[TriEmbed] Sealed Lead Acid Batteries - how low will they go?

[Carl Nobile]

Shane,

Looks like a conversation we had about a week ago.

Carl


On Fri, May 29, 2015 at 8:25 PM, Shane Trent via TriEmbed <
triembed at triembed.org> wrote:

> Chip,
>
> The end point voltage of a sealed lead acid battery is a little arbitrary.
> The point is that you are reaching the point that there is little usable
> energy left in the battery. At very light load you could keep running
> longer but  you will be reducing the number of cycles you can get out of
> the battery in it's operating life.
>
> At moderate to heavy loads the battery voltage will generally recover once
> you reach your cut-off voltage and remove the load. But when the voltage
> recovers, the battery still contains very little energy and will quickly
> drop the voltage under load.
>
> The East Penn Manufacturing (I love their batteries, sold under many names
> including Energizer at Sam's Club) documents below show the battery
> capacity remaining at specific open circuit voltages. They show 0% at 11.80
> volts. A table in the other document shows that stopping 12:00 volts would
> extended your AGM battery expected life by over 33% (450 cycle at 100%
> depth of discharge to 650 cycles at 80% depth of discharge.
>
> Another issue often missed is that battery terminal voltage, charging
> voltage and capacity all vary with temperature. So lab measured battery
> operating time will probably not be matched in the field. Be conservative.
> But it sounds like your solar cell is going to be giving your battery much
> more power that you will be needing. If you hit only 50% depth of
> discharge, your battery should last for 1000 cycles or around 3 years. Cut
> it to only 25% depth of charge an you stretch the battery life to 6 years.
>
> Great technical reference about AGM and Gel batteries
> http://www.soligent.net/uploads/products/32669_3.pdf
>
> http://www.eastpennmanufacturing.com/wp-content/uploads/Guide-to-Commercial-VRLA-Batteries-2007.pdf
>
> I hope the information is helpful!
>
> Shane
>
> On Fri, May 29, 2015 at 8:04 PM, Chip McClelland via TriEmbed <
> triembed at triembed.org> wrote:
>
>> To all,
>>
>> Taking your collective advice, I have been testing a sealed lead acid
>> battery with my cellular data logger.  It has been dutifully sending
>> updates to Ubidots hourly for almost three weeks now.  Here is a link to
>> the current voltage
>> <http://app.ubidots.com/ubi/getchart/page/fwweXqpV5QlRbiZ8nzEvou4nNi8> of
>> the 12V battery
>> <http://www.amazon.com/UPG-UB1280I-Sealed-Lead-Batteries/dp/B0009GIKNE/ref=sr_1_1?ie=UTF8&qid=1432943993&sr=8-1&keywords=UPG+UB1280I+Sealed+Lead+Acid+Batteries> that
>> has been running things.
>>
>> The question is, when do I stop the test?  I have read different articles
>> stating that these batteries should be discharged only to 11.9V (but, this
>> is a 12V battery - albeit one that started at 13.1V at full charge) and
>> others that say that a full discharge is OK as long as you recharge the
>> battery quickly.
>>
>> Any advice would be appreciated.
>>
>> Thanks,
>>
>> Chip
>>
>> P.S. - the LiPo Solar version
>> <https://twitter.com/chipmc86/status/604435703653658625> s now ready to
>> make it’s public debut on the Greenway trails.
>>
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>>
>
>
> --
> A blog about some of my projects.  http://fettricks.blogspot.com/
>
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Carl J. Nobile (Software Engineer)
carl.nobile at gmail.com
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