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Old 12-02-2006, 12:25 PM   #1
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Default so much for "not equivalent" voltages between nimh/lipo

a chart showing voltage V vs time in minutes

batt:------- 0:00- 1:00- 2:00- 3:00- 4:00- 5:00- 6:00- 7:00- 8:00- 9:00- 10:00 11:00 12:00
nimh 3800:::8.90-- 7.53- 7.36- 7.34-- 7.30- 7.25- 7.20- 7.14- 7.06 -6.94- 6.490
lipo 3200::::8.37-- 7.60- 7.42- 7.28-- 7.17- 7.08- 7.06- 7.00- 6.93- 6.55
lipo 4400::::8.38-- 7.58- 7.43- 7.34-- 7.25- 7.19- 7.15- 7.09- 7.05- 7.02- 6.990- 6.920 6.700

Avg V, 3800 7.01/3390 mah
Avg V, 3200 lipo 7.075/3133 mah
Avg V, 4400 lipo 7.14/4260 mah

20 amp discharge on Reedy Quasar
Average taken from 1:00-x:xx min readings from DMM
1 year old nimh
3 month old 3200 lipo
2 month old 4400 lipo
These test results to me say that this:
"11/12/06 LiPo battery decision clarified.

For 2007 Lithium Polymer batteries are not permitted to compete with NiCad or NiMh batteries in electric class racing because the voltages are not equivalent nor do the pack dimensions match those currently observed by ROAR and IFMAR."

is crap!

Granted, this test could be done better, say with a newer 3800,4200,4300 nimh etc and other 3200/4800 lipo. I could connect the DMM to the PC and get a better set of measurements rather than 1 per minute. But I think this helps show that lipos are not a super on track advantage with regards to voltage. Plus, these batteries fit just fine in my B4, rc10 T, and T2R. So, ROAR, why the hate?
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Old 12-02-2006, 01:10 PM   #2
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The 7.4V LiPo is pretty close in performance to a new, matched 4200 pack. The difference being that after a certain number of cycles, the 4200 will lose voltage, while the LiPo will stay very much the same for a much longer period of time. I would be interested to know exactly how many cycles it takes for a matched 4200 with good numbers to lose its "advantage." But yea, in competition, head-to-head, where nothing but voltage matters, and weight requirements are in place, the 4200 appears to "win."

So, like you said, as long as you keep weight requirements in place, there's really no reason not to let the two coexist. If the R/C world moves toward LiPo, and reduces the minimum weight requirements, all kinds of interesting things could happen.

Because ROAR is an insurance company, presumably their ban has something to do with fears about LiPo safety. This is a heated (no pun intended) issue, and is worthy of some attention. However, if anybody tells you that all LiPo is equally volatile, they're uninformed, and clearly don't care enough to get all the facts. You should probably stop trusting anything that person says, as they're likely biased and looking for a way out, or can't be bothered with intelligent thought.
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Old 12-02-2006, 01:44 PM   #3
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Im for Lipo all the way.
Like syndr0me said "anybody tells you that all LiPo is equally volatile, they're uninformed". The Sony Lithium Ion pack thats were racalled had a problem with metal particles getting into the manufacturing of the cells which i swhy they recalled so many because they have to be sure they got all of them. So technically it was not the type of cell fault the ones that set on fire.
One argument is they were not desighned for type of use that RC delivers but are any type of cell ?
The sooner that LIPOS become accepted in RC cars the better for the new comers as well.

gacjr0 those figures of yours prove the Nominal Voltage is not a problem unless you are a racer that get new packs all the time and will not have the advantage over people who have to keep thier packs for 50 or more cycles.
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Old 12-02-2006, 05:41 PM   #4
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This question has been posted many times. As the rules are written the cells must fall within a certain size per cell and be rated as 1.2 volts per cell. Unfortunately Lipo doesn't come close on cell size and its not rated at 1.2 by its manufacturer. This means it cant possibly be legalized under the CURRENT rules.
Yes, ROAR can write new rules to fit Lipo's but has not done so yet. So the question should be "when will ROAR write a lipo spec rule". Only then can Lipo's be submitted to be legalized.
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Old 12-02-2006, 07:29 PM   #5
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Not a good comparison at all, a 1 year old 38800 ?
If youre going to do a comparison, use new batts, 4200's have been out qite a while, if youre trying to scew numbers, that was a poor atempt.
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Old 12-02-2006, 07:46 PM   #6
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Syndrome keep up the good fight buddy. That was very well put.
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Old 12-02-2006, 08:40 PM   #7
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Quote:
Originally Posted by syndr0me
The 7.4V LiPo is pretty close in performance to a new, matched 4200 pack. The difference being that after a certain number of cycles, the 4200 will lose voltage, while the LiPo will stay very much the same for a much longer period of time. I would be interested to know exactly how many cycles it takes for a matched 4200 with good numbers to lose its "advantage." But yea, in competition, head-to-head, where nothing but voltage matters, and weight requirements are in place, the 4200 appears to "win."

