agm or acid

[naz2017]

any advise please

I need to replace three aux batteries was wondering if anyone thinks AGM are any better than acid

if anyone has any pros and cons

thanks

[Tony Brooks]

Unless you are far more specific about what type of battery you call "acid" we can not give a valid answer. My guess is that you mean a wet open cell battery but even then it is not much help.  These run from car type starting batteries through leisure types and semi-traction to AGMs, gels, spiral wound to full traction. All contain acid in one form or another. Ten there are lead calcium or lead antinomy designs. I guess you mean fairly cheap lean calcium  leisure batteries. If not come back and be more specific.

Point 1 is that however much you pay you will destroy an expensive battery virtually as fast as a cheap battery if you do not take proper care of it,  especially ensuring it is kept as fully charged as possible and never deeply discharging it.  If you have no means of battery monitoring and no means of non-engine charging you may as well buy cheap.

Point 2 is that wet open cell batteries are easy for an ordinary boater to diagnose/test when compared with sealed types like AGMs.

Point 3. If you have an Amp Hour counting battery monitor and you do not fully understand how it works, how to set and reset it, and its shortcomings it will be your battery supplier's best friend in encouraging you to ruin batteries.

Point 4 If you have a charger capable you can equalise (charge for a short time at a higher than normal voltage) open cell batteries. This may produce a longer useful life. Normally you can not do this on any from of sealed batteries.

Now to answer your question. I want an easy way to test and diagnose my batteries so despite some advantages for AGMs I use wet open cell batteries from a well known brand. Others will differ in their views and so would I if my batteries were not easy to get at for maintenance. If being sealed is important to you then AGMs or sealed versions of open cell batteries may be more appropriate.

Please take on board my comments about the ease of ruining expensive batteries as fast as cheap ones.

It may make better sense to put the money saved by buying wet open cell batteries towards solar  charging.

 

[Robbo]

1 hour ago, naz2017 said:

any advise please

I need to replace three aux batteries was wondering if anyone thinks AGM are any better than acid

if anyone has any pros and cons

thanks

A better question would be.  What type of batteries are best for me.  As no one battery type suits all situations.   It helps if we know, 

Power Usage (daily average)

Peak power usage (and for how long).  Microwave / washing machines, etc.

Charging methods (both summer and winter).   If using genny, how often can you or want to charge?

Maintenance free or not?   Do you just want to install and forget even tho this may cost extra?

Amount of battery space available (including height)

 

 

Edited April 3, 2017 by Robbo

[stegra]

AGMs seem to have come down a lot in price which makes them much more difficult to dismiss as an option. Large variety of 110Ah AGMs at little over £100 available now.

[rusty69]

1 minute ago, stegra said:

AGMs seem to have come down a lot in price which makes them much more difficult to dismiss as an option. Large variety of 110Ah AGMs at little over £100 available now.

I was caught out recently buying a budget AGM. It was not rated at the 20hour rate, so do read the manufacturer spec sheet if you go this route. 

[Dave_P]

2 hours ago, Tony Brooks said:

 

It may make better sense to put the money saved by buying wet open cell batteries towards solar  charging.

 

This is the route I took.  I have 3 x 110ah standard leisure batteries and 525w of solar.

From late feb to early nov the solar provides enough electricity (apart from occasional things like a vacuum cleaner).  I just make sure my resting voltage doesn't go below about 12.3v when I go to bed.  Next day the solar brings them back up.  I expect to replace my batteries every few years and don't worry about them much more than that.

 

[Neil2]

It's a very broad question so a very broad answer is "wet" batteries make a lot more sense if you have an efficient charging/maintenance set up.  Most narrowboat owners don't so as the cost of "sealed " batteries comes down they are probably a better choice as they stand a bit more abuse and charge up faster that's a sweeping generalisation of course.  

I think the case for sealed batteries on narrowboats is strengthened by the sheer inaccessibility of many battery banks.  I've seen boats made by so-called respected builders where the batteries are placed in such a location that routine maintenance - even just checking the voltage - is virtually impossible.   

