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Old 04-16-2003, 12:12 PM   #16
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As I remembered correctly "Ap lui Street" does not sell matched.

But you are correct 3300 will last longer than 3000.

Bashing is " running up & down the street" or anything else than running on a track.

Dicey,
GP3300 5A charge with .04 cut-off
Sanyo 5A charge with .05 cut off
I never re-peak. I want to use them as long as possible.
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Old 04-16-2003, 12:31 PM   #17
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There is nothing you can do to racing to make any class cheap. Especially when it comes to batteries. We found that out recently with a spec class our track put together.

We have a class based on off-road trucks that runs on our carpet oval. Any transmission based off-road truck (T3, XXX-T etc) with the Losi blue Spec ribbed tires, Traxxas Stinger 20 turn motor and Duratrax Dyna-Fun 1500 stick packs.

The reason for the choice of the battery was the cost. Hobby shop price was $13-$14 or so. Definitely cheaper than the $50-$80 matched packs.

What we found was that the batteries being unmatched stick packs (and low quality cells) didn't last more than a few runs. So, with 3 qualifiers and a main plus practice, you needed to buy a battery just about every week to stay in the hunt. Pretty soon we were spending just as much on batteries as we would have with matched packs.

Stock racing (as ROAR rules have it) is just another spec class.

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Old 04-16-2003, 12:36 PM   #18
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Quote:
Originally posted by davioh
the tip of the sanyos (not tamiya ones) stick out.....like the casing....so it doesnt' fit....i'd show u a comparison...but i cut the other ones cuz they didn't fit...
The pack probably has shrink wrap on each cell.
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Old 04-16-2003, 02:21 PM   #19
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Quote:
There is nothing you can do to racing to make any class cheap. Especially when it comes to batteries. We found that out recently with a spec class our track put together.
Re, the spec truck class, they do that here in Antioch but allow you to run any sealed 1500 packs. If you use decent 1500 packs with sanyo cells I have found that the packs have decent longevity, although nobody took the racing seriously enough to charge them at 7+ amps.

Perhaps you are right, at least as to the batteries. But the motor situation should improve with brushless.
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Old 04-16-2003, 03:08 PM   #20
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i don't htink its so much a question of tolerances, the manufacturing methods they use have got better so even the crap cells are within limits. that extra 5 or so % of runtime and voltage will only come from a true matched pack.

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Old 04-16-2003, 04:51 PM   #21
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I know a few racers over here in Oz that have started using non-matched packs and claim thie is no discernable difference. I Think there is allways the chance you could build a pack with one bad cell, maybe the answer is to build a jig so you can check them on the Pro-Trak before soldering them together.
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Old 04-16-2003, 08:26 PM   #22
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95% of the racers out would never feel the difference between a matched and an unmatched pack. Unless there was a bad cell, the voltage from the unmatched pack would probably be within 1% of the voltage of a matched pack.

The main advantage I see with matched packs is the fact that all of the cells charge and discharge at a similar rate. This just keeps individual cells from failing due to charging and discharging at the extreme rates we use.

The second advantage of matched packs is the ability to see the the labels and know what you are buying. This way, if you are willing to pay the extra money for a matched pack, you can decide if that specific pack is worth the price.

On the spec 1500 batteries, I didn't charge them at 7 amps. That is just asking for trouble. I usually charged them at 5 amps with a .03 cutoff. Since they are unmatched and in a stick pack, it is impossible to maintain them properly. They are made of NiCD cells, so memory and heat are their enemy. You can only discharge them to 5.4 volts and hope for the best. With these old NiCD cells, traying is critical to long life of a pack.

Our track recently legalized the new Spec battery from Trinity. I believe the cells are GP 1800's. The track owner put a couple of packs through some pretty abusive tests to see if it held voltage better than the DynaFun packs. After a month of this, he deemed them legal. They are a little more expensive ($20 vs $14) but their longer life will make them cheaper in the long run.

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Old 04-16-2003, 11:52 PM   #23
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Default Charge rate versus unmatched

I got one 1700, which are 1 years old. One Sanyo 2000, which I got for 3 years. The 2000 was used, when I got them !

