Mah resitrictions

[jaike5]

So if 5500mah are allowed in 2,3,4,5,6s, in a 2p set up, 2000mah extra is quite an advantage , or even more with miss labeling. And yet again buy more batteries to keep a level playing field. Keep the max at 10k mah prop down for offshore.

Cheers, Jay.

[Doug Smock]

"If any changes are made to either organizations battery spec can we please have a conversation about keeping them similar? I don't care if it's just the IMPBA chair calls the NAMBA chair and they cook up something sane".

I hear you, really do.

I don't expect to see a change in battery spec. in the IMPBA until the HV cells go mainstream. A quick update of the safety rules by the BOD and it's done. Capacity limits? Not interested in addressing a problem that doesn't exist.

My hope is that if we put something in place in NAMBA, it will be something that can, and will be teched. Why bother otherwise?

[T.S.Davis]

Yeah but how do I prove it Jay? Say I dunk my batteries repeatedly. I do by the way. The labels get sacrificed when I peel the shrink to dry them out properly. I go to a race with my exactly 10k worth of 4s2p and stomp the crap out of everyone. How do I prove to a CD or a protest committee that I'm legal?

For that matter, lets say a racer has what appear to be the right stickers on his batteries. They say 4s/5000 on the labels. He stomps everybody. Someone protests because they are convinced he's cheating. How does a CD prove that someone is not legal?

Right now there is a difference between the two orgs rules. I don't like that there is a divide. A solve? I don't know.

[T.S.Davis]

Not interested in addressing a problem that doesn't exist.

Agreed Doug but is it possible that it's not an issue for IMPBA because WE (almost said you) don't have offshore?

You can run offshore in limited with 1P but you can't run do it in P or Q or even N2. I wont run P mono on 1P. Not because it isn't possible but because the cells get all pissed off about it when I do. I would prefer them to last a little longer.

[Darin Jordan]

Not pushing this, one way or the other, but it should be part of the discussion to consider that actually TECH'ing the current NAMBA mAh limits isn't practical, or even possible, at all but the most well-equipped racing venues. I doubt anyone other than Tyler, and maybe one or two others, actually has the correct equipment to do it fairly, and I think it would be a laborious process...

Just Sayin'

[NativePaul]

Having raced to Naviga rules with LiPo weight restrictions for years, I would advise against going that way, even though it is the only way that can be realistically teched.

[Darin Jordan]

Having raced to Naviga rules with LiPo weight restrictions for years, I would advise against going that way, even though it is the only way that can be realistically teched.

I think this might be why the IMPBA just doesn't have any limits. They aren't REAL limits if they can't be tech'd, and, frankly, they can't be accurately.

[Doug Smock]

Agreed Darin. Good to hear from you on this Paul, would like to hear more.

Hey Terry, glad you didn't say you. lol Yes, we are ALL in this together.

You, we, lol, (it shouldn't be this complicated) can run offshore in the IMPBA, just don't have specific FE offshore rules.
I'm not understanding why not having capacity limits is a problem for offshore. I would think that no capacity limits would solve more problems than it creates.
Personally, I'd be worried about the pitting next to a guy that is charging the cells that he just "pissed off",again.

I lack offshore experience, what have I missed?

Thanks fellas.

[Doby]

In my experience, people win the majority of the races not because they have a bigger gas tank and can pull more consistent voltage out of the LiPos.....

Its because they can set up there boats properly and DRIVE!!!!! (Luck helps as well)

[RaceMechaniX]

Doug, We'll cross paths at another venue now that I am on the East Coast.

In gas/nitro/FE open offshore run at a district level you can pretty much run your full 6-lap set-up with full power. Race duration may be around 2-3 minutes. It's hard on the batteries, but I would argue not as hard as a timed 4 min race.

In regards to NAMBA 4 min FE offshore (excluding P-ltd) it is very much a balance of trying to get maximum efficiency from your power system and boat with hopefully a little left over in the cells to avoid severe degradation. Running 4 minutes with the same set-up as you normal heat race boat will kill the batteries around the 3 min mark (from experience). Most guys and gals who race FE offshore have specific boats with reduced power systems or smaller props that reduce current draw. I would estimate most of them come back with single digit % left in the cells(I do). Don't get me wrong, it is a great challenge trying to make a boat survive 4 min with very equal boats without completely destroying cells. I recall the NAMBA FE nats back in 2012 in Michigan where one diehard racer must have destroyed two or three pairs of batteries in multiple offshore classes trying to beat the competition.

