Nope. When I do such testing I just use the Mynolata A1's
intervalometer. I had set up the flashes in the basement level family
room, put my AB slave receivers on the flashes and the transmitter on
the A1. Since I had previously done 15 in manual testing I set the A1
to fire every 30 seconds for 60 more shots and went upstairs to eat
dinner. I'm sure the neighbors must have been curious about what was
going on.
Chuck Norcutt
Charles Geilfuss wrote:
> 75 flashes! I hope you wore your welding goggles.
>
> Charlie
>
> On Fri, Sep 18, 2009 at 6:51 AM, Chuck Norcutt <
> chucknorcutt@xxxxxxxxxxxxxxxx> wrote:
>
>> I did some more testing with the old battery tonight and, regardless of
>> its actual state of wellness it was able to deliver the goods. From a
>> no load voltage measurement of 13.25 volts it was able to fire two Alien
>> Bee B800 (360 watt seconds each) studio flash units at full power 75
>> times with an ending no load voltage of 12.75 volts. I don't know how
>> many more it might do. I just quit at 75. I would expect the upcoming
>> shoot not to be more than 25 shots and at most at 50% power and more
>> likely 25%. So the old battery is now capable of delivering all I need
>> and much more.
>>
>> However, about half way through the inverter started chirping to
>> complain about low battery voltage. I finally checked the specs on the
>> inverter and found that the low voltage warning is issued at 10.5 volts
>> so obviously the two lights (which, together, recycle in about 3 seconds
>> from a full dump) are putting a large drain on the battery and drawing
>> the voltage way down. The inverter shuts down at 10 volts but that
>> hasn't happened yet.
>>
>> I think the Schumacher 1.5 amp charger/maintainer is much more a
>> maintainer than a charger. It's designed to be mounted in the engine
>> compartment of a truck or car and left on for months at a time. I think
>> the maximum 12.85 no load volts I've been able to get out of it is
>> deliberate to avoid any risk of overcharging. It's probably fine to
>> keep the cells from falling too low but I think I'm going to have to put
>> the cells on the 6 amp automotive charger to get the voltage up before
>> use. That charger is no less than 43 years old. Anyone have a
>> recommendation for an equivalent but modern low power charger.
>> Something that can be, as Tim suggests, a bit more aggressive.
>>
>> Chuck Norcutt
>>
>>
>>
>> Tim Hughes wrote:
>>> Chuck,
>>> those numbers don't make a lot of sense.
>>>
>>> I have not followed this thread, but the least aggressive float charge
>>> regime for any SLA (can float indefintely) is 2.25V/cell near end of
>>> charge , so 13.5V for a "12V battery" . A more typical still
>>> conservative charger can float for long periods at 2.3V/cell near end
>>> of charge, or 13.8V for your battery. If you want to have any hope of
>>> recovering sulphated cells and for cyclic applications,rejuvenation etc
>>> 2.45V/cell or 14.4V, which is about what a car alternator is set to
>>> charge at. A smart charger may charge at higher voltage
>>> (2.45/cell) until current drops to a certain level and then drop back
>>> to a less agressive long float regime, so it is possible that one of
>>> your chargers does that, but you are reading the lower voltage in float
>>> mode when it has already throttled back
>>>
>>> The cutoff voltage where the inverter stops operating is typically set
>>> to somewhere between 1.5 and 2V a cell, depending on expected max
>>> current of load, with 1.8V being a common value for moderate load (10.8V
>>> cut off V for battery). 12.3V is way too high. I think what may be
>>> happening is you have a sulphated battery and the internal battery
>>> impedance is now so high, the voltage drops out at peak load to below
>>> the cutoff point immediately, even though the battery is fully charged.
>>> When you read voltage, it is oscillatiing between switching invertor on
>>> and off giving a misleadingly V value.
>>>
>>> If you had a battery cycler with an aggressive charge regime and fully
>>> discharged and charged the battery 10 or 20 times, you likely could
>>> reduce impedance quite a bit and might get your bees flying a bit more.
>>>
>>> At 2.3V/cell it takes more than 20 hrs to fully charge most SLA's,if
>>> you want to prevent your battery from slowly cycling down.
>>>
>>> There are a number of slightly different SLA technologies and some have
>>> much higher self discharge than others (not good for occoasional use)
>>> and also some have better recovery from abuse. Try cycling the batteries
>>> using a light load like an 8W car indicator light. Be very careful to
>>> set an alarm clock or something to be sure you don't overdischarge.
>>>
>>> Tim Hughes
>>>
>>>
>>> --- On *Wed, 9/16/09, Chuck Norcutt /<chucknorcutt@xxxxxxxxxxxxxxxx>/*
>>> wrote:
>>>
>>>
>>> From: Chuck Norcutt <chucknorcutt@xxxxxxxxxxxxxxxx>
>>> Subject: Re: [OM] More on the 12 volt SLA battery
>>> To: "Olympus Camera Discussion" <olympus@xxxxxxxxxxxxxxxxx>
>>> Date: Wednesday, September 16, 2009, 7:48 PM
>>>
>>> Recall that this is just a little battery, only 12 amp hours. And
>> the
>>> inverter starts complaining about low voltage when the battery gets
>> to
>>> 12.6 volts. It can still keep on for quite a while but the chirping
>>> from the inverter gets bothersome.
>>>
>>> Looking back on my 5 year old test notes I see that the Schumacher
>> 1.5
>>> amp battery charger/maintainer never got the battery over 12.85
>> volts.
>>> The 6 amp auto charger, however, it running them up to 13.5. That
>>> should probably give me a lot of extra shooting life.
>>>
>>> Chuck Norcutt
>>>
>>>
>>> Ken Norton wrote:
>>> > Chuck, that number of full-dump flashes just doesn't seem right
>>> to me. I
>>> > know those inverters are pigs when it comes to "overhead" current
>>> draw, so
>>> > maybe you might be running into a time-based discharge pattern
>>> when using
>>> > the AB 800s.
>>> > Of course, this is referring to "normal" usage, not your current
>>> problem
>>> > with a battery on life support.
>>> >
>>> > I do plan on seeing how much oomph my deep cycle marine battery
>>> gives when
>>> > powering a pair of monolights. I know it will keep a laptop
>>> computer alive
>>> > for 20+ hours. Hmm... Actually, now that I think of it, we got
>>> at least 24
>>> > computer hours (sometimes with two computers) and six hours of
>>> 18w compact
>>> > florescent runtime and the battery voltage was still about 10V
>>> >
>>> > AG
>>> --
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