Float Batteries for solar? Help!

[edmundp]

Hi All,

Some advice - what would the effect be to cycle a float design (BSB DB Range) battery EVERY day to 20%DOD be vs something like an Omnipower battery cycled DAILY to 20%DOD?

I am looking to compare apples with apples, but the BSB DB range does not appear to get measured for cycle life - just a 10-12 yr float life?

What does this in reality mean to me from cost vs benefit as both ranges come in at approx. the same price point?

Please?

 

[envo]

any battery will suffer severely if you let it go to 20% before recharge everyday

 

[Renaissanceman]

Ok, this looks like it can get harmful because there appears to be little bits of half-info being past around and some poor fellow might end up loosing expensive batteries if this is not cleared up.

DoD stands for Depth of Discharge, therefore if a batteries DoD is 20% that means for optimal use and longevity, you should aim to only let it discharge by 20% (leaving 80% of the power in the battery, relatively speaking)

Or to put it another way: You need to consider the relationship between the remaining battery capacity and its voltage, as it does not run in a straight line. As the voltage goes lower (~10 volts), the amount of energy left in the battery and the amount of current it can deliver both drop off drastically.

The Ah (Amp hour) capacity of a battery is rated to a specified low voltage cutoff number which the manufacturer considers the point where you must:
A. Stop using it, to avoid risking immediate damage to the battery and
B. The energy left is diminished in terms of Amperage to make it worthwhile to try to use it.

Your goal, to keep a Lead Acid battery (or Gel) in good condition and maximize its lifetime in cycles, is to aim to not routinely go below 20% DOD (and that does not mean .8 x 12 volts. For a sample battery, that would be 12.42 volts instead of full charge 12.7 volts.) and to avoid discharge below 50% except in real emergencies.
Also, the deeper you discharge it, the more important it is to recharge it promptly to avoid permanent loss of capacity.

So although the above information does not give you a simple answer to your question it hopefully explains to you that the answer to your question or heading {Quote: Float Batteries for solar?} really depends on what you need the battery for, how many Amps will it be pulling and how long it needs to run for?

I hope this sheds some light on your project.