.
sooooo, lipos have the same voltage as good nimh's, but don't need to be replaced as often and thus save the average racer money in the long run so they should be banned... got it...
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Old 12-02-2006, 08:52 PM   #8
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Quote:
Originally Posted by C_O_jones
Not a good comparison at all, a 1 year old 38800 ?
If youre going to do a comparison, use new batts, 4200's have been out qite a while, if youre trying to scew numbers, that was a poor atempt.
So there's a pretty good chance that the new 4200's perform better than the LiPo's... I don't think he was trying to screw with the numbers, he just tested what he had....
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Old 12-02-2006, 09:17 PM   #9
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I can tell you first hand by competing in this years KO Grand Prix where they allowed Lipo.

That they were even on power.
The high end Nimh packs were just as good as the Lipo packs.
Fred Lidel(sp) came in third over all in the spec motor class with a Lipo.
There were a couple more peeps in the A main that were running Lipo.
The power was even Steven....
They had to charge them in a Battery Bunker, but wasn't much of an inconvenience as far as I was told.
Most were running just one pack....Cracked me up....The other guys were balancing and setting chargers while the guys running Lipo were walking around hanging out with peeps.........
I can not wait till next year.....
I think KO got it right....Set a minimum weight and leave it alone.
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Old 12-02-2006, 09:38 PM   #10
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Quote:
Originally Posted by Mr. Shookie
They had to charge them in a Battery Bunker, but wasn't much of an inconvenience as far as I was told.
Most were running just one pack....Cracked me up....The other guys were balancing and setting chargers while the guys running Lipo were walking around hanging out with peeps.........
-Just think how many more people would race electric if you could buy 2 packs and have them last WAAAY longer that Nicd/Nimh. The main reason so many people are going gas? battery expense.................
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Old 12-02-2006, 09:44 PM   #11
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lipoo hmmmm well what ever lipoo in a 1/12 hmmm longer mains thats cool, but lipo and sub c should not run together thats it.
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Old 12-02-2006, 09:45 PM   #12
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Quote:
Originally Posted by Taylorm
-Just think how many more people would race electric if you could buy 2 packs and have them last WAAAY longer that Nicd/Nimh. The main reason so many people are going gas? battery expense.................
ya but gas rullz.
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Old 12-02-2006, 09:46 PM   #13
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THe best NiMh cells are holding higher voltages than the current lipos. I race offroad and the "punch" is where the difference. Between the nearly non-existent IR of lipo and far lower weight (my B4 weighs 5+oz above legal weight with 3800's, right at the limit with lipo) it does have an advantage. Even if you are talking about TC's a racer would have to have fresh 6 cells more often and while those are closer to legal weight with conventional 6 cells, using lipos gives a racer fine control of where a large portion of the weight in their car goes. To the onroad set that's a big advantage.

Lipo will eventually be legalized and nimh will probably go away.
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Old 12-02-2006, 09:48 PM   #14
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Quote:
Originally Posted by vtl1180ny
So there's a pretty good chance that the new 4200's perform better than the LiPo's... I don't think he was trying to screw with the numbers, he just tested what he had....
Not that at all, if you are going to all that trouble to do a test and then proclaim that they are equal, that just isn't a good comarision, use new batts.
The 3800's do drop off, not as quickly as the 4200's, and how were they treated up to the test date?
I'm not against lipos, just fair testing results.
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Old 12-02-2006, 10:04 PM   #15
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Quote:
Originally Posted by gacjr0
a"11/12/06 LiPo battery decision clarified.

For 2007 Lithium Polymer batteries are not permitted to compete with NiCad or NiMh batteries in electric class racing because the voltages are not equivalent nor do the pack dimensions match those currently observed by ROAR and IFMAR."

is crap!
So how is this crap? As I pointed out earlier LiPo does not meet the current cell rules... size or voltage wise so of course they wont be legal. LiPo for RC didnt exist when these rules were written.

ROAR didn't say anything about the discharge voltage... the ROAR and IFMAR rules states 1.2 volt per cell. Read the label on a sub C cell... it states 1.2 volts. A lipo is 3.7 volts. This is what they mean "voltage is not equivalent"

I agree LiPo will become legal but not until ROAR and IFMAR make a LiPo spec rule. The rules now are for sub C cells... you know the "Round peg in a square hole" analogy

Why don't you guys start writing the sanctioning bodies... that will do more for the LiPo cause than complaining here
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