RCCrawler Forums

12flex · 02-23-2008, 02:00 AM

i got this piranha charger. and im getting ready to charge my elite 1500 7cell pack.

i wanna do it right

i know i charge them @ max 1.5a

but what is the mV/C rate that i want to charge these batterys @
this charger ranges from 3mV/C to 20mV/C

thanks,

12flex · 02-23-2008, 02:47 AM

does 7 mV/C sound right?

anyone anyone?

2Slo2Curious · 02-23-2008, 03:00 AM

For NiMH battery use 5mV per cell. And for NiCd use between 7 - 10mV. I use SuperBrain 977 charger

ClodMaxx · 02-23-2008, 08:39 AM

for any battery, regardless of chemistry, it's best to set the peak detection threshold as low as possible. in this case, 3mv.

the peak detection threshold setting is you telling your charger how sensitive you want it to be in 'seeing' whether your battery is charged or not. a small setting will make it 'see' the full charge sooner and stop the charge. a large setting per cell may make it 'ignore' a full charge longer until it stops it, resulting in possible overheating. too much heat for batteries = damage.

Scattman · 02-23-2008, 11:09 AM

Quote:

Originally Posted by 12flex

i got this piranha charger. and im getting ready to charge my elite 1500 7cell pack.

i wanna do it right

i know i charge them @ max 1.5a

but what is the mV/C rate that i want to charge these batterys @
this charger ranges from 3mV/C to 20mV/C

thanks,

I have the same charger. I would start at 4 or 5. If the pack is not sufficiently warm at the end of the charge, bump it up a notch. Not all packs are the same so someone just telling you what it needs to be is wrong. You will need to a tad bit of testing.

I don't need to go over 7 on any of my 2/3 a packs.

ClodMaxx · 02-23-2008, 11:19 AM

Quote:

Originally Posted by Scattman

I have the same charger. I would start at 4 or 5. If the pack is not sufficiently warm at the end of the charge, bump it up a notch. Not all packs are the same so someone just telling you what it needs to be is wrong. You will need to a tad bit of testing.

I don't need to go over 7 on any of my 2/3 a packs.

this is true - not all packs are the same...so it's better to be safe than sorry, no? what does sufficiently warm mean... warm by the touch? a hand is a very imprecise indicator of heat. how about an exact temp from a temp probe? if a pack comes off the charger at 90 degrees, does that mean it's not fully charged?

telling someone to bump up a peak detection setting if a pack isn't warm enough at the end of a charge seems very strange to me. where did you acquire this information? i guess it makes no difference... except when people start losing battery packs.

Scattman · 02-23-2008, 12:41 PM

Quote:

Originally Posted by ClodMaxx

this is true - not all packs are the same...so it's better to be safe than sorry, no? what does sufficiently warm mean... warm by the touch? a hand is a very imprecise indicator of heat. how about an exact temp from a temp probe? if a pack comes off the charger at 90 degrees, does that mean it's not fully charged?

telling someone to bump up a peak detection setting if a pack isn't warm enough at the end of a charge seems very strange to me. where did you acquire this information? i guess it makes no difference... except when people start losing battery packs.

Yes, at 90 degrees that pack is not fully charged.

Don't quote me on it but I believe JRH once said 130-140 was proper temp at end of charge for nimh.

I will check with him and get back to ya'.

This just in, 140-145 is the temp to shoot for in nimh. Straight from JRH himself.

HndsWthtShdws · 02-23-2008, 12:48 PM

You should set it as low as possible without false peaking the charger. The optimum setting will take a few cycles to find out. One you find it write it on the battery or tape a list to the charger.

ClodMaxx · 02-23-2008, 02:14 PM

i guess basing your mv/c setting on the final temp is an approach i've not heard before.

i was told by the head engineer at a very well known battery matching/building company the information that i posted. he emphatically urged me to set the mv/c as low as possible for long battery life and performance. that's the approach i took, and had battery packs that lasted ~100 cycles in a couple years.

batteries can be one of the facets in this hobby that are the most intolerant of abuse, yet there is a lot of misinformation about battery care. some information i've read will downright kill any battery in no time. i'm just trying to share what i learned, and has worked for me. good to know that there are other methods too.

