Replacing leisure batteries

[Dr Bob]

5 hours ago, Dr Bob said:

Read the battery primer that Wotever wrote ....linked to in an earlier post...he knows what he is talking about.

 

Go back and read through the thread and pick out all Wotever's posts. Make sure you have answered his questions fully. He is your Guru here.

To Tony R. Please read what wotever wrote about plate shedding. Construction of lead acid batteries has changed considerably since 1975. I would never dream of letting my batteries go lower than 12.1v.

[rusty69]

WotEver 

[Mariner]

Looking for information on effects of discharging down below~ 10 Volts, I found the website of Northern Arizona Wind and Sun. They have an FAQ’s on Deep Cycle Batteries;

https://www.solar-electric.com/learning-center/batteries-and-charging/deep-cycle-battery-faq.html#Battery%20Voltages

In a section entitled “Why 10.5 Volts” (which I have edited, but visit it yourself)

“Throughout this FAQ, we have stated that a battery is considered dead at 10.5 volts. After it gets below 10.3 v you only have 35 mins of anything useful available from the battery.

The battery is now dead and most likely will not fully recover”.

 

The keyword here is "fully". If someone has a boat and operates the batteries so that by the end of each night the batteries are below 10.5V, those batteries will show decreasing capacity and poor lifespan.

I did have a look on the Rolls website to see if they suggest a minimum voltage but could not find anything there. Maybe I'll mail them.

[WotEver]

44 minutes ago, Mariner said:

What I said in post 66 was "This damages the battery and will reduce its performance and shorten its life".  I did not say deep discharge totally destroys the battery

More significantly you wrote:

4 hours ago, Mariner said:

discharging them below 10V and at some point the battery is supplying power by means of an irreversible chemical action (i.e. it's working as a "Primary Cell".

... which is, quite simply, incorrect. 

 

Take a look at any battery manufacturer’s performance charts and (as you might expect) the number of cycles decreases in line with the depth of discharge. Once you regularly go below 12.2V (approx 50% DoD/SoC) the number of cycles decreases more rapidly. This has absolutely nothing to do with an irreversible electrochemical process and everything to do with corrosion. 

[Alan de Enfield]

4 minutes ago, Mariner said:

Looking for information on effects of discharging down below~ 10 Volts, I found the website of Northern Arizona Wind and Sun. They have an FAQ’s on Deep Cycle Batteries;

There are very few 'deep cycle' batteries used on boats I would suggest that 99%+ use standard 'leisure' batteries which in many cases are simply re-badged starter batteries.

 

Deep cycle (traction) batteries will take some severe abuse.

Semi-Traction (such as Rolls) will take 'some' abuse

Standard 'leisure' batteries need looking after very carefully and rebel in a big way if the SoC drops much below 50%

Edited May 11, 2018 by Alan de Enfield

[Tony Brooks]

Remember that the vast majority of inland boaters do not use true deep cycle batteries. Most are glorified start batteries while even the Trojan 105s often spoken well on on here are I believe a form of traction battery.

 

Alan got in first.

[Mariner]

7 minutes ago, WotEver said:

 This has absolutely nothing to do with an irreversible electrochemical process and everything to do with corrosion. 

Corrosion is an irreversible electrochemical process. That pin-head you are standing on looks very small.

 

Regarding deep cycle, surely is refers not to discharging a battery to anywhere near zero volts but simply towards even 10.5V. Again, there is literature around that the number of cycles generally diminishes with the extend to which the battery is routinely discharged. Batteries can be optimised for different functions but the underlying chemistry is the same.

Edited May 11, 2018 by Mariner

[WotEver]

13 minutes ago, Mariner said:

I did have a look on the Rolls website to see if they suggest a minimum voltage but could not find anything there.

You’ll probably find that they publish figures for a maximum DoD of 80%, which is about 11.7V.  10.5V is flat. 

 

I never said that Rolls publish that you can take their batteries down to 0.5V, it’s a stupid thing to do. What I know is that in bench tests after being discharged to 0V and then recharged back to 100% SoC they demonstrated no adverse effects. 

7 minutes ago, Mariner said:

Corrosion is an irreversible electrochemical process.

Of course it isn’t. It’s a physical process. You wrote “an irreversible chemical reaction”. Do you not understand the difference between chemistry and physics?

