HOHM Wrecker 151W TC ?

[f1vefour]

Okay this device is aggravating me today also, or least causing a minor annoyance.

I was running two old Sony VTC5s and when pressing the fire button the battery meter would change from 100% to say %93 (back to %100 when releasing fire button) when the batteries were freshly charged. I asked Matt from Suck My Mod if that is a method of testing battery sag and he said yes.

I figure okay the batteries are right at 2 years old, sag is to be expected even at 35 watts.

I got a pair of Samsung 35Q today, charged them up at 0.5A to make sure they got a nice full charge. Put them in and they are showing a 5% to 9% sag at only 35 watts (3.7v), I know they aren't sagging that much. I like this feature but apparently it's buggy or something is wrong with these batteries.

@350ZMO
Have you noticed this? What batteries do you use?

I researched plenty and went with the 35Q because @Mooch the resident battery expert tested these and they are 20A safe and 3000mAh just like the LG HG2.

I am not a battery expert but certainly these batteries aren't sagging that much at only 3.7v?

 

[f1vefour]

I'm doing this from my understanding, someone who knows could you correct me?

Battery: Samsung 30Q
Battery Voltage: 4 (probably 4.2 but simplified)
Internal Resistance: 14 milliohms
Amperage: 20

20 x 0.014 = 0.28v (sag)

It's two batteries and myself being no battery expert this is where I don't understand what's next.

Would it be 20 x 0.028 = 0.56v

4.2v / 0.56v = 7.5% (Sag)

If this is correct then the mod is indeed showing the correct information for the most part.

*Edit*
It's got to be a bug, it jumps all over the place and I notice that the applied wattage isn't hitting 35w even when setting the temperature to 700°. Conclusion is the displayed information in XXX mode is not accurate.

 

[350ZMO]

@f1vefour

Yes batteries are in series so the voltage drops or sags are additive. Current through each is the same in series. If they were in parallel then the voltage sag would be less as each cell would share the current ie half each assuming they are electrically identical.

Yes the battery meter does that in xxx mode. Switch to watts mode and set to 35W and see what the battery meter does.

I have used the Hohm Work batteries and some Panasonics. I have LG 2s and 4s and Samsung 25rs and VTC5s and 4s and several others but I have not tried them. Keep those 30s, those are good batts nothing wrong with them.

Now here is something I have noticed. If I set the G2 to 151W with a .86ohm load it shows 7.5V. I can lower power setting all the way to 65W and it stays 7.5V. When I get to 64W then it shows 7.4V and starts lowering from there. So even though the specs say 9.5V, it isn't. That tells me there is no boost, just buck in digital watts mode. IE 7.5 / 2 = 3.75. And that matches what Phils video showed. So his prototype and my production model are doing the same thing in that regard.

So assuming it can deliver 151W at 7.5V that would require a build of .37ohms and that would be 20.1 amp ignoring losses. I'll see if I can do one of those.

I have no idea about the 9.5V spec. Maybe that is the limit with a 3 cell which really should be 11.2. Or maybe it can boost in modes other than digital watts mode. I don't know.

I have called Hohm tech asking if I could purchase just the board to build one with a 3s lipo and 1590B box but they have yet to reply. In fact I have emailed them on other topics and they have yet to reply to any of my contact attempts. Not even a simple no which would be sufficient. So I do find that troubling.

So what you are experiencing may be a bug or it may be a device limitation. I have not had battery contact issues like Phil did but I haven't pushed it that hard in current yet.

What is the resistance of your build?

 

[f1vefour]

The resistance of the build is 0.40. You can't see battery sag in wattage mode because of that stupid puff counter.

Them not responding to your queries isn't good, let us know if they never do. I'm sure they are following this thread since it's the only active discussion on the G2 here on ECF.

