Total Noob - help too optimistic?

I don't understand my balance charger, Thunder 1220 charger. I have two battery packs: 1) 12S1P - 8ah, and 2) 12S2P - 16ah.

The charger has a 180 minute time limit for charging. I set the charger to target 4.2v per cell.

When I balance charge my 12S1P it takes about 90 minutes. Cells 8 & 10 are over 4.2v and the rest are under.

My 12S2P is brand new ... the four batteries were fresh from the factory. The first time I balanced charged the charger timed out at 180 minutes. Cells 8 & 10 were over 4.2v. The rest were under. The total charge was 49.5v. I didn't start my charger over. I just used the battery. Went 22 miles and the battery was down to 45.2v at rest.

I balance charged again. This time I let the charge run for 170 minutes - then I needed to use the battery and I figured in the last 10 minutes it wasn't going to level all the cells at 4.2v so I just stopped the charge cycle and used the battery. But I shot video of the cell levels:

http://youtu.be/fu9lIknJWeY

As you can see - the charger reports cells 8 & 10 are over and the rest are under. And the total charge is 49.75 - target is 50.4v.

Immediately after I took the battery pack off the charger I checked the cells with a hand held checker - this checker (Bluecell Lipo Digital Battery Voltage Checker - http://www.amazon.com/gp/product/B005HG54UI/ref=oh_details_o03_s00_i01?ie=UTF8&psc=1) gets good reviews for accuracy on Amazon. I got two them. I shot video of the result:

http://youtu.be/6ULD0IKOvpY

AS you can see - no cell is over 4.2v. I don't understand. Doesn't my charger need to be most accurate so as to not overcharge a cell? But it appears the charger readings aren't accurate. And cells 8 & 10 are the ones the charger reports as over for both battery packs: 12S1P and 12S2P. The same cells (8 & 10) in both battery packs - that seems odd. I'm confused. I'm thinking this is operator error as this is my first experience with LiPo / RC / Balance Charging and everything.

Also, both the charger and the checkers report cell levels that are not within 0.01v tolerance of each other.

What gives - any insights would be greatly appreciated.

Thanks!

See safety timer on page 6 of the manual. It says there you can adjust it from 10 to 300 minutes or turn it off (for lithium batteries). Not adjustable for other battery types as stated on page 19.I'd turn it off and do a full charge and see if it balances better. But first I'd do a storage charge setting store voltage to 3.9V. Also you need to make sure you have the balance plugs plugged into the right ports. If you reverse them on my charger, it won't balance properly either. I may have missed it, but I didn't see anything about which balance port was high or low in the manual. Although I think I saw somewhere where the high side was the left port.

Yes high side voltage is the left balance port on the Thunder. I do have to admit that theThunder takes a long time to balance and is not the most accurate charger I have used. In my case I have LiFePo and it is fine for them. The A123 can easily get out of balance and eventually the Thunder gets them back to 0.01 volts. Perhaps not accurate enough for LiPo.
otherDoc

When I have drastically out-of-balance cells following a full charge I rig a small pigtail with pins that stick into the appropriate cell of the JST connector. Set the charger to 1S and bring low single cells up to the SOC of the rest of the brick.

Obviously, several caveats exist with this method but it's much quicker and more direct than dealing with time out and and the slow bleed method of balance most of these chargers employ.

OMT - I'd avoid 4.2V/cell (adjust Lipo settings or use Lilo function if equipped?). When I did temperature testing with 20C Turnigy cells I detected rapid rise in cell temps while charging between 4.1-4.2V. Which can't be good for longevity IMO.

I would agree.
Set your safety timer to the full ammount of turn it off.
In the battery choice options look for an option that says something like "continue" or "stop" when TCS capacity is reached. Set it to continue.
If you have a TCS option with a % setting I'd set it at 95%. This will charge your bats to 4.15v instead of 4.2 and will increase cycle longevity while losing only 2-5% of useful charge.

I apologize in advance for ill-structure of paragraph/thoughts and stuff ... I'm doing the best I can without doing umpteen drafts.

