gp3700 maintence

[aus jd 2703]

i recently bought 4 voltage enhanced gp3700 packs and an intellipeak ice charger. my method so far is charge run then discharge to .9v per cell then eaither recharge if racing or charge to 40% for storage then when i want to race again discharge to .9v and recharge from there. now i discharge at 10amps and charge at 5 amps i use a bit of a cheap powersupply (from jaycar kind of like radio shack just an aussie version) and set the delta peak to 4mv percell and lately its been bout 32'c and my cells hit 50'c before they peak so i have heard that u warm ur packs to 40.c (just charging will do) then place them over a fan so they dont over heat is this correct? even in winter when it 25'c they dont over heat so i think it is the ambient temp that is doing this??
also my packs only ever take about 3100mah charge even when discharge to .1v do i need a discharge board likee the integy 6s? or would the zero 30 be better? its just 3100mah in a 3700mah pack isnt right? please help these are my race packs and first "good" race packs ever.

[losiguy1090]

Go through all the settings on your charger and make sure theyre all correct. Make sure capactity is at 3700, that you have it set to charge 6 cells, and try changing your delta peak to 6mv/cell. Also get a discharger that will do 20 to 35 amps. This is around the kind of amp draw you have on your motor and trains your packs to run at that amp draw. Integy makes a nice discharger that will do 30 amps for around 50 dollars. And as far as trays go, its a nice thing to have if you race. They kind of "wake up" your packs a lil bit. I have a tekin discharge tray, its pretty sweet cuz its non polarized so you cant mess up your batteries or the tray. Oh yeah, and theres no need to put a fan over your batteries while they charge. It's a good idea to do while they discharge though as they can get rather hot.

Also, did you assemble the packs yourself? There could be a possibility that you cooked one of your batts during assembly and its only charging 5 batteries.

Hope you get your stuff figured out, cuz my 3300's will peak around 3800 mah when discharged to .5v/cell so your 3700's should peak out around 4200ish.

[loopy]

I had to set my APC dyna charge to 50mv(6 cells) peak detect to get a full charge in my 3700's.

They now charge to approx 4200mah at around 119 degrees F.

Try gradually increasing the threshold until they peak around 120F.

[rcguy2477]

Putting a fan on the cells during charging is actually bad for them(if you search, you will find a full explanation by "ikraj"). Using a fan or heatsink while discharging though, is fine. Todays batteries opperate at their peak when warm.

The 0-30 from Integy is good for discharging the packs when they first come off the track. The only bad thing about them is that they discharge to 0.0v, which isn't good for the cells. Also, this unit doesnt actually equalize the batteries. The best combination would be an Integy 0-30 and a regular equalizing board. www.axxis-racing.com is also comming out with a mod that will allow the 0-30 to cut-off at .9v while still maintaining the 30 amp discharge rate.

50mv for a pack is extremely high unless the Apc charger calculates the cutoff voltage differently. Normally, the mv setting should be between 3-6 per cell.

[aus jd 2703]

ok whats ur ambient tempreture guys cause i seriously think that the temp is making my batteries to warm so the hit peak temp before the delta peak??? what do u guys do in summer because i cant get a full charge right now the batteries get to warm i mean the ambient is about 90 is that to hot??? also i set my temp threshold to 122 i converted my temps to Fahrenheit so u might see what i mean. its just my packs are not taking a full charge and never take on 3700mah i use an ice i thought they were good could my charger be the problem??

[loopy]

50mv for a pack is extremely high unless the Apc charger calculates the cutoff voltage differently. Normally, the mv setting should be between 3-6 per cell.



Yeah I know it is, its just the setting that peaks the batts fully. Before that I was only getting around 3400mah and the batts were peaking at 95/100deg from 0v after using my integy 0-30.
The guys at fusion told me to keep raising the threshold until the temp started to rise around 125 deg F.
Needless to say I do keep a close eye on things using this setting! :D

[loopy]

ok whats ur ambient tempreture guys cause i seriously think that the temp is making my batteries to warm so the hit peak temp before the delta peak??? what do u guys do in summer because i cant get a full charge right now the batteries get to warm i mean the ambient is about 90 is that to hot??? also i set my temp threshold to 122 i converted my temps to Fahrenheit so u might see what i mean. its just my packs are not taking a full charge and never take on 3700mah i use an ice i thought they were good could my charger be the problem??

Our ambient is prob no where near your aussie summer temp!maybe around 30 deg C

[aus jd 2703]

so should i use a fan to simulate a cooler ambient??

[losiguy1090]

If its like really really hot outside, then it should be ok to use a fan or heatsink on the batts while charging.

[aus jd 2703]

is 7mv percell to high??? also how do u guys discharge ur batts before charging??

[losiguy1090]

Experiment with the peak detection until your battery peaks at about 120-140 degrees. Preferrably around 125-130 though.

I discharge my batteries after a run by putting them on a 20 amps bulb discharger from Deans. Then I put them on an equalizing tray made by Tekin that discharges down to .5v/cell. And after a race day, to condition my packs, I'll charge em all up, discharger them on a trinity dynapulse discharger, equalize em and put about 5 min of charge on them.

The dynapulse is a pretty sweet lil device cuz it pulses the discharge rate between 0 and 30 amps so the pack stays at room temp, and it conditions the pack. It takes about 8 hours to discharge a peaked pack, but it breaks down the crystal structures inside the cell so it increases voltage, runtime and lowers IR. It also has a small backlit display that tells you your voltage, runtime and IR. It does this all for about 50 bucks.