 

[350ZMO]

Yeah that's right. Well at .4 ohm and 35W your only drawing 9 to 9.5 amps, so with an internal resistance of .014 (might be less at half its rated current capacity), that sag would be .25 to .27 total. Given series, the batteries are at 7.4. And given 35W and .4ohm, the voltage supplied to the atty needs to be around 3.75V. Factor in the sag and that total is around 4V and that's definitely within the capability of the G2s 7.5V. So either its trying to max out power or there are battery contact issues or its a bug. If the vape experience is ok then probably a display bug.

 

[f1vefour]

Vape experience is correct, that's why I believe it's a bug.

 

[350ZMO]

Well I did try a dual build with 5 wraps each 2.5mm 28 gauge Kanthal and it still will not limit. It does single coils with 28 and 26 gauge from 5 to 10 wraps from 2.4 to 4mm ID. Just no go with duals from 5 to 10 wraps each from 2.5 to 4mm ID with either 28 or 26 gauge. I don't have 30g Kanthal but I do have some 32. But I don't see the point in trying given this last build. So I'm ready to stop and say I can't get a dual to limit.

 

[f1vefour]

Odd, I have seen a review or two using duals.

 

[AtmizrOpin]

@f1vefour

Yes batteries are in series so the voltage drops or sags are additive. Current through each is the same in series. If they were in parallel then the voltage sag would be less as each cell would share the current ie half each assuming they are electrically identical.

Yes the battery meter does that in xxx mode. Switch to watts mode and set to 35W and see what the battery meter does.

I have used the Hohm Work batteries and some Panasonics. I have LG 2s and 4s and Samsung 25rs and VTC5s and 4s and several others but I have not tried them. Keep those 30s, those are good batts nothing wrong with them.

Now here is something I have noticed. If I set the G2 to 151W with a .86ohm load it shows 7.5V. I can lower power setting all the way to 65W and it stays 7.5V. When I get to 64W then it shows 7.4V and starts lowering from there. So even though the specs say 9.5V, it isn't. That tells me there is no boost, just buck in digital watts mode. IE 7.5 / 2 = 3.75. And that matches what Phils video showed. So his prototype and my production model are doing the same thing in that regard.

So assuming it can deliver 151W at 7.5V that would require a build of .37ohms and that would be 20.1 amp ignoring losses. I'll see if I can do one of those.

I have no idea about the 9.5V spec. Maybe that is the limit with a 3 cell which really should be 11.2. Or maybe it can boost in modes other than digital watts mode. I don't know.

I have called Hohm tech asking if I could purchase just the board to build one with a 3s lipo and 1590B box but they have yet to reply. In fact I have emailed them on other topics and they have yet to reply to any of my contact attempts. Not even a simple no which would be sufficient. So I do find that troubling.

So what you are experiencing may be a bug or it may be a device limitation. I have not had battery contact issues like Phil did but I haven't pushed it that hard in current yet.

What is the resistance of your build?

here's my response from htech a while ago.

Hohm Tech <hello@hohmtech.com>
Jan 20

to me


We sell them for $49.99 plus shipping for single chip (FSK G2 Chip). If you're referring to FSK G1 chip that came in 1st version Wrecker, those are $33.99 plus shipping.

Just like our products, this email is Hohm Made...

Benjamin
Hohm Tech Corp.
(O): 626-962-2823
(F): 626-814-2823

imo the board is 'meh'. i haven't tried with a 3S batt config yet. it's 100% only a synchronous buck converter. no boost.

 

[350ZMO]

here's my response from htech a while ago.

Hohm Tech <hello@hohmtech.com>
Jan 20

to me


We sell them for $49.99 plus shipping for single chip (FSK G2 Chip). If you're referring to FSK G1 chip that came in 1st version Wrecker, those are $33.99 plus shipping.

Just like our products, this email is Hohm Made...

Benjamin
Hohm Tech Corp.
(O): 626-962-2823
(F): 626-814-2823

imo the board is 'meh'. i haven't tried with a 3S batt config yet. it's 100% only a synchronous buck converter. no boost.

Thanks I'll try again Monday. I know, I would just like to try it with a good 510 and a 3s.

