Benefits Of Allspark Lithium Iron Phosphate Batteries; What Size Do I Need - Offroad Living AllSpark 100ah-175-320A BMS User Manual

2. Benefits of AllSpark Lithium Iron Phosphate Batteries

LiFePO4 batteries are far superior to lead acid batteries in every way:

1/4 of the weight of AGM batteries with the same usable capacity

Smaller physical dimensions (2/3 of the size)

Up to 2000-5000 cycles

Very low self-discharge – safely store for 12 months without charge

Sealed and maintenance free

Higher charge efficiency of 95% vs 70-80% for lead acid

Rapid charge rates - allowing for rapid charge rates up to 1C – fully charge a battery
in 1-3hrs

3. What size do I need?

If you have already purchased your battery, then you may well have already answered this
question, however if you haven't here are a few important things to consider. Our
recommendation is to have 2 days power usage as storage capacity in your batteries. This
will provide you with a longer life for your battery and maintains higher overall battery voltage
levels, whilst giving you a buffer in the event of using more power on occasion or if you
aren't able to charge at expected levels (i.e. poor solar conditions)
To calculate capacity:
If your regular usage is only for only 1-3 days (overnighters and long weekends) then back in
storage (and on charge) till the next use, then you can get away with a smaller battery bank.
Calculate your daily power consumption (total amp hours required per day), minus any solar
or DCDC charger input each day x 50%. If staying off-grid for extended durations, then a
minimum of 2 days power consumption divided by 0.8 x 2 to give you the minimum battery
capacity you should have.
To calculate maximum continuous current:
Capacity is measured in amp hours. A 100ah battery will last for 20 hours at a 5A current
draw for example. Maximum continuous current is calculated by adding together the current
draw of every device or appliance that may conceivably run at the same time. Add up all
loads that could operate simultaneously on 12v or 230v from an inverter. Running small 12v
devices will never be an issue all at the same time – i.e. fridges/freezers, lights, pumps,
travel ovens, fans etc however if you plan to run larger inverters for powering microwaves,
coffee machines, kettles, toaster, hairdryers or even air conditioning, then you will need a
battery (or multiple batteries) than each can sustain the continuous output current required of
the total load. Take a coffee pod machine at 1400w. When run through a pure sine wave
inverter it uses 10% more power in the conversion process and will draw 115-130 Amps
across a 12V to 13.5V range. All AllSpark LiFePO4 battery have a continuous output current
of 175 Amps (320A peak) with some models also having a 200A continuous output (and
500A peak). Each battery on its own can power a 2000w inverter. You can then parallel
batteries up to 600ah to provide longer run time. Contact us for assistance if you need help
with sizing or calculations.
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