Everyone to my knowledge likely runs the maximum 10Ah(N2,P and Q) or 12Ah(for S and T) in the offshore classes. If NAMBA allowed free capacity limits, I believe most would add another 5Ah maybe more to the hulls to be more powerful. The extra weight would not be such a penalty if you had more capacity.

-Tyler

[Doug Smock]

Looking forward to it Tyler. Good luck this weekend!

[jaike5]

Hi Terry, I'm with yuh on the dunk'n thing !! mine are marked with a sharpie . Dig out your old triple beam weed scale and weigh the packs, any suspects charge them up and check with multi meter, any problems your out of the class for the weekend. Pain in the ass I know, If everyone knows your checking 1st, 2nd, 3rd. should keep everything on the up and up.
prop down for offshore will keep you out of the single digits for the % left in your packs.
Cheers, Jay.

[NativePaul]

OK a couple of people have asked me to explain my aversion to weight limits so here goes. Feel free to ignore me as I am not a NAMBA member and have no intention of becoming one in the foreseeable future. I have read the NAMBA rule book and seen a lot of race videos, but have never attended a NAMBA race, and the last time I spoke face to face with NAMBA racers and saw NAMBA boats we were all running NiCads, from what I gather it has affected us more than it will most of you, it should only affect 2p racers not 1p, and except the offshore runners they could mitigate all the problems just by running 8000mAh ish instead of 10000mAh+, so only offshore racers would feel the pain after the first year.

Firstly I should probably explain why we in Naviga have a limit. Almost all our classes are timed endurance races similar to your Offshore classes. With a set time and voltage, limiting the capacity of the pack will limit the average amp draw and wattage keeping racers on a level playing field and giving us close races.

Why didn't we just use a capacity limit? Realistically it can't be teched. The cell makers can't agree on a cutoff voltage for capacity measuring, and the capacity of any given pack will change depending on the discharge current and temperature, after much arguing it may be possible to come up with a set of lenient conditions for discharging that would be the same for all, but you would spend longer teching your cells than you do racing, and nobody wants that, I suspect that we would have very few racers left if that happened. Personally I would rather have an untechable limit, take it on trust that my fellow racers are playing by the rules and be beaten by the odd cheater, than have an easily techable weight limit, read on to find out why.

Why did we choose the LiPo weight limit if it is such a bad idea? Pack weights limit capacity and thus power to keep racing close and is easy quick and cheap to tech, anyone can use a digital scale with little training, you can tech a pack quicker than you can sign and fit a tamperproof sticker, and you can get accurate digital scales for just a few pounds/dollars/euros/yuan. The only other semi viable alternative was a F5B/F5D style electronic power limiter, and at the time they were still in there infancy, would need to be altered to our use, were an additional expense we would have had to make on our already expensive hobby, and quite frankly I dont think anyone invisioned that weight limits would become problematic. The limits we chose were 110g for Mini classes 280g for 2 cell classes and 560g for 4 cell classes, which with the then current technology gave us about the same capacity of the top NiMh cells which were 7cell 1600mAh for minis and 7/12 cell 5000mAh for the full size classes which allowed rough parity for the changeover season. Looking back I could probably have bought 2 power limiters for every boat in my fleet and still had money left over.

