stacking some lipos. Need some guidance

[waxman123]

Ok taking the lipo plunge as it were and need some help and guidance.

My goal is to make a 48V 15 AH lipo pack hopefully in the 10 to 12 pound range.

Starting with 6(amount of packs) 6 cell 22.2V 5000mah. Taking 2 packs and putting them in series (negative/positive to negative/positive) to get 44.4 (48V)V and 5000mah.

Next taking the 3 packs that are now in series i will wire them up in parallel (negative/negative/negative and positive/positive/positive) to get 15000mah or 15 ah.

Is this the right path?

Next questions about charging:
1. each pack (6) comes with positive and negative main wires and small wires hooked into plastic plugs. These plastic plugs are for the charging (I know silly question but like my kidergardner teacher said there are no dumb question and I am just trying to be thorough and safe) to a high end balancing charger. Do I need to get a charger that can handle 6 cells and more?
2. Each time I charge the batteries do I need to hook each cell (6 of them) to the charger separately each time and charge them. If so is there an easier one plug for all six solution?
3. Suggestions on chargers please! I want the safest and fastest. Cost is secondary to safe and fast!

Thanks for the help ahead of time. I would have asked Matt but I have already ask to much from him (what a great helpful resource he is, what an asset to this site and all ev projects with bikes)

Erik

 

[vanilla ice]

You want to parallel down to cell level.. get each group of 3p connected at the balance wires.

 

[nomad85]

Read this for info on charging - http://endless-sphere.com/forums/viewtopic.php?f=14&t=17168
Read this for more info on the Lipo's from Hobbycity.com - http://endless-sphere.com/forums/viewtopic.php?f=14&t=10817

12s will not equal 48v, personally I went for 15s and used 3 5s packs in series for 55v, 63v hot off the charger, most controllers can handle that, check your caps if you aren't sure.
edit..
Doh. this is in the non hub section, 12s is your best bet then

 

[recumpence]

I hate to disagree, but, a 12S pack is 50.4 volts hot off the charger. For the vast majority of its discharge cycle, it will be at or very near 48 volts. Also, very few RC controllers will handle over 50 volts.

Lastly, you do not really need to parallel down to the individual cell level. That may be a slightly better way to do it. But, I have never, EVER in 5 years of running lipos, had a pack out of ballance. Just get a decent ballancer and check the packs once in a while.

I just charge right at the main inputs to the pack as though it is one large pack.

I hope that helps!

Matt

 

[RWP]

I have questions about this as well.

...Just get a decent ballancer and check the packs once in a while

What balancer do you recommend?
What balancer do you out there in ES land recommend?

...I just charge right at the main inputs to the pack as though it is one large pack.

If I understand this correctly you would charge all 6 packs (above project - 12s 3p) all at the same time.
You set up your charger to charge 12s?
How long does it take to charge the entire pack (approximate for pack above)?
What is the maximum cell voltage you program into your charger?

Specifically what charger do you recommend for charging large packs like this?
What charger do you out there in ES land recommend?

I have an iCharger 1010B - I do not think this will charge 2 6s packs, or 12s packs...what should I get?

Thanks,
Roy

 

[nomad85]

A meanwell 48v supply would do the trick. I have the SP-320, you have to use a charge controller from GGoodrum with it. The S-350 can work with out the charge controller. You can get them on ebay, and trim the voltage to the exact level you need. The 48v model can adjust from 41v-56v(approximately)

 

[dozentrio]

If I remember correctly, the 22.2V lipos that hobbycity had weren't the most cost effective. You will save some money if you get a couple 3000 mah, 3s or 5s packs. I made a lipo battery price comparison spreadsheet which will help you compare the costs. If you search Lipo Comparison you'll probably find it. You enter the voltage/capacity that you want and it will tell you how many packs you need to get, and how much it will cost total. You just enter the information you find from hobbycity (or other places, but honestly, hobbycity has the best price unless you go for el cheapo ebay batteries-- EC Power, which over-rate their packs)

 