[aus jd 2703]

ive read bout the dyna pulse and the magazines arnt convinced its gonna stay they think it might be a fad thats why i was leaning towardsa tray but what u said makes sense so i unno last night i used a fan and 7mv stopped the false peaking but the pack hit 129 before peaking and only took on 3400mah i justcant seem to get a peak and the temp at the same time which should i trust? aslo i discharge at 5 amps to .1v before charging so the pack was close to discharging i was only using the charger though i think ill either buy a integy 6s rack or dyna pulse depending on what every one says?

[losiguy1090]

I beleive that on the ice, you can use a capacity cut off? If you can, try cutting it off at 3700 and see what the temps are.

You wanna have a high amp discharge rate to train your packs to run at that amp draw. I would have a high amp discharge device and a tray. Make sure the tray has a cutoff though, like the tekin or novak smart tray. I have a 20 amp bulb discharger that I use at the track (takes a lot less time than the dynapulse) and then inbetween race days I cycle the packs once or twice on the dynapulse. If you get a bulb discharger, wait till the lights are about to go out on it, then put it on a tray.

[aus jd 2703]

im no were near my capacity though my cell take between 3100 and 3400 before temp cut of of 120'f to get 3400 i had to sit them over a fan the whole time

[gizmoguy303]

Are all the packs peaking at this capacity? It sounds like you may have damaged them when soldering. The higher capacity cells are more easily damaged during the assembling process and you have to take extra care when soldering them.

If the packs still perform well I would not worry about it. Depending on how the packs were discharged before charging and what voltage they are at the numbers you are getting may be normal. Also, I have noticed that if you run a pack more than 2 times a day the mah at peak is much lower than usual. I don't run my packs more than twice during a race day.

[aus jd 2703]

i might get a friend to charge them and see what he says and what his charger does

[rcguy2477]

Even if the ambient temperature is high, you still should not put a fan on your batteries. This causes the outside of the battery to be at a lower temp than the inside which can be bad for the pack(do a search on it and you will find more info). Make sure that you use a discharge board after each time the pack is run. This will ensure that the packs peak at the same time. When you don't use a discharge board, the cells in the pack will peak at different times. Also, check to make sure that you dont have a bad cell in the pack, as this could make the pack appear as though it doesn't have much runtime.

Interesting fact of the day- did you know that the deans discharger does not discharge at 20 amps? Though the bulbs are rated at a 2 amp discharge rate a piece, this rating is done at 12v. When these types of bulbs are run at 7.2v, they pull approximately 1.5amps. Therefore, the deans discharger should rather be labled as a 15 amp discharger.

[highroller]

With cells that are new, or haven't been used the packs may take 1-3 cycles before showing normal peak voltage and MAH rates. What effects these rates is how the pack is discharge and settings on charger. If pack is discharge to a .90 volts per cell level not all the cells may discharge to the same levels and this may have an effect when the pack is charged again, it may cause false peaks, peak voltage and MAH rates may not be at normal levels. Most equalizing trays will discharge each cell individually, allowing the cells to charge better. All NIMH can be taken down to a zero voltage level but only the GP cells respond better leaving them at a zero voltage level longer (can be left in tray until it has cooled enough to be charged) the other brands Sanyo, IB, IP3800 should only be left in tray for 5min or until the bulb goes out which is about .15 - .05 voltage per cell depending resistor rates. For equalizing trays I use the Integy Zero30, which will discharge each cell but a power supply is needed when pack is half to fully charged to operate fan to keep things cool. The Trinity Real Time2(2.5), Integy Octane 1-2, 20, will also work well but the Real Time2 has been discontinued. These trays had individual contacts, so if one cell discharged before the other others you could loosen the corresponding contact for each cell as bulb went out - even with closly matched cells you may get a pack where one or two cells don't stay matched with the rest.

Personally I store packs with only a .90 voltage level, with some packs stored as long as 8 months. The only adverse effects I encountered when using packs again where runtime decreases a little more, pack doesn't reach normal peak levels, pack doesn't have the snap it did. However after 1-3 uses or once the pack gets active use it was pack up to normal levels.

For charging I used the Tekin 112A On P2 mode, detect setting is .3 (30mv) for 4cell and .05 - .06 (50-60 mv) for 6cells. Charge rates are normally 5-6amps but for oval stock & 10turn oval racing it's 6.50 to 7amps. Tempature of cells should be around 140 to 145 degrees. On days when ambiant temperatures are very high either decrease the charge rate a small degree or decrease the MV detect setting. The only cell I had to use a fan with were the Panasonics, cells were so delicate the only way of getting to accept more voltage was to cool them - the other brands of NiMH like more heat in them.

Remember this warm battery, cool motor gets better results.

[guver]

im no were near my capacity though my cell take between 3100 and 3400 before temp cut of of 120'f to get 3400 i had to sit them over a fan the whole time

There are only 2 things that will raise temps. Charge rate and overcharge. Pay attention to the temps throughout the charge process and you will even be able to make a rough graph of temp vs. mah (or time) If the temps just steadily increase until the end and finally hit the limit then it is rate doing it.
If it is staying around 100-105 during the charge, yet coming right up quickly at the end then the battery is full and climbing quickly at the end like it should.

One other tip is to put a delay in between the discharge and charge, I didn't see if that was being done or mentioned. Try to get them cool before chargeing if possible. It all rather sounds normal to me (like your batts are full)
The ice comes with a nice graph, if at the end it shows a nice voltage drop then the batt is full.