Will AGM batteries be ok with my cruising style?

[Tim Good]

We have 360w solar and a Victron MPPT which has an AGM setting. Our Freedom Heart charger also has an AGM setting.

We spend most of the time on the hook, fridge but no freezer. Main autopilot is hydrovane. We'll be heading south from the UK to cross Atlantic this year so sun should be relatively plentiful. Do you think I'll regret moving away from wet lead acid to AGMs? Should I just stick with decent Trojan wet flooded?

Thoughts?

 

[RobbieW]

If your primarily heading for high latitude cruising you should be fine with AGM. If your going to stick around in the heat, I think wet cells are your friend - you can top up the water as necessary

 

[mariadz]

Hi. I went through a similar predicament recently and decided to go with gel batteries which I personally think are more suited to cruising domestic loads. That is having had Agms previously.

More info on the thought processes behind the decision in the attached:
https://mariadz.com/2018/02/27/shorepower-problems-and-batteries/

 

[geem]

Wet cell every time. What advantage do you think AGM will give you?

 

[Tim Good]

Wet cell every time. What advantage do you think AGM will give you?

Additional capacity for the weight plus no maintenance.

 

[geem]

Additional capacity for the weight plus no maintenance.

Maintenance of wet cell batteries is topping up with water. Done that once in 18months.
My pal has Rolls AGM of same capacity as my wet cell batteries. They are the same weight. If your AGMs are light are they cheap batteries? If you are living off the hook then AGM will not get a full charge. Budget marine here in Caribbean have a warning in their catalogue about reduction of life of AGMs if you cannot get them FULLY charged on a regular basis. I would go wet cell with what you plan to do

 

[Tim Good]

Maintenance of wet cell batteries is topping up with water. Done that once in 18months.
My pal has Rolls AGM of same capacity as my wet cell batteries. They are the same weight. If your AGMs are light are they cheap batteries? If you are living off the hook then AGM will not get a full charge. Budget marine here in Caribbean have a warning in their catalogue about reduction of life of AGMs if you cannot get them FULLY charged on a regular basis. I would go wet cell with what you plan to do

Fair points. I've just got to T-105s and will try to adjust my battery box to suite them.

 

[RobbieW]

... If you are living off the hook then AGM will not get a full charge....

What's your basis for that assertion ? If the charging system(s) are optimised for the installed batteries (whether AGM, wet cell or whatever) theres no reason they shouldnt get a full charge. T105s have a slightly non standard charging regime which requires an optimised charging system(s) to make best use of it(them)

 

[geem]

What's your basis for that assertion ? If the charging system(s) are optimised for the installed batteries (whether AGM, wet cell or whatever) theres no reason they shouldnt get a full charge. T105s have a slightly non standard charging regime which requires an optimised charging system(s) to make best use of it(them)

The OP says he has 360w of solar. There are times when this may not be enough from my experience so under charging is possible. Trojans take a lot of abuse

 

[Heckler]

Wet cell every time. What advantage do you think AGM will give you?

Indeed, as posted many times, my Numax from the farmers shop lasted 9 years!

 

[RobbieW]

Indeed, as posted many times, my Numax from the farmers shop lasted 9 years!

Quite so, but when asked about your usage you decline to answer. So, you would warrant those Numax batteries to someone planning to live on the hook for 6-8 months in 12 for how long ?

 

[geem]

Quite so, but when asked about your usage you decline to answer. So, you would warrant those Numax batteries to someone planning to live on the hook for 6-8 months in 12 for how long ?

Whether those batteries perform or not is down to depth of discharge and frequency of discharge. Cram enough battery capacity onboard and carry enough solar or other forms of charging and even as a liveaboard you can treat your batteries quite gently. On the other hand, small bank, poor charging capacity and deep discharge and almost all battery types will suffer from shorter life. It is very difficult to predict life expectancy of a bank of batteries without knowing the full picture

 

[RobbieW]

Whether those batteries perform or not is down to depth of discharge and frequency of discharge. Cram enough battery capacity onboard and carry enough solar or other forms of charging and even as a liveaboard you can treat your batteries quite gently. On the other hand, small bank, poor charging capacity and deep discharge and almost all battery types will suffer from shorter life. It is very difficult to predict life expectancy of a bank of batteries without knowing the full picture

Very true, but the margin for error (or life) of an SLA from the farm shop tends to be less than that of a deep cycle unit of whatever type

 

[geem]

Very true, but the margin for error (or life) of an SLA from the farm shop tends to be less than that of a deep cycle unit of whatever type

Quite possible, but if it costs third of the price and last half as long then i can be the correct choice for some people. The problem with choosing batteries for somebody heading off long distance or trans Atlantic is when they fail it can be difficult to source replacements and/or very expensive. If I was in the Uk and needed to replace batteries I would fit Trojans over any AGM for full time liveaboard use, living off the hook, in a hot climate. The bank would be circa 1000amp hr and I would expect to get 7-10 years life

 

[RobbieW]

Quite possible, but if it costs third of the price and last half as long then i can be the correct choice for some people. The problem with choosing batteries for somebody heading off long distance or trans Atlantic is when they fail it can be difficult to source replacements and/or very expensive. If I was in the Uk and needed to replace batteries I would fit Trojans over any AGM for full time liveaboard use, living off the hook, in a hot climate. The bank would be circa 1000amp hr and I would expect to get 7-10 years life

In a hot climate, I entirely agree - using Tayna's pricing the T105s give a better price/performance than Stu's Numax batteries so it seems deep cycle can be cheaper than the farm shop. T105s are typically a bit taller than thier equivalent in the same form factor which can make them a challenge to fit (and is mostly why I didnt but then I got some GC2 form factor AGMs at an equivalent price which fitted without much modification)

However the OP has indicated in the past that his objectives are more high latitude than equatorial cruising so the distinction between open LA and 'maint' free is less important.

 

[geem]

In a hot climate, I entirely agree - using Tayna's pricing the T105s give a better price/performance than Stu's Numax batteries so it seems deep cycle can be cheaper than the farm shop. T105s are typically a bit taller than thier equivalent in the same form factor which can make them a challenge to fit (and is mostly why I didnt but then I got some GC2 form factor AGMs at an equivalent price which fitted without much modification)

However the OP has indicated in the past that his objectives are more high latitude than equatorial cruising so the distinction between open LA and 'maint' free is less important.

OPs first post suggests south from UK and Trans Atlantic. Sounds like the traditional warm route.

 

[RobbieW]

..using Tayna's pricing the T105s give a better price/performance than Stu's Numax batteries so it seems deep cycle can be cheaper than the farm shop...

oops, mea culpa. In realising that 2xT105s are required to get the 225A C20 @ 12v for comparison I quadrupled the number of Numax batteries, of course just two are required. That makes the Numax roughly half the price of the T105. The problem with Stu's statement is that it gives only a part of the equation, life without usage data is pretty meaningless in assessing whether a commodity where usage affects life will work in a specific scenario.