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1. 06:53 AM - Re: Battery charger/minder/tender (Bill Watson)
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| Subject: | Re: Battery charger/minder/tender |
Having ruined a number of 680s during my 10 year odyssey, I've come to
the same conclusions as Kelly has below. I'm a bit late to this
discussion but here one thing I have empirical evidence for;
undercharging these batteries will slowly kill them, slowly but inevitably.
Three things I KNOW will do this is
1. Inadequate voltage in aircraft charging circuit (read the spec
sheet and obey it). This seems straight forward but do check that
the voltage you are displaying is the voltage the battery sees. I
was measuring the voltage for my two charging circuits in two
different places (EIS and EFIS). Turned out one was accurate and
one was not.
2. Old battery tenders/minders not intended for AGM batteries.
During my build, I had a few left over from my gel cell days in
gliders. They will not adequately charge a discharged 680 but it
takes about 1.2 years to discover that. I'm not sure, but using an
old one to just maintain is worse than throwing the old thing away.
If there are tenders/minders on the market now that are unsuitable
for AGM batteries, I wouldn't know, but see Kelly's points below -
you just don't need one, you need an AGM capable charger.
3. Parasitic loads when not in use. My load was fully documented; the
clocks in my (3) GRT EFISs (this has since been eliminated thru an
enlightened SW upgrade). It was a very small load but it was 3X a
small load. I have 2 batteries but the load was connected to only
one, which made diagnosis easier but more expensive. Why is such a
small load in a frequently flown plane such a problem? Didn't
grandpa drive cars with electric clocks? That didn't seem to be a
problem. Well it was occasionally a problem. And with AGMs, a
parasitic load seems to be equivalent to undercharging it; the
battery is sits in a slowly declining state then is undercharged the
next time it gets hit with the starter load. I don't know whether
that is actually the mechnism but I KNOW a parasitic load will
slowly, inevitably, kill a 680 or 2. I guess you could keep it on
an AGM certified minder/tender but I'd suggest hunting down the load
and killing it.
Things will work just fine with any 3 of these conditions for 1-2 years
then they won't. It's a slow death that may mystify you for $awhile$.
I have a boat but 680s make lousy anchors.
Speaking of boats, my little jon boat is parked next to my '10. The
Walmart/Schumacher charger with settings for AGM, Lead and Gel Cell(?)
batteries worked fine until I apparently wore it out charging the lead
acid trolling motor battery every other day. I'm going to separate
chargers as a result.
Regarding 'empirical evidence'; label, log and track your batteries,
especially if you have 2 of the same installed like I do in my Z-14
scheme. That data is the key to figuring out whether you have slow
death problems or not and what might be causing them. Problems are
easily mitigated with a dual batt/alt/bus Z-14 which is good and bad.
It can delay diagnosis of electrical system problems because they aren't
so critical. Which means that you can kill 2 batteries with one problem
before you decide to act.
Bill "I KNOW is shorthand for 'ask me how I know and how much it cost me
to figure it out' " Watson
On 12/6/2017 10:45 PM, Kelly McMullen wrote:
>
> The Odyssey is a variant of the AGM technology. I suggest that you do
> not need a "tender". You need something that can recharge the battery
> whenever it has been run down. Most any automatic charger with an AGM
> switch will do...as long as you only charge things when you are present.
> AGM batteries have a very low self discharge rate, and if there was no
> leakage of current, would be very fresh after 3 months of sitting.
> If you want a genuine Odyssey charger, you can go with
> https://www.batterymart.com/p-obc-12a-odyssey-portable-charger.html
> or
> https://www.batterymart.com/p-obc-6a-odyssey-portable-charger.html
> Both a lot less than the overpriced Battery minder models.
> Again, I would NOT leave a charger of any kind on a battery unattended.
> There are several unnecessary risks.
>
>
> On 12/6/2017 8:24 PM, Ed Godfrey wrote:
>>
>> I am looking to get a battery charger/tender and was looking for the
>> Walmart one that Tim had suggested a number of years ago, to charge
>> my Odyssey PC-925 battery. It seems that they no longer carry the
>> WM-2500A model any longer. Does anyone have any suggestions as to
>> what would be a suitable replacement? Thanks.
>>
>> Ed Godfrey
>>
>>
>>
>
>
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