OK to mix capacity in parallel string?

I am building a 12s6p pack. All the brand new packs are sittingb here ready to go Zippy 5000mahr packs. One was dead and puffed out of the box. Can I add an 8000mahr zippy pack to the parrallel string without issue

Yes, you can. It won't be a problem.

BTW, did you discharge test all of those packs for funky cells before putting them in permanent parallel?
And do you have a parallel balance lead harness?

I checked all the packs with a cell log before assembly. I would like to find and install parallel cables for the cell tap wires. Where can I get those

icecube 57 makes them and so does EPBuddy.
otherDoc

OK I see the parallel connectors on EP Buddy looks like the perfect addition to this pack for better balance. plus it will allow me to use my little cell log based LVC.
Are the plugs on the Zippy packs Hyperion or JST-XH plugs?
Thank you

Checking them with a cell log is an entirely inadequate way of testing them.
Packs with cells that are bad, extremely short on capacity, or will puff/explode during the first charge need to be singled out before putting them into a permanent parallel group.

2 members have had massive fires recently due to not testing their lipos before OKing them for use.
Never assume anything hobbyking ships is good.

It's a bit late now to test them individually. But i wanted to make that known for other people reading this.

So what's an adequate way to test cells before charging or discharging them? Just test the cell voltage as shipped, or is there much more to it than that?

Moreover, since charging or cycling them voids HK's warranty, is there any recourse for the buyer once a cell is conclusively determined to be bad?

Chalo

No, that means that if you cycle it, you can't claim 'under voltage'. You still have a 30 day warranty that ensures that all cells have 5000mAH ( or whatever the pack is rated at )

http://www.hobbyking.com/hobbyking/store/lipo_policy.html

5) Rapid Capacity Loss. Should your pack fall well short of it's stated capacity, please indicate to us how you achieved capacity claim. We will test packs for charge and discharge values. Should the battery have severe capacity loss, we will test each cell for maximum and minimum voltage charge as well as I/O. This can indicate to us if the pack has been over-discharged. Packs which are over-discharged will not be replaced.

Click to expand...

But cycling them ( full balance charge, then discharge until 1 cell hits 3.0v ) tells you this about a pack:

1) if a cell is going to puff up and explode, it should do it at that point. Dud cells are shipped often enough to be a high probability.

I had one pack out of 13 have a puffy cell in it. It had been shipped 1 month earlier, and had not touched my charger. If i put that in a parallel pack without testing, i would have had a 1 kilowatt fire. Which would be cool, if it didn't happen in my apartment and wasn't $400+ worth of batteries going up in smoke

2) if a cell is low in capacity, it will touch the 3.0v mark far, far quicker than the other cells.
3) if a cell has mismatched internal resistance ( causing it to bear more of the discharge load than the other cells ), it will show up then as one that sags under load harder, and depletes itself sooner. )

You can either use a lipo charger to do it ( very slow to discharge ) or some other device that will pull tons of amps, like an array of 12v 50w halogen bulbs in series or parallel.

I don't see your answer in the posts. It's JST-XH plugs.

to discharge packs I took a power strip and some 120v bulbs with screw adapters and plugged them into the power strip. I even use a old iron to up my load. At 60 volts 15s I draw about 7 amps. Through a CA-SA I can get my Ah of the packs. You do have to check the cells while doing this.

Dan

neptronix said:

Yes, you can. It won't be a problem.

BTW, did you discharge test all of those packs for funky cells before putting them in permanent parallel?
And do you have a parallel balance lead harness?

Click to expand...

I did as suggested with the Hyperion charger. (slow discharge).
All packs that had the closest cell V's did just fine.

The one pack that had a larger V-gap (.02V gap while the others had around .005-.010 V gap)
Was a little more 'all over the map" on the charge as well as the discharge.
(the Hyperion allows you to view the charging and discharging in graph form while it is happening)

It took me almost 2 full days to cycle all of my 9 batteries. Of which I decided not to use the one that was slightly strange on the graphs.
I did this on my desk in my small apartment with the lipo in a Lipo-Safe bag. Fire extinguisher and open window at the ready.

Good start to at least look at voltage before paralelling packs permanently. But better to run them a few cycles and see how they actually act before soldering them in. A temporary paralelling harness could be one way to do that. Discharge em paralell, but then charge them individually and see how they balance. By cycle 5, you will see a really bad cell if you have one. It will start to self discharge.

Since you have not permanently paralelled the balance leads yet, you can still check individual cells for their ability to hold a charge after charging anytime during thier lifespan.

Ok thanks for the good advice Dogman. The pack has been cycled twice so far. I checked each pack with a cell log . Bulk charging to 4.1/cell.