I've always charged both packs at 6,5 amps on my Apex Sigma Plus which got approx. 0,04 volt cut off pr. pack. I'm traying the packs on an active equalizer with 0,6 volt cut off.

The Sanyo 2000 aint good any more, the first run is slow and usually it false peaks in the first charge in a day. But other than that, this pack have served me well so far and it's so old now, that I wouldnt have espected more anyway.

The Sanyo 1700 still serves me well. The IR has gone up a little, but it's still a good pack, with good punch.

I believe the active equalizer, ensure longer life and better performance.
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Old 04-17-2003, 12:33 AM   #24
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I have personally started using unmatched cells bought loosly from a Battery Wholesaler. In the packs that I have made up I can honestly say that I have experienced no detrement in buying the non matched cells. In fact the first unmatched pack I ever made gave better voltage and run time than ANY Matched Pack that I have had.
Just my 2cents

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Old 04-17-2003, 01:13 AM   #25
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Quote:
Originally posted by dicey
What I find interesting about charge rate is that rates of charging are so much lower than discharging yet it causes damage to the cells.
A big issue here, is the cut-off. The higer the charge rate, the more critical the cut off are. And a higher charge rate, also means much more expensive chargers.

From a common sense point of view, discharging at those high rates, are stressing for the cells. But no stress on the cells, means no fun on the track. But in the charging process, less stress wil still gain a lot of fun.

There might be more into it, I think the chemical processes are different in charging, respectively dischaging. Maybe you can find something more in-depth here: http://www.repairfaq.org/ELE/F_NiCd_Battery.html
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Old 04-17-2003, 08:38 AM   #26
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Quote:
There might be more into it, I think the chemical processes are different in charging, respectively dischaging. Maybe you can find something more in-depth here: http://www.repairfaq.org/ELE/F_NiCd_Battery.html
Excellent link! The gist of it is that high charge rates are not necessarily bad for the cells but when you combine high charge rates with overcharging, even slight overcharging, then you damage the cells.

So I gather that the moral of the story is to not overcharge and if you repeak it's probably best to do it conservatively as to charge rate and peak detection sensitivity if you want to protect your investment.
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Old 04-17-2003, 08:57 AM   #27
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My understanding is the charge rate helps determine how punchy the battery will feel. The harder you charge it (to a point) the more punch you get.

I was told with the GP3300's that you need to charge them pretty hard to lower the IR. They should be about 140 degrees F when you hit the track. This is VERY hot by my standards, but it does seem to work.

What I have found with ALL of my NiMH batteries is that this sort of charging enhances the average voltage of the cells as they age, but the runtime goes down. Some of my early Panasonic Stock Metals lost as much as 30-40% of their runtime, but the voltage and IR were incredible. Great for stock racing, but the runtime wasn't there for mod.

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Old 04-17-2003, 09:56 AM   #28
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Quote:
My understanding is the charge rate helps determine how punchy the battery will feel. The harder you charge it (to a point) the more punch you get.
So when you say "harder" charging you mean higher amp rates, right? My thought is perhaps on the first peak you charge at a high rate then on the repeak you lower the amps to prevent damage.

I race stock as well and am not at all concerned with run time as my 3300's tend to go about 9 minutes at 20 amps.
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Old 04-17-2003, 11:54 AM   #29
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The higher the charge rate, the steaper the discharge curve. That is, more punch in the beginning and less at the end.

This is very pronounced with 1700 NiCd. Charged at 6,5 amps, they got plenty of punch the first minute. After 4 -5 minutes, they flatten out. With cells like Sanyo 3000 HV, the result is the same, but they got so much capasity, that you dont get to the flat-out within 5-minutes in stock class.

The new Robitronic Expert charger, offers a 3 stage charge process: Very high amps in the beginning, medium in the middle and lower amp near the cut-off. Accordingly to Robitronic, this will both give higher voltage AND more runtime. I havent seen it action though, but it seems promising.

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Old 04-19-2003, 11:32 AM   #30
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Sosidge, it would be interesting to se the result, if you could put some matched GP3300 on your ProTrak. Maybe you could borrow a pack at your club?
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