voltage. So you could have 3 cells at 3.2v and one at 2.4v and the lvp would see 3v total and think it’s fine, but really one battery has gone much too low. This can ruin that battery and make it dangerous to continue using.

Nope, the strongest cell will be stressed the most, not the weakest.

Ok…… but ’I’ am still not gonna do it. :wink:

I’m with teacher, won’t catch me mixing cells like that.

I got my Sofirn Q8 today from Amazon. Charged up 4 30Q cells with a solder blob on the otherwise flat top, straight away right out of the box it makes 5775.3 lumens.

Do solder blobs perform much better than button tops or is it negligible? 30Q’s and the 10A Panasonic/Sanyo are easy to find in BT but seems like almost nothing else is readily available.

I just charged four new 30Q button tops to 4.1V and they ended up from 4.080 to 4.091V. Is the spread in voltage safe enough to use in parallel in my Q8?

Yes, it’s safe

Is there some type of maximum difference in voltage before batteries should be charged again until they are closer before using in parallel?

That is remarkable, I’m getting 5780 with brass screws and 18awg spring bypass’s VTC5A’s 4,21v off the charger….the bypass’s only netted me 3-400lm more, so the springs are not so bad. The three times I did this all the batteries were drained to the exact same voltage, so I know the raised flat tops are all making full contact.

Stock, out of the box, it made 5775.3 lumens on the 30Qs fresh off the charger.
With brass M3 screws it made 5909.85 lumens on the 30Q’s fresh off the charger. A 134.55 lumens gain.
With Blue’s springs it made 6020.25 lumens on the 30Q’s fresh off the charger. A 110.4 lumens gain.
With 20ga spring bypasses it makes 6330.75 lumens with the 30Q’s, again, fresh off the charger. A 310.5 lumens gain for an overall increase of 555.45 lumens since I took it out of the box just after lunch.

Edit: At this point, I haven’t opend the bezel end nor have I touched the screws holding the driver in.

I already noticed that the XPL-Hi leds performed a bit better that they should in a completely unaltered Q8, so the difference may indeed be better conducting springs.

That’s really close. 11 hundredths thousandths. It’s when you have a bigger gap that you get a bigger transfer of energy. So 1 tenth of a volt will probably transfer a lot of energy really quickly. Your 11 hundredths thousandths only transfers a little energy. Not enough to hurt anything. I’m not really sure how big a difference is okay and what’s not. I’ve heard of battery chargers deviating 4 or 5 hundredths. So 1 hundredth can’t be that bad.

Does anyone have any first hand experience with this? How much is too much difference?

I think DB’s light box might read higher than yours. So it may not be a direct comparison.

Would be cool if someone could take their q8 body and put on sofirn q8 head and measure both using the same body. Relative difference between two emitters ya know

The springs are not only better they are much stouter and longer than the BLF Q8’s so you are getting way better contact then the old BLF Q8, I tried bouncing the batteries off the driver trying to break the contact, my hand is still sore….my BLF Q8’s were so very easy to do before I modded them. I asked Sofirn to sell me a couple of the Sofirn Q8’s spring PCB’s for my stock BLF Q8’s I have in storage….they said they will take care of me. :+1: Got to Love that! :wink:

Wait, could someone actually picture and measure the height of the springs?

I have the impression they actually changed the spring material to phosphor bronze, or even BeCu :money_mouth_face:

Also, how stiff are they? If they’re a bit stiffer, then they should be phosphor bronze. If they are again a bit stiffer, they should be BeCu C17530. If they are VERY STIFF, which seems not to be the case at all, BeCu C17500. Although that would restrict compatibility quite a bit due to its low yield strength and high plastic deformation potential.

I also have the feeling they made the inner spring taller and thicker to make for a better dual spring array, so higher conductivity.

TLDR: Higher conductivity materials and/or better dual spring array.

Opened up the driver bay and they have what appears to be 18ga leads on it already. I swapped the FET for the Infineon FET from my BLF GT mini, to gain only 48.3 lumens. At any rate, I now see 6379.05 lumens at start with fresh charged 30Qs.

That is a difference of ’11 thousandths’ of a Volt klrman… Nothing at all to worry about in any way for parallel or series connections.

Wow! You guys and gal summed it quite clearly. Thank you. I meant to relay the experience so I cut out some details.

I have a Miboxer C4 and of the four (out of 6 button tops I have), they are all under 20 cycles with 36 mOhms for the 25R, ~70 for the 35E and ~100 for Nu 188.

I bought those 30q Ali fakes for a multi- batt light but not button top. Solder blobbing came to mind. Just didn't have time.

As far as series V'S parallel, I'm wary about series but I've been using a 3C light with two 18650s in parallel. New batteries, old pack pulls, etc. w/o problem but I monitor SOC regularly.

I prefer 30q but since I have two 35Es already, I'll probably just buy two more. I'll derive more current via brass screws and spring bypasses.

I read as much on best practices as I can and y'all's posts certainly are part of that curriculum. Thank you!