5s or 10s A123 setup for boat? - RC-Monster Forums

gimpygolden · **5s or 10s A123 setup for boat? -** 07.02.2009, 09:40 PM

I'm thinking of building another brushless boat and considering 2 different setups.
I have the A123's ,actually Linc is building me 4 5s packs right now

Should I run 5s2p(4600Mah) with a 1700kv motor or 10s1p(2300Mah) with a 850Kv motor.
Battery setups will weigh the same either way and take up the same space.

Equipment wise the cost is not much different if looking at comparable components for each setup. Motors are the same price either way looking at 70mm Medusa's, and as for the Ecs's
the Turnigy 80Amp Hv is $75 plus &25 for a ubec Vs. the $70 for a Turnigy 120A.
The 80HV is good for 12s Lipo /45v and my 10s A123's are only 33v so theres a bit of head room there.

Any input on which will be more efficient and yield the longest run times, All the guys over at Offshoreelectrics.com seem a little spooked at the idea of High Volt setups so I wanted the opinions of those more versed in big power setups.

gimpygolden · 07.02.2009, 09:43 PM

Both setups come out at about 42Mph with a 42x1.6 prop 2 blade.

What's_nitro? · 07.02.2009, 10:17 PM

I'd go HV. Efficiency is much higher, therefore temps will be much lower and runtime will increase.

zeropointbug · 07.02.2009, 10:35 PM

I wouldn't say efficiency is 'much' higher, it is higher yes, but as an example, say if the 5s2p system was 89% efficiency, then the 10s system would be around 90.5 - 91% max efficiency. And you are right, every point higher the % efficiency is, turns up as a noticeable difference as far as heat in the wires a bit, and motors would run a touch cooler, and the runtime will increase, but not noticeably.

But ya, go for the HV setup of course. What are you using to charge 10s A123? Are you going to have them as 2 separate packs charging separately, then connect them in series for running?

gimpygolden · 07.02.2009, 10:41 PM

I would be charging with an iCharger 1010b (300watt)@10s.
The Batteries will assembled as 5s packs then use a serial adapter to both charge and run the boat.

zeropointbug · 10:57 PM

Right, one pack per each side of the boat?

I'm actually running 5s1p packs in my Villain EX with great results, I have to watch it though!.... when the packs dump, they dump FAST! I get into trouble at times!

gimpygolden · 07.02.2009, 11:03 PM

Yup 1 pack per side. The boat is an Aeromarine Titan 29
http://www.offshoreelectrics.com/pro...?prod=Aero-T29
I know what ya mean about fast "dumpage" a low charge pack dips quick in the water.
I have a Villain that I still run on 12 or 14s NiMh with upgraded props,its a fun boat that wife or friends can try out.

Snipin_Willy · 07.02.2009, 11:14 PM

Yeah from experience, when A123's are done, they're DONE. And they wont give you much warning either.

zeropointbug · 07.02.2009, 11:44 PM

I know, I have been running them for 3 years now, and I can barely read their warning signs, which are almost non existent.

zeropointbug · 07.02.2009, 11:46 PM

Did he get 2 dewalt packs, or one of the '20x A123' eBay items?

gimpygolden · 07.02.2009, 11:53 PM

Quote:

Originally Posted by zeropointbug

Did he get 2 dewalt packs, or one of the '20x A123' eBay items?

If your referring to me I got them as A123 Systems 2s2p packs, buy 4 get 1 free. If i recall they were $48.00/pack brand new.

lincpimp · 07.02.2009, 11:57 PM

Quote:

Originally Posted by gimpygolden

If your referring to me I got them as A123 Systems 2s2p packs, buy 4 get 1 free. If i recall they were $48.00/pack brand new.

And they are sitting in a box waiting for me to get them built into 5s packs... I should have some time this weekend, and I can sit in the a/c in my office and build these. Damn a/c in my hobby room is acting weird, need to take the heavy beast off the wall (huge 70's 2 ton window unit!) and have a look at the internals. Maybe it has seen its day? I have a couple of the split systems waiting for me to install them, but maybe I can con my buddy into doing it for me, he does a/c for a living.

lincpimp · 07.02.2009, 11:29 PM

I have no experience with the 70 mm medusa, but it should perform close to a 1515... Now I do have experience with the kb45 motors, and considering you will be water cooling the motor I would go with the kb45xl, maybe the 10xl-11xl on 10s a123? Big motor, with big power! I ran a 1/8 on road car geared for 50mph with a L can kb45 and it performed very well, at least as good as a 1515, so the xl should perform as well as a 1521. They are 2 pole motors, and they will not run as efficiently as a neu, but water cooling will keep the heat down, and you cannot beat the price, get 2 for the price of that 70mm medusa, and it will put out more power. Hope those a123 cells can handle it... Maybe go 2p (use all 20 cells).

nitrostarter · 07.03.2009, 01:32 AM

Quote:

Originally Posted by gimpygolden

....All the guys over at Offshoreelectrics.com seem a little spooked at the idea of High Volt setups so I wanted the opinions of those more versed in big power setups.

Honestly, I highly doubt this is the case. Most guys there run boats that are setup to spec. N, P, Q classes, etc... They are listed as to which battery setups are used.

Have a look at this chart:
http://www.castlecreations.com/suppo..._boat_apps.pdf

This is a helpful tool for boating.

Honestly, I don't think A123's are worth there salt in boats... Most setups require high quality Lipo cells as boats can pull SIGNIFICANTLY more amps than the car world. For instance, most people that run 1515/1Y use a Hydra 240 because the amps spike up pretty high continuously. Its also very easy to use the wrong prop and burn up something in a heart beat.
Also, most FE boating setups only get 3-7 minutes of runtime. I would want to most mAh available.

Now on to your setup...

Aeromarine Titan 29, a beautiful mono with the ability to take a decent chop. In order to make boats work properly, you want to spin 28-33k rpm's. SO if you're insisting on pushing a 850kv motor, 10s will be necessary.
Honestly speaking tho I would opt for the 5s2p setup for not only more available amperage, but more than likely, more runtime.

Motor choice: The KB45 1700kv would be a great choice, KB's seem to be a hard to beat motor in boats when properly used. However, a Feigao 11XL would work just as well in this hull. This 29" hull doesn't really require more than a feigao 9XL for power. A 10XL would be optimal.

I don't know your asperations for the boat but for anything over 30mph I would run a Feigao 11XL on 5s2p, with a X445 prop. Should be a reliable setup with those A123's being the weakpoint...

Enjoy.

zeropointbug · 02:01 AM

If this helps, here is an Eagletree of my Villain EX on a hard run. After the pack has dumped, there being no airflow through the hull, the pack temps usually around 115F. That being around a 10 min runtime, or 6C average discharge, which is quite a bit. They are still preforming like day one though, discharging over 2250mah. I would say it clips along the water at up to 22mph? Give or take 2mph.

IMO, boats are a good use for A123's... as there is not much "peaking" in currents, more of a constant current relatively, so you can design a setup around your discharge currents and calculate your voltage drop, and adjust your setup accordingly.

EDIT: OOPS, almost forgot the eagletree graph.