Review: Small Sun ZY-T08 2 x 18650 (Parallel)

thanks for the tip up, deleted :slight_smile:
always forget that this forum has a delete button not like the others :smiley:

Anyone try a U3 or XM-l2 in this? I have some of both on the way and am thinking of trying one or the other.

I know it has a giganto star, but if I center it right with a little Fujik, I’m thinking a 21 would work fine with that big plastic white retainer to center it and cover up hot wires.

Imagine two water tanks, one full, one empty, connected together with a pipe. Once connected, water will immediately level off until both tanks are at the same level. That’s how it is with voltage when placed in parallel.

Different water tank size = capacity. Water will level out regardless of tank size, so will voltage level out between batteries regardless of the battery capacities. 200gallons tank linked to 400gallons tank will have 600gallons capacity when linked, and both will drain appropriately and self levelling - similar to batteries put in parallel.

The only “bad” thing would be if you put empty battery + full battery in parallel, immediately the full battery will charge the depleted one at high rate it can give - meaning it will hurt the batteries capacity a bit, and it might heat up. Either way, even at worst case, it is not too risky.

intuitive illustration. Now the question is, is it actually technically safe when the full voltage battery try to flow into (aka "charging") the so called empty battery to level the voltage?

XM-L2 U2 1C/SinkPAD mounted on copper disc, copper heat sink in pill, Nanjg 4.2A, UCL/p lens, copper braid added to tailcap springs:

1,200 lumens at 30 secs, 210 kcd measured at 4.31 meters. It's a little beast!!

An amazing instrument for it's size - don't know of anything that compares for its size! An HD2010 should do the same, but on a single battery, it won't hold up as well as this light does. Second one I built that produces these numbers, other one was measured by rdrfronty the same as my measurements, this one slightly better. I've noticed it just doesn't drop off the longer the battery depletes like a single cell Nanjg based XM-L2 would.

I notice that even button top battery placed side by side will have outer diameter more than 24 mm (larger than circle ring on the contact board). Reading from Betweenrides posts, he said his are overlapping the circle ring but nothing bad is happening.

So is it consistent for T08 that all users here have?

I’m asking because I just ordered this light and dumb enough to measure my battery just now (TF flame and panasonic button top), all are measured more than 24 mm (so must overlap the circle ring).

thanks :slight_smile:

The T08's I've worked with (3) all work ok with various sorts of batteries that I've tested - only bad if they overlap the outer ground ring...

Hi Tom…
is the outer ground ring same with the circle ring on the board that shown in the pictures earlier in this thread? (the one marked with arrow and question mark)

Oh boy, can't find that pic, but looked at the op and it is very tight, forgot about that. But I've used KP 3400's, Pana PD's, and others and haven't had a problem - the Pana PD's have a pretty wide + end.

Think about it this way (a kind of “made up” example, and not really exact…):

- Voltage is ~ to height (= “potential”)

- Current is a “flow” (like water flowing)

If you have two voltage sources (batteries) with different voltages, it’s like two pipes of different heights. Let’s say they’re filled with water.

Now, connect the two pipes together at their tops with a pipe between them.

What happens?

The water (~ current) will flow from the taller pipe (the battery with the higher voltage).

Basically, it will try to bring the shorter pipe to the same level as itself.

Now, one more thing. Let’s say that there’s a huge difference in height. If that’s the case, the water will flow through the cross pipe FASTER (more current). If it flows really fast, and if, say, the inside surface of the pipe is really rough, it’ll create friction inside the pipe, and the pipe would get warmer from that friction.

Going back to the situation with the batteries in parallel, the same thing applies if the voltage between the two batteries is very large.

That voltage difference will cause a current to flow between the two batteries. The amount of current will be determined by the voltage difference and the resistance of the path (i.e., the wires) between the two batteries.

current = voltage/resistance

so, that means that if the voltage difference is very large, or if the resistance is very low, then there’s going to be a large current flow between the batteries, and if you get enough of a current flow, the wires between the batteries will get (maybe, very) hot. Try dropping a metal screwdriver across the terminals of your car battery if you don’t believe me (NO, DON’T DO THAT!!).

guess the picture is somewhere in page 2-4 in post by scaru or betweenrides…i’m on mobile can’t search for it…

anyway if you are saying panasonic protected is doing fine in this light, I guess I’ll be fine too using that battery…

thanks Tom :wink:

Panasonic PD's are unprotected, as sold at FastTech.

mine is the protected one.

Just an update to previous post:

here's the picture I meant (it was posted by kramer though..sorry..)

Distance between button outer diameter side by side (touching each other):

Panasonic protected = +/- 25 mm

TF flame 2400 = +/- 25 mm, too..

if placed with a space/gap just like in the battery compartment, then will be larger measurement.

Referring to Betweenrides post, the circle diameter is 24 mm.

Hhmm, never really noticed this tight fit - I got a stock T08 at home, will check measurements this evening.

much appreciate Tom :slight_smile:

To me, it looks like 26.0mm across, ground ring to ground ring. The + inner contact is 24.3mm in diameter. 25mm should just barely make it...

I guess the ground ring you referred to is the most outer gold ring…I’ll test mine first, should be arrived within day or two, already inbound in the post office. if doesn’t work well, might need a small magnet to elevate the + pole and create a smaller foot print…

Man; the Small Sun is completely different inside than the UltraFire version. (T60) Both the gold ring and center contact are spring loaded, against the corresponding brass center and aluminum end of the battery magazine.

Wonder how they did it with the Asgard . . .

Foy

Looks like this one UltraFire UF-T60

Be nice if it was a bit cheaper, build quality looks good though.

Better internal design (and supposedly alum reflector instead of plastic) for more than triple the price, yikes, and it has that mode lock feature (annoying). If it was $35-$40 instead of $89, I'd buy one or 2, but $89 puts it in a whole nother realm, and it still has to be mod'ed to beat out a HD2010 in lumens and throw, accept of course the HD2010's you are buying today at some patheticly low amps...