Are lithium batteries worth it?

[aandncaravan]

Tracker, This is a long complicated answer which you may need to read 4 times to take in, but I think it's worth the effort as it breaks so many myths.

 

A battery loses a little a little bit of efficiency each time it is used as a tiny bit of the Lead paste 'dies' in the process.

 

A car modern car battery doesn't do any real work. A modern car engine starts in about 3 seconds. This takes the charge from the battery in what is commonly referred to as 'Plate Surface discharge'.

Effectively just draws off what is 'stored' in the surface of the plates without any real chemical reaction taking place to produce the electricity.

So putting this 'surface charge' back doesn't, generally although not this simple in real terms, involve any chemical reaction to put it back. Because the lead paste has not changed 'chemically' there is little degradation in it's state. Resulting in almost zero real 'use'.

 

That all changes if the engine begins to suffer issues and takes longer to start, is left a longer period of time between use or if the lights are left on, etc.

 

So while a charge/discharge cycle for a Car starter battery might not include 'light' use', your definition of a cycle in relation to a leisure battery is more accurate.

It is any discharge and recharge no matter how small or large.

 

 

The industry generally regard a battery as expired once it will no longer return more 80Ah per 100Ah battery on a cycle.

 

It is regarded as past it, even though it may still hold a charge, because dropping such a battery down to 50% (i.e. leaving 50Ah left in the battery) yields just 29Ah per cycle, not so useful?

 

You can go on using the battery and it will behave as per normal but will appear to discharge quickly, maybe only giving two nights 'off grid' not the previous 4 nights?

 

Veletrons batteries are exhibiting signs of being expired.

 

Exide give three figure for the G80 series 50% DOD = 900 cycles, 75% DOD gives 500 cycles, 80% DOD = around 200 cycles.

The graph they publish suggests that 1,300 cycles are available if the battery is only 20% discharged. If fully discharged it returns just a handful of cycles.

 

Clearly Deep discharging a battery affects it's life massively.

 

Varta quote their charge/discharge cycles as ones down to 50% DOD and back, I think for the Varta LFD90 it is 300cycles?

Obviously that wouldn't be the 'end of the batteries life' as there would still be a number of shorter cycles available.

 

We think the Budget battery manufacturers include 'short cycles' that go below the Industry norm in their figures. So Ying Jon Wii battery company might quote 200 cycles, some of which will return less than 19Ah on a 100Ah battery.

 

The manufacturer may also 'turbo' charge a battery at 16v just prior to a test to inflate the batteries true capability. The battery will be damaged long term but can give a 10% higher charge/discharge figure purely to inflate the test figures in the laboratory.

We think this is done in some of the Budget 110Ah batteries.

 

As Veletron says there isn't an industry standard definition so 'open to interpretation'.

 

However, there are other factors that come into play that can effect the on paper laboratory test figure by a major margin, as much as 70%.

 

When a the typical motorhome battery ages, the internals of the battery degrade for other reasons than 'Paste death', like corrosion, Antimony poisoning, Sulphation, etc.

 

Factors that will all reduce a batteries real life.

 

So a battery, like the G80 that has a paper figure of 500 cycles in the Laboratory, might reach only 300 true cycles in real use through corrosion.

 

While a Powerframe technology battery might not match the G80 in the laboratory, it doesn't suffer the corrosion that impacts all other Motorhome batteries. Bosch and Varta claim up to 70% better electrical flow than it's nearest rival once past a year or two of use.

 

If a Far East battery is going to lose 70% of the electrical flow getting the power out of a battery, you can imagine just how many amp hours will make it to habitation area Lights, even if the internals have 45Ah to give?

 

A battery can have very little Paste degradation so near 'full' capacity, but if Corrosion has coated the Grids blocking that electrical flow, then it won't all make it out of the battery. See the Bosch photo attached of how bad it can be on a conventional battery.

 

Battery behaviour in a laboratory test is very different in the real world, because so many other factors come into play..

One of the reasons a Powerframe Bosh L series/Varta LFD range perform beyond normal expectations.

 

 

The NCC battery approval scheme takes little of this into account.

 

 

[Tracker]

Many thanks for taking the time and trouble Alan, and what you say does make sense!

 

Shame we don't live in a perfect world where manufacturers are all honest about their products and nobody feels the need to exagerate their product's abilities or to be economical with the truth just because everyone else does and they feel the need to compete?

 

How much is the ferry to Utopia!!