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Batteries

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Old 05-22-2011, 06:33 AM
  #1
Idasam
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Default Batteries

A question about batteries; I have quite a few Hobbico HydriMax 5C 6V 2000mAh NiMH AA battery packs. The problem is that I've been very busy over the last 9 months, not to mention that it's been fall and winter as well. My planes and radios have been sitting without any attention at all for all that time and I guess my question is; are my batteries going to be okay when I go to charge them and head back out to the field?
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Old 05-22-2011, 06:38 AM
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Default RE: Batteries

I would cycle them a couple times to see...

but they should be OK.. but no way to tell without cycling them.....
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Old 05-22-2011, 06:50 AM
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Default RE: Batteries

Exeter_acres is right on the money. More than likely they will be just fine. Cycle them to ensure they are, then put em in a plane and go fly!!!!

Ken
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Old 05-22-2011, 10:11 AM
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Default RE: Batteries

+3 on cycling them. Everyone in RC should have a decent charging system and they don't have to be expensive. I have 3 of these and they work very well.

http://www.hobbypartz.com/60p-dyc-1004.html

Youll need a power supply.

http://www.amazon.com/Pyramid-PS3KX-.../ref=pd_cp_e_3
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Old 05-22-2011, 10:12 AM
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Default RE: Batteries

BTW, with that charger you can charge just about any battery made. Including glo igniters and the lead acid battery running your starter.
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Old 05-22-2011, 10:25 AM
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Default RE: Batteries

Does cycling ensure that the pack is "good"? Why I ask - I had a pack similar to Idasam's. I cycled it several times. I did a volt meter test using a meter that could apply a load. When I tested it without a load it tested "good". When I tested it with a load the voltage dropped off the scale - below 4.0 v.



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Old 05-22-2011, 10:37 AM
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Quote:
ORIGINAL: SeamusG

Does cycling ensure that the pack is "good"? Why I ask - I had a pack similar to Idasam's. I cycled it several times. I did a volt meter test using a meter that could apply a load. When I tested it without a load it tested "good". When I tested it with a load the voltage dropped off the scale - below 4.0 v.



Cycling will tell you the capacity of the battery pack. When a pack is new it should be cycled to determine it's initial capacity, and that should be recorded. Then throughout the life of the battery it can be cycled to see how it's capacity is faring. When a pack drops to about 80% of it's initial capacityIwill usually take it out of service and put a new pack in. Cycling the battery after a long period can tell you what the capacity of the pack is.

Most chargers that can cycle will allow you to set the discharge rate for the discharge cycle. This will allow you to set a discharge rate that is realistic to your real world flying. Doing this will spot dead cells and other problems as the pack will quickly discharge.

Ken
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Old 05-22-2011, 10:45 AM
  #8
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Default RE: Batteries

A guy at work is just getting into planes and bought a used trainer off of CL. He mentioned that he charged the RX and the TX using the walwart and was ready to go. I convinced him to give me the RX pack to check and cycle with my RC car charger. Turns out he had a bad cell. My guess is the plane would of taken off and then gravity would take over. At one amp discharge, the pack dumped in 56 seconds on the charger. On the plane, It might of lasted 2-3 minutes IF it had enough power to make the first bank.
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Old 05-22-2011, 01:18 PM
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Default RE: Batteries

How I bit the bullet. My favorite planes battery was needing a charge after flying a 10 minute flight. I brought it home and stuck it on the charger. It charged great and was showing good voltage. I cycled and it pulled a bit over 300MAH and started charging again. I cycled it three times and just over 300 was all it would pull. When I pulled the battery to replace it I looked at the date I had printed on it. 2004, I guess I got my moneys worth and was lucky I checked voltage after each flight. I cycle every few months and this battery tested good a few months ago.
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Old 05-22-2011, 02:10 PM
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Default RE: Batteries

Always always check a battery under load...as SeamusG found out.....
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Old 05-22-2011, 03:13 PM
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Default RE: Batteries

I have a plane, actually two planes, with two 1200 mah NiMh 6 volt packs each, that have been basically ignored for about a year. After the original post, I checked them out. All four batteries (two per plane) are just fine. They were a tad low in voltage, but they are looking good on the recharge (fast charge).

This is not an endorcement for outright using batteries that have sat around for a while. The point is that not all of them will go bad if not used. The best bet, before flying with them, is to give them a good check out, a charge, and possibly a cycle charge, and, if they look good, well, fly with them.

I have a pair of LiFe packs that I bought last year. They have sat around also. But, they both are just fine and, after a short charge on my Triton 2 EQ, are right up there and ready to fly with.

Check them, and don't be afraid to replace them if needed, yet don't be afraid to use them if they do check ok.

