[NSRCA-discussion] AAA NimH batterys

[Dean Pappas]

Oh yeah,
Almost forgot: the lack of NimH durability is related to the higher cell resistance. Low resistance cells last longer due to having less internal heating, especially under fast charge.
Dean

Dean Pappas
Sr. Design Engineer
Kodeos Communications
111 Corporate Blvd.
South Plainfield, N.J. 07080
(908) 222-7817 phone
(908) 222-2392 fax
d.pappas at kodeos.com


-----Original Message-----
From: nsrca-discussion-bounces at lists.nsrca.org
[mailto:nsrca-discussion-bounces at lists.nsrca.org]On Behalf Of Dean
Pappas
Sent: Thursday, January 26, 2006 10:55 AM
To: NSRCA Mailing List
Subject: Re: [NSRCA-discussion] AAA NimH batterys


Hello Bob!
You nailed it right on the head! The commbination of cell resistance and wiring/switch harness is what gets us. In general, NimH batteries have higher resistances than NiCads, but lower than Li-ion.

Even so, the batteries are only the source of about half of the voltage droop under load. The other half is wiring/switches. I use a battery pack that has double wires/plugs and either twin stock switches into two sets of pins on the RX, or one beefy switch with double wires in and out. As long as the leads are short, this is reasonably light. I use a 5-cell NimH pack from SR batteries that has literally half the cell resistance of any low-cost NimH you get elsewhere, that SR puts the double wires on, at my request. I use no regulator. The 5-cell 900 mAH pack is 3.7 oz, and the 500 is something like 2-1/2 oz. If you look at his site <srbatteries.com> and look up the resistances of the "H" series cells, and compare to others ... oh my, others generally won't even list their NimH cell resistances!
hint-hint.

P. S. I have no interest in, or relationship with SR, I changed to them years ago, and the only battery problem I have ever had, since '84 was when I flew too many flights on a small battery. That was my stinkin' fault.
Dean

Dean Pappas
Sr. Design Engineer
Kodeos Communications
111 Corporate Blvd.
South Plainfield, N.J. 07080
(908) 222-7817 phone
(908) 222-2392 fax
d.pappas at kodeos.com


-----Original Message-----
From: nsrca-discussion-bounces at lists.nsrca.org
[mailto:nsrca-discussion-bounces at lists.nsrca.org]On Behalf Of Bob Kane
Sent: Thursday, January 26, 2006 10:13 AM
To: NSRCA Mailing List
Subject: Re: [NSRCA-discussion] AAA NimH batterys


Maybe somebody with direct experience will chime in,
but I would be concerned about the higher impedence of
AAA cells compared to AA or A cells. The high
impedance will cause the voltage output to drop during
high current peaks and may manifest itself as sluggish
performance.


--- Ed Miller <edbon85 at charter.net> wrote:

> Is anyone using AAA NimH batteries for a RX pack ??.
> I am looking at 
> Batteries America ( EHYOST ) and they seem to have
> AAA NimH's in 720, 800 
> and 900mah ratings. I currently use their 2/3A 5
> cell NimH pack at 1100mah 
> and a weight of 3.85 ounces complete with the long
> lead I have on the pack. 
> Going to their AAA 5 cell pack looks like I can save
> about an ounce or so. 
> Mah isn't an issue, I can get in excess of 7 to 8
> flights on the 1100mah 
> pack I use now before charging so going to 900mah
> shouldn't be a big hit. 
> Don't suggest Lithium anything as lighter, want to
> continue to use my Alpha 
> 4 charger and am not convinced those new batteries
> are safe.
> Ed M. 
> _______________________________________________
> NSRCA-discussion mailing list
> NSRCA-discussion at lists.nsrca.org
>
http://lists.nsrca.org/mailman/listinfo/nsrca-discussion
> 


Bob Kane
getterflash at yahoo.com

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