BigRagu
10-23-2005, 10:29 AM
Well . . .lesson learned about NiMh storage.
I'm back from almost a year off muckin' around with Gas Boats . . .I know, don't go there!
Anyhow, I haven't flown my ION since last April so I dust it all off Cycle the 2400mah EXPERT battery for the radio 3 times! all checks good with the battery checker and kick the LiPo's back to 100%. Do the Nuts & Bolts check, Lube it up off we go, my friend does a quick turn around the field and hands it to me, I do the same and still had some welcome back jitters so I set it down and said let's fly the pack out and we'll take a break and put the second one in.
He makes a nice long slow pass down the runway at 10-12 feet off the deck and at about 200 feet away from us it does a Slow Roll to the right, skids about 10 feet on the head button . . .crap.
Not bad, a set of Blades, Flybar, Paddles and a few scuffs.
But upon Crash Investigation heres what we found:
The 2400mah NiMh pack was at 3.2V . . .took a dump. So I went looking for an explaination and found the following from "Battery University".
"Manufacturers recommend to trickle charge a nickel-based battery for 24 hours when new and after long storage. This service brings all cells to equal charge level and redistributes the electrolyte to remedy dry spots on the separator brought on by gravitation of the electrolyte. It is advisable to verify the capacity with a battery analyzer before use. This is especially important in critical applications.
Cycling (priming) is recommended to regain lost capacity after a nickel-based battery has been stored for 6 months or longer. A slow charge followed by one or several discharge/charge cycles will do this. The recovery rate is governed by the condition under which the battery was stored. The longer and warmer the storage temperature, the more cycles will be required. The Prime program of the Cadex battery analyzers automatically applies the number of cycles needed to regain full capacity.
Nickel-based batteries are not always fully formed when leaving the factory. Applying several charge/ discharge cycles through normal use or with a battery analyzer completes the forming. The number of cycles needed to attain full capacity differs between cell manufacturers. Quality cells perform to specification after 5-7 cycles. Those lacking formation may need 50 or more cycles to reach acceptable capacity levels.
What is the difference between priming and forming? For the user, both symptoms manifest themselves as insufficient capacity. The difference may be explained in that forming needs to be done only once when the battery is new, while priming must be repeated after each prolonged storage."
DON'T LET THIS HAPPEN TO YOU . . . :oops:
BigRagu
:( :( :(
I'm back from almost a year off muckin' around with Gas Boats . . .I know, don't go there!
Anyhow, I haven't flown my ION since last April so I dust it all off Cycle the 2400mah EXPERT battery for the radio 3 times! all checks good with the battery checker and kick the LiPo's back to 100%. Do the Nuts & Bolts check, Lube it up off we go, my friend does a quick turn around the field and hands it to me, I do the same and still had some welcome back jitters so I set it down and said let's fly the pack out and we'll take a break and put the second one in.
He makes a nice long slow pass down the runway at 10-12 feet off the deck and at about 200 feet away from us it does a Slow Roll to the right, skids about 10 feet on the head button . . .crap.
Not bad, a set of Blades, Flybar, Paddles and a few scuffs.
But upon Crash Investigation heres what we found:
The 2400mah NiMh pack was at 3.2V . . .took a dump. So I went looking for an explaination and found the following from "Battery University".
"Manufacturers recommend to trickle charge a nickel-based battery for 24 hours when new and after long storage. This service brings all cells to equal charge level and redistributes the electrolyte to remedy dry spots on the separator brought on by gravitation of the electrolyte. It is advisable to verify the capacity with a battery analyzer before use. This is especially important in critical applications.
Cycling (priming) is recommended to regain lost capacity after a nickel-based battery has been stored for 6 months or longer. A slow charge followed by one or several discharge/charge cycles will do this. The recovery rate is governed by the condition under which the battery was stored. The longer and warmer the storage temperature, the more cycles will be required. The Prime program of the Cadex battery analyzers automatically applies the number of cycles needed to regain full capacity.
Nickel-based batteries are not always fully formed when leaving the factory. Applying several charge/ discharge cycles through normal use or with a battery analyzer completes the forming. The number of cycles needed to attain full capacity differs between cell manufacturers. Quality cells perform to specification after 5-7 cycles. Those lacking formation may need 50 or more cycles to reach acceptable capacity levels.
What is the difference between priming and forming? For the user, both symptoms manifest themselves as insufficient capacity. The difference may be explained in that forming needs to be done only once when the battery is new, while priming must be repeated after each prolonged storage."
DON'T LET THIS HAPPEN TO YOU . . . :oops:
BigRagu
:( :( :(