lipos

[saleens7]

well, ive been hearing news about the fate of the IB3600 cell and am now strongly considering lipo's as a power source for my SW36 build....

im a complete newb to lipo's, so i need all the help i can get...

my esc can only take up to 6 lipo cells....

im going to need to take two packs and combine them using a Y harness, will this work with lipo's? the total voltage of both packs will need to be close to 28.8v...i dont want to spend too much money (no more than 200$)

any suggestions?

[sjslhill]

What is a SW36?

[saleens7]

Shockwave 36

[sjslhill]

Motor, controller, ESC, highest amps required?

[lferguson]

Steve, not to hi-jack the thread, but I have FMA DPM (lvc) units and I guess they work. My cells are always very balances going in and coming out. These units don't have startup tones or LED's so I guess they work but wouldn't know unless I ran my cells beyond what I know is a safe run. For these units to be efective you have to set the ESC to the lowest possible cutt-off or disable the LVC on the ESC.
The question is since thes cells are always very well balanced, should I not even worry with the FMA units and just rely on the ESC?

[sjslhill]

Sorry, I have no knowledge of FMA units.

[saleens7]

motor

Quantam 36-70 BL motor

http://www.unitedhobbies.com/UNITEDHOBBIES/store/comersus_viewItem.asp?idProduct=2036

esc:
Welgard 100amp no BEC

http://www.bphobbies.com/view.asp?id=A0780193&pid=B0558276

i dont know how to find the highest amos required, what do you mean?

i need to have around 28.8 volts....

i did some reaserch and found some polyquest 14.8v 4000mah packs for only 60$ each (ill buy two)

but if i wire them up to a Y harness, will they double the voltage and keep the same mah like nimh cells??

[saleens7]

what else will i need to run lipos? i think i might need a lipo balancer, but what else??

like i said, im a newb to lipos and have no expeirence...

[sjslhill]

Series = double the voltage
Parallel = double the current ablility and capacity.

Polyquest 14.8V 20C or what exactly? A Polyquest 4,000mh 20C can do not 80 amps in theory constant, however, we know from professional racers that this will not hold up for long if ran at 80 amps.

[saleens7]

polyquest 14.8 volt 4S lipo cells

its factory rating is 40 amps and the ideal rating is 34 amps...im still new to FE and dont get where amps would come into the equation....some elaborating may help...

[sjslhill]

Watts = Voltage x Amps(current) different motors with different props change the amps required. The knowledge should be out there for this motor and prop.

[saleens7]

if the esc is rated for 100 amps, will it try to pull 100apms from the lipo's?

im a little confused....will the setup im using work??(minus the motor, ive been hearing so much bad stuff about thw quantam that i think im going to use a feigao 14XL instead)....

[sjslhill]

The motor pulls the amps and the ESC will fail if pushed over 100 amps. I would say that you need 2, 20C 4000 packs in parallel to be safe, unless your ESC is over rated for your application.

[saleens7]

but will parallel give me double the voltage too?

[sjslhill]

Nope, paralle =double the current ability and capacity

[saleens7]

the motor pull about 75 amps....the batteries are rated for 40 amps, but run the best around 35-40 amps....but if i run them in parallel, i wont get the required voltage...but if i dont i will be pulling too much amps for the batteries to handle...

basically, ill need to either run four 4S packs with 2 groups of two pack running in parallel or either run two packs not in parallel but i woll be pulling too much amps for the batteries to handle....with both options, ill either have to replace my esc or motor....did i get this right? i think i did....correct me if im wrong...

how many amps does a feigao 14XL pull??

[saleens7]

if i wire two 4S packs in parallel, then wire another two 4S packs in parallel and connet the two groups of two packs in a series to double the voltage, that will give me the desired voltage AND current and capacity ability, but will this be too many cells for my esc to handle? it can take up to 10 cells, a 4S has 4 cells right? then all together, the 4 packs will have 16 cells, WAY more than my esc can handle...is there any 14.8 volt pack that already has around 20C that i can just hook both up in a series so i wont have to get a new esc?

[sjslhill]

Nope, nope, nope, nope....when you parallel you do not count the added cells. 14.8V is 4 cells, period.

If you wired two 14.8V in series, you have an 8 cell count.

