Why Parallel LiPoly

[TRUCKPULL]

Next 2S2P in "n2" - "P" - "Q" etc.

It is not because I want to pull 200AMPS

It is because I don't want to pull more then 10C

and my packs will weigh more then my old 6 sub C's packs.

Reason is if you pull 20C you will only get about 50 good cycles out of your packs.

If you only pull 10C you will get over 200 cycles out of your packs.

Pack life is one of the big reasons that we want to change to Lipos

2P packs is what is going to give us good pack life. staying closer to that 10C

Also If I buy a 2S2P - 10,000mAmp pack to use in a "N2" offshore 4 Min. race.

it is the same pack that I am going to use in my "N2" sprint boat also.

Saftey wise the larger mAmp packs that you run, the safer you will be.

They tell us to never use more then 80% of your pack total mAmp.

So to be safer I want to run packs that are 40% over my race setup mAmp.

And my packs are heavier then yours.

So why should any racer tell an other racer that he has to run a smaller mAmp pack

and not be as safe as he wanted to be, and now has to pull a larger C rate out of his packs,

which in turn will give him a shorter pack life.

Larry

 

[TRUCKPULL]

The future of using total Amp limiters as I see it.

After a while it will be proven (for example)

If you don’t run a XXX motor (higher efficiency)

An XXX ESC , a XXX prop, and a XXX hull

You don’t WIN

It will end up being spec racing in every class.

Racing will be a lot more expensive because

The XXX units are $300.00 each

No more $70.00 motors or $225.00 speed controls.

What is wrong with me using cheaper equipment?

Drawing more amps to run the same speed, and the same distance.

We have a person in our club that is running a mechanical speed control in LSH is he wrong????

Larry

 

[JfromJAGs]

It is not because I want to pull 200AMPS
...

So why should any racer tell an other racer that he has to run a smaller mAmp pack

and not be as safe as he wanted to be, and now has to pull a larger C rate out of his packs,

which in turn will give him a shorter pack life.

Who asked you to run 100A now? You could have raced 50A and it would have been fine for everything.

So maybe YOU will not WANT to run 200A, but soon you will have to - or loose. Because someone else will find out he'll be faster running @ 200A. In fact your theory would only work if you would LIMIT the currents to 100A.

 

[JfromJAGs]

What is wrong with me using cheaper equipment? Drawing more amps to run the same speed, and the same distance.

What makes you think you can run more amps than the faster guy?

 

[TRUCKPULL]

If you don’t run a XXX motor (higher efficiency)

An XXX ESC , a XXX prop, and a XXX hull

You don’t WIN

READ higher efficiency

By the way we are runing well over 70Amps already in "N2" mono with Sub "C's"

Larry

 

[JfromJAGs]

You did'nt answer my question.

Anyway, I'm not promoting a limiter here. It would just solve the battery issue - all would run basically the same identical battery - black box battery. Sure, other parts would become more important and there are many things which needed to be thought of.

 

[TRUCKPULL]

It would just solve the battery issue

What Battery issue,

I explained above why we want to run 2P packs.

1 - Safety

2 – pack life – over 200 cycles not just 50 cycles

3 - my 2P packs will be heaver then your 1P

Just because you have lots of money or sponsors.

Don’t try to force us racers to use 1P packs.

You or any body else can use 1P packs.

But we want the choice to use 2P

 

[JfromJAGs]

Larry, as long as you don't listen what I'm saying it does'nt make sence to argue. But again: allowing parallel packs for N2, P etc. will NOT reduce the initial nor long term costs - because there's no or no big enough current limiter involved.

FYI, I don't have lots of money, but still I don't want to get sponsored. So I pay for the s**t I'm doing myself.

 

[Andrewg]

Larry

some real world results

1 - Safety: safety has very little to do with capacity. LIPO are most often damaged by overcharge; over discharge or impact damage. The most important safety issues are:

* a lipo specific charger,

* a balancer preferably one which interacts with the charger

* an ESC featuring the correct voltage cutoff;

* to discharge and dispose of damaged cells.

A data logger makes financial sense and is the best tool to ensure the boat is propped to prevent cell overheating. If a logger is not used prop conservative as the heating issue is three times as costly for these cells vs Nimh.

2 – Pack life – this is relates to load and the degree to which the cell is discharged/heated. We run a longer faster race than NAMBA and use 2200 mah. A single series 5AH cell is not going to be even halfway emptied in NAMBA racing.

Again a data logger to help with setup is your best friend. The fastest boat is always a balance between current draw and prop rpm (voltage), voltage even more so with a hydro.

3 - 2P packs will be heaver and more expensive than a good 1P pack. This means the advantages of reduce weight and lower real cost than nickel are lost. The risk of a failure increases in parallel pairs.

Joerges idea of a limiter is a concept but perhaps no limiting device as such is needed. Already cheaper digital displays which read AH used are available for approx $US35 if I recall correctly.

You could set a limit on capacity to be used. The amount used could be read at the end of a race - if it was exceeded the boat would be DNF'd as if the cell capacity had been exceeded, but it wouldnt stop someone racing and having fun. Set intelligently the "limit" would ensure racing is much faster and control costs by reducing the adavantages of packs 4 times the capacity used, may have.

This would also help protect cells from overdischarge / heating and ensure offshore remains a race involving efficiency and speed, not just a long sprint race with a LH bend which costs twice as much to power.