Jump to content

For Battery Techno Heads


aandncaravan

Recommended Posts

I knew that batteries took a few charge/discharge cycles to reach full capability, but I thought that was only in the region of 10 - 20 cycles.

 

The attached graph was supplied by a battery manufacturer and shows that this particular battery takes over 60 charge/discharge cycles to reach peak capacity, or 50 cycles for 100% capacity.

It also shows that the battery starts off at just 85% capacity.

 

I have no reason to believe this isn't typical Wet Acid battery behaviour.

 

Has anyone seen similar graphs for Gel and AGM technology, I wonder if they behave differently?

 

You might note in the graph that the manufacturer seems to be counting every cycle right down to 50% capacity, even though 50% is the recommended minimum Depth Of Discharge and won't actually deliver any real power.

 

When the battery has dropped to 51% capacity, that is to say it's capacity is just 51Ah on a 100Ah battery, a cycle would yield only 1Ah on this battery if you only discharged the battery to the recommended 50% Depth Of Discharge (DOD).

Not exactly a useful cycle.

 

If you look at the graph the number of cycles that deliver more than 80% capacity (even then with only 30Ah usable power) is only 160 cycles versus the manufacturers claimed 220 cycles.

 

 

Allegedly the likes of Yuasa, Varta, etc only rate their batteries cyclic ability where a cycle will deliver greater than 80% capacity. When a battery falls below 80% capacity the battery is regarded as exhausted and End Of Life.

 

One battery manufacturers 220 cycles down to 50% Capacity (with some cycles delivering as little as 1Ah) is not equivalent to another's 200 cycles where in each cycle delivers at least 85Ah.

At the moment cyclic comparisons between manufacturers are meaningless with some manufacturers deliberately misleading customers.

 

 

While I have got you guys here, can I ask a favour?

 

We are working with Manbat to create a new Code of Practice for Leisure batteries and one of the things we want adopted is the definition of a Cycle as being at least 80% battery capacity.

 

 

Please can we ask you to suggest other ideas we can try and get adopted?

 

So far we have the ideas on this page :

http://www.aandncaravanservices.co.uk/campaign-for-battery-change.php

 

 

120498593_CapacityvsCyclessmall.jpg.3518a6b1b5627c757da185d56876db7d.jpg

Link to comment
Share on other sites

Allan,

 

More excellent information and thank you for keeping it coming in the face of challenges, and I'm glad you are now working with ManBat to try and highlight the big issue of alleged capacities.

 

Have a read of this which I picked up from an email earlier today...

 

https://www.roadpro.co.uk/catalogue/02b02-banner-energy-bull-batteries

 

Keith.

 

PS And you need to read the FAQ page for the real info!

Link to comment
Share on other sites

Keith, thank you.

How can Roadpro get away with saying,

"Banner "Energy Bull" batteries are probably the best wet lead-acid leisure batteries you can buy"?

 

I wonder if Victron Energy or Trojan have seen the advert?

 

 

At least Roadpro are no longer claiming that these Banner batteries are maintenance free, but to still say,

"evaporation of the electrolyte will be minimal..........." when the whole World now knows they are one of the thirstiest Leisure batteries ever made!!!

 

 

But the best is,

"“Energy Bull” batteries don’t need to do this ( have a external venting pipe) as they are “recombination batteries”..........."

That is an absolute load of Bull%$!@, they are absolutely NOT recombination batteries they are the most prolific gassing batteries we have ever encountered!!!

Exactly as you would expect from a high fluid loss battery.

 

They also make a big deal about the Banners being better than all others because they are guaranteed freshly manufactured so won't have discharged, and degraded, in storage.

Yet the Banner energy Bull is the fastest deteriorating battery in storage we have ever come across.

 

Because of it's high Antimony content it self discharges more quickly than even the budgets so can be down to damaging charge levels inside 3 months. Yes it is important that most batteries are bought 'fresh' but it is super, ultra important for a Banner Energy Bull battery.