The order in which you plug in the balance taps makes a difference? I noticed you can do it two ways. But I didn't know it made a difference with regard to operation of the charger and/or results of the charge. Is this stuff explained anywhere? There are two ports on the charger, 1-6 and 7-12. For the sake of consistency I've been connecting the balance lead associated with RED/SERVICE to port 1-6 and the balance lead associated with BLACK/SERVICE to port 7-12. I use SERVICE as a distinction from the other leads being used to SERIES the batteries. I've either +lucked into doing it consistently right OR -lucked into doing it consistently wrong. How do I decipher which is high and which is low?

I can set the target cell voltage. I've set it to 4.2v/c. I did this because I want to maximize the useful longevity of each charge (go far). But I don't mind sacrificing some distance for battery longevity and health. All of my batts are Zippy 8000mAh 6S 30C. I have 6 of them = (1) 12S1P and (1) 12S2P. I haven't noticed any discernable temperature variation to touch when charging. I have noticed they can be slightly warm after discharge. My "in-use" container is an insulated lunch bag - the 12S2P fits VERY SNUG in the bag. I don't think an insulated bag is ideal by any means ... is it outright bad? As for accessing cells manually - I was feeling comfortable with that but now I better understand the physical make up of the batteries ... by understanding this I'm now afraid to interact (charge/discharge) with the battery in a manual way. I'm OK with checking voltage at the cell level at the balance taps with a multi-meter. I thought the balance leads were one RED across all cells and each NON-RED connected to one cell. Now I understand each cell has two leads connected to it - the cells are in series and at each series connection a balance lead is attached + one balance lead on each end where (I assume) the main output leads are connected. I need to GROK how this works before I'll be comfortable accessing individual cells. I think the way to understand is to think in terms of the direction of electromagnetic force - any hints would be appreciated.

I turned the timer off. I'm using the storage program set to 3.85v/c with my 12S1P pack now. I'm doing this because I think I'm only going to use the 12S2P pack. I'll just let it run and see what happens.

I want to turn on regen braking - I think I'll set the target voltage to 4.15v/c. This will give me a target full charge of 49.8v when all cells are in perfect balance and at Top of Charge. I saw wesnewell said he noticed a .5v increase in battery voltage when regen was on and active ... so even if I start a ride and need to brake early, the total voltage will likely only go up to 50.3v which is under 50.4v = 4.2v/cell*12cells ... is my plan any good? I think setting the target voltage to 4.15v/c serves two purposes: 1) extends longevity of battery pack, and 2) allows for odd times when I start a ride by braking.

I also want to turn on Cruise Control - this is almost a must as my thumb gets tired and it will be much better because I like to pedal as well as use power. I think cruise control will help a lot in this capacity - pedal and power at the same time. I assume cruise control only sets the throttle position and does not vary the throttle depending on terrain as it does in a car.

Turning these functions on will be a different post ... either a reply to one where wesnewell has already explained it or a PM.

How often to you guys balance charge? I've been doing it every time. Now seeing it can take hours and hours it doesn't seem practical to balance charge every time. How do you bulk charge? Do you just skip the charger and hook directly up to the power supply? Or do you hook up to the charger and skip the balance taps? OR ???

Thanks for all your help ... I think I'm still danger boy but I'm becoming safety boy. I aspire to be e-bike LiPo man like all you all.

Here's my 12S2P inside my insulated lunch container getting ready for a ride.



It weighs about 12 lbs.



Here it is mounted



49.8v 16ah = fun and exercise

I think I'll ride north on the Santa Ana river trail ... May be stop at The Block at Orange for lunch.

Hopefully, nothing gets stolen!

I won't get into a long reply about some good points you make but the temperature increase I spoke of between 4.1-4.2 is not something felt but mainly obvious if/when graphing cell temps over multiple charge/discharge/charge test runs.

4.1-4.15 is also a nice "safety buffer" for those occasions when meters are in error or you/we simply confuse something that we "should" know better. 4.2V doesn't amount to much greater capacity IMO and the longevity I've experienced using conservative values is simply amazing. 3 full years, +500 cycles and still very useful capacity. Sure, 'been some repairs (couple cell replacements) but I'm convinced "derating" daily capacity and careful monitoring results in excellent value in a small package.

I rarely balance charge and when I do it's usually a 1S charge through the appropriate balance connector. BM6 is cool, CellLog 8s is amazing, those little monitors you got look cool. Can't have too much of that kinda thing IMO. Watch 'em, pay attention to 'em, maintain safe voltage range, etc.

