200Ah LiFePo4 Auxiliary System

[SeanC]

So with the cranking battery on the way out and questions about the 80Ah deep cycle battery l started thinking about replacements. Together there was 160Ah. The SC80 works well but I was finding the on occasions some extra capacity would be good. Overcast days when I was planning a lazy day at the camp etc.

First idea was putting another AGM behind the second row seats.

Then I started thinking about lithium. Found Deep Cycle Systems batteries which were rated for cranking and under bonnet use with 3 year replacement warranty, which was difficult to find in other brands. So this plan was to do a straight swap with a 75Ah auxiliary and 100Ah (1000 CCA) cranking LiFePo4 batteries that can be charged directly from the alternator.

But I though why would I pay that sort of money and then put the batteries in the worst place possible for longevity. If you can’t get the increased longevity that removes one of the benefits of of paying extra for lithium.

So I ended going with 2 x 100Ah LiFePo4 behind the second row seats and an Odyssey PC1350 as a cranking battery. With only cranking duty hopefully I should get increased life span.

As I was mixing battery types I needed an ignition switched DC2DC charger. So the SC80 has been retired for the moment.

Time will tell if it will be a good investment.

Heard a lot for and against so I decided to give it a go and find out.

LiFePo4 Auxiliary Set-up - Google Photos

[p38arover]

Would we be frightened by the cost?

[Milton477]

Good system, you won't be sorry.

[SeanC]

Would we be frightened by the cost?

Maybe.
About $3000 all-up including fitting.

[DiscoJeffster]

Maybe.
About $3000 all-up including fitting.

OMFG. And here I am questioning whether I get home brand or original muesli

[SeanC]

OMFG. And here I am questioning whether I get home brand or original muesli

l did a bit of a comparison. 198Ah Yellow Top vs 200Ah LiFePo4 ignoring the cranking battery which can be used for extra capacity I know.

Optima Yellow Tops (Atutomotive Superstore)
2 x 31T 75 Ah 150Ah 54.2Kg $810
1 x D35 48Ah 16.5kg. $325
198Ah 70.7kg $1135


2 x 100Ah LiFePo4 24kg $2200
$2200 + DC2DC $300 = $2500

About twice the cost a third the weight. I’m not expecting on saving money. If I get around breaking even I’ll be happy.

Playing the long game. Might have an answer in 8-10 years. Who knows. So stay tuned.

[Hugh Jars]

I had 300Ah of lithiums in my camper. 2 ½ years on and no noticeable reduction in capacity. They weren’t rated for cranking, but the best option on the list by far.
Never had any problems with them

[drivesafe]

Hi Sean, I have set up a few D4 Lithium Battery systems now. The first being about 7 years ago.

At that time, neither the customer ( now a good friend ) or I knew much about Lithium batteries but he already had one of my systems, with an Optima Yellowtop as the auxiliary battery.

Thanks to his assistance, we both learnt quite a lot from that first setup and the first thing learnt was that my Sc80 isolators will not work with a Lead Acid - Lithium battery combo.

No isolator will work in this type of setup.

While the initial Lithium setup was done by replacing the Optima with a lithium. This was very quickly reversed and the Optima was reinstalled and the lithium was moved to the cargo area and charged with a Sterling setup.

I had been recommending to my customers to use Sterling charges for a good few years and then started setting up lithium battery charging with Sterling Battery to Battery chargers.

The main advantage, besides their reliability when charging lithium batteries, is their size.

I now set up these systems with 60 amp Sterling BB1260 battery to battery charges.

I'm guessing you are using something like a 20A or 30A DC/DC charger.

This means if your two 100Ah lithiums are low, you will need to drive for around 8 to 10 hours to fully charge them, but the BB1260 will do a full recharge in about 5 hours and this is about what it would take to recharge a setup using those conventional batteries ( Optima batteries ) you mentioned in your comparison above, using direct alternator charging.

[SeanC]

Hi Sean, I have set up a few D4 Lithium Battery systems now. The first being about 7 years ago.

At that time, neither the customer ( now a good friend ) or I knew much about Lithium batteries but he already had one of my systems, with an Optima Yellowtop as the auxiliary battery.

Thanks to his assistance, we both learnt quite a lot from that first setup and the first thing learnt was that my Sc80 isolators will not work with a Lead Acid - Lithium battery combo.

No isolator will work in this type of setup.

While the initial Lithium setup was done by replacing the Optima with a lithium. This was very quickly reversed and the Optima was reinstalled and the lithium was moved to the cargo area and charged with a Sterling setup.

I had been recommending to my customers to use Sterling charges for a good few years and then started setting up lithium battery charging with Sterling Battery to Battery chargers.

The main advantage, besides their reliability when charging lithium batteries, is their size.


I now set up these systems with 60 amp Sterling BB1260 battery to battery charges.

I'm guessing you are using something like a 20A or 30A DC/DC charger.

This means if your two 100Ah lithiums are low, you will need to drive for around 8 to 10 hours to fully charge them, but the BB1260 will do a full recharge in about 5 hours and this is about what it would take to recharge a setup using those conventional batteries ( Optima batteries ) you mentioned in your comparison above, using direct alternator charging.

Hi Tim. The DC2DC charger is a 40 amp.

[p38arover]

That cost is better than I expected.

My starting battery is 18 months old and is noticeably degraded. When I bought it, I didn't realise it should have been an AGM.

Add to that the two 45Ah deep cycle AGM aux batteries that are the same age and are now of reduced capacity that they struggle the supply just a fridge overnight.

Replacing all within 2 years isn't a good deal compared with your system.