Castle Chart

[AndyKunz]

I wish I could take an oscilloscope to everybody and show exactly what is going on.

Ripple destroys caps, but internal impedance of the cells is what causes the droop. This is Ohms Law.

It's actually pretty slick to see the operation.

Andy

[ReddyWatts]

FINALLY, that is great stuff, the kind of info FE has needed for years. Makes it so much easier to decide on your initial setups without the dreaded smoke. This thread needs to be tacked in "Tips and Info for building a Fast Electric Boat !!!" since OSE sells this equipment.

[Bill-SOCAL]

As a side note, I see lots of FE guys who appear to lack a basic grasp of the fundamental of DC electronics. There is a great book worth reading, it is called:

"There Are No Electrons" In a very easy to read format it takes some pretty dry electronic concepts and makes them clear.

Link to Book

Review

Take a look, it really is a fun way to get a grasp on the basics of DC circuitry.

[Flying Scotsman]

Douggie

You are a little lost here.
If you look at a discharge graph for any cells be it lipo or Sub C.

Example
4S 4500 – 25C
At 32A you would average 14.4 V
At 64A you would average 14 V
At 90A you would average 13.7 V
At 96A you would average 13.3 V

As you can see the voltage under load drops with the amp draw.

If you run a 2P setup the amp draw that each pack sees is cut in half.
Resulting in a higher voltage under load that is put to your motor.

Also only half the stress put on your cells.
If I run a 4S2P set up in my Wip and draw 100Amps each pack only has to deliver 50A
They run a lot cooler and will last a lot longer (more cycles)
If I run it on 4S1P the pack has to deliver 100A to the motor, resulting in a
- Lower motor Voltage,
- Higher battery temperature which turns into higher internal resistance
- Less Voltage under load output.

The biggest loss is in speed of the boat, even with the extra weight.
At 1850KV-- 0.7V = 1295 RPM on the motor = about 3 MPH
Even with my bad driving I will still beat you in a 1 mile race with a 3 MPH advantage
And my cells will still like me.

Larry

Larry, and all thanks for the great advise. Now Larry what format because my 1P setup will beat your ass on 1/3 rd mile

Douggie

[Fluid]

Unless I missed it they don't say 1p or 2p.

Better read the chart again, it clearly states 2P for every setup on the chart. It's in the second column under Cell count.



.

[TRUCKPULL]

The chart was writen by Brian B. I beleive.
They are suggustions for race and sport setups so you will not hurt your equipment.
2P is better for your equipment.

Less heat
longer battery life
safer for your ESC's
EYC

Larry

[alvinsmith75]

Looks to me that Castle isn't interested in supporting the FE Racing community.

[Bill-SOCAL]

Looks to me that Castle isn't interested in supporting the FE Racing community.

I wonder if they are very worried about the 100 or so of us out here?? 17 drivers at the NAMBA FE NATS, and I am not sure about IMPBA, did they even have an FE NATS this year?

Point is that the FE racing community is so small I doubt Castle could care less about it. In fact I wonder what percentage of their sales the marine controllers are in the first place. I'll bet a very tiny slice.

Sad fact is there just are not enough of us to really get the attention of too many vendors. I am actually amazed there are as many as we have. But let's face it, even Steven does OSE as a sideline to his real job so it's not like any vendor is getting rich off of the FE community, let alone the tiny percentage of that group that race.

Until we figure out how to grow this segment of the hobby we will continue to suffer the result of being a very small fringe group.

[ghostofpf1]

Better read the chart again, it clearly states 2P for every setup on the chart. It's in the second column under Cell count.



.

You're right....thanks....I still think it's an ampacity thing though unless someone can convince me otherwise ie: If the same ampacity could be achieved with a 1P pack it would suffice just as well as a 2p

Ghost

[TRUCKPULL]

You're right....thanks....I still think it's an ampacity thing though unless someone can convince me otherwise ie: If the same ampacity could be achieved with a 1P pack it would suffice just as well as a 2p

Ghost

You are right in a way.
25C - 5000 packs
1C = 5Amps
25C = 125 Amps

If my setup pulls 125Amps and I use a 1P pack, my packs would be toast in about 50cycles

If I use a 2P pack and pull 62.5 Amps from each pack (still 125A to the motor) my packs will last over 300 cycles with out any loss in battery power.

Now if they made a 50C- 5000 pack (that would be a 250 Amp max) I could pull my
125 Amps and still get over 300 cycles.

The trick here is to only pull 1/2 of what a cells "C" rating is, to maintain full power throughout the cells life, and to extend that life.

Also there is still the higher voltage under load with a 2P setup = faster (see my post above, http://forums.offshoreelectrics.com/...2&postcount=10 )

Larry

[ghostofpf1]

Only valid if you double the ampacity at the same time....ie: 62.5 amps from a 2500 mah pack is still 25c

Ghost

[TRUCKPULL]

Only valid if you double the ampacity at the same time....ie: 62.5 amps from a 2500 mah pack is still 25c

Ghost

Yes - but would you want to pull 62.5 Amps from a 2500 pack?
Not much run time in that setup.

Larry

[line6]

What do you guys think would be the better setup and why. A 2s2p High kv motor or a 4s1p low kv motor if they both are achieving the same rpm. say 35,000. and the packs are the same 25c 5000mah 2s1p

[AntronX]

What do you guys think would be the better setup and why. A 2s2p High kv motor or a 4s1p low kv motor if they both are achieving the same rpm. say 35,000. and the packs are the same 25c 5000mah 2s1p

4S1P is better. Half the amps of 2S2P but same power. Much easier on the ESC. Would not matter to the packs though, just to the ESC and possibly the motor.

[TRUCKPULL]

What do you guys think would be the better setup and why. A 2s2p High kv motor or a 4s1p low kv motor if they both are achieving the same rpm. say 35,000. and the packs are the same 25c 5000mah 2s1p

It would depend on the size, weight of your boat,
and what you wanted to do with it,
Race, Sport, or a pool toy.

35,000 prop RPM is a rigger setup.
Larry