Heck, I have a couple of real old NiCd packs that sat around for a while and some took a charge just fine.. others, well, they found their way to the recycle bin.

One point, though.. if you are reluctant about batteries you don't trust, do not hesitate to replace them. Peace of mind is a good thing when it comes to our aircraft electrical power sources.

CGr.
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Old 05-23-2011, 06:51 AM
  #12
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Default RE: Batteries

Another battery question. In my Futaba 9c, which unlike most Futabas can be discharged without removing the battery. I recently started using it again after a period of storage. If I put it on my Accucycle and discharge it with the battery in the radio it only shows 78 Mah. When I remove the battery and cycle it separatly it shows 650 Mah, its rated capacity is 700 Mah, so I figuring it's still OK, but why the big difference?
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Old 05-23-2011, 01:08 PM
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Default RE: Batteries

So what discharge rate would you use for a 2200 mah nimh pack on a 60 size model? .2 mah? And then what charge rate?
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Old 05-23-2011, 02:05 PM
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Default RE: Batteries

.2 miliamps = .0002 amps or 200 microamps. I think you meant .22 amps or 220 miliamps, which, for that battery, 2200 mah, is C/10.

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Old 05-23-2011, 06:10 PM
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Default RE: Batteries

Yeah that's what I meant was .2 amps for discharge or should I use a higher or lower discharge rate? What rates would you use on. The described battery of 2200 mah 6v.
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Old 05-24-2011, 03:01 AM
  #16
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Default RE: Batteries

1 amp should be fine.
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Old 05-24-2011, 03:46 AM
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Default RE: Batteries

Well, the recommended charge rate for these batteries is no greater than .1C or C/10. But, that's a ball-park figure. We all charge them at the field at much higher rates, such as 1C, with field chargers, and that doesn't seem to do any short term harm. If you do this with LiPo packs, do it outside. Meanwhile, any reasonable rate of charge, as GaryHarris suggested 1 amp.. would probably work ok, but the recommended rate is no higher than C/10 or .1C.

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Old 05-24-2011, 04:27 AM
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Default RE: Batteries

Ok thanks guys I think I will go with the .2 amp discharge and charge rate for cycling. Also what voltage cutoff would you use ? 1 volt or .8V pee cell
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Old 05-24-2011, 06:55 AM
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Default RE: Batteries

I'd use 300 mA discharge rate if you use analog servos, and 500 mA rate if you use digital servos. Even then, it will take 7 to 4 hours respectively to discharge a 2200 mAh pack.
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Old 05-24-2011, 09:00 AM
  #20
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Quote:
ORIGINAL: RCKen

Cycling will tell you the capacity of the battery pack. When a pack is new it should be cycled to determine it's initial capacity, and that should be recorded. Then throughout the life of the battery it can be cycled to see how it's capacity is faring. When a pack drops to about 80% of it's initial capacity I will usually take it out of service and put a new pack in. Cycling the battery after a long period can tell you what the capacity of the pack is.

Most chargers that can cycle will allow you to set the discharge rate for the discharge cycle. This will allow you to set a discharge rate that is realistic to your real world flying. Doing this will spot dead cells and other problems as the pack will quickly discharge.

Ken
What most newbies may miss in the above, is that you need to have some way of MEASURING the amount of current over time, the batteries provide after or during the cycling process.

Most newbies have typical "wall wart" chargers that do not produce any type of reporting.

RCKen is talking about rather "intelligent" chargers that report the amount of current put back into a pack during a charge cycle, and are often also capable of determining how much current over time is withdrawn as the pack is run back down.

So given his recommendation, if you have a 1000mAh pack, then cycle it using an intelligent charger, and the charger reports that it can only draw the battery down by 800mA, it is time to replace that pack.

I've seen newbies with packs that have a bad or weak cell, who have cycled their packs with a wall wart charger, checked them with a load meter, only to find their plane looses control after a few minutes in the air.

Servos can put a substantial load ( 2A PER SERVO is not uncommon, at stall !!! ) on the packs.... Problems may not be apparent without a decent test...

So a decent computer controlled, charger/discharger/balancer is an IMPORTANT investment.

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Old 06-08-2011, 02:50 PM
  #21
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Getting back into cars and this is what I'm doing now. [link]http://garyharris.smugmug.com/Other/Stuff/i-Tz57jJ6/0/XL/0021024-XL.jpg[/link]
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Old 06-08-2011, 03:15 PM
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Uh Gary - this affliction of yours can be cured but only with professional help. [&:]
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Old 06-08-2011, 04:11 PM
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Quote:
ORIGINAL: SeamusG

Uh Gary - this affliction of yours can be cured but only with professional help. [&:]

I had professional help once. I divorced her!
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