Edited May 11, 2018 by WotEver

[Mariner]

4 minutes ago, WotEver said:

You’ll probably find that they publish figures for a maximum DoD of 80%, which is about 11.7V.  10.5V is flat. 

 

I never said that Rolls publish that you can take their batteries down to 0.5V, it’s a stupid thing to do. What I know is that in bench tests after being discharged to 0V and then recharged back to 100% SoC they demonstrated no adverse effects. 

Of course it isn’t. It’s a physical process. Do you not understand the difference between chemistry and physics?

At this stage, I will simply let others judge your "personal views" for themselves. At least for the time being!

[WotEver]

1 minute ago, Mariner said:

At this stage, I will simply let others judge your "personal views" for themselves. At least for the time being!

Nope, that won’t work. I always leave personal feelings out of any discussion of this nature as other posters will well know. I simply called you out on your ridiculous assertion that a lead acid battery becomes a primary cell at very low voltages. Because it doesn’t. 

[WotEver]

17 minutes ago, Mariner said:

Batteries can be optimised for different functions but the underlying chemistry is the same.

But the physical construction is not the same. Again, you demonstrate that you don’t appreciate the different physical characteristics of different lead acid batteries. 

[Dr Bob]

4 minutes ago, Mariner said:

At this stage, I will simply let others judge your "personal views" for themselves. At least for the time being!

Wotever is not a chemist so does get confused over Chemistry type thingys like corrosion being a chemical process. I understand what you are saying (I have a PhD in Chemistry) BUT he is totally right about his facts on batteries. He is an expert on batteries. What you heard in 1975 may have been totally out of context for what we have today. The chemistry is complex and not fully understood. The corrosion/errosion are words used that are likely out of context and describe a physical process that is occuring in the batteries....so not the normal corrosion reactions you are used to. Pore shapes, depths, blocking, steric hinderance all come into play and likely our pretty poor lesiure batteries will be well knackered once those pores are fully gummed up with sulphate...never to recover. Dont believe what a Chemistry professor told you in 1975. Look at the evidence generated in the last 10 years.

[WotEver]

2 minutes ago, Dr Bob said:

The corrosion/errosion are words used that are likely out of context and describe a physical process that is occuring in the batteries...

The plates bend. The paste falls off the bent plates. That’s a physical failure, not an irreversible chemical process. 

And no, I’m not a chemist. I failed chemistry O level. I passed Physics A level though

 

[Mariner]

5 minutes ago, Dr Bob said:

 Look at the evidence generated in the last 10 years.

Fair comment, limited only by the fact that I now have to hand over my personal cash to get copies of (most) published papers in journals and that information found on the web is not edited or reviewed but is often presented in the context of trying to sell products. But it was Wotever who raised peer review papers and if someone wants to give me copies of such, I'll promise to read them! Dan Eley's use of the term "primary cell" is clearly not to everyones liking, but who wants to stand up in court and say it was wrong!

 

IS Wotever associated with any specific battery companies... maybe Rolls?

[WotEver]

3 minutes ago, Mariner said:

IS Wotever associated with any specific battery companies... maybe Rolls?

No, and no. 

 

I mentioned Rolls simply because tests taking a couple of Rolls batteries down to 0.5V and recharging resulted in no loss of performance. I’m sure many others would demonstrate a similar performance. Proving that they didn’t behave like a primary cell at all. 

 

My comment about peer reviewed papers was with reference to snake oil high frequency desulphators. 

[Mariner]

IN post 74, Wotever stated

 

It is possible to discharge a quality deep cycle battery such as a Rolls all the way down to 0.5V and then recharge it all the way back up to 12.6V, If that recharge is performed immediately following the discharge then the battery also won’t demonstrate any significant corrosion or sulphation.

On that basis, I mailed the following enquiry to Rolls;

 

 

Hi, I am just about to buy marine batteries for the first time. A colleague recommended Rolls. I had always believed that discharging a battery below ~10.3 volts did some degree of permanent damage (perhaps small, but accumulative if this re-occurs). He tells me that your batteries have been shown to be able to discharge down to voltages as low as 0.5V (perhaps repeatedly?), with no adverse effect if immediately re-charged. Can you confirm which of your battery type is able to do this?

