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Old 07-01-2003, 08:34 AM   #1
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Default GP's going off already?

Anyone else noticing a drop off in runtime on the GP cells after not much use - I'm talking 20 or so cycles, and losing about 10% of runtime. Voltage seems to stay good.

I've had about 8 cells in three packs drop off like this, fairly suddenly as well.

Part of me thinks it's because I was using the packs too quickly between runs and not letting them cool and rest enough (treatment my Sanyo HV's took without a problem), but another part thinks it may be that the cell isn't as durable as we're led to believe.

I've been using a gentle charging routine on the pro-trak, 4A and 0.03 cutoff normally, occasionally up to 5 or 6A on the charge as an experiment to get a bit more punch in the races.

Anyone else had similar experiences?
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Old 07-01-2003, 08:53 AM   #2
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yes,me too,i tot it was me.
BUT it happens to some packs and not all.
i have 3 packs
1.3000
2.2900
3.3300
they are all used similarly,charged at 5A with 18mV cutoff,discharged to 5.4 before charging.
i think they have gone to more than 20 cycles though.
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Old 07-01-2003, 09:08 AM   #3
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happened to me too. Are you guys putting a charge back into them after the race day? I think that may be my problem. I have been charging mine on a turbo at 5.5 and then at the end of the day discharge on an eq board and then putting about 1000 sec on until day before the next race. Then I discharge on a board the night before.

My number are good and did a cycle on the turbo. I am getting 1.17-1.19 out of the pack for about 450 sec. so lost about 100 secs. I never did do a cycle when they were new, so don't know what the run time was. I can only trust the labels.
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Old 07-01-2003, 09:10 AM   #4
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i suggest charging and discharging them the usual as constant as possible... if you charge at 5amps, charge them consistently at 5amps...

also the discharge or motor you use them for, in my opinion affects the batts.

using them without letting the batts cool sufficently may deteriorate the batts
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Old 07-01-2003, 05:28 PM   #5
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I have had my GP's for about 6 months and they are just as good as when I got them.

I charge at 6 amps, leave to cool after race and re-peak. After the last race of the day they go pack in the box and stay there 'till the next race day when they are discharged, left to cool and then re-charged.

I also tray them one every couple of weeks on a realtime 2.

Are they coming off the Pro-track warm? what delta V setting are you using? I use 0.05V if you are using much less it could be that the cells are false peaking and they didn't when they were new.
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Old 07-01-2003, 06:51 PM   #6
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Tray them and u will see the diffrencel. Traying them wil
make them close or lyk new again
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Old 07-01-2003, 07:01 PM   #7
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One thing that I have found is that the GP's do not like to be run in a car where the amp draw is low, like 4 cell stock oval. After running them in stock a few times the cycle numbers dropped way off. The only way I got them back up was to cycle them at 35 amps and then they ran better than they ever had!

If you want to keep runtime then tray them in an Integy octane 2 tray for 3-4 minutes before you charge them, discharge them on a t-35 @ at least 30 amps after your run down to 5.4 or 3.6 (6 cell, 4 cell) and let them cool before charging again. If you run stock and dont care about runtime the deadshorting the pack really ups the voltage but you will lose 20-30 seconds of runtime.

I always charge at 6 amps and discharge at 35 amps. My batteries are better now than when I got them new.

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Old 07-01-2003, 07:31 PM   #8
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No problems with my Trinity Gp cells...
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Old 07-01-2003, 07:43 PM   #9
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Yep. traying is definitely the way to go with GP3300's.

I use a Team Orion equalizing tray and just leave cells in them overnight as it has a built in cut-off at 5.4v.

I have cells that are more than 6 months old and they still have between 3500 to 3800mAH capacity.

These cells are used 2-3 times a week and have been charged at 5A with a 24mV per pack cut-off.
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Old 07-02-2003, 03:37 AM   #10
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Well, i am using them for stock touring on a low-grip surface, so I'm never using all the packs performance.

I'm running a 0.03 cutoff usually, but when I tested the individual cells I actually had to use a 0.02v per cell cutoff (they would continuously false peak on 0.01v).

I'm not going to tray them or deadshort them.
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Old 07-02-2003, 05:24 PM   #11
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Quote:
Originally posted by sosidge


I'm not going to tray them or deadshort them.
Sosidge, the advice above suggests traying occasionally is the best way to keep your GP's in shape. Why not give it a try on one pack and see how you go?

I have done this and my GP's are as good as ever, capacity is 3500 - 3800.
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Old 07-02-2003, 10:12 PM   #12
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A couple of people here are using the following regemen with good results:

Charge at 5.5 amps for stock, 5.0 amps for mod.
Discharge to .9 volts per cell after running.
Partially charge the pack to 8.5 or 8.6 volts for storage.
Discharge to .9 volts per cell on day of use.
Place on an equalization tray until the lights start to dim.
Then, charge at 5.5 or 5.0 amps and run them.

According to them, this has kept their GP's strong after more than 6 months of weekly use.

Rob
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Old 07-03-2003, 03:29 AM   #13
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i found that using them on low amp draw decreases the performance of the GP's, just what EAMotorsports mentioned.

also i found that they have lower peak voltage if i do NOT tray them...
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Old 07-03-2003, 04:55 AM   #14
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I think I'll try running a mod geared to dump and see what happens to the cells.
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Old 07-03-2003, 06:42 AM   #15
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Quote:
Originally posted by highwayman
i found that using them on low amp draw decreases the performance of the GP's, just what EAMotorsports mentioned.

also i found that they have lower peak voltage if i do NOT tray them...
Funny... mine do the opposite. They peak lower if I DO tray them before ... Oh well, go figure.

As far as dropback is concerned... The advice coming from a drag-flier champion will surprise you... The guy recommends using a .1 dropback for a 6-cell pack (that's one TENTH of a volt)...

I haven't been brave enough to try so far. 0.04V gets them plenty hot enough for me

Later
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