Scattman · 02-23-2008, 02:26 PM

I typically stop my charge when they around 130*. Gives me a little headroom.

You are correct though that you want to have the m/v cutoff as low as possible, just not so low that the pack doesn't get fully charged.

floogldood · 02-24-2008, 08:20 AM

The battery is full at the top of the peak so any amount of drop is overcharged. Setting it to 0-20 mv won't make 100 mah difference.

It is not nearly as big a deal as most users think. A battery that drops 50 mv is only slightly more overcharged than a battery that was stopped at 20 mv.

It is customary to use 5 mv for nimh and 10 for nicads. Smaller batts use 3 mv and 6-8 mv , and the 2/3 A nimh use 3-4 mv.

The manual is wrong on the digital piranha, but many times the value needs doubled. It has something to do with the open voltage check.

02-23-2008, 02:00 AM	#1
12flex Quarry Creeper Join Date: Apr 2006 Location: winchester Posts: 423	mV/C ? i got this piranha charger. and im getting ready to charge my elite 1500 7cell pack. i wanna do it right i know i charge them @ max 1.5a but what is the mV/C rate that i want to charge these batterys @ this charger ranges from 3mV/C to 20mV/C thanks,

02-23-2008, 02:47 AM	#2
12flex Quarry Creeper Join Date: Apr 2006 Location: winchester Posts: 423	does 7 mV/C sound right? anyone anyone?

02-23-2008, 03:00 AM	#3
2Slo2Curious Newbie Join Date: Apr 2007 Location: Malaysia Posts: 18	For NiMH battery use 5mV per cell. And for NiCd use between 7 - 10mV. I use SuperBrain 977 charger

02-23-2008, 08:39 AM	#4
ClodMaxx Pebble Pounder Join Date: Oct 2006 Location: rochester (detroit area) Posts: 116	for any battery, regardless of chemistry, it's best to set the peak detection threshold as low as possible. in this case, 3mv. the peak detection threshold setting is you telling your charger how sensitive you want it to be in 'seeing' whether your battery is charged or not. a small setting will make it 'see' the full charge sooner and stop the charge. a large setting per cell may make it 'ignore' a full charge longer until it stops it, resulting in possible overheating. too much heat for batteries = damage.

02-23-2008, 12:48 PM	#8
HndsWthtShdws Quarry Creeper Join Date: Jan 2007 Location: Ontario, Canada Posts: 341	You should set it as low as possible without false peaking the charger. The optimum setting will take a few cycles to find out. One you find it write it on the battery or tape a list to the charger.

02-23-2008, 02:14 PM	#9
ClodMaxx Pebble Pounder Join Date: Oct 2006 Location: rochester (detroit area) Posts: 116	i guess basing your mv/c setting on the final temp is an approach i've not heard before. i was told by the head engineer at a very well known battery matching/building company the information that i posted. he emphatically urged me to set the mv/c as low as possible for long battery life and performance. that's the approach i took, and had battery packs that lasted ~100 cycles in a couple years. batteries can be one of the facets in this hobby that are the most intolerant of abuse, yet there is a lot of misinformation about battery care. some information i've read will downright kill any battery in no time. i'm just trying to share what i learned, and has worked for me. good to know that there are other methods too.

02-23-2008, 02:26 PM	#10
Scattman Official Cook of the ECC Join Date: Dec 2005 Location: Hawthorne, Florida Posts: 2,653	I typically stop my charge when they around 130*. Gives me a little headroom. You are correct though that you want to have the m/v cutoff as low as possible, just not so low that the pack doesn't get fully charged.

02-24-2008, 08:20 AM	#11
floogldood Quarry Creeper Join Date: Nov 2005 Location: Planet Earth Posts: 350	The battery is full at the top of the peak so any amount of drop is overcharged. Setting it to 0-20 mv won't make 100 mah difference. It is not nearly as big a deal as most users think. A battery that drops 50 mv is only slightly more overcharged than a battery that was stopped at 20 mv. It is customary to use 5 mv for nimh and 10 for nicads. Smaller batts use 3 mv and 6-8 mv , and the 2/3 A nimh use 3-4 mv. The manual is wrong on the digital piranha, but many times the value needs doubled. It has something to do with the open voltage check.

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