 

This is the reply from Rolls

 

"Yes and No... Yes in the past we've been able to do this, but every time you do some damage results.   

 

That damage is usually heating/corrosion on the plates.   This damage is cumulative, and if you keep doing so it will significantly reduce the life of the battery, regardless of make or manufacture. 

Wish I could tell you otherwise, but I be lying to you if I did..."

Regards, Steve Higgins, Technical Service Manager

 

So Wotever the “battery expert” says no significant damage and Rolls say every time there‘s damage and it’s accumulative.

 

As (yet) another PhD in chemistry (corrosion), that's what I expected. Godspeed Dan Eley!

This is a great forum!

 

 

[WotEver]

21 minutes ago, Mariner said:

Yes and No... Yes in the past we've been able to do this, but every time you do some damage results.   

Of course. Why did you expect otherwise?

22 minutes ago, Mariner said:

perhaps repeatedly?

No, I never said that. That was your addition. 

 

Thats still not primary cell behaviour, now is it?

[WotEver]

34 minutes ago, Mariner said:

So Wotever the “battery expert” says no significant damage and Rolls say every time there‘s damage and it’s accumulative.

Yes, that’s correct it’s not significant, and on a single cycle not measurable, but if you keep doing it you’ll buckle the plates and the paste will fall off. 

 

ETA and that’s STILL not primary cell behaviour, it’s physical damage caused by abuse. 

Edited May 11, 2018 by WotEver

[Mariner]

I replied to Rolls;

 

Thanks for the honesty Steve. I’m a PhD in chemistry so it fits in with everything I’ve picked up about lead acid batteries this last 40 years.

When I get my boat, I’ll certainly be looking for Rolls batteries, which I’d already picked up as being highly rated in the UK.

Best

 

Wotever, are those some species of dogs in your avatar- hard to tell.

[WotEver]

8 hours ago, Mariner said:

it fits in with everything I’ve picked up about lead acid batteries this last 40 years.

Where then does it say that it will behave like a primary cell and will be destroyed and only good for recycling once the voltage drops below 10V?

 

It doesn’t, because that’s not what happens. You appear to think you’ve found a Eureka moment but all the tech was commenting on is the well known fact that the deeper you discharge a LA battery the shorter its life. It’s not a straight curve and excessively deep discharging will shorten its life more rapidly.  At no point however do the batteries magically become a primary cell. 

 

8 hours ago, Mariner said:

Wotever, are those some species of dogs in your avatar- hard to tell.

Two Yorkie pups. They’re 9 years old now. 

[bizzard]

11 hours ago, Dr Bob said:

To Tony R. Please read what wotever wrote about plate shedding. Construction of lead acid batteries has changed considerably since 1975. I would never dream of letting my batteries go lower than 12.1v.

In 1975 batteries had lovely cell connectors on top, ideal for testing bulbs and things of different voltages, and could be used for speed controlling on 12v model railways.    They also had proper tangible stopper knobs.

[WotEver]

1 hour ago, bizzard said:

In 1975 batteries had lovely cell connectors on top, ideal for testing bulbs and things of different voltages, and could be used for speed controlling on 12v model railways.    They also had proper tangible stopper knobs.

You could drill & tap those interconnects to feed your 6V ‘appliances’

 

Oh, the days of ‘flashing’ a dynamo when you changed over to negative earth. 

 

Kids today, eh?

 

Edited May 12, 2018 by WotEver
It was a mess...

[bizzard]

1 hour ago, WotEver said:

You could drill & tap those interconnects to feed your 6V ‘appliances’

 

Oh, the days of ‘flashing’ a dynamo when you changed over to negative earth. 

 

Kids today, eh?

 

Not forgetting to swap the coils LT leads over.

[WotEver]

57 minutes ago, bizzard said:

Not forgetting to swap the coils LT leads over.

And the ammeter if you have one. 

[MtB]

3 hours ago, bizzard said:

In 1975 batteries had lovely cell connectors on top, ideal for testing bulbs and things of different voltages, and could be used for speed controlling on 12v model railways.    They also had proper tangible stopper knobs.

 

You can still get those.  My mate just acquired a new one and fitted it in some old Rolls Royce he has lying around in his workshop.