"Hard Case" 7.4v 4000mAh 25C Lipo Under $60
07-14-2008, 11:14 AM
#76
I have both the Yeah 3200 and 4000 batteries as well as several other brands. After cycling them 5 times I test their capacity.
The 3200's always have just over 3200 capacity when discharged at a constant 20 Amps.
The 4000's had 3500 capacity when discharged at a constant 20 Amps.
I thought the 3200's were exceptional value but the 4000's cost a fair bit more than the 3200's and have nothing like their stated capacity. Tomorrow I am going to verify the 25C claim. The 3200's easily sustained their 20C claim.
I am not all that surprised that the 4000's do not even have 90% of their claimed capacity as they only weigh 14g more than the 3200's and you can't get capacity out of thin air. I would not be surprised if they can't handle 25C either, but I won't know that until tomorrow.
The 3200's always have just over 3200 capacity when discharged at a constant 20 Amps.
The 4000's had 3500 capacity when discharged at a constant 20 Amps.
I thought the 3200's were exceptional value but the 4000's cost a fair bit more than the 3200's and have nothing like their stated capacity. Tomorrow I am going to verify the 25C claim. The 3200's easily sustained their 20C claim.
I am not all that surprised that the 4000's do not even have 90% of their claimed capacity as they only weigh 14g more than the 3200's and you can't get capacity out of thin air. I would not be surprised if they can't handle 25C either, but I won't know that until tomorrow.
I look forward to your testing of the 25c rating on that 4000.
07-14-2008, 12:39 PM
#77
The mah rating is to their 6 volt capasitity. Lithium batteries, generally, give this reating to include the useable power. Anything other than that would be dishonest. I say generally because I have never seen it to be different but you know as soon as you stat it as fact someone dose it the other way.
07-14-2008, 02:04 PM
#78
I have tried both 3200 and 4000.When i charge the 3200 from 6.3v it takes 3200mAh but the voltage is lower than expected.It's about 4.13-4.14v/cell so i recharge it and it takes 200mAh more to get the maximum voltage of 4.2v/cell.
Now the 4000. I charge it from 6v and it takes 3700mAh to maximum voltage (4.2v/cell) untill the charger stops.The strange thing is that im getting the same runtime with both packs 3200 and 4000.My guess is that the 4000 is a misrated 25C pack with lower that 4000mAh capacity.Both packs performing the same good but at this point i don't understand why someone have to pay 25$ more? I think i'll stay with the 3200.
Now the 4000. I charge it from 6v and it takes 3700mAh to maximum voltage (4.2v/cell) untill the charger stops.The strange thing is that im getting the same runtime with both packs 3200 and 4000.My guess is that the 4000 is a misrated 25C pack with lower that 4000mAh capacity.Both packs performing the same good but at this point i don't understand why someone have to pay 25$ more? I think i'll stay with the 3200.
07-14-2008, 06:53 PM
#79
Tech Initiate
When I test the capacity of batteries I first charge them on my Hyperion balanced charger and then I discharge them at 20 Amps until they hit 6v. I use a Futaba CDR-5000 charger for the discharge test as it graphs the voltage at 4 sec intervals and it can discharge at up to 40 Amps. I always use the same leads and setup with all the batteries I test, as there could be different resistances between different leads. I really try to make the test as fair and repeatable as possible.
I have tested ProTek, MaxAmps, TrueRc and YeahRacing batteries of various capacity and I always buy at least 2 batteries in case one of them is a dud.
So far all the batteries deliver their stated capacity to 6v within 2%. The Yeah 3200's are actually a little higher giving 3244 during testing, the ProTek 4000 gave 3932. I consider that reasonable and I am sure the variance is just part of the normal production variance.
The 2 Yeah 4000 that I bought gave 3497 and 3525 mAh. I would not really call that a 4000 capacity battery, considering a 20A discharge is only a 5C discharge, which is very conservative.
I am charging them as I am typing this to do the 25C test. So far all batteries that I have tested for stated discharge ability were successfully able to maintain the continous C rating at 3.5V+ per cell for the majority of their stated capacity, other than MaxAmps batteries. Their 20C batteries hit 6V within 1/3 of their capacity and are 160+ degrees by then. They also drop to close to 3v per cell the moment you apply their stated C load on them. I found MaxAmp 20C batteries to be in reality 10C batteries.
