battery charging/cycling question

[rckjeep]

Ok so I've been having issues with my battery's not holding a peak. I charge them up with an Integy 16x3 V6 charger at the max 6 amps and then peak them again. Now I get a about 5-10 mintues of good battery then it's down hill. So I was told to cycle the batteries by Badger. I started to cycle one but had to leave so I stopped it. Then just charged it and it seemed to be better. So I went to cycle another one today and it's been cycling for like 10 hours on .5 amps. When does it finish cycling? I mean thats ridiculous.

I'm a charge it and drive it kinda guy, I don't know much about battery tech.

[NickRummy]

Neither do I. I'm interested in seeing some replies in this thread.

I picked up an SMC 3600 and a duratrax piranha digital charger. The charger shows what capacity the battery is at while charging. The charger stopped charing at 2850mah. Sup with that? I charged at 3a and it took about an hour.

[6x6bigdollars]

Hi I do Weight Pulling,what we do with our Battery is Charge them,Cool them,DisCharge Them,let them cool or Keep a Fan on them at all times,so they Don't get Hot,do that about 8 to 10 time on a Battery,now for the Person that has been Charging his Battery,it not Peeking,I would say you could have a COLD solder Joynt,if you Drop your battery Packs on the Floor Check the Battery's to make sure the connection is not Loose,if the Battery pack is Tight then I would say you have some Cells going BAD,then take the Pack a part,Clean the solder of the Ends,Check with a Volt Meter,it should read 1.07 threw 1.27 and Higher, if it reads 1.00 or 1.02 that Cell is on it's way out the DOOR.Jim

[Frakk]

rckjeep what mah battery are you using? charging them with 6 amps is a little high imo. I charge mines with 3A and even that makes some heat. try charging them, then with 0.3-0.2 trickle charge for a while, and cycle them like this a couple times.

[badger]

Like I told you on the phone Dave you need to slow charge your packs and cycle them to hopefully fix them. This info is in the Sticky right above your thread.

C = Capacity or charge current
1C = Charge the pack at 1x it's capacity (3000mAh at 3.0 amps, 2400mAh at 2.4amps)
C/10 = Charge at 1/10th the capacity (3000mAh at 300mAh, 2400 mAh at 240mAhs)
Slow Charge = C/10
Peak charge = Charge at 1C and Slow or Trick after pack peaks.
Fast Charge = Charging above 1C


Out of balance battery

Pack is out of balance is when some of the cells in the pack still had some charge left in them while others have no charge remaining. So when you charged the pack three of the cells peaked before the others did. That would leave the other cells a little under charged. So when you ran the pack out the undercharged cells dumped before the fully charged ones causing the under charged cells to feel warm. Cells begin to really heat up when they reach their "dumped" point.


Fixing an Out of Balance pack - The C/10 charge theory

Just do a C/10 (c = capacity i.e. 2400mAh pack is charge 1c at 1.2A) charge for 14-16 hours, the magic of "slow charge" is that it equalizes the cells. As the cells fill up some will get full before others, but at the C/10 rate there is no danger of over charging because the cells that are full can safely dissipate the "over charge" as heat, without damage, giving the other cells time to fill up. This is also why it's a good idea to occasionally C/10 charge all your packs, in normal use over a number of cycles they will start to become unbalanced and the C/10 charge will rebalance them. Setting a C/10 trickle rate after a pack peaks will also do this, the pack will peak when the first cell or two does, but the others may not be quite full yet, if left at the C/10 trickle for some time after peak the cells will rebalance. Some people say that they see a reduction in power if the trickle charge after the pack has peaked, stating they perform best hot off the charger. This is not as noticed with NiCds but it does seem to be true for NiMHs, but Suspicions are it is temperature related as NiMHs always seem to perform better when warm and the time spent trickle charging will let them cool.

[rckjeep]

I did do what you said but haven't had time to so to it to all of them. I cycled the one pack for quite sometime yesterday and drove it today with more of the same issues. I tried the slow charge at 2.5 amps and they peak around 2300mah even though they are 3000 packs. Should I just keep charging them till they reach 3000? Or just go buy some new packs?

[Frakk]

it peaks when one cell peaks. it is probably a damaged or unbalanced cell. as badger posted, you should keep charging the pack with a trickle charge (to about 3100mah) after it peaks so the cells that you overcharge dont get damaged because of the heat. cycle them a couple times, if it doesnt help, we need to troubleshoot the bad cell(s).

[SPEED_RACER]

on some my older packs(ni cads) when this starts to happen i peak them with a slightly higher amp and they will peak normally.not sure if wll apply to NiMHs .mine haven't givin me any problems

[Reflection]

Originally Posted by 6x6bigdollars

Hi I do Weight Pulling,what we do with our Battery is Charge them,Cool them,DisCharge Them,let them cool or Keep a Fan on them at all times,so they Don't get Hot,do that about 8 to 10 time on a Battery,now for the Person that has been Charging his Battery,it not Peeking,I would say you could have a COLD solder Joynt,if you Drop your battery Packs on the Floor Check the Battery's to make sure the connection is not Loose,if the Battery pack is Tight then I would say you have some Cells going BAD,then take the Pack a part,Clean the solder of the Ends,Check with a Volt Meter,it should read 1.07 threw 1.27 and Higher, if it reads 1.00 or 1.02 that Cell is on it's way out the DOOR.Jim

Thanks for the migrain headache. I can tell what subject you failed in all through highschool......even gradeschool for that matter.

[JasonInAugusta]

I recommend charging these cells at 5-6 amps with a .04 peak detect (6CELLS) on a (CEI turbo thirty/thirty five). A lower amp rate will give more run time and a higher charge rate will give more voltage. When using any charger follow the manufacturers recommended settings for charging. If no instructions are available start with the lowest possible peak detection setting (if available) and charge the pack. Check the temperature of the pack immediately after the charger shuts off. If the temperature falls within our recommended settings then leave the peak detection setting there. If it is too low the increase the setting and try again. Continue to use this method until satisfactory results are obtained. Use a charger that was specifically designed to charge NI-MH cells. To verify that the pack is fully charged you should check the temperature. We recommend a temperature reading of 125 degrees F when the charger first shuts off. This assumes that you will be charging packs that are at an ambient temperature of between 70-85 degrees. The temperature will continue to rise after the charger has shut off so the temperature reading should be taken immediately after the charger first shuts off. NIMH cells do not peak like ni-cads do. When a ni-cad battery reaches a full charge the voltage in the pack starts to drop quite rapidly. With ni-mh cells the voltage does not drop as rapidly when the pack reaches full charge. On the other hand the temperature does rise quite rapidly as the pack reaches full charge. The cells can get extremely hot when using some peak detection chargers as the peak detection circuit is not sensitive enough. If the cells get too hot damage to them will occur.

The longer you plan to not use the packs the more charge you should leave in them. For long term storage (more than 30 days), I would completely charge the packs before storing them. Also expect some false peaking problems of these cells after long periods of inactivity. This problem should correct itself after one or two uses.

Also after several discharge/charge cycles your packs will begin to get "out of sync". This means some cells have more of a charge left in them than others within the same pack. Once the cells are out of sync and you charge them, the cells that started out with more charge in them will peak (reach full charge) before the other cells finish charging. The charger may overcharge these cells and possibly cause damage to them while not fully charging the other cells in the pack. You charger cannot see what is happening to each individual cell since it is hooked up to the battery pack in series. It only takes an average of what's happening with the whole pack. For this reason it is imperative that you discharge and equalize your packs on a regular basis.


From: http://www.promatchracing.com/faq.htm