 

[350ZMO]

Odd, I have seen a review or two using duals.

Yeah its behavior is different, I can set temp down to say 400 wont fire bump it to 410 and it fires as long as you hold the button down to the point of burning and with no pulsating. On any single I have thrown at it, it will pulsate and shut off preventing burn.

 

[f1vefour]

If I could find my kanthal I would test dual.

 

[350ZMO]

No worries. I do have some good news, the UD 316L was spot on, so was NI200. So I retested the unkamen 430 and still way off. Unkamen also supplied a sample of Ti so I tested it. And it was off, though not as bad as the 430. Ni in Ni mode, Ti in Ti mode, 316L and 430 in SS and XXX mode with 14%. Hopefully I'll get the video up tomorrow. I am considering testing to generate a TCR curve for the unkamen 430. But for now, I was pleasantly surprised the UD and Ni was spot on.

Edit: As I was putting the video together I noticed the Ti was actually even farther off than the 430. So 430 off by 100F and Ti off by 150F, UD 316L and Ni very close.

Link to video.

 

[f1vefour]

I had a feeling the 316L would be better since it's likely what HT used for testing.

 

[350ZMO]

Well finally got around to a dual unkamen 430 build in the Billow V2 and it vapes and limits fine. No way it's off by 100F. Can't explain why it just is. So even though the thermocouple test was repeatable, it obviously is incorrect.

 

[f1vefour]

Well finally got around to a dual unkamen 430 build in the Billow V2 and it vapes and limits fine. No way it's off by 100F. Can't explain way it just is. So even though the thermocouple test was repeatable, it obviously is incorrect.

Good to know I'm not crazy

That's what I was saying about the way the device limits temperature with a wet wick but not as well or even correctly when dry.

I think I may try some UD 316L eventually, I would like to have something a little larger than 28g.

 

[350ZMO]

Good to know I'm not crazy

That's what I was saying about the way the device limits temperature with a wet wick but not as well or even correctly when dry.

I think I may try some UD 316L eventually, I would like to have something a little larger than 28g.

Nope you're not crazy. Have you noticed if FSK percentage affects SS mode?

Also, Google thinks HTs site has been hacked. So does my virus scanner.

 

[f1vefour]

Yea I noticed that about HT site for days now, haven't researched the criteria of how Google assumes that.

FSK Temp Curve percentage definitely affects SS, I am currently running a 0.40 (0.41 depending on ambient temp) build at 15.4% 420°F and it feels about right.

I like for the build to ramp then limit and pulse, basically shut down unless you are inhaling. That's when it seems to be the most accurate.

 

[Wingsfan0310]

I think I may try some UD 316L eventually, I would like to have something a little larger than 28g.

When I use the 28ga 430 I got from Unkamen, it doesn't feel like I'm working with 28ga, more like 26ga. Am I the only one that feels that way. Just doesn't seem like the 28ga of other wires I've worked with. Maybe because it's on the stiff side.

Cheers,
Steve

 

[350ZMO]

When I use the 28ga 430 I got from Unkamen, it doesn't feel like I'm working with 28ga, more like 26ga. Am I the only one that feels that way. Just doesn't seem like the 28ga of other wires I've worked with. Maybe because it's on the stiff side.

Cheers,
Steve

It is very springy and tough. I presume that's due to the higher C content.

I uploaded the .csv from steam engine into the DNA and measured the results with the thermocouple.

Here was typical plot of live resistance monitoring.

The results were very good between set temp and thermocouple reading and the live ohms is typical of using this test method. I saved the live ohms recording for each set temp run and used excel to average the resistance data at the end of the file once the thermocouple leveled off. Used sequential 10s puffs.

So this confirms for me that the TCR in the vaping range between 400 and 500 F is at least close to .00125 for the Unkamen 430SS I received. Which for me combined with the same vape experience off the same atty with the same 430 build between the two mods is more evidence that using this test method with the Hohm Wrecker G2 just doesn't work.