batteries for racing in p limited sport hydro class

[dethow]

Thanks but I can"t go over 4000 may for stock class.

No problem if you don't want them, but I think you are slightly confused on whats allowed. You're limit in P-Limited class is 4S (14.8v), 10000mAh.
What Larry is recommending are two 4S (14.8v), 4000mAh batteries in parallel which gives you a total of 4S (14.8v), 8000mAh.
While Larry is a great racer and has a lot of experience... many would say that 8000mAh for a P-limited 6 lap sprint is overkill.
As I said... many are running these (2S 6000) batteries in P-limited class. And most are using between 5000 to 6500 mAh in P-limited sprint classes.

These batteries are two 2S (7.4v) 6000mAh which you'd use in series for a total of 4S (14.8v), 6000mAh.

But no problem... I think these long sticks would probably not fit in most hydros. Just wanted to throw it out there just in case they would. Because like I said, you will find no better battery for the $$$.

[dethow]

Here's what I'd recommend if you want to go with two 4S in parallel as Larry does.

Turnigy Graphene 4S 3000mAh 65C - $54.68ea or $109.36 for a pair.
For the extra $14 compared to the Turnigy Heavy Duty, these are much better and would save you on some weight in the boat.
https://hobbyking.com/en_us/graphene...___store=en_us

Giant Power Graphene 4S 3300mAh 70C - $67.99ea or $135.98 for a pair.
These are your more expensive option but the best bang with the least weight.

https://www.mojoracingproducts.com/collections/graphene-2-0-giant-power-70c-140c-lipos/products/4s-14-8v-4-cell-3300mah-70c-140c-graphene-2-0-lipo-battery-by-giant-power

[TheShaughnessy]

just to be clear I'm only referencing my own data, which came from a p ltd set up so the amp draw is on PAR. I was seeing a little bit less sag with a set of zippy compact 60c packs. 3700 mah 4s wired in parallel vs 2 2s 5000. Talking about 0.5 v or less. Driving is going to be far more important than battery choice for heat racing.

[TRUCKPULL]

Jerry

I am just reading back through this.
You have not said what hulls that you are running.
P Spec Sport Hydro - hull?
P Spec Cat - hull? also will this be for 6 lap oval racing, or 4 minute Offshore or both??

In my P Spec Sport Hydro I use the two 4S - 4000's in Parallel. In this hull I need the weight up front to keep it down because of the speeds that I am running.
Before I had two 2S - 6600's in series but I had to add some lead to the inside nose because of the speed.
So by changing over to the two- 4S -4000's I got some extra weight along with some extra depth in power.

In my P Spec Mono I run two 4S - 5000's in Parallel because of the 4 minute Offshore racing.
I also run the same setup in 6 lap oval racing because this is the way the boat was setup to run.

Also remember that the higher the "C" rating and the higher the mAh rating (example 5000mAh)
Equals a Higher Voltage Under Load (H.V.U.L.)
Seeing that our motors are rated by KV (RPM per Volt). Having a H.V.U.L. equals more speed in the second half of the run.
When the other guys start to drop in voltage because of smaller packs or lower "C" packs - You can continue at full go.

Larry

[dethow]

Hey Larry,
Title of the thread is "batteries for racing in p limited sport hydro class"

But yes... I believe the knowledge of what exact sport hydro hull is being used would help.

And yes, totally agree with you Larry that sometimes more weight from batteries is necessary to keep a boat on the water. With that said... that's not the normal in sport hydro classes. Most are doing everything they can to cut weight and balance the center of gravity (CG) by other methods.

And while I hear you on the H.V.U.L. - I still feel that 8000mAh is overkill for a P-limited sprint class. Just my opinion.... I use 6000mAh and come back with 40 to 45% battery life left. While I can't deny you may have a VERY slight uptick in H.V.U.L. using the 8000mAh, its not worth the extra weight and money spent on batteries.

[jerry123]

Larry, I will be running p spec hydro and cat. I thought I read that in p spec class you can't exceed 4000 mah.

Can I get away with running 4pks of batteries for 1hull. I would think I can repeak after they cool.

[dethow]

NAMBA RULES.jpg

And you can run any configuration of batteries you want as long as you are within the voltage limits of 11.1v to 16.92v pre-run/race.

[TheShaughnessy]

Dethow. Why do you say the graphene packs are better than the HD there have been many good reports with the HD packs. I think the graphene packs are more hype and marketing that anything else.

