nuckolls.bob(at)aeroelect
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 Posted: Wed Nov 04, 2020 5:37 pm Post subject: Ni-Cd Battery Safety Information Bulletin |
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At 10:38 AM 11/4/2020, you wrote:
| Quote: | On 11/4/2020 10:11 AM, Sebastien wrote:
| Quote: | Interesting, I have never heard of this.
Aircraft Maintenance Manual Aircraft Parking Procedures usually require the physical disconnection of the aircraft batteries, and the periodic reconnection to carry out the parking or storage checks. A Type Certificate (TC) holder in conjunction with a battery manufacturer has identified that when a Nickel-Cadmium (Ni-Cd) battery is disconnected from the aircraft loads, it self-discharges due to an electrochemical phenomenon, thus inducing a reduction of battery capacity. When the battery is charged again from the aircraft, the battery does not recover 100% of its initial capacity. Therefore, after each cycle of battery self-discharge, the available battery capacity will decrease progressively. |
Interesting, but isn't it more of academic than practical interest, for most of us? I doubt that you could find a NiCd starting battery in a homebuilt these days. |
Agreed. In fact, I thought the Ni-Cads were outlawed
in Europe for new/replacement back about 2010. I'm assuming
also that this document is talking about wet cranking
batteries . . . a very unlikely candidate for an
amateur built application.
Even so, the admonition seems a bit of overkill.
The operator of an aircraft stored for prolonged
periods without active battery maintenance is
well advised if not obligated to cap check the
battery (amongst other things) before putting
the a/c back in service.
According to this article:
https://tinyurl.com/ycukwcmb
"Nickel-cadmium stores well. The US Air Force was able to deploy NiCd batteries
that had been in storage for 5 years with good recovered capacities after
priming. It is believed that priming becomes necessary if the voltage drops below 1V/cell."
"Priming" is a specialized charging protocol for
NiCads that often brings a long-stored NiCad
back to serviceable condition. This would be
the consistent with the bulletin's reference to
a competent battery maintenance shop.
In any case, a veteran user of Ni-Cads already
understands this. This bulletin seems kinda
redundant . . . sorta like reminding you to
tie your shoes.
Bob . . .
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