I'm not sure what the experts say, but, in my experience, one needs about a
1-volt "headroom" between the charger output under load, and the voltage
expected from the fully charged battery. Anything less just leaves you
partially up on the recharge curve, and cannot fully recharge the battery.
Jim Nichols
Tullahoma, TN USA
----- Original Message -----
From: "Chuck Norcutt" <chucknorcutt@xxxxxxxxxxxxxxxx>
To: "Olympus Camera Discussion" <olympus@xxxxxxxxxxxxxxxxx>
Sent: Tuesday, September 15, 2009 6:18 PM
Subject: Re: [OM] 12 volt battery advice
> Possibly. I measured the output of the maintenance charger and could
> only see 12.85 volts which is about what the battery was raised to. But
> it dropped to about 12.5 after firing two Alien Bee B800s only 6 times.
> I had expected to see something between 13 and 14 on the maintenance
> charger. The old car charger puts out about 13.5 so I hope to see a bit
> more voltage in the morning. But the charge rate has already dropped to
> something very low... something I can't accurately read on the guage.
>
> Chuck Norcutt
>
>
> Jim Nichols wrote:
>> Since a car alternator puts out a little over 14 volts, you have probably
>> gone about as high as it will go. I usually see a recharged battery sag
>> a
>> little if it sits overnight. Could your problem be with the maintenance
>> charger?
>>
>> Jim Nichols
>> Tullahoma, TN USA
>> ----- Original Message -----
>> From: "Chuck Norcutt" <chucknorcutt@xxxxxxxxxxxxxxxx>
>> To: "Olympus Camera Discussion" <olympus@xxxxxxxxxxxxxxxxx>
>> Sent: Tuesday, September 15, 2009 5:02 PM
>> Subject: Re: [OM] 12 volt battery advice
>>
>>
>>> I have assumed it's toast and ordered a new one from a local electronics
>>> supplier who promises delivery in 3 days. That's good because I need to
>>> do some formal outdoor portraits of a friend's daughter in her wedding
>>> dress before the wedding day. In the meantime I have put my old 6 amp
>>> car charger on the old battery and it is now charging at about 2 amps
>>> vs. the other 1.5 amp maintenance charger. After a couple of hours it
>>> raised the no load voltage to about 13.25 or about 0.4 volts higher than
>>> I had seen before. I think I will let it charge, then rest for 24 hours
>>> and then charge it again as per the advice on the Battery University
>>> link.
>>>
>>> I'm sure I'll send it off to the local toxic waste facility but I'm
>>> curious to see if it will be at least somewhat rejuvenated.
>>>
>>> Chuck Norcutt
>>>
>>>
>>> Ken Norton wrote:
>>>>> This battery is about 3 years old but rarely used and rarely charged.
>>>>> Do you think it's toast?
>>>>>
>>>>
>>>> Without a regular float (maintenance) charge on the battery, I'd say,
>>>> yes,
>>>> it is probably toast. SLAs don't take to slow-drain very well.
>>>>
>>>> AG
>>> --
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>>>
>>
>>
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>
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