What is wrong with using LiPo weight limits? You don't always know what you are getting, I must have spent hundreds of pounds over the years on LiPos that were overweight and never saw the inside of a boat, some advertised weight are off, some advertise the weight of the cells as the pack weight, I have had legal weight packs from one batch then on the next order of the same packs had them overweight, I have taken my scales into an LHS and found a 15% variance between a basket of the same packs so some would have been legal and some not.
Tyler mentioned TP "lite" cells which brought our <110g Mini's capacity up from 1600-2100mAh and they are a few years old now, the current state of affairs gives us 2650mAh for the same 110g and 7200mAh under 280/560g, while not as high as a "high C" pack the voltage is pretty good so there is a healthy advantage to be had from running them, but there is no such thing as a free lunch and the cells are not as robust so while they cost the same you will need top replace them more and spend much more over time on the high capacity cells. The newcomer can't always tell what they are getting either, take these 65C-130C Aspec 6600mAh cells, you might think that they were robust "high C" cells, but there is no way in hell, check the weight i know they have short leads, but they are 30g heavier than the same brand's 65-130C 5000mAh that are not marketed towards boaters, in fact they have a remarkably similar shape, size, weight and discharge curve as cells sold by another make as 20C.
The cost of progress, battery technology increases year on year but with a capacity limit the improvement is only voltage under load and is a relatively small difference each year not being worth an upgrade, but with weight we are getting big capacity improvements which directly relate to power so even if the cells weren't fragile and lasted forever, you would probably want new cells every year or two anyway, this year packs have gone from 6800-7200 a 6% capacity boost last year it was 6600-6800 so 9% capacity in two years plus voltage under load improvements, so probably around 10% extra power over someone with 2 year old technology.
Brian mentioned pushing the rules and this has happened with batteries the rules say the cells must be covered in heat shrink, but a few years down the line the silver cell casing is heat shrink, wires are either nominal or connectors are soldered directly onto tabs, balance wires are tiny or sometimes holes are drilled into tabs for separate balance leads to be inserted when charging, there is little in the way of strain relief, so tab and balance wire failures are not uncommon, and you can kiss goodbye to the ease of mounting cells with velcro. Tenshock are amongst the best cells we have available so I won't knock them, but check out the instructions for their packs to see what we are dealing with, I am not keen on it myself and it is certainly not a way to get youngsters into the sport.
If you live near the sea and want to silicone up your cells you have to either take the disadvantage of running less capacity to allow for the extra weight, or not do it and risk your cells. On the subject of water, you can put legal cells in your boat, develop a leak for one reason or another and now your wet cells are overweight and illegal.
Last but not least is availability, there are 3 competitive cells for each class that I know of and none of which are available anywhere in my country, and all need to be imported.

What are we doing about it? we are trying to get away from it as fast as we can. On a club level most clubs in the UK are already offering an alternative to the weight system where you can chose to go by capacity if you prefer as long as the shrink and label are unadulterated from the distributer. On a national level it has been proposed that we adopt a 2 tier system where if you are trying to qualify for the Naviga worlds you have to go by the naviga weight rules, but those not interested in racing abroad can chose weight or capacity as they prefer. At an international level Naviga are looking at F5B/F5D electronic power limiters again, as everyone now knows it isn't really an added expense as we originally thought it would be, and I believe some prototypes are being made as I type. (off topic so PM me if you want, but Brian I would like to know your views on this as I think you come from an F5D background.)






As an aside from my experience with weight limits, I have long thought of your 10000/12000 limit or no capacity limit for sprint races was unlimited power, just because it is so much more power than we have available with our 6 minute races, whereas it has of course been limited by the availability of reliable high current ESCs. With the discussion of twins in this thread I take it that twins have started appearing effectively doubling power availability, are you worried at all by the new MGM 400A and 800A ESCs that would allow leagues more power from singles, and that the first one to go there might cause a cascade reaction meaning next year you would all have empty wallets and MGMs with 2220/1Ds in your P boats, or is your current power pushing your hull lengths to their limits already?

[NativePaul]

Oops.

[RaceMechaniX]

Good discussion Paul,

There are some twins being raced mostly in the hydro classes and the T classes. Although twins could double the power of a class, there are few classes for heat racing that could take full advantage. The boats are also prohibitively expensive to build and given the lack of popularity you only get to run them at larger events or in open class racing at the district level. Large singles tend to be the preferred setup for open racing although there are some big twin electric riggers being built by several guys across the country.

P mono is an excellent example of variety. The 34" length limits slows all out power wars. You will see the full spectrum of competitive power systems from a Castle 1515 1Y and T-180 ESC to Neu 1530 1D with Castle Hydra 240's or LMT 2260's with Schulzes. The standard and reliable power system is the Neu 1521 1.5D with 4S2P 10Ah total. Hull set-up and driving skills make this a very competitive class.

SAW's are the one exception where twin's are gaining popularity particularly in the Cat classes where the HPR, MHZ and similar hulls are being built for maximum speed. These are very high power set-ups which use every inch of the rules to their advantage. The top level guys are pushing 50kW+ with 10SP to 14S2P using old Schulzes and hot wind LMT 30 series motors.

Tyler