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My experience last 12 months tells me that is a recipe for disaster.... I had 4x big expensive AGMs fitted to my boat last year by a well known professional marine electrics company and they made

What type of boat are you building?   Money no object,  no question, Lithium titanate for any purpose.   Otherwise for a cruiser/liveaboard Lithium Iron Phosphate or Lead carbon from a reput

Go for the Lead Carbon. There are a couple of options to suit budget. Far faaaar better choice and If money is not so important, get a Narada.
https://www.trademe.co.nz/motors/caravans-motorhomes/parts-accessories/batteries-inverters/listing-2783275888.htm?rsqid=e874c0e0720b4a22874022a1c89aa82f-002

A slightly cheaper option but still high quality is this one.
https://www.trademe.co.nz/motors/caravans-motorhomes/parts-accessories/batteries-inverters/listing-2784737863.htm?rsqid=eb8e62c0c1b945db9b98bfd46ade5234-002

And cheaper again, but still good
https://www.trademe.co.nz/motors/caravans-motorhomes/parts-accessories/batteries-inverters/listing-2784066448.htm?rsqid=eb8e62c0c1b945db9b98bfd46ade5234-002
 

If budget is a concern, there are some Chinese versions.
https://www.trademe.co.nz/motors/caravans-motorhomes/parts-accessories/batteries-inverters/listing-2778133347.htm?rsqid=eb8e62c0c1b945db9b98bfd46ade5234-002

If you want to go Gel, this is a "new guy in town" battery.  Personally I don't like Gel for House duty. But this one seems ti have all the right specs
https://www.trademe.co.nz/motors/caravans-motorhomes/parts-accessories/batteries-inverters/listing-2778141124.htm?rsqid=8c3f2ebcb204491dbf4a4bf63ac599cb-003

And this one.
https://www.trademe.co.nz/motors/caravans-motorhomes/parts-accessories/batteries-inverters/listing-2784066015.htm?rsqid=f99088d5dd764531958d8c204ff1b193-001

There are many others if you want to take a look. It really comes down to what you want to spend

 

 

 

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Thanks Wheels. My concern with the Lead Carbon was supposedly needing different charging gear which I am not interested in doing. This is based on comments in the recent thread on crew re these batteries.

I am "technically challenged" (retarded) so I am not interested in trying to understand all this technology. I just want a plug and play type deal.

My charge controller is an  Epever 30a which I am sure has a setting for agm.

The prices for the two AGM's you linked look good.

 

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No you don't need anything special with lead carbon. Only Lithium requires specific charge equipment. And that is why I did not suggest Lithium. It is more expensive than just the very expensive battery.
The advantage with Lead Carbon is that you can charge with all the standard gear you have. But as it will accept a higher charge current compared to standard LA, then you can use bigger charge gear if you so wish. Thus if you are buying a charger, you would want to get something close to the batteries max input charge rating to take advantage of this. If you already have the charge gear, then stick with what you have. 

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16 minutes ago, wheels said:

No you don't need anything special with lead carbon. Only Lithium requires specific charge equipment.

Thats not totally correct.  The first battery in your links above, the Narada has a cycle voltage of 13.8v and float of 13.5v @25 degress C on the spec sheet in the image,  That will require a charge controler that is set up with custom charge profile, by someone that knows what they are doing. I would highly recommend a temp sensor if you went down this path.

 

If you just want a good AGM then you are looking for a AGM deep cycle battery that weights a lot for its capacity. It's hard to get away from the physics with lead acid chemistry, this is a area where there are no free lunches. I personally like the Yhi vision Fm battery's,  but they arent the cheapest.  If you have a google and compare their weight vs Ah rating it would be a good guide for your shopping and comparisons.  

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57 minutes ago, mcp said:

Thats not totally correct.  The first battery in your links above, the Narada has a cycle voltage of 13.8v and float of 13.5v @25 degress C on the spec sheet in the image,  That will require a charge controler that is set up with custom charge profile, by someone that knows what they are doing. I would highly recommend a temp sensor if you went down this path.

