5s or 10s A123 setup for boat?

[nitrostarter]

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]

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.

[gimpygolden]

Originally Posted by nitrostarter

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.

Well, posting this same question on HV setups another OSE member looking to do a 10sLiPo setup got every response telling him HV is "not needed" or "I don't know" so I basically took this as not many FE guys are running or have experience with High Volt setups.

Since the whole build is around my A123's (because of charge time) I am trying to pick components to work with these cells in a 10s1p configuration.

This is a play boat as I don't have any clubs close by so high 30's-low 40's is my goal.
Plugging in my proposed setup here
http://www.offshoreelectrics.com/conversion.htm on the
Speed Estimate by Use of Voltage & Constant "Kv" table nets me 38mph
with
Medusa 36x70 880kv
10s A123 (33v)
and a X442 prop
should get 3+ min run times with under 15min charge times plus I have 2 sets of 5s Lipo to run as 10s as well.

Yes the 5s2p setup will have more available amperage but it will also consume 2x the Amps for the same Wattage. So how can it get more runtime having less efficiency?

The 5s2p setup you suggest comes out at 37mph which is bang on what I'm looking for just want to know why you feel 5s2p over 10s1p w/lower kv motor?

I think if the A123's in 10s can handle 2000+ watt loads in todays 3D helis
they can hold there own in my reasonable setup.

[zeropointbug]

Is that 2000watts sustained? or bursts?

2000watts is quite doable with 10 cells sure, but I am just wondering about air flow... Example, I ran a 8s1p A123 pack in my lawn mower at 800 watts sustained, and even higher bursts (~1000watts), that lasted roughly 4 minutes, and discharged 2200mah (of 2300mah 'rated'). NOTE: A123 cells sure do put out their rated capacity, no matter the load on them.

Did you take a look at my eagletree graph I posted?

[zeropointbug]

2000watts, I would design the setup then for 2.4v - 2.5v/cell @ ~90 amps. For a 10s pack. Just a quick calc.

[gimpygolden]

Originally Posted by zeropointbug

Is that 2000watts sustained? or bursts?

2000watts is quite doable with 10 cells sure, but I am just wondering about air flow... Example, I ran a 8s1p A123 pack in my lawn mower at 800 watts sustained, and even higher bursts (~1000watts), that lasted roughly 4 minutes, and discharged 2200mah (of 2300mah 'rated'). NOTE: A123 cells sure do put out their rated capacity, no matter the load on them.

Did you take a look at my eagletree graph I posted?

I don't intend on running 2000+watts, just an example of their capability.

I did check out the ET graph,was that on the mower?

[gimpygolden]

Looking at same kv which will pull less amps a 36mm Xl size or a Kb 45Xl?
Looking at things like weight, space and hardware compatibility I'm leaning towards a 36mm can over the 45mm unless the 45 is a better choice in terms of efficiency.

[gimpygolden]

Originally Posted by nitrostarter

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

Great chart as a guideline for lower voltage setup's but not much help as I'm looking at going HV.

I guess all I really want to know is, is there any draw backs to going HV.
I realize lower volt setups are tried and true and probably even a few buck$ less, but in an effort to put less stress on these cells wouldn't a High Voltage setup be the way to go?

[zeropointbug]

For lowering cell stress, yes, HV will reduce it a small amount, not much.

The system as a whole will be more reliable however (usually), because of less resistive heat losses; wires, esc, motor...

[gimpygolden]

So since I've got one of these kicking around
http://www3.towerhobbies.com/cgi-bin...&I=LXHYK6&P=ML
do you think it will cut it for the 10s setup if I add watercooling or just not enough?

[zeropointbug]

Hmm, that would be pushing the limits of that ESC pretty hard. I don't really know how Kontronik rates their controllers vs. realworld, but I would say a ~80amp continuous controller is what you need. But you never know, you could just try this one out for a while, go easy on it, check the temps and keep pushing it until you are satisfied. Water cooling system just might do it though.

[gimpygolden]

I have one sitting in an e-Raptor converted heli that I'm not using.
I think I'll try it out on a small prop & watch the temps.

[zeropointbug]

yah, do that, cuz with water cooling, you tend to need a less rated current capacity compared to surface vehicles. Try it, and report back with temps, and the go from there.