is it safe to let yellowtops be discharged below 12 volts? And what is fully discharged considered?Sceen name use to be "wantsanlr3"
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14th Jul 2009 2:13 pm
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Not sure, but I have a similar linked question, I hope you don't mind me adding in this post.
I'd like to know what voltage you'd normally expect at what % discharge figures.
I have a voltage display in my trailer connected to the 115Ah battery. it reads 12.73vlts after charging and being allowed to settle removing the peak voltage.
I don't have a voltage display connected to my YT in the aux (but may get one)
Does the voltage drop vary depending on tha Ah capacity. or is it just based on Voltage.
I found this...
Bushwanderer wrote:
I can't answer specifically for the Optima, but deep cycle batteries can generally be discharged by up to 80% of their capacity (this occurs at about 11.1V).
With the 115Ah battery, I work out that 80% charged is 10.18v I've simply used the formula of 12.73 * 80% = 10.18v
Is this correct or is there some other variable I need to take into account?
For bushwanderers account to be correct by my maths, that makes the starting voltage 14volts.
80% charge doesn't mean 80% voltage - the discharge (voltage) curve is not linear, so the battery will hold it's voltage up during discharge and the drop towards the end of the cycle.
Ok I talked to are UPS guy here about batteries he is in charge of all of our battery back up systems some are multi-million dollar systems. For a deep cycle batter 10.5 volts is basically "dead", from full charge down to 10.5 volts is considered one full discharge cycle. But he says for the health of the battery its better to never take it past 50% of the Amp Hour capacity.
I think most of us have D34 yellow tops. Its a 55 amp hour battery. Amp Hours = Amp output sustainable for 20 hours before dropping to 10.5 volt recharge level, multiplied by 20.
so 55/20= 2.75amps so you can run something that draws 2.75 amps for 20 hours. So for the health of the battery lets say we have something that draws like 6amps it would be 27.5/6= about 4.5 hours. So after running that item for the 4.5 hours we would need to recharge our battery. But it would be safe to run it for 9 hours with out ruining the battery.Sceen name use to be "wantsanlr3"
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14th Jul 2009 7:09 pm
heine
Member Since: 07 Feb 2007
Location: Midrand
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What makes Optimas different is that you can discharge to 10.5 V safely and also that they have almost no internal resistance , hence the fact they charge back up so much quicker .
In my experience , UPS batteries tend to be normal run of the mill sealed lead acid batteries which do not have the same capabilities .
14th Jul 2009 7:33 pm
heine
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The calculation could be about right.
I get 7 to 8 hours out off my YT before my refrigurator stops. The fridge stops at between 10.7 and 11V running. The voltage comes up a little after that. I think the fridge pulls about 4 Amps Never checked that.
I get about 8 hours if I fully charged it with the Ctek and about 7 when charged by the D3.Roel
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