 

The same High Antimony content makes it unsuitable for Long term EHU connection/permanent Solar charging where Antimony poisoning destroys the battery.

 

A great example of why we need better battery labelling that allows a consumer to see how well a battery matches the marketing, or in this case doesn't.

 

 

Link to comment
Share on other sites

Allan,

Two other parameters that I can think of that will affect capacity characterisation measurements are battery test temperature and discharge current.

Characterisation at say 0degC will give quite different results than say at 40degC. It would be nice to specify the test temperature at 25degC if possible (+/- 5degC maybe?).

Battery capacity will vary if you discharge at C/20 than it would at C/5. C/20 will give a higher capacity than the C/5 figure. C/20 for a 100AH battery means a 5Amp discharge current which is probably reasonable for most users (unless they use something like a big inverter). Whoever does the testing would probably prefer the higher discharge rate so that can get the testing done quicker though.

 

Phil

Link to comment
Share on other sites

Phil, Yes I agree, both good points.

 

I had in my head that the manufacturer would specify the ideal current for both charge and discharge that works for their particular battery build.

But while they specify the 'ideals' and 'maximums' which the consumer may adopt, that doesn't mean they have not themselves used an ultra low 3amp charging current and a 3amp discharge current at the optimum low temperature to achieve the best cycle life figures.

 

As you say Temperature can affect things, just a rise in 10 degrees can reduce a batteries life by years.

 

So should the definition of a 'Cycle' also specify the current/voltage for both the cycles charge and discharge? Should it also specify a temperature.

 

As you say the number of cycles a Battery can achieve at 0 degrees may be double that at 30 degrees.

 

 

Ideally we want to make it quite tough to create realistic figures for someone using the Motorhome in Spain, so stipulate a 30 degree evaluation rig, but that might mean the Manbat batteries would appear excessively under performing compared to batteries that have been 'rated' using the existing most ideal, low temperature and low current conditions.

 

If that is the case then Manbat may resistant putting themselves at such a marketing disadvantage.

 

I think, but need to think about this some more, that I would rather go for weaker standards initially, just to get some improved change, and then try and uprate the standards later.

 

Maybe tackle this by having dual information labels, with the old and new together?

I will have a think.

 

Thank you, that was a good one.

 

 

 

Link to comment
Share on other sites

Interesting, if a bit bewildering, reading Allan, and I heartily applaud your efforts on behalf of everyone.

 

Dare I venture to suggest that at least as far as batteries destined for leisure use is concerned that what is really needed is a way to determine what is needed by the end users?

 

In an ideal world a battery that will not self discharge much over lengthy periods of non use, will resist being knackered by occasionally being run flat and left discharged, and will have longevity whether it be very partially or heavily discharged and recharged - and a definitive way of comparing different makes would be good too!

 

And then I woke up from the dream!

Link to comment
Share on other sites

Tracker - 2018-03-18 11:48 AM

 

Interesting, if a bit bewildering, reading Allan, and I heartily applaud your efforts on behalf of everyone.

 

Dare I venture to suggest that at least as far as batteries destined for leisure use is concerned that what is really needed is a way to determine what is needed by the end users?

 

In an ideal world a battery that will not self discharge much over lengthy periods of non use, will resist being knackered by occasionally being run flat and left discharged, and will have longevity whether it be very partially or heavily discharged and recharged - and a definitive way of comparing different makes would be good too!

 

And then I woke up from the dream!

 

 

One of the reasons we don't like the Banner Wet battery range is because they Self Discharge so quickly causing the issues you describe, so rest assured that a Self Discharge rating is on the list.

 

 

It is a bit of Dream (turning into a nightmare?) that may not go very far, but worth bashing my Head against a Brick Wall for a short time at least. Being Hard Headed does have some value.

 

 

 

 

Link to comment
Share on other sites

Archived

This topic is now archived and is closed to further replies.

×
×
  • Create New...