Lithium Battery Technology for Motorhomes and Caravans

Updated : 28/06/2019.  

                     . 

                          WE DO NOT SELL ANY BATTERIES, THIS IS INDEPENDENT ADVICE

The only Lithium Iron Phosphate battery we have tested and recommend is the Poweroad PRLR-100 but there are limitations as with ALL Li batteries.

Lithium batteries have revolutionised our World but are the Lithium marketing teams playing fair over batteries specifically aimed at the Leisure market?

Let's start with the marketing hype first?

The marketing says that a Lead Acid battery can only be discharged to 50% and that Lithiums discharged to 100%. 

Yet it has been long known that the Exide G80 Lead battery, introduced over 18 years ago, could be discharged to 80% DOD and still deliver useful life. This battery is legendary, selling more of this model in the last 20 years than any other motorhome Leisure battery, so why isn't that being used as the benchmark by the Lithium retailers?

There are also Lead Acid batteries that discharge right down to 100% Depth Of Discharge (DOD) and still give strong life. 

Of one of them the manufacturer writes -

"The Super Cycle batteries are the result of recent battery electrochemistry developments. The paste of the positive plates is less sensitive to softening, even in case of repeated 100% discharge of the battery, and new additives to the electrolyte reduce sulfation in case of deep discharge".

See the documents from the highly respected Victron Energy company further down the page for proof of such batteries capability. 

So that is two things that contradict the usual Lithium 'marketing' misinformation, here are several more :

Further to the above batteries, there are additionally Lead Acid batteries that have 1,500 cycles, even when discharged down to 80% DOD and a huge 4,500 cycles when shallow discharged to 30% DOD. 

See the evidence/graphs below that show 3 different battery ranges, that not only drop to 80% DOD, but they all deliver useful cycles at that ultra deep depth of discharge -

The Green column batteries are big so not suitable for a motorhome installation, but shows what Lead batteries are capable of, yet conveniently ignored by the Lithium marketing teams who seem to be comparing their Lithiums to the poorest quality Lead Car Starter battery technology from the 1980's. 

Clearly the Lithium marketing teams are using comparisons designed to deceive.

Lets examine one brochure statement, see bottom of page for the full document, "the lithium gives 100% of the power as useful power so 1 x lithium = 2 x lead acid for power".

If you look at the Lithium cycle life versus Depth Of Discharge graph below, you will see how the number of available cycles 'drops like a stone' the deeper you discharge it? 

The cycle life when only shallow discharged to 20% DOD is good, but when deeply discharged to 80% it is much lower. 

You can clearly see how a Lithium battery can be discharged to 90% DOD, but you suffer massive loss of cycle life if you do.

According to that graph, if we assume that the very shallow 20% DOD discharge figure is equivalent to 3,000 cycles, then the 100% figure is a miserable 500 cycles. 

That is a huge amount of lost life if you do discharge a Lithium to 100% DOD, and clearly why the most honest retailers/manufacturers are now quoting Lithium 'realistic' operating ranges between 20% and 80% DOD. 

More on that below.

The renowned charger manufacturer Votronic, Battery University, etc. all say never discharge a Lithium cell to 100% or stress in the cell will occur. If a Lithium battery is damaged in any way there is a risk of fire.  

The Lithium marketing teams are quoting the shallow discharge figures, yet encouraging 100% discharge, without explaining about the massive loss of cycle life. 

It is because of the huge loss of cycle life from Deep Discharging, that the Lead Acid manufacturers recommend 50% DOD as the best compromise between life and usability. It is not a physical limit. Even a sub £100 battery like a Varta LFD90 can be discharged to 90% DOD, but it won't give it's best life. Just as a Lithium won't.

Contrary to the Lithium misinformation, the best Lead batteries can discharge to 100% and give useful life, the Victron Super Cycle battery is a perfect example, and if you compare that to a Lithium, with it's 'ideal' operating range of just 20% down to 80% DOD, the tables turn around dramatically in the opposite direction. 

A Lithium used sensibly will then deliver just 60Ah usable power, whereas the Victron Super Cycle Lead acid battery can deliver a full 100Ah. Click here for the Super Cycle Lead battery at £269

That is 40% more power in the Lead Acid batteries favour, totally the reverse of the Lithium marketing misinformation.

Obviously my comparison is as much a nonsense as those of the Lithium marketing teams, as there are so many factors to consider, but clearly "lithium doesn't deliver 100% of the power AND  "1 x lithium doesn't = 2 x lead acid for power" if you compare the best with the best.

If you see these kinds of claims for Lithium, the Retailer is being deliberately dishonest, which should put you on your guard for the rest of what that say. Before you buy a Lithium battery for a motorhome, ask to see the manufacturers graphs so you can see if it will give you the lifetime you require for your specific use. You may find the real figure is a long way from the sales brochure figure.