I have tested ProTek, MaxAmps, TrueRc and YeahRacing batteries of various capacity and I always buy at least 2 batteries in case one of them is a dud.
So far all the batteries deliver their stated capacity to 6v within 2%. The Yeah 3200's are actually a little higher giving 3244 during testing, the ProTek 4000 gave 3932. I consider that reasonable and I am sure the variance is just part of the normal production variance.
The 2 Yeah 4000 that I bought gave 3497 and 3525 mAh. I would not really call that a 4000 capacity battery, considering a 20A discharge is only a 5C discharge, which is very conservative.
I am charging them as I am typing this to do the 25C test. So far all batteries that I have tested for stated discharge ability were successfully able to maintain the continous C rating at 3.5V+ per cell for the majority of their stated capacity, other than MaxAmps batteries. Their 20C batteries hit 6V within 1/3 of their capacity and are 160+ degrees by then. They also drop to close to 3v per cell the moment you apply their stated C load on them. I found MaxAmp 20C batteries to be in reality 10C batteries.
07-14-2008, 08:57 PM
#81
Tech Initiate
I have just completed the current test twice (wanted to make sure the results are consistent), and as expected, the 25C rating is rather fabricated.
I tested the Yeah 3200's at 60 Amps (20C), Yeah 4000's at 100 Amps (25C) and the ProTek 4000's at 100 Amps (25C).
I have a board with resistors and switches where I can vary the load and I use an Eagle Tree 150Amp Data Recorder in Live Mode connected to a Laptop to monitor the voltage and current. I calibrate the Eagle Tree every time I use it with a 40 Amp power supply with an internal digital reading and a current shunt to make sure it is accurate to within 1% of its reading. Once I am happy the Eagle Tree is calibrated I use it to adjust the resistors to give the load I need for testing. I read the voltages of the balance tabs from the batteries to see how the batteries are going so I do not have to compensate voltage loss across the wires and Deans plugs.
The Yeah 3200's at 20C performed amiacably. 3.6-3.7v at full load giving full capacity and reaching 147 degrees at the end.
The ProTek 4000's at 25C performed well. 3.5v at full load giving full capacity and reaching 149 degrees at the end.
The Yeah 4000's at 25C did not go so well. Within 10 secs they were at 3.38v and after 90 secs I had to stop because the battery reached 180 degrees in the centre and 215 degrees at the end where the wires were soldered on. I did not want to have a fire at home.
The ProTek batteries are considerably heavier and thicker than the Yeah batteries which leads me to conclude that you don't get capacity and performance from nothing.
It's a shame Yeah did not market these batteries as 3500 mAh and 20C and they would have had another winner on their hand, but unable to ask for those extra $19 per pack.
I tested the Yeah 3200's at 60 Amps (20C), Yeah 4000's at 100 Amps (25C) and the ProTek 4000's at 100 Amps (25C).
I have a board with resistors and switches where I can vary the load and I use an Eagle Tree 150Amp Data Recorder in Live Mode connected to a Laptop to monitor the voltage and current. I calibrate the Eagle Tree every time I use it with a 40 Amp power supply with an internal digital reading and a current shunt to make sure it is accurate to within 1% of its reading. Once I am happy the Eagle Tree is calibrated I use it to adjust the resistors to give the load I need for testing. I read the voltages of the balance tabs from the batteries to see how the batteries are going so I do not have to compensate voltage loss across the wires and Deans plugs.
The Yeah 3200's at 20C performed amiacably. 3.6-3.7v at full load giving full capacity and reaching 147 degrees at the end.
The ProTek 4000's at 25C performed well. 3.5v at full load giving full capacity and reaching 149 degrees at the end.
The Yeah 4000's at 25C did not go so well. Within 10 secs they were at 3.38v and after 90 secs I had to stop because the battery reached 180 degrees in the centre and 215 degrees at the end where the wires were soldered on. I did not want to have a fire at home.