[saleens7]

so if i run 4 4S cells (two groups of 2 packs in parallel) and then connect the two groups in a series, i will essentially have two 4 cell packs with double the current ability and capacity as a regular one....thats good, but it means more cash to earn to buy the packs......
i think i have figured out what ill need to run lipos in this boat then....

but what else will i need (balancer, lipo cutoff, etc.)??

thanks for the help Battlepack, i really needed it)

also, how would i wire two lipo packs in a series?

[sjslhill]

Woops, forgot you needed alot more voltge, your wanting 29.6V

[saleens7]

where can i find 20C lipo packs?

ive been looking in all the regular places and all of the 14.8V pack are only 10-12C....

[sjslhill]

How many Volts are you running again?

[saleens7]

29.6 volts

[sjslhill]

Geewizz.....if you want my honest opinion, sell that boat and get two of something else. LiPoly is cost you a fortune if you run 20C packs.

[saleens7]

but i can still run 4 4S packs in the way i described earlier..... (i think ill also use these packs in the Drifter L once i get that started....)

if i do, ill be spending 240$ on batteries....but i cant go nimh becuase by the time i can get them you probably wont have enough left of those 400 old IB3600 cells left...this sucks, either i spend a whole lot of cash on a reliable lipo setup, or go the cheap way and use batteries that will eventually fail on me anyway.....

[sjslhill]

There will be NIMH cells around, stay with that if I were you.

[saleens7]

ok, in that case, i will.....but i will probably have to use expensive lipos on my drifter.....but thats fine with me, i was planning on spending way more than 1000$ on that build anyway.....

anyway, thanks for the help, i basically went from a lipo newb to almost completely understanding them in about one day thanks to your help...

[saleens7]

how to run lipo's in parallel? any pics of it?

[sjslhill]

Two black wires together and two red wires together for parallel.

Series would be + - + - The + - in the middle would be joined.

[saleens7]

you mean like this? i can understand a picture better, so just make sure i made one....

http://i86.photobucket.com/albums/k87/saleens7_01/124235437565427.jpg

[sjslhill]

exactly correct

[SJFE]

i basically went from a lipo newb to almost completely understanding them in about one day

I have been @ this for weeks now and I still don't know crap.....lol. I won't claim to know anything untill I have used them with out toasting anything. House included:D ...Jk..that was a poor attempt @ humer;)

[saleens7]

ok....let me rephrase that...i went from a lipo newb to understanding a lot of it (not all) in a day or so....

[SJFE]

I'm just breakin ur stones man...LOL:D

[Fast Guy]

So if I understand all this, for my SuperVee 27 I could buy two 14.8V 4000mah 145 44 23 380g 10C/12C Lipo batteries and run them in parallel. Would I then have a 20C max continous discharge on a 8000mah total or a 10C max continous discharge on a 8000mah battery? Would I also need a low voltage cut-off and a cell balancer? Also could I charge these batteries on my Super Brain 898 charger? It is claimed to be able to charge 1 to 8 cell lithium ion/lithium polymer batteries.
Thanks, Jamie

[sjslhill]

20C on parallel or 80 amps
Low Voltage Cuttoff is always a good idea, however, 8000mah should run a SV27 for 12 mins even at 70% battery capacity usage.
Balancer always needed
I have never seen this charger, looks like it can do the job

[Darin Jordan]

So if I understand all this, for my SuperVee 27 I could buy two 14.8V 4000mah 145 44 23 380g 10C/12C Lipo batteries and run them in parallel.

NO... this isn't correct....

The SV27 is designed to run 2 6-cell packs in series... The wiring on the ESC is essentially identical to OSE's Y-Harness setup...

You want to get two 7.4V packs of whatever mah and whatever paralleling you like, and then run them in series on the SV27...

In other words... or in LIPO speak... the SV27 is designed to have one 2S pack connected to each of the two factory connectors... This wires the packs in series...

At each connector, you can parallel the packs as much as you like...

So, if you want lots of runtime, you'd buy a pair of 2S2P packs of 8000 or 10,000 or ??? mah and plug them in...

If you pluged in a pair of 14.8V lipos, like you suggested in your post... You'd fry the ESC in a hurry...

[sjslhill]

2-14.8V packs in parallel is 14.8V Yes, the wiring needs to be changed, your correct. Sorry about that one.

I'll get my boat out today and look into this.

Darin is probably giving the best advice if your not advanced at this, my fault.

thanks,
Steve

[Darin Jordan]

2-14.8V packs in parallel is 14.8V Yes, the wiring needs to be changed, your correct. Sorry about that one.