Enjoy the ride!

Thanks.

With wesnewell's advice I think I had the balance leads hooked up to my charger wrong. I switched them to the other way (in the sense of high/low) and did a storage charge on my 12S2P pack - 3.85v/c. After 6 hours all cells were in the range of 3.849v-3.855v. This morning I re-did a storage charge to my 12S1P pack - 3.85v/c. It also took 6 hours. Now, all cells are in the range of 3.841v-3.847v.

I did storage charges on both my packs because I've taken apart my controller to enable Cruise Control. I really don't know when I'll be back up ... I'm hoping for tomorrow, but who knows.

I started a new thread in E-Bike Technical for this endeavor. Here's a link.

http://www.endless-sphere.com/forums/viewtopic.php?f=2&t=51160

Many thanks for the awesome advice from everyone!

Cheers ...

OK. Cruise Control works! Cool!

I ordered (3) ZIPPY Flightmax 8000mAh 3S1P 30C and (2) JST-XH Parallel Balance Lead 3S 250mm (2xJST-XH) today.

The goal is to have (1) 15S2P - 16000mAh pack and (1) 15S1P - 8000mAh pack.

At 4.2v/c the packs would be at 63v. I think that's the limit of the capacitors in the controller. I'll charge to 4.1v/c = 61.5v at full charge.

I'll have to be my own BMS I think because the 41.5 LVC of the controller is too low (unless the cells are in perfect balance). The plan is to re-charge whenever the battery is 54v-55v (3.600v-3.667v per cell) . And to cutoff and use pedal power only whenever I'm down to 52v (3.467v/c). But I think there's a caveat - if I'm running low (down to 52v) I think I could stop and check the cell balance. If the cells are in good balance I could continue to use the battery - may be checking the cell balance every 0.5v-1.0v used. This would be limping home. Because at 52v the throttle still going to have plenty of GO I think. I'll have to use restraint and a knowing that I could damage the batteries and/or start a fire on my bike (which would just spoil my day/week/year/life - may be).

But when you think about it ... my charger is set to discharge to 2.8v/c in it's discharge program. That's really low!?! So, I guess if the cells are balanced, it's OK to use up a lot of charge. 2.8 * 15 = 42. dogman's LiPo rules say never below 2.7v/c. I don't know how sag works into the equation. I don't think you ever want to sag below 2.7v on any cell. If you do, you're probably just killing that cell. But that means a well balanced 15S pack could run down to, say 44v (2.933v/c), and not have a problem. Still probably better to keep to a policy of recharge between 54v-55v and use 52v as a LVC (but it will be a manual LVC, meaning I just manually shut of the controller and pedal).

Does this make sense -- or am I just being a loose canon?

Hook one of these up and recharge when you hit 54V no load and your batteries will last a long time. Run them down to 42V and you'll shorten their life.
http://www.ebay.com/itm/Waterproof-Digital-Voltmeter-DC-15V-To-120V-Red-Led-Voltage-Digital-Panel-Meter-/170846310527
The batteries are 100% drained at ~3.4V no load. See this.
http://endless-sphere.com/forums/viewtopic.php?f=14&t=47294

Hello,

I received three 3S1P 8Ah LiPo's from Hobby King. I've played with them and created a 15S1P pack which I've used -- charged to 4.1v/c or 61.4v. Put it on the bike and it goes 35.9mph now ... pretty cool - but too fast!

That's OK though ... I can restrain myself and only use it when a situation calls for it.

But I'm concerned about altering my 12S2P pack to create a 15S2P pack because I'm not sure (positive) I'll be doing it right. If I didn't have you guys to run it by, I'd just do it. So, I'm pretty sure this is right ... but I want to check.

I created a diagram to show how I'll hook it up:



This is correct, right? Where I'm concerned is I'm only paralleling the outputs on the ends. The 3S's I'll insert in the middle and are only paralleled by the balance leads. Is this correct? Doing it this way (inserting the 3S's in the middle) allows me to not disconnect my y-connectors one the ends. I don't want to do something stupid because I'm ignorant. It's OK to put the 3S's in the middle of the 6S's - correct. I mean I'm just making two 15S1P's and paralleling them at the cell level. This has to be correct -- but Fing up could be a distaster!

Thanks!