Inverter battery selection

[ians]

I am busy with a few backup solution projects ... backup system only ... no solar.

Back in the old days it was simple ... you go to the battery shop and buy a 105 amp/hr deltec deep cycel battery and bingo ...sorted.

Not so simple anymore ... now you have too many choices and everyone is fixed on convincing us that lithium is the way to go.

Which is the best option (best bang for your buck) considering times are tough for many ... blowing R20 k on one battery is not an option even though it long terms etc etc ... you could take a loan to add to your overloaded monthly budget ... not going to happen.

The options (3-5 years lifespan)

Lead acid - flooded

Lead acid - Gel

Lead acid AGM

Lead acid being labeled as amp/hr (generally around 105 amp/hr)

Because I am using 48 VDC system ... to work out the available capacity - 48 v x 105 amp/hr = 5040 W / 1000 = 5.04 kwh but because they say the battery can only discharge 20 - 50 % ... the capacity is reduced - 5.04 x 0.5 = 2.52 Kwh

Prices ranging from R2000 - R5000.

To purchase a 48 VDC set will set you back around R10k


Lithium ion - labelled as kwh and the efficieny is 80 - 100 % (however ... I have read that Polytech are also have a 50 % rating so you spending around R13k for a battery which will offer 1.2 kwh)

There are many brands of lithium avaialbe on the market at present ... ranging for R13000 - big bucks.

I have 3 x 5 kva inverters in parallel to backup a 60 amp supply and I need to make a decission of what type of battery to use there were flooded lead acid batteries which lasted around 4 years ... cost to replace R30 000 (3-5 years ... if we go lithium to give the same amount of backup the cost will be around R75 000 (they say 10 -20 years) it seems like a no brainer.

I would like to hear your view ... how would you decide ... and am I alooking at this in the right way ...or should I be doing more research.