LiPo connections. Good idea or bad?

[Cold-E-Commuter]

I will start off saying that I cannot upload photos for some reason, so please try to picture what I have to say.

I have 12 pieces of Turnigy 5S 5Ah from Hobby King. http://www.hobbyking.com/hobbyking/store/__15008__Turnigy_5000mAh_5S_20C_Lipo_Pack_USA_Warehouse_.html
All cells have checked out and are balanced to each other. I am using 2 Turnigy chargers and a power supply (220V) also from Hobby King to keep them all balanced.
http://www.hobbyking.com/hobbyking/store/__11444__Turnigy_A_6_10_200W_Balance_charger_discharger.html
http://www.hobbyking.com/hobbyking/store/__16534__Hobbyking_PS35_DC_Power_Supply_for_Chargers_35A_350W_.html
My ultimate goal is a 20S3P pack or 74V15Ah. For this I need to series sets of 4 packs, then parrallel the 3 sets for 15Ah. These all came with 4mm bullet connectors. The question is, is it acceptable to series LiPo packs by simply using the bullet connectors and plugging + to - accross 4 packs then to an output cable? After that, what is the recommendation for parralleling the sets? I have seen this at Home Depot.
http://www.homedepot.com/h_d1/N-5yc1v/R-202786639/h_d2/ProductDisplay?langId=-1&storeId=10051&catalogId=10053
I have thought of connecting the negative of 3 sets of batteries to 3 of the holes then creating an output off the fourth and using another to do the same for the positive. Any help would be greatly appreciated.

 

[neptronix]

Aw man.. you could have got a 10S charger at hobbyking and cut your charging/wiring straight in half.

I'm not sure about your idea, but you might want to consider a 10S charger to simplify your charging and wiring.
The more complex it is, the more likely you are to have a KFF event or damage your lipos. I've been dealing with lipo for 1.5 years now and even i am not immune..

I went to permanent 10S groups after making sure all the packs were proper.. and actually.. it makes life a lot easier.
Just a suggestion, not trying to speak poorly of your idea.

Copper bus bar is definitely not necessary unless you want to draw well over a hundred amps.


Oh also, about chargers.. if you're going to be rocking over a kilowatt hour, i recommend you use a better charger for another reason.. those cheap hobbyking units are often pretty inaccurate, they also don't have a lot of features that prevent you from doing dumb things that produce pyrotechnics. Really consider getting something like a hyperion 1420 or iCharger 1010b+.

Also, with all those bricks, you are going to get at least one dud and you need equipment to test the packs. The chargers i mentioned have functions for this. I have a feeling the cheap hobbyking charger you ordered does not have discharge graphing over USB..

 

[Cold-E-Commuter]

The Turnigy charger actually has all the safety features I could find including balance charging, reverse polarity protection, cell count detection, chemistry detection and they even show the volts per cell. I have even installed the disc on the computer and viewed the graphs you speak of as they do have a USB connector to do so. That part I am comfortable with. I do like the idea of combining packs though. You are correct that a charger that is 10S would be good. How do you connect the balance ports from two 5S packs though? I did buy a couple of parrallel charge boards so I can charge 6 batteries at a time from a single charger.
http://www.hobbyking.com/hobbyking/store/__16564__Parallel_Balance_charging_Board_for_6_packs_2_6S_XT60_.html
http://www.hobbyking.com/hobbyking/store/__17672__XT_60_to_HXT_4mm_Battery_Adapter_Lead_2pc_.html
This allows me to charge all 12 packs at the same time using the 2 chargers. I agree that fewer connections reduces the risk of a "problem" and I appreciate the advice. Should a charger crap out and need to be replaced I will look into the 10S unit. It's just that I have invested in this set up for now. The pictures you attached are very helpful. It let's me know that connecting the packs directly to each other rather than thru a protection board is OK to do. Now, how the frick do I upload pics using Windows 7? The last pic I uploaded was on my old comp using XP.

 

[neptronix]

Yeah... if you want to charge through those boards, you're going to have to disconnect all the lipos each time and reconnect them to a parallel harness to discharge. That board is not meant to handle more than 10, maybe 20A. It's not a substitute for a proper lipo wiring setup.

It's cool that your charger has decent features. But my accuracy statement still applies. If you're charging over a kilowatt hour of lipo, you don't want to cheap out on the hardware. You should be able to do a discharge-graph test with that unit, which is a plus.
200w will be painfully slow though and all the parallel-series connections and reconnections you'll have to make will be a severe pain in the ass with a 6s charger.

I would recommend that you go with parallel THEN series for this style of setup. You can break the serial group up and charge 4 bricks separately this way to balance each one. or you can hook them into a big parallel group ( 60AH, wow that should take a while ) for a bulk charge. But each time you will need to switch a harness with 4 connectors on it. Kind of a pain.

As for your 10S charging comment, an iCharger or hyperion 10-14S charger will have two balance ports for each 5S pack. The connection order of the balance leads depends on your charger. On the iCharger, the pack next to the red positive wire goes in cells 5-10, the pack closest to the negative wire goes to cells 1-5. Pretty simple really.

 

[Cold-E-Commuter]

How do you parallel the 10S packs you have? I am assuming you run more than 37V5Ah at a time. The copper bus bar was just an idea. I am certainly open to others. And yes, dud's have been a reality. I do have one of these packs that have a dead pouch. As it stands, 4.18 volts in four cells and .8 in the fifth. I keep it with the thought of replacing a bad one in another pack if needeed.

