AGM batteries: Someone using them?

[PCP]

AGM batteries have a big defect, they are expensive but have many advantages and mainly two that make them very interesting for cruisers:

1 – They lose very little charge so they can be let alone with minimum maintenance if you don’t use the boat in the winter.

2 – And main advantage, they charge 3 times faster than normal batteries.

Providing you have a big enough alternator this means that you have to run the engine for 3 times less hours (for charging) than with regular batteries. This is a huge advantage and will make them not expensive at all because the running hours of the engine are expensive. Of course the main advantage is that you gain a much bigger electric autonomy on your boat.

Well, this is what I have read and it is consensual but I would like to know if someone is using them and if this works out like that in reality, meaning if there really are a big difference in charging time?

..

[Minnewaska]

I have them and like them specifically because they hold a charge longer when stored over the winter. I have 13 batts in total (4 house), so it's impossible to take them out and leave them on a trickle charger all winter. I head out about every 6 weeks and top off.

[mightyhorton]

If you don't like running your engine to charge your batteries, the fast charge thing is huge. In the Sea of Cortez and Banderas Bay, where it is almost always cloud free, you can keep them charged just with solar panels, even running refrigeration and making ice, nav gear, lights, stereo, water makers, etc.

Their initial and replacement cost is horrible if you are retired and cruising. One of my pals is trying to figure out where he is going to come up with $6k for a new AGM battery bank.....

Ian

[PCP]

Originally Posted by mightyhorton

....

Their initial and replacement cost is horrible if you are retired and cruising. One of my pals is trying to figure out where he is going to come up with $6k for a new AGM battery bank.....

Ian

That should be a huge bank of batteries. For what I have heard they cost about 3 times more than regular batteries.

Regards

Paulo

[Paul_L]

Originally Posted by PCP

...
2 – And main advantage, they charge 3 times faster than normal batteries.
....

This just doesn't happen in practice. The acceptance rate is definitely higher, but the last 10 to 15% charge is still going to be at low rates. AGMs need to be 100% charged periodically, so you can't just stop at 90% full.

[PCP]

Originally Posted by Paul_L

This just doesn't happen in practice. The acceptance rate is definitely higher, but the last 10 to 15% charge is still going to be at low rates. AGMs need to be 100% charged periodically, so you can't just stop at 90% full.

You have them or work with them and that statment results from personal experience or is just your opinion?

Regards

Paulo

[HMoll]

Paulo,

I never had lead acid or lead. When I bought my boat, and studied a bit, aside from cost, AGM was a no brainer. They lasted four years, and my use was very irregular. Last year, I upsized my battery bank to (7) 105Ah battery bank, AGM. I run a 10,000BTU air conditioner with it. Love it, no genset. Turns out that my engine is quieter than my single-cylinder genset too. Another advantage is that AGMs are sealed, zero maintenance and zero gas emmissions from what I have read. Good AGM bank and large alternator. More than enough for your refrigeration. Do the numbers. Good luck!

[HMoll]

BTW, cant wait till LiIon come down in cost!

[Maine Sail]

Originally Posted by HMoll

Paulo,

I never had lead acid or lead. When I bought my boat, and studied a bit, aside from cost, AGM was a no brainer. They lasted four years, and my use was very irregular. Last year, I upsized my battery bank to (7) 105Ah battery bank, AGM. I run a 10,000BTU air conditioner with it. Love it, no genset. Turns out that my engine is quieter than my single-cylinder genset too. Another advantage is that AGMs are sealed, zero maintenance and zero gas emmissions from what I have read. Good AGM bank and large alternator. More than enough for your refrigeration. Do the numbers. Good luck!

AGM IS.......lead acid......... They can also vent gas if over charged, and when they do, the lost electrolyte can not be replaced.

If your bank of AGM batteries is made by Lifeline they are not maintenance free and need to be equalized occasionally, or as Lifeline calls it "conditioned", at 15.5V temp compensated for about 8 hours, especially if you are a cruiser.

My experiences with AGM, to summarize, are that:

They cost a lot more
Have shorter cycle life
Accept more current than wet lead acid
When they fail they tend to fail with little to no warning
Need to be charged to 100% SOC as often as possible

My experiences & thoughts.....


AGM's Making The Choice (LINK)

[PCP]

Originally Posted by HMoll

Paulo,

I never had lead acid or lead. When I bought my boat, and studied a bit, aside from cost, AGM was a no brainer. They lasted four years, and my use was very irregular. Last year, I upsized my battery bank to (7) 105Ah battery bank, AGM. I run a 10,000BTU air conditioner with it. Love it, no genset. Turns out that my engine is quieter than my single-cylinder genset too. Another advantage is that AGMs are sealed, zero maintenance and zero gas emmissions from what I have read. Good AGM bank and large alternator. More than enough for your refrigeration. Do the numbers. Good luck!

Thanks! Yes I have done the math and it looks good on paper, just wanted someone that uses them to confirm that on the reality. It seems that you have done just that

Just a last question: For your 735Ah battery bank what is the power of the alternator you use to charge them, the one on the engine?

Regards

Paulo