MED HP Batteries
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Installation & User Guide
Installation & User Guide
HP Batteries; Medium Size
7
4.0
Longevity & Depth of Discharge
One of the advantages of lithium batteries over lead-acid batteries is longevity. If you want to realise
the long life potential out of your lithium battery, then consideration must be given to depth of
discharge.
The electronics inside the battery enclosure is designed to monitor the charge
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if you connect a
solar panel to your battery for the purpose of maintaining 100% charge, this will be switched on
when needed. You do not have to keep a constant watch on the screen display
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a constant green
LED on the battery display panel means that the battery is charging. The internal electronics are
working to protect the battery from being overcharged, as well as when the battery is close to
empty.
When the battery is supplying current to a connected device such as an inverter, the green LED on
the battery display marked ‘STAT’
will continuously flash on and off every second.
For example, if you have solar panels continuously connected to your battery, the electronics will
not allow the battery to remain at a maximum charge level. Keeping your battery at a maximum is
not as important as it is for lead acid batteries.
A battery lifespan is rated by the number of cycles before the original capacity has reduced by a
certain amount; a cycle is defined as discharging from fully charged, to a percentage Depth of
Discharge (DOD), and then charging back to full again. So, DOD describes what percentage of the
battery capacity is being used each time.
Note: DOD is different to State of Charge (SOC, also known as Charge Level); in fact, they add
together to 100%. So, 80% DOD equates to 20% SOC.
The less DOD you use each cycle, the longer the battery will last.
This fact should be considered when choosing the battery Amp hour capacity. You will have a higher
return on battery investment if there is enough capacity at hand such that you are not heavily
discharging the battery on every cycle. Extra capacity ensures lower DOD, extended life and a higher
financial return on your investment.
LBS batteries have a cycle life of 5,000 at 50% and 2,000 at 80% DOD.
4.1 Discharge Curve
Note that unlike lead acid batteries, lithium batteries hold their voltage over the cycle, dropping off
only when the battery is about 90% discharged, as indicated in Figure 4-1 for illustrative purposes.
