Myles,
The FAA specs replacement when much of the battery storage is still there. I have an order in with my family aircraft mechanic but I may have to wait a while. Charging is another thing. You would just have to look to see what is out there. Have you considered that big aircraft plants salvage yard up near you.
Kevin Pemberton
On 08/26/2010 09:08 AM, Myles Twete wrote:
According to the internets, wet cell nicads "can last" 20yrs or longer but are typically spec'd at 5000hrs.
So they may last longer than my flooded lead acid T105's (4 of which are now 11 yrs old).
What is the cost per kwh for wet cell nicads? What else would it cost---eg a special charger?
Finally, are there sources you recommend for good used cells?
-Myles
From: electricboats@yahoogroups.com [mailto:electricboats@yahoogroups.com] On Behalf Of Kevin
Sent: Thursday, August 26, 2010 8:02 AM
To: electricboats@yahoogroups.com
Subject: Re: [Electric Boats] Re: Maintaining batteries over the winter
Typically a wet cell Nicad will not have dendrite problems, and comes in larger battery size ( used in aircraft).
Properly cared for, i.e. not overcharged and maintained, one can get the life out of a nicad drycell. But it is true a dendrite marks the end of a nicad. Lithium iron is by far the best over nicad or lead acid, but nicads are an alternative that should get serious attention for anyone wanting longer life than they can get with lead acid batteries at a much better weight. Like most all batteries, poor habits cause shorter life.
Kevin Pemberton
On 08/23/2010 09:09 AM, Myles Twete wrote:
And then the cell lasts how long after?
Wikipedia comment on doing this: "Sometimes, applying a brief, high-current charging pulse to individual cells can clear these dendrites, but they will typically reform within a few days or even hours."
From: electricboats@yahoogroups.com [mailto:electricboats@yahoogroups.com] On Behalf Of Kirk McLoren
Sent: Monday, August 23, 2010 9:00 AM
To: electricboats@yahoogroups.com
Subject: Re: [Electric Boats] Re: Maintaining batteries over the winter
I have had good success clearing dendrites. The trick is a good enough short to deal with the dendrite not just its tip and yet not destroy the cell.
Only lost one on the learning curve.
Kirk
From: Myles Twete <matwete@comcast.net>
To: electricboats@yahoogroups.com
Sent: Mon, August 23, 2010 10:51:15 AM
Subject: RE: [Electric Boats] Re: Maintaining batteries over the winter
Re: Memory Effect in NiCds being urban legend: That the effect is not as easy to produce as we have all been led to believe does not make it an urban legend. The fact that it was observed and documented with satellite battery banks makes it clear that the effect is not a myth. The only thing that's not clearly understood is how closely a cell would have to repeatedly discharge, how deep and how many times before this effect is observed and whether or not it's recoverable. As one of millions of folks who have had NiCd power tool batteries loose capacity early, I am one of those who'd rather not take a chance and always discharge the battery deeply before recharging----why take a chance…
Bigger concern with NiCds and possibly the reason for what we tend to call 'memory effect' is Dendritic Growth and shorting:
Dendritic shorting
NiCd batteries, when not used regularly, tend to develop dendrites, which are thin, conductive crystals that may penetrate the separator membrane between electrodes. This leads to internal short circuits and premature failure, long before the 800–1000 charge/discharge cycle life claimed by most vendors. Sometimes, applying a brief, high-current charging pulse to individual cells can clear these dendrites, but they will typically reform within a few days or even hours. Cells in this state have reached the end of their useful life and should be replaced. Many battery guides, circulating on the Internet and online auctions, promise to restore dead cells using the above principle, but achieve very short-term results at best.
From: electricboats@yahoogroups.com [mailto:electricboats@yahoogroups.com] On Behalf Of Kevin
Sent: Saturday, August 21, 2010 9:48 AM
To: electricboats@yahoogroups.com
Subject: Re: [Electric Boats] Re: Maintaining batteries over the winter
Contrary to popular belief NiCad batteries have to be used on a constant cycle for any memory effects. According to accounts the memory effect was only noted on satellite battery banks where cycles of the batteries were almost set by a clock ( one revolution of the satellite around the earth). No memory has been observed in any other use, only rumor keeps the myth going.
Load tests on batteries is the best way to test your batteries. Lead acid batteries should not be drained of charge for any reason it lowers battery life.
Kevin Pemberton
On 08/16/2010 05:22 PM, greenpjs04 wrote:
Not all batteries are the same. That advice was good for nicads, but your AGMs do not need to be discharged regularly.
Pat
--- In electricboats@yahoogroups.com, "rwsandersii" <rwsandersii@...> wrote:
>
> I've read that batteries need to go through a discharge/charge cycle once a month to keep them in good shape.
> Does anyone know of a reasonably priced charger that will do a discharge and charge cycle for my Group 37 AGM batteries?
> Thanks,
> Richard
>
--Ubuntu10.04, Acer AspireOne, Virgin Mobile 3G Broadband2go.Doesn't get any better than this!
--Ubuntu10.04, Acer AspireOne, Virgin Mobile 3G Broadband2go.Doesn't get any better than this!
-- Ubuntu10.04, Acer AspireOne, Virgin Mobile 3G Broadband2go. Doesn't get any better than this!
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