HELP charging NiMH's

[henry_huckem]

Hi
Cant seem to get more than 540 Mah out of my Epic 3000 packs.
I used the following settings on my superbrain 969 charger. 1.5 amp charge rate per the book for the charger for NiMH batts, 30Mv peak setting, and the 3000Mah max charge setting... but as I said I got 400 once and 540 the next time. anyone got any ideas why??

oh, and these are on 2 different packs, both barnd new.

[krentler]

Hi
Cant seem to get more than 540 Mah out of my Epic 3000 packs.
I used the following settings on my superbrain 969 charger. 1.5 amp charge rate per the book for the charger for NiMH batts, 30Mv peak setting, and the 3000Mah max charge setting... but as I said I got 400 once and 540 the next time. anyone got any ideas why??

oh, and these are on 2 different packs, both barnd new.

I would set your delta peak much lower than that. 30MV is very high at that current. I had a similar problem with a different peak charger. Some of it was that my cells just sucked. I bought some nicer matched cells for $41 and they charged up great.

Bob

[henry_huckem]

I would set your delta peak much lower than that. 30MV is very high at that current. I had a similar problem with a different peak charger. Some of it was that my cells just sucked. I bought some nicer matched cells for $41 and they charged up great.

Bob


I'm confused. If I set my delta peak lower, wont the packs peak sooner? and will that solve my problem or will that make it worse?? God I hate these technical battery chargers........ thanks again

[SS Pede]

Unfortunately the 969 has similar (or the same) programming as the 959, and both chargers can false-peak. I have both, and both have malfunctioned. Lower charge rates could help, but you seem to already be using a low charge rate. Another thing to try is to discharge the pack pretty low before charging. That could help it charge better. And another thing: the power supply that comes with the 969 is pretty weak. A better power supply could help.

A lower delta peak could make it peak earlier (or false peak more easily)...I don't know what that has to do with charge rates though. I've charged a pack at 2 amps, I think it was a 30 mV cutoff and nothing happened to indicate that the threshold was too high. In any case, it's best not to go higher than 30 mV.

[-=ADA$=-]

as i said in other thread its pack that fals peak not charger Im using 959 and on some packs i can only charge on 0.5-1A and on others i can go all to 4,5A (max) and it will charge properly. So i would say it will be the pack. Try charging them @ 0.5A once and see if it helps

[henry_huckem]

OK thanks, we'll see.

[rcguy2477]

Its most likely your charger, they are prone to false peaking. If your batteries are getting hot, than its not your charger. Try charging at a higher amp rating, and see what happens.

[highroller]

First be sure the pack is discharged and cooled properly before charging.
Discharge the pack with a string of bulbs (10) giving it time to cool then before charging take voltage down a little more by attaching one single bulb to pack (to get all cells as close to the same voltage and as low as possible).
Start discharging packs after using down to 5.40 volts and storing that way, then before using charging them the next time discharge at a lower amperage to remove any built up voltage this should help cut down on the false peaking problem. A general setting to use depends on the type of NiMh they are for Panasonics use charge rates of 3.5 to 5amps with .03mv detect with Sanyo and GP NiMh use 3.5 to 6amps charge rate with .05mv detect setting, .03mv will work fine if pack seems to be above 145 degrees.
Packs should be reaching 8.38 to 8.58 volts a peak. If cells are in good to decent condition they should peak at 3285 mah rates maybe low 3300.

[henry_huckem]

First be sure the pack is discharged and cooled properly before charging.
Discharge the pack with a string of bulbs (10) giving it time to cool then before charging take voltage down a little more by attaching one single bulb to pack (to get all cells as close to the same voltage and as low as possible).
Start discharging packs after using down to 5.40 volts and storing that way, then before using charging them the next time discharge at a lower amperage to remove any built up voltage this should help cut down on the false peaking problem. A general setting to use depends on the type of NiMh they are for Panasonics use charge rates of 3.5 to 5amps with .03mv detect with Sanyo and GP NiMh use 3.5 to 6amps charge rate with .05mv detect setting, .03mv will work fine if pack seems to be above 145 degrees.
Packs should be reaching 8.38 to 8.58 volts a peak. If cells are in good to decent condition they should peak at 3285 mah rates maybe low 3300.

Nice. thats what I was looking for. Now when you say .03mv, is that like the setting that says 30 on my charger?? I dont know if it goes to .03mv... god I'm such a battery noob. lol. thanks again..