[rodgah]

If you want to charge 12s there are hobby chargers as matt says that can do it, he has recommended the Hyperion EOS1210i before. Apparently they are discontinued but you can still buy them on ebay for less than $100US (I have a few of them in preperation). They require external balancers for balancing, but as Matt says not really required if you maintain your packs every now and then and use smart methods of discharge and charge(not over charging not over discharging etc....see thread in battery tech). If your really cautious you could use Gary Goodrums charge controller and balance boards for lipo and use a eos1210i to charge. My view is using a proper charger compared to a power supply has benifits like greater flexability with charging to different voltages, ie charging for storage (60%) is just a few quick button presses, where a power supply would have to be manually programmed(altered) to that voltage. My 2c

Rodger

 

[AussieJester]

Best advice...gotto tppacks.com an buy some LVC boards, battery medic mod a charge controller...go buy a meanwell psu and your
good to go. I have a 44v 15ah (~50v off charger) pack myself from 22v 5000mah packs it weighs less than 5kilo (is 5 kilo with all the electronics, i.e esc, throttle interface, dc-dc converter....GGoodrum lipo BMS is the way to go IMHO.

KiM

 

[hydro-one]

I would buy a accucel 8 or 6. I did and it helped me to figure it all out. This thing is smart!!!wont let you screw up. and cheap .then move to a meanwell..

http://www.hobbycity.com/hobbycity/store/uh_viewItem.asp?idProduct=7523

I also use a hot rodded computer psu, barley works- but get 7 amps at 22v out of my charger!!!

mike

 

[nomad85]

I hate to disagree, but, a 12S pack is 50.4 volts hot off the charger. For the vast majority of its discharge cycle, it will be at or very near 48 volts. Also, very few RC controllers will handle over 50 volts.

I took your word for it, but after trying out my new lipos,(flightmax 25c) during discharge the pack will be at the nominal voltage. My pack started at 62.4v and after 1Ah it was at 55v under a 22amp load and is now resting at 57v. So I stand behind my statement that 12s of lipo will not equal 48v in use.

 

[AussieJester]

I'm with Matt i run 12s (44v 15ah was 20ah previously) 50v off the charger and stays above 48v for loooooong time
i don't ride great distances myself and have never seen my pack dip below 46v without re-charging it.
If yoiur using RC ESC 12s is the max the esc will recognise so 15s ain't isn't doable.

KiM

 

[nomad85]

I'm with Matt i run 12s (44v 15ah was 20ah previously) 50v off the charger and stays above 48v for loooooong time
i don't ride great distances myself and have never seen my pack dip below 46v without re-charging it.
If yoiur using RC ESC 12s is the max the esc will recognise so 15s ain't isn't doable.

KiM

Is that under load or a sitting voltage. Doesn't make sense that my setup would pull the voltage down more, I pull 30 amps max. Maybe having 2p/3p makes a big difference, I'll try that out later on. We have the same/similar batteries they should behave in the same manner regardless of how many cells are in series.
Oh and pics or it didn't happen

It's awfully cool to be able to fit my battery in my laptop bag and be able to go to work and back. Beats the shit out of lugging my 22lb ping lifepo4 around.

 

[AussieJester]

Is that under load or a sitting voltage.

Under load...and it makes perfect sense your using what 3 packs? I was using 8...anyone with 6 or more packs will likely tell you same thing. I can do better the 'pictrues or it didnt happen" theres video of the Turnigy reading in one of my online videos. volts were around 48 at the time Vm was 44.7 IIRC that particular ride 112 was max amps. I run 20c Turnigys to not 25c Zippys.

KiM

 

[nomad85]

Sweet, I will look forward to using all these in parallel then, thanks for the clarification :wink:

 

[AussieJester]

^^^thats the ticket You will only be able to hook 8 of them up to the lead i posted out to you though the 9th is a spare i presume?

KiM

 

[nomad85]

It's going to be 15s3p for now, I really want to do 20s4p, but I have to wait for my wallet to catch up