 

[neptronix]

Yeah - i made a few parallel balance harnesses..

Then i got tired of those, not compact enough.. and made 2 of these:

( note: there is a giant non-conductive plastic piece between those fat connectors.. not pictured.. :lol:

Then i pair those with balance parallel cables on each 5s group ( yah, wiring for that gets messy.. :/ )

So essentially i have two large 10AH groups of 10S..

Then i have a series harness at the end of both of those groups. ( you would want fatter wires than these pictured, i think i built this one for my MAC bike, which was set to use 36A only )

So when i need to charge using a 36v bulk charger ( meanwell ), i switch out the series harness to another 2x parallel harness, then swap the connector out for the series when it goes back on the bike.

This works great for me since my non-race bike runs on 36v.

Eventually i will have a 72V bulk charger.. you will prolly end up with one as well.. and something like an iCharger 1010b+ could just serve as a more convenient balance charger.

 

[neptronix]

Another pic. I hope you're a visual person because i am

 

[Cold-E-Commuter]

Neptonix, looks very similar to what I have. Wish I could upload a pic. What would be the advantage/disadvantage of series then parallel or parallel then series? I can already see that fewer connectors are needed when used as series first. Also, just watched vid of the pie motor. Nice. Now you need to race a vette light to light.

 

[neptronix]

I'm not sure what your issue with pictures is.. i usually upload mine on my webserver and use the IMG tag to link 'em up.. never upload.. we've lost plenty of pictures on this forum, so.. :|

Series then parallel then series is just to simplify balancing when you have a 10S charger. it wouldn't make any sense to have this setup with a 6S charger. You'd have 4 groups instead of my 2.

 

[neptronix]

Also, my series then parallel then series would be good anyway, if you had a high power 36v bulk charger like i have.

The least amount of connections and re connections you have to make, the better.

As for the pie bike, i've been trying to race the bigger displacement cars, but they don't take me seriously lol..

 

[Allex]

The red plastic connectors(for bullets), any idea on how to disassemble them? I Have those, made one harness wrong and had to cut through the plastic and buy new ones.

 

[Cold-E-Commuter]

@Allex. Still working on that. The ones that come pre attached to the Turnigy batteries seem to pop out from the rear. Meaning that a sharp blow on the back of the plastic with an opposite member of the core inserted at the front and placed on a stable surface pops the core out the back. Exactly the opposite with the purchased ones from Hobby King! Make sure to pre-load the case on the wire before soldering, otherwise it really sucks.

 

[Cold-E-Commuter]

@neptronix Correction, the bigger displacemnet cars don't take you seriously until they are behind you! Then you can hear them step on the gas. Wouldn't want to loose to a bike by God! I get that all the time. On average I get across the intersection from a red light faster than 98% of cars. Zero to 30mph faster than 80%. Losers!!

 

[Cold-E-Commuter]

I have also found that a good BernzOMatic torch does a far better job soldering the bullet connectors than anything else. Strip the wire and hit it with flux, set it aside. Take the bullet tip and flux the inside with a q-tip. Then hold the 4mm bulet upright with a clamp, needle nose piers also work, and heat it with the torch. Melt the solder in the cup. Once the flux starts to boil, stuff the wire into the cup and the solder sucks into the wire. I will post a video as soon as I figure out how.

 

[recumbent]

Then i have a series harness at the end of both.

I have the same serial harness except one extra set of leads to bulk charge without unpluging anything, this way you can monitor charging through your Cycle Analyst.

Great thread guys, for people that are too shy to use Lipo, it's easyier than we think. Just make sure you have extra amp/hrs for safety.

 

[Cold-E-Commuter]

Yeah, I use 85% DOD as my max when figuring out what to set up for the day when running the LiPo batteries. By having 12 individual packs I can create anything from a 37V5Ah (10S1P) pack up to the exciting 74V15Ah (20S3P) pack. It's far more veristile than being stuck with a 16 pound Ping at all times. Today I rode 6 miles round trip to the store and back on a 55.5V5Ah pack (15S1P) at less than 4.4 pounds and only used 2Ah. Could have done it twice at only 80% DOD. It also makes the recharge simple as you only need to charge the packs used. I have read several other threads that indicate a longer life span from LiPo when used less than 80% and charged at 2C or less. Someone even indicated that they had over 1000 cycles on LiPo! WOW. So the way I see it, correct me if the math is wrong, 74V15Ah (20S3P) provides for 1110 Wh. total power. 1110 x 80% = 888Wh usable. 888 Wh / 32 Wh per mile = 27.75 miles at 80% DOD. Would be 31.21 miles at 90% DOD. That's 30+ miles at 30 MPH from a 17.6 pound pack. Beats the hell out of lead.

 

[Cold-E-Commuter]

Cool, figured out why I couldn't upload. HP-Share-To-Web program now gone. Enjoy.

 

[AARONHAI1]

HEY... DO THESE MALE FEMALE HEADS SELL ANYWHERE?

SEE MY HARO F-1 500W E-BIKE USING A 'PING' 36V 15AH LIFEPOV4 4.8 KILO BATTERY...
https://plus.google.com/photos/101191962521634380909/albums/5717173894477813409

 

[Cold-E-Commuter]

Bullet connectors are available at hobbyking.