[highroller]

With different charges the millia amp is displayed differently some will display a .03mv as .30 or .028 mil amp. Try the 30mv setting prepping the packs like I suggested by ensuring they are discharged if packs aren't too warm try the 50mv setting if packs false peak at the 30mv setting or just restart the charge function but monitor pack closely to ensure it doesn't overcharge.

[SS Pede]

I've never really had a pack overcharge when I've restarted the charge. Never above 30mv for me. Highroller - is 50mV safe for NiMH, like my GP3300's? Technically it's not...have you ever used a threshold that high and gotten away with it? My 969 false peaks sometimes with 30mv setting, so I could try using higher but I wouldn't want to hurt anything. The voltage increase on my packs seems to "flatten out" at around 8.21 volts. The charger gives the "02" error message, which is a "slow peak." Seems like it has trouble getting past 8.2 volts. Once it is up over that point, it apparently does fine. Do you know if a higher peak threshold would fix this problem?

[highroller]

For 6cell Sanyo and GP the .05mv (50 depending on charger) works good with a 5-6 amp charge rate but if battery seems too warm then try .03mv setting.
Panasonic cells were the only ones that did not seem to respond well being charged above 5amp or more than .03mv.

Some chargers may continue to charge once pack has reached peak charge either when cells are new or in the case you restart the charge function after a false peak so to be safe it's a good idea just to pay close attention.

[jocktheglide165]

set your charger setting ats .9v/cell, charge 5amp, discharge 20amp then see what you get? heck sometimes you might have a bad battery period.

[highroller]

The packs should last up to over 2 years if you take the time to use a setting based on how they are used. The only cells that had a short life or showed any decline were the Panasonic batteries.
For bashing or club racing (depends on whether cells are unmatched stick packs or assembled from matched cells) anytime you want decent performance and long life charge at 3.50 to 6.00amp use a .03 (30mv) detect setting .05 for racing. Discharge the pack at as close to the loads it sees during use which is 18 to 30 amp or 8-15 lightbulbs. Discharge down to a .90 volts per cell level (5.40 volts for 6 cell, 3.60 for 4cell) and store. If you plan to use the pack again or when you charge it the next time use a single bulb (2amp) to get cells as low in voltage as possible. The major cause for packs false peaking is cells being at different voltage levels when charged - the other is from cells that start to detoriate but with NiMhs the unequal cell voltage is the major cause.

For competitive racing where performance is more of an issue vs cell life different charge, voltage detect setting and discharge rates are used to get as much power out of pack as possible.
Stock and 19turn offroad/touring car you see 5-6amp charge rates used, with .03 to .07 voltage detect and 20 amp discharge
Modified offroad/tc - 5-6 amp charge rates with discharge rates 20-30amp
Stock and 19turn oval (4cell done at most tracks) charge rates are 6 amp generally with some using 8-10amp, voltage detect setting .03 to .05 for 4cell and .05 to .07 for 6cell discharge rate is 30 with the move to using 35amp and dead shorting the packs.
Modified oval - charge rate 5 to 6amp (passed on runtime), with .03 to .05 voltage detect, discharge rates are generally in the 30-35 amp with some using 40 to get pack to develop more punch.

The problem I've seen with setting the peak detect setting above .07mv or using charge rates above 7amps (NiMH) is like with NIcads the pack develops punch for a short time generally for the first minute of use then goes into extreme cruise mode or seems to drop off quickly in speed.

[henry_huckem]

Well I dont know exactly what the cells are in my pack, its an Epic Sport pack, 3000Mah, are those the panasonic or can I go ahead and try a charge with the peak detect set at 50? the highest I have tried so far is 30mv, and the most I've gotten yet is 1190mah. thanks again.

[highroller]

You could set the detect higher to see if that stops the early false peaking and to see if packs gets too hot. You may have to let pack sit for a day (give it time to cool and stablize) or you may not see any stable numbers until after the 3rd-4th cycle depending on how long the pack sat before you bought it. Follow the routine I suggested discharge it at a lower amp rate just before you charge it. It no telling what the pack is made of unless it's on the label or was identified when you purchased the pack.

[impe2s]

I'm using the same charger and battery packs and I'm having the same results. Did some web browsing and found this site (http://members.aol.com/davthacker/nimhfaq.htm) which says that "If you take a new pack and put it on a Delta Peak or Peak detect charger or any other kind of NiMH rated fast charger it will not be filled up." I'm not to sure how true this is though. But if anyone else has any idea how to resolve the issue, please comment. mahalo, Chris