 

If you just want a good AGM then you are looking for a AGM deep cycle battery that weights a lot for its capacity. It's hard to get away from the physics with lead acid chemistry, this is a area where there are no free lunches. I personally like the Yhi vision Fm battery's,  but they arent the cheapest.  If you have a google and compare their weight vs Ah rating it would be a good guide for your shopping and comparisons.  

Agreed. I have the charge profile but don't like Max current of 75A with Naradas.

Means I have to derate my DIY alternator/smart charger setup so all I get is PSOC tolerance and a longer, relatively higher average absorb current as the  Amps/time curve is different. So charge time will be about the same.

Hard to toss out $1400 FLA's that are bullet proof too.

2x Fireflys G31 @115Ahrs (12V) $1080 +500 freight +15% = $1817/0.65= $2800NZ

Freight will probably be more.

Naradas definitely look attractive then at half the price for another 70Ahrs,   and no need to change your belt drive that will be required for sustained 100A+ charging.

Maybe someone on crew has tried Narada’s and can offer their experience?

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2 hours ago, Sabre said:

Thanks Wheels. My concern with the Lead Carbon was supposedly needing different charging gear which I am not interested in doing. This is based on comments in the recent thread on crew re these batteries.

I am "technically challenged" (retarded) so I am not interested in trying to understand all this technology. I just want a plug and play type deal.

My charge controller is an  Epever 30a which I am sure has a setting for agm.

The prices for the two AGM's you linked look good

 

My experience last 12 months tells me that is a recipe for disaster....

I had 4x big expensive AGMs fitted to my boat last year by a well known professional marine electrics company and they made the schoolboy mistake of assuming all AGMs are the same. So they installed them and made sure all my charging systems were set you AGM (engine, shore, solar) and declared it “job done”.

9 months later I noticed performance dropping off and at 10 months my shiny new AGMs were taken off the boat, bench-tested by the official supplier and declared dead.

The cause was at time of installation the marine electricians should have looked at the exact product spec for these batteries and compared it with the exact product specs for the chargers on my boat the ensure they would give charging outputs within required spec of the batteries. They failed to do this. The difference was only around 0.3v (undercharging for bulk, absorption and float) but over 9-10 months the accumulated effect was enough to kill the whole bank of 4x new AGM batts.

So don’t make the same mistake!

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Good catch mcp. You are correct. As usual, these subjects are always more complicated than simple explanations.
The Epever has a user defined set up. So I am pretty sure it can be configured to suit. In saying that, it may well be more complicated and involved than Sabre wishes to get.
However, as said just above in Aleana's post, AGM's are not all created equal either. The specs are extremely important to understand and the charger needs to be set up just right, or the batteries will die in a very short time.

Sabre, it is probably well worth buying from someone that can install and also set up the charger for you.

5 hours ago, lateral said:

Agreed. I have the charge profile but don't like Max current of 75A with Naradas.

Sooo, what were you charging before. The LC batteries should accept a much higher Charge Current than any FLA of same Ahr capacity.
You do not have to charge at the full charging current. If you are currently charging FLA with say 50A, then the LC batteries will charge just fine. (not factoring the voltage as in the above discussion)It is just that they are capable of taking much more. If we look at the Narada, they are only 6V Batteries, so you need 2 to get 12V. Thus they are capable of handling 140A being fed into them.

I didn't consider Firefly as I don't know of a NZ supplier.

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I believe that you are one of many Aleana, a year ago I did a lot of research on AGM batteries as I needed a good reliable start battery for a classic car that did not have room for a properly sized FLA. I discovered that one Auckland marine sparky crowd had been supplying sets of AGM batteries (of good quality) to a number of craft but not checking on the boats charging regime. For these batteries to last and give the paid for life -your charger has to be capable of charging at a rate of over 24% of the batteries A/H rating -when required in the bulk phase. To ignore this  little fact is to accept very much shortened life and battery performance.  Only this week I discovered another boat set up this way.

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