I'd emphasise the point, made many times on this forum, that solar power is the best way to extend battery life, it's so cheap these days the only reason not to have solar panels is aesthetics.   

[MtB]

On 03/04/2017 at 09:34, Neil2 said:

It's a very broad question so a very broad answer is "wet" batteries make a lot more sense if you have an efficient charging/maintenance set up.  Most narrowboat owners don't so as the cost of "sealed " batteries comes down they are probably a better choice as they stand a bit more abuse and charge up faster that's a sweeping generalisation of course.  

I think the case for sealed batteries on narrowboats is strengthened by the sheer inaccessibility of many battery banks.  I've seen boats made by so-called respected builders where the batteries are placed in such a location that routine maintenance - even just checking the voltage - is virtually impossible.   

I'd emphasise the point, made many times on this forum, that solar power is the best way to extend battery life, it's so cheap these days the only reason not to have solar panels is aesthetics.   

 

Greenie for that. I was about to make all the same points.

One thing though, there is a tendency in this thread to conflate AGM batteries with 'sealed for life' batteries. They are chalk and cheese.

Yes AGMs are sealed, but 'sealed' batteries are not necessarily AGM.

Batteries described simply as 'sealed for life' are usually just ordinary lead acid wet cell batteries with the caps glued down to stop the user having access to the acid. The worst of all options.

[Neil2]

1 hour ago, Mike the Boilerman said:

 

Greenie for that. I was about to make all the same points.

One thing though, there is a tendency in this thread to conflate AGM batteries with 'sealed for life' batteries. They are chalk and cheese.

Yes AGMs are sealed, but 'sealed' batteries are not necessarily AGM.

Batteries described simply as 'sealed for life' are usually just ordinary lead acid wet cell batteries with the caps glued down to stop the user having access to the acid. The worst of all options.

Yes of course, I agree it's an inappropriate shorthand for AGM/Gel batteries I presumed the OP knows the difference.

 

[MtB]

On 03/04/2017 at 11:48, Neil2 said:

Yes of course, I agree it's an inappropriate shorthand for AGM/Gel batteries I presumed the OP knows the difference.

 

 

Even AGM and gel are two different battery types with different characteristics.

From the Victron book:

 

"The sealed (VRLA) gel battery Here the electrolyte is immobilised as gel. Familiar as the Sonnenschein Dryfit A200, Sportline or Exide Prevailer battery. 

The sealed (VRLA) AGM battery AGM stands for Absorbed Glass Mat. In these batteries the electrolyte is absorbed (“sucked up”) into a glass-fibre mat between the plates by capillary action. In an AGM battery the charge carriers, hydrogen ions (H2) and sulphate ions (SO4), move more easily between the plates than in a gel battery. This makes an AGM battery more suitable for shorttime delivery of very high currents than a gel battery. Examples of AGM batteries are the Concorde Lifeline and the Northstar battery."

https://www.victronenergy.com/upload/documents/Book-EN-EnergyUnlimited.pdf

[Neil2]

11 minutes ago, Mike the Boilerman said:

 

Even AGM and gel are two different battery types with different characteristics.

From the Victron book:

 

"The sealed (VRLA) gel battery Here the electrolyte is immobilised as gel. Familiar as the Sonnenschein Dryfit A200, Sportline or Exide Prevailer battery. 

The sealed (VRLA) AGM battery AGM stands for Absorbed Glass Mat. In these batteries the electrolyte is absorbed (“sucked up”) into a glass-fibre mat between the plates by capillary action. In an AGM battery the charge carriers, hydrogen ions (H2) and sulphate ions (SO4), move more easily between the plates than in a gel battery. This makes an AGM battery more suitable for shorttime delivery of very high currents than a gel battery. Examples of AGM batteries are the Concorde Lifeline and the Northstar battery."

https://www.victronenergy.com/upload/documents/Book-EN-EnergyUnlimited.pdf

Yes they are different but in the context of a domestic battery bank on a narrowboat I have yet to hear a convincing argument for one or the other.  If anyone thinks they know different I would be very interested as I have to make a decision on battery replacement in the fairly near future.