Aaron: I had a bit of spare time and decided to do a graph to illustrate the effects of IR on the voltage curve.

I've tested various samples from various Lipo suppliers/factories and I came across these 2 packs of 3S.

Both packs from the supplier are rated at 30C. One is 6200 and the other 4100.

GFX data at 25 amp discharge.

6200-30C: 6013mAh - 10.96 Avg V - 19.1 mOhm

4100-30C: 4125mAh - 11.09 Avg V - 12.2 mOhm

As you can see there is a big difference in IR which results in a difference in average voltage. When looking at the graph you can see that the 4100 for the first part of the curve has an edge but the higher mAh over comes this. The test was done at 25 amps as this is the max I can do with my GFX on a 3S pack. I could hook up my Camlight load and do 40 or 50amps and this would favor the 4100 even more due to it's lower IR.

This also shows how irrelevant C rates have become as a true 30C-6200 would have to be much lower in IR than a 4100-30C.

Danny
I know this is off topic but...any future plans on releasing a LiFe rx pack in the 2000mah range? Just wondering for Nitro season next year.

I need to better understand what is needed for TX and RX packs as I would like to add these to our lineup.

For RX LiFe is preffered over LiPo ? Is there a specific pack size that is more popular ?

Any info you can give me would be great and I will talk to the suppliers about getting some of these packs.

From what I've seen LiFe is used for TX and LiPo is used for RX.
Not sure why, maybe the TX batt will work with all TX's and not cook them? Maybe some TX's don't like more than 6(ish) volts? I run 2s LiPo in my MT-4 with no issue.

Most big brand TX & RX batts are $25(ish) but nano techs in the US warehouse are $8.50 to $12 and we don't have high demands for that battery so cheap may be OK for most of us. Talk about slim profit margins to compete... probably not worth the cost to stock and sell those.

4 AA's just charged show voltage in the high 5's for voltage on my TX and a LiPo is giving more than 8v so even a lame high IR LiPo is more than good enough I would think.

My view anyway.

Thanks for the info. If most are happy with 8 to 12 dollar packs from Hobby King then this really isn't worth it. Got to love that they claim Nano receiver packs. Thought Nano was there best stuff oh wait now they have Nano A Spec. lol

Yeah, Jang did a test on the A-Specs and it didn't put out as well as the regular nano. Go figure.
For the right application their OK though I guess.

Awesome info Danny! Now let's see a graph of the same capacities, high IR vs. low IR. Compare apples to apples. Most guys shopping for a full size pack aren't interested in what a shorty puts out... It's all about providing users with information to make an informed decision. This is really great to help explain to your followers and gain new customers.

Here is my take on these big online places that supply packs and I'm not saying this because I want to get more business. I'm saying this because I understand the battery market and care about customers being taken advantage of.

These places don't care what they sell. They don't really test the packs they just sell them as they get them in. They have clever marketing strategies and have a good concept of what racers/customers are looking for. For example putting higher weights on the specs of the packs. Some think higher weight means a better pack but this isn't really true. When I read the Nano hype I almost feel like buying them and I know there is no such thing as Nano. Now Nano is a thing of the past it's A Spec. What happened to Nano being the best of the best ? Anyway sad to see so much emphasis placed on marketing instead of R&D and offering better packs.

As not all our batches are the same and in fact with the latest shipments having higher IR I know these cheaper packs sold have to fluctuate allot more from batch to batch. This means one time you may get a pack and it's actually good and does what you expect and next time you order one and it runs differently as they might of switched suppliers or the latest batch is off.

My goal with SMC is to make a difference and not sell packs just to sell packs. I think we can make an impact and offer competitive pricing and make sure our customers know what they are getting. Yes this means less profit but I hope our sales will keep increasing to offset the lower profit.

Best thing to do is to go visit this thread I did awhile ago which compares many similarly rated packs. The SMC Premium Certified 6500-25C is the same pack as our 6500-70C we offer now as Factory Spec. You can see the graph below that compares all the higher mAh packs tested in the thread below.

http://www.hobbytalk.com/bbs1/showthread.php?t=362697

The shorty is a bit tricky as the voltage curve is lower but the weight is also lower so we would need to be able to do Raygon graphs but I'm not setup for that. Hope someday to add this to my testing arsenal.

With the current weight rules in offroad can you get to minimum weight with a 315gr regular pack ?

Is stock 4wd offroad still being raced ?

Danny,

Does this graph really show that unless I am taking more than 6000 mah out of my pack there is little difference between the packs that you tested?

Not enough head count running 4wd to make a stock and mod class. When there's enough for a class, it's just open.

Other areas may differ I guess. Coming into winter and the cold states will be putting away their 1/8 buggies and bringing out the indoor arsenal.

The 6500-65C is the same pack as our 6500-70C the company selling these buys from the same factory as us. The 6800-70C is from the second best factory in my opinion. So these 3 packs are low IR packs and you can see this is reflected on the voltage curve.

Thanks for the info as I wanted to maybe change the way the saddle is built if stock was popular as there is some voltage drop due to the way they use a jumper wire.

If mostly mod is popular than the packs performance is irrelevant. Can always get more power by using a lower turn motor.

How would you jump the two differently? And yeah, 6.5t is already ridiculously fast :D