For anyone that has eagle tree software, or would want to download the free software from http://www.eagletreesystems.com/inde...ormation_id=12
I would be willing to share my most recent data, you would need to download the software for the e logger (second one down) to be able to view the file. It logged gps speed, amps, watts, pack voltage, mah used, motor temp at endbell, etc. My zippy compact 2s 5000 mah 60 c packs are on their second season and still have excellent IR numbers according to my TP820cd and is further evidenced by a more than acceptable voltage under load. The load being an average of 60 amps or more depending on the run with 115 amp spikes.

[dethow]

Dethow. Why do you say the graphene packs are better than the HD there have been many good reports with the HD packs. I think the graphene packs are more hype and marketing that anything else.

For anyone that has eagle tree software, or would want to download the free software from http://www.eagletreesystems.com/inde...ormation_id=12
I would be willing to share my most recent data, you would need to download the software for the e logger (second one down) to be able to view the file. It logged gps speed, amps, watts, pack voltage, mah used, motor temp at endbell, etc. My zippy compact 2s 5000 mah 60 c packs are on their second season and still have excellent IR numbers according to my TP820cd and is further evidenced by a more than acceptable voltage under load. The load being an average of 60 amps or more depending on the run with 115 amp spikes.

To be honest, I've never used the HD packs so maybe it is unfair of me to say the graphenes are better. Don't see or hear of many running the HD packs to be honest.
The only thing I do know is that when I and many others made the leap from normal lipo to graphene we saw improvements in under load voltage and significant decrease in battery temperatures. So no I don't think it is just hype and marketing.

But based on your statements you seem to be basing everything on what your zippy packs are doing. Have you used the Turnigy Heavy Duty packs or any graphenes to compare to your zippy packs? Or are you just saying you are so happy with them that you can't believe anything else would be better?

[jerry123]

Larry pro boat ul 19 and Veles 29 cat

[TheShaughnessy]

I guess my main reference to the HD packs are from Doby who has used them successfully for years. I have not personally used the graphene batteries but a couple of the guys I race with are and I've charged some of them up on my charger cause one of the guys is more of a gas racer and needed some help getting his electric stuff going. The IR numbers were basically identical. I haven't had a chance to data log them and look at the load under voltage so I can't say definitively that they don't hold higher voltage under load. What I can say is that I've lined up with boats that had revolectrix and rt graphene batteries , respectively and visually we were unable to detect a performance difference in speed. We noticed it was more important to find clean water and exit the corners cleanly to get the best speed in the straight aways. Sometimes it would look like their boat was pulling and sometimes it would be mine depending on the run up, if we put them side by side from the same rolling start it was pretty much impossible to say that one was faster than the other.

[dethow]

Not an expert on this stuff by any means... And I hear what you (TheShaughnessy) are saying about no noticeable differences observed on the water between 2 different boats. Maybe other factors such as esc, motor or prop playing a role... but who knows.

The one thing that is undeniable without getting into data logging is that the temperatures of the graphene batteries are much lower. Again not an expert, but wouldn't that be a result of less internal resistance? And if there's less IR happening wouldn't that result in higher voltage under load?

Anyway,
jerry123... sorry to slightly hi-jack your thread here. I've given you my recommendations and it looks like you only want to talk to Larry so I'll bow out. Best of luck on your search and at the races.

[TheShaughnessy]

I don't claim to be an expert either. I do have at least a few years of experience doing this though. You are right about the lower temperatures with the graphene, I'm just not convinced it's going to be the deciding factor in heat racing. If it were a 2 lap or a SAW time trial then I think it would be justified to go all out. But for a "budget" class I think the low cost alternatives are adequate with where we are at in terms of battery technology in general.

OP asked for batteries that wouldn't break the bank, my suggestions are based on that. Two hardcase 60c direct connect turnigy packs vs 1 graphene. Not that the higher end batteries are super expensive but if you a fueling multiple boats it add up If you have limited time between heats you might not be able to charge in time unless you charge at the max charge rate of 5c for the turnigy packs

[TRUCKPULL]

Larry pro boat ul 19 and Veles 29 cat

Jerry
What race is it that you are planning to go to?

Larry

[jerry123]

Larry, I plan on going to the Michigan cup/impba Nat's. My wife has serious health problems and as long as she is up to it I will be going. I hope I will be able to park close to where I pit so she has air conditioning.

I hope the rules such as motor and batteries apply at this race for p spec.