question

It sounds like you're looking at a land based / fixed installation. For a given capacity (figure this bit out without committing to a battery technology), lead acid will have a much lower upfront cost, if you're not being ripped off in quotes.

LiFePo's great if you're in a mobile environment because of weight savings.

LiFePo's ability to repeatedly draw down to a much lower depth of discharge and longer cycle life is I think very dependent on manufactured quality, system design and just plain luck. I can't recall seeing evidence that gives me the warm and fuzzies on longevity aside from claims in datasheets (it probably exists, but is locked up as very expensive IP).

LiFePo's cost savings over LA in the longer term is highly dependent on the above playing out in your favour.

Additionally you will need to get used to the Battery Management System attached to the LiFePo (unless your installer keeps an eye on it for you).

On balance, at this point in time I'd say look harder at lead acid unless you're prepared to deal with new technology and everything that comes with it. Its a risk-reward thing.

(Fyi, I'm using LiFePo myself)

moose4621 Some basics about lead acids & lithiums the deeper they are discharged each cycle the shorter their life is. Life is defined as being the point at which the battery holds only 80% of it original capacity when fully charged.

Victron Lithium will do 5000 cycles discharged to 50% of capacity and discharged to 80% of capacity they will do 2500 cycles.

I think the biggest advantage that lithiums will have for you is that they make far better use of the solar input, charge in about a third of the time to the average lead acid if on occasion you have to revert to a generator etc for charging.

Yes it should be quite easy to integrate lithiums into your system it is something I do all the time albeit for much smaller system on boats.

In order to help we need to know what is the daily usage, the daily input from the solar and any other charging source.

Thanks for the responses people. I appreciate it.

The DOD of the lead acids were approximately 15% for the last few years, but for the first few years of their life it was more like %30 or even 40% at times.

At the moment the batteries are easily reaching full charge by am 10am on sunny days. The generator usually never kicks in. I tend to use it for high ac loads like large welding jobs.

Doing a straight lead acid battery replacement is certainly the easiest way to go for me, but is it the best option for the money.
I do not have an aversion to new technology as long as it is proven.

@kai it is a land based system, yes.

I have been hearing a lot about nickel iron batteries too. Seems the maintenance can be high though.

Arrrgh, my head hurts!