The ProTek batteries are considerably heavier and thicker than the Yeah batteries which leads me to conclude that you don't get capacity and performance from nothing.
It's a shame Yeah did not market these batteries as 3500 mAh and 20C and they would have had another winner on their hand, but unable to ask for those extra $19 per pack.
07-15-2008, 01:32 AM
#82
JorgD,
Thanks for the info.
I currently use the Yeah racing 4000 Lipo in my Mini, so it will be fine for this application. I could have saved some money and purchased the 3200 instead.
Oh well, never mind.
Thanks
Calvin.
Thanks for the info.
I currently use the Yeah racing 4000 Lipo in my Mini, so it will be fine for this application. I could have saved some money and purchased the 3200 instead.
Oh well, never mind.
Thanks
Calvin.
07-15-2008, 03:00 AM
#83
07-15-2008, 09:17 AM
#84
Tech Rookie
Greetings
JorgD:
thanks for posting your testing results. too bad I had a friend order two of the 4000 packs for me before you posted this I would have went with the 3200's instead.
too bad you can't change your order. I might just send them back unopen and order the 3200's
regards
JorgD:
thanks for posting your testing results. too bad I had a friend order two of the 4000 packs for me before you posted this I would have went with the 3200's instead.
too bad you can't change your order. I might just send them back unopen and order the 3200's
regards
07-15-2008, 01:19 PM
#85
well i ordered one...
but some stuff got screwed up and im getting a free 3200 to make up for the issues so that means for the price of a 4000 i got a 4000 + a 3200. No complaints, looks like from the testing they'll perform the same and im happy with the 3200 so again, no complaints here haha.
but some stuff got screwed up and im getting a free 3200 to make up for the issues so that means for the price of a 4000 i got a 4000 + a 3200. No complaints, looks like from the testing they'll perform the same and im happy with the 3200 so again, no complaints here haha.
07-15-2008, 08:14 PM
#87
So far all batteries that I have tested for stated discharge ability were successfully able to maintain the continous C rating at 3.5V+ per cell for the majority of their stated capacity, other than MaxAmps batteries. Their 20C batteries hit 6V within 1/3 of their capacity and are 160+ degrees by then. They also drop to close to 3v per cell the moment you apply their stated C load on them. I found MaxAmp 20C batteries to be in reality 10C batteries.
07-17-2008, 09:20 AM
#88
Tech Rookie
Greetings
Has anyone had problems with shipping from Ultralinehobbies??? my freiend ordered packs last week with 2 to 3 day shipping and stil a no show.... so much for racing this weekend. we are not happy people
Has anyone had problems with shipping from Ultralinehobbies??? my freiend ordered packs last week with 2 to 3 day shipping and stil a no show.... so much for racing this weekend. we are not happy people
07-17-2008, 04:03 PM
#89
same happened to me but if u look a few pages back they said everyone that ordered before 6/24 would get theres but orders placed after 6/24 would have to wait till the next shippment, basically saing if u placed your order after 6/24 you would be on back order. anyways they said they were going to get there shipment this week. ultraline have u guys got the new shipment yet?
07-17-2008, 05:10 PM
#90
Tech Initiate
After complaigning to the Hong Kong supplier from where I bought my Yeah Racing 3200's and 4000's and explaining what is wrong they tested their stock and agreed with me that the 4000's do not measure up to their stated capacity. They have refunded me the price difference between the 3200 and 4000, so basically I paid for 2 3200's and got 2 3500's labelled as 4000's.
The MaxAmps batteries I tested and found to be 10C and completely unable to provide their stated 20C capacity due to massive voltage drop and overheating were the 3000 2S1P 20C and 5000 2S1P 20C. I have 5 of them in total and none were even close to spec regarding continuous current. They do deliver their stated capacity though if you do not stress them, so depending on your application they may still work really well.
The MaxAmps batteries I tested and found to be 10C and completely unable to provide their stated 20C capacity due to massive voltage drop and overheating were the 3000 2S1P 20C and 5000 2S1P 20C. I have 5 of them in total and none were even close to spec regarding continuous current. They do deliver their stated capacity though if you do not stress them, so depending on your application they may still work really well.