I'll get my boat out today and look into this.

thanks,
Steve

Steve,

I think it would just take a quick wiring change to make a single 14.8V pack work... If you look at one of OSE's Y-Harnesses, that's how the stock ESC is wired... I think if you took out the wire in-between the two connectors, then removed one of the connectors and connected the loose wire to the remaining connector, you'd have it set up for a single pack arrangement and you could use a saddle setup of 14.8V cells paralleled together...

[Fast Guy]

If you pluged in a pair of 14.8V lipos, like you suggested in your post... You'd fry the ESC in a hurry...

Thanks guys. I should of mentioned that the wiring to the ESC would have to be modified to eliminate the series connection. That could have caused a disaster as you noted for those that don't completely under stand the electrical side. I will have to be more detailed in my posts in the future. To me running the batteries in parallel means connecting them to the ESC in parallel also.

Running this configuration in my SuperVee with the Lipo batteries from BattlePacks site seemed good to me as I was getting the required 20C, low cost and a 8000mah run time to boot.

[sjslhill]

It is a good idea if the wiring is correct. You do not need 20C type packs to run in a SV27, the low costs ones will work well.


thanks,
Steve

[SJFE]

Next weekend i'll prove it;)

[Fast Guy]

It is a good idea if the wiring is correct. You do not need 20C type packs to run in a SV27, the low costs ones will work well.


thanks,
Steve

Would two 7.4V 4000mah 145 44 14 200g 10C/12C from your site in series be OK for the SuperVee? How would they compare to the IB 4200's for performance, run time and their expected life time.
Thanks, Jamie

[sjslhill]

You have to get a LVC and can't run it that long. The IB4200's would most likly outrun the 4000 LiPos.

Woops, forgot the life time. IB4200's, can't stand them myself, 25% failure rate on these cells. 4000mah LiPoly, if you use the LVC and keep the temp down to 110 or less, I'd guess several runs and much longer than NIMH cells.

This is all new however and I don't want to mislead anyone. Several are trying it, Joey did it with 2 7.4V3600 packs, Tom just ordered some packs as well. Another person ordered 4. We will see where this all ends up. I ordered a SV27 from OSE as well to do testing. Tom has a DPR to give us info back and I'll add one as well.

thanks,
Steve



Would two 7.4V 4000mah 145 44 14 200g 10C/12C from your site in series be OK for the SuperVee? How would they compare to the IB 4200's for performance, run time and their expected life time.
Thanks, Jamie

[SJFE]

In order to switch the stock SV esc to a parallel setup(for14.8) you would have to unsolder from the deans and go with +to+ and -to-. Then a resolder would have to be done for series running....I will be buying another esc...that would be a PIA in the field.

[ice329]

FastGuy, I think you might be cutting it thin running 2 of the 7.4v 4000mah 10/12c packs. If you run 4 of them then you got a powersupply that would kick butt. The 7.4 3600 12/16c packs would be a better choice for just running 2 single packs. Comparison against the subC packs...There is no comparison there a differnt animal, the LiPo's are or make the boat light, fast and into a beast. The subc packs pour raw power out but the boat may be a bit more stable due to weight. So both setups have there place. I love both of them both are awsom. Love the 3600 NiMh BattlePacks but I also love the LiPo's.

I ran the stock boat yesterday after I balaced the LiPo packs with a CF48 prop. The boat became a BEAST... it was so quick it was unreal. I didnt GPS it but she was absolutly flying.

[Fast Guy]

If you run 4 of them then you got a powersupply that would kick butt.

Thanks for the info ice. Whats a powersupply?

[saleens7]

a powersupply would be the batteries in this case, providing power to the motors.

[ice329]

FastGuy, I said power supply which would be your batterys. The 7.4v 4000 10/12c packs are good for 40 amp continuios with 48 amp bursts. Might be cutting it close in the SV. The 7.4 3600 12/16c are good for 43 amps continuios and 57 amp bursts. Next week NJFE will be doing testing with equipment in the boat to get a better Idea of actual numbers.

The 7.4 3600 12/16c packs seemed to work fine in my boat, the pack temp were under 115 and I had solid power threw out, take off acceleration etc.

here is a vid from this past weeks testing

http://s110.photobucket.com/albums/n103/ice0329/?action=view&current=0e474f23.pbr