Riva Battery Voltages

[robl45]

Question the riva batteries, I got the starter kit with 2 batteries, charge it with the usb charger. I notice fully charged they come out at 3.7 volts or so and then fairly quickly drop down to like 3.3 volts tested with my voltmeter. is that standard for these batteries? shouldn't they come off the charger at 4.2 volts?

trying to figure out if I got bad batteries or a bad charger or if this is normal, I'll have to use lower ohm cartomizers. the 2.6-2.8 work great for like 30 minutes, but then performance suffers. when I use my box mod with normal 900mah batteries, ti works fine.

 

[pm2006]

I thought Rivas like Egos were 3.2. Huh.

 

[JollyRogers]

No eGos are regulated to 3.4vdc using PWM. Rivas are not. I just checked one, I used it a bit, but it reads 4.0vdc unloaded. I had checked one last night after some use and it read 3.7vdc. I used that one through the evening last night and till lunch this morning before putting it on a charger... I am not Abe or Imyoursalt, so can't say one way or the other.

 

[swt_silhouette]

Maybe it's a, "Hit-Or-Miss", thing with the Rivas... I ordered a black starter set... that worked so well, I ordered a second in Titanium. The titanium batts don't work well at all. Right off the charger, they are just not very strong, and in under an hour their basically useless.

The black one's are still going strong though, and I just placed an order, (today), for juice, atomizers, connectors and stuff, so I obviously don't think this issue is a reflection on LF. From what I've read, It just seems like this happens with all vendors, from time to time.

 

[robl45]

Maybe it's a, "Hit-Or-Miss", thing with the Rivas... I ordered a black starter set... that worked so well, I ordered a second in Titanium. The titanium batts don't work well at all. Right off the charger, they are just not very strong, and in under an hour their basically useless.

yea mine are decent for like an hour, then its like sucking really hard through a straw to get anything. they are coming off the charger at 3.7 so maybe I got a bad charger? I know my voltmeter is good because the batteries I use in my box mod are coming off fully charged out of their charger at 4.2 volts.

 

[swt_silhouette]

I don't know. I got two new chargers. One with each Riva set I ordered, and the black set works great with either of those. I use the same chargers for the titanium set, and it's not the chargers over here.

 

[robl45]

i just checked again now, one fresh off the charger is 3.7 volts, doesn't make sense since the charger says 4.2volts output. and i plugged it back in and it won't charge anymore, other battery is charging now, that was was at like 3.5 volts.

 

[pm2006]

getting closer.

 

[robl45]

getting closer.

huh? its the same as before.

 

[Katya]

All testing needs to be done under load or it doesn't mean much. What mattters is the voltage delivered, under load. Nominal voltage of these batteries is always 3.7v. Please check these threads. Very informative.

http://www.e-cigarette-forum.com/forum/joye-510/65055-battery-voltages-surprise.html#post962734

http://www.e-cigarette-forum.com/fo...41-ohms-volts-some-surprises.html#post2230390

 

[robl45]

thats the dead battery voltage, 3.7, fully charged should be 4.2.

 

[Katya]

thats the dead battery voltage, 3.7, fully charged should be 4.2.

???

Per specs, a Li-Ion cell has a nominal voltage of 3.7v. They are fully charged at 4.2v. Did you read the linked theads (in my previous post--#10)? Did you watch Dave's video? Please read post #1 in Scottbee's thread and watch Dave's video (about 5 min into the vid he begins testing the battery under load).

"Dead battery voltage 3.7v"? I don't understand.... All eGo/Riva/Tornado batteries regulate at 3.1-3.3v, depending on who's testing. That's the true voltage delivered.

 

[swt_silhouette]

Well I don't have to be a Rocket Scientist to tell ya mine don't work right lol!

 

[Scottbee]

No eGos are regulated to 3.4vdc using PWM. Rivas are not.

I'm sorry... that's not correct. The Riva system also uses a PWM algorithm.

 

[JollyRogers]

Hey Scottbee. Does the PWM only occur when under load? I only ask because when I check my eGo without a load it reads 3.4, when I check my Riva (I just got from LF) it is reading 4.0vdc.

Edit: In fact I just compared them right off the charger, under no load. Riva from LF 4.2vdc, eGo that is 6 months old 3.41vdc. These are the SE edition of Rivas.

 

[Scottbee]

Hey Scottbee. Does the PWM only occur when under load? I only ask because when I check my eGo without a load it reads 3.4, when I check my Riva (I just got from LF) it is reading 4.0vdc.

I haven't done traces on unloaded units being that the unloaded voltages and waveforms don't really mean much.

 

[Cee_Jay]

Although not a precise way of measuring, the unloaded voltage of a Lithium cell gives a good ball-park figure of the charge state.

4.20v = 100%
4.03v = 75%
3.85v = 52%
3.79v = 30%
3.70v = 10%

Discharging above 4.2v or below 3.6v is detrimental to the chemical composition, and if repeated often will lead to premature failure. Extreme abuse of these limits can lead to more serious consequences. Fortunately, most chargers are programmed to perform their function within in the above limits.

 

[JollyRogers]

Sure they don't. However, if the Riva is exactly like the eGo, then it should also read 3.4vdc unloaded. It doesn't in this case. I don't believe that PWM requires a load to regulate the voltage to 3.4vdc, or the eGo wouldn't bring it down to that. Because I know you have tested them, I do not doubt that the Riva's you have are PWM. However, I now wonder what the deal is with the Riva SE edition from LF. They definitely are starting off at 4.2vdc off the charger, and after some use are dropping to 3.7ish here.

I don't have a resistor here to load the battery, however I can definitely tell the difference between a the Riva battery and eGo when using an atomizer. I know, very subjective.

Edit: I forgot about my ato-miser which is currently running with a 3Ω as measured coil on it. I used that as a load. The Liberty Flights Riva SE battery I got this week fresh off the charger reads 3.85vdc with that 3Ω load. The eGo I have reads 3.25 with the same 3Ω load. Didn't take pictures, but certainly can. This tells me that the Riva batteries I just got from Liberty Flights are not PWM and I believe they are different from what Scottbee has. Whatever the deal is with these, they are coming off the charger @4.2vdc and running @3.85 with a 3Ω load. I am using a cheapo CE multimeter and wish I had my fluke from work to test to be more accurate (especially on the 3Ω load). If I get a chance, I can certainly take an o-scope reading while at work to verify these are not PWM batteries. However, I believe the batts I got in my SE kit from LF are not, maybe because they are "SE" and a true 3.7vdc... or maybe there is another explanation?

 

[JollyRogers]

OK here is a picture of the LF "Riva SE" edition battery with a 3Ω load on it. Notice the atomizer spitting vapor in the picture. It is reading 3.84vdc in this picture. And my wife is now playing with my multimeter

 

[Scottbee]

OK here is a picture of the LF "Riva SE" edition battery with a 3Ω load on it. Notice the atomizer spitting vapor in the picture. It is reading 3.84vdc in this picture. And my wife is now playing with my multimeter

Please get a scope trace of that if you can!

If there is a "different version" Riva with the PWM disabled.... I'd certainly like to hear about it! The 6 or 7 Rivas that I have here all have the same circuit board and the same PWM configuration......