Turnigy Heaven

[markcycle]

So Mark, have you convinced Jon to stick some LiPo into his bike yet? That alone would give him 5 seconds a lap!

I'm trying I know he is willing but it just comes down to money

 

[Arlo1]

Cool I have ordered 25 of these pacs with no problems and will likely order ~ 100 more unless something cheeper comes out!

 

[markcycle]

Cool I have ordered 25 of these pacs with no problems and will likely order ~ 100 more unless something cheeper comes out!

To me they are the best deal going, not that this is the only good Lipo Solution to building a larger battery pack, there are many

 

[ZOMGVTEK]

So if he were to discharge it at 4C to 3.5V, he would also get 4.7Ah? I speculate that he would get less than 4.7Ah because 3.5V would be reached sooner due to higher voltage sag.

If you cut off when the loaded voltage of any single cell hit 3.5V, then you would get less capacity. However, the resting voltage is often more meaningful at determining the cells SOC, which is the important part. It all depends on how the system is setup and used, but the real danger is over discharging the cell, not bringing its loaded voltage down. If you ran a 20C discharge on one of these packs, it would show near zero capacity cutting off to 3.5V loaded, but unload it and the battery would appear to be at a very high SOC.

Basically all I'm saying is these cells don't exhibit much of a peukert effect. It's just the sag that might cause issues, which all depends on how the system is setup and used. On the average programmable controller, you can set the LVC and rise required to allow the controller to work again. On Infenion's, this is called the 'tolerance'. Set this value to something low, like 0.1V, but keep the LVC at 3.65V/cell or so. Then you can hammer the throttle, the controller hits LVC and cuts out, but works fine as soon as you let off. You are informed the voltage is low, and you can safely continue riding until the bike no longer works at all, meaning the resting voltage is at LVC.

 

[Deutch420]

I got about 30x of the 4S 5000mah 20C hardcase packs from HK; and like the OP, ALL of mine arrived inbetween 3.77-3.87v. I have about 30 or so discharges on them and they are all working prefectly.

 

[SamTexas]

If you cut off when the loaded voltage of any single cell hit 3.5V, then you would get less capacity. However, the resting voltage is often more meaningful at determining the cells SOC, which is the important part. It all depends on how the system is setup and used, but the real danger is over discharging the cell, not bringing its loaded voltage down. If you ran a 20C discharge on one of these packs, it would show near zero capacity cutting off to 3.5V loaded, but unload it and the battery would appear to be at a very high SOC.

Basically all I'm saying is these cells don't exhibit much of a peukert effect. It's just the sag that might cause issues, which all depends on how the system is setup and used. On the average programmable controller, you can set the LVC and rise required to allow the controller to work again. On Infenion's, this is called the 'tolerance'. Set this value to something low, like 0.1V, but keep the LVC at 3.65V/cell or so. Then you can hammer the throttle, the controller hits LVC and cuts out, but works fine as soon as you let off. You are informed the voltage is low, and you can safely continue riding until the bike no longer works at all, meaning the resting voltage is at LVC.

That's my understanding too. It's good that programmable controllers have the "tolerance" feature, but it's still very limited. To be truly useful, the LVC function needs to take the current into account as well. For example LVC is triggered at 3.5V and 1C, but 3.3V at 2C and 3.0V at 4C. In other words it needs to be dynamic.

 

[Ypedal]

Damn that's a lot of lipo .... beautiful sight...

I usually string them up in series ( 24 cells ) and run household lightbulbs to capacity test at 1~2 C .. with 6S packs you can run 4 packs at a time, wich does fairly quickly.... the cba2 one pack at a time would be time consuming..

 

[markcycle]

Here are plots of some of the packs The variation I attribute to temperature. some were done at 55 to 60F and others at 65 to 70F

 

[neptronix]

Why'd you start your discharge at about 4.125v/cell?
You can get the full 5AH, maybe a smidge more by charging to a full 4.2v/cell and discharging to 3.4v/cell average.

16.5v / 4S = 4.125v

 

[neptronix]

Damn that's a lot of lipo .... beautiful sight...

I usually string them up in series ( 24 cells ) and run household lightbulbs to capacity test at 1~2 C .. with 6S packs you can run 4 packs at a time, wich does fairly quickly.... the cba2 one pack at a time would be time consuming..

How do you monitor & graph the individual cells of each pack for dud cells when you discharge like that?
Do you manually just check after a certain point?

I do 10S at a time since that's the maximum that i can graph & monitor with the iCharger 1010b+.
It's slow, but it's accurate, and i get a nice RI / voltage curve out of the deal.

 

[markcycle]

Damn that's a lot of lipo .... beautiful sight...

I usually string them up in series ( 24 cells ) and run household lightbulbs to capacity test at 1~2 C .. with 6S packs you can run 4 packs at a time, wich does fairly quickly.... the cba2 one pack at a time would be time consuming..

How do you monitor & graph the individual cells of each pack for dud cells when you discharge like that?
Do you manually just check after a certain point?

I do 10S at a time since that's the maximum that i can graph & monitor with the iCharger 1010b+.
It's slow, but it's accurate, and i get a nice RI / voltage curve out of the deal.

Used a BM6 to monitor the indivdual cells and as a low voltage alarm so if i got any cell going under 3.5 volts i terminate the test.

 

[wesnewell]

These are back in stock at the USA warehouse.
http://www.hobbyking.com/hobbyking/store/__18631__Turnigy_5000mAh_4S1P_14_8v_20C_hardcase_pack_USA_Warehouse_.html

 

[cwah]

Damn it, 0.30$/wh!!

It's really really cheap

It's also available in europe but 50% more expensive. Too bad because this one seems to be the super deal for a cheap lipo pack..

 

[Punx0r]

That is cheap