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Old 11-02-2023, 17:33   #16
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Re: AGM as house Bank

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Originally Posted by Tupaia View Post
Agreed but lithium are not without their problems. Cannot be left at 100% SOC for long periods an issue with solar if you leave the boat unexpectedly. Nothing is perfect.
Programmable charger
Easy
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Old 11-02-2023, 20:22   #17
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Re: AGM as house Bank

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Originally Posted by Tupaia View Post
Agreed but lithium are not without their problems. Cannot be left at 100% SOC for long periods an issue with solar if you leave the boat unexpectedly. Nothing is perfect.
True, but easily solved with some of the better programmable solar regulators.
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Old 11-02-2023, 20:23   #18
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Re: AGM as house Bank

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Programmable charger

Easy
Ha ha. Snap.
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Old 11-02-2023, 20:49   #19
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Re: AGM as house Bank

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Originally Posted by Tupaia View Post
Agreed but lithium are not without their problems. Cannot be left at 100% SOC for long periods an issue with solar if you leave the boat unexpectedly. Nothing is perfect.
any brand name lithium battery has a float voltage listed. many boats are plugged into a dock 360 days a year and are now getting lithuim. which will sit at 100% except the 2 weekends a year the boat is used. time will tell I guess.
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Old 12-02-2023, 02:26   #20
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Re: AGM as house Bank

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any brand name lithium battery has a float voltage listed. many boats are plugged into a dock 360 days a year and are now getting lithuim. which will sit at 100% except the 2 weekends a year the boat is used. time will tell I guess.
Again, programmable charger
Why is it so hard?
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Old 13-02-2023, 08:07   #21
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Re: AGM as house Bank

The number of respondents who have mentioned here that AGMs are great so long as they are kept fully charged got me wondering how much damage might they suffer if not plugged in over the winter storage season?

While my solar panels keep my house AGM set fully charged almost every day through the sailing season, the batteries regularly drop down to at least 80% while stored indoors over winter.
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Old 13-02-2023, 08:34   #22
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Re: AGM as house Bank

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Originally Posted by christianbarner View Post
The number of respondents who have mentioned here that AGMs are great so long as they are kept fully charged got me wondering how much damage might they suffer if not plugged in over the winter storage season?

While my solar panels keep my house AGM set fully charged almost every day through the sailing season, the batteries regularly drop down to at least 80% while stored indoors over winter.

Winter storage (and resulting cold weather concerns) is one of the reasons I haven't gone LFP. We're in inside storage right now. I just keep things as de-powered as possible over the winter and plug the boat in for a bit whenever I'm there to work on something. That's generally enough to keep them topped off and happy. I've seen some people just disconnect the batteries and let them sit all winter without issue though, as self discharge is low for AGMs in cold weather.
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Old 13-02-2023, 11:57   #23
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Re: AGM as house Bank

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Anyone using AGM as their primary house bank?

How was it?

Did you make any changes to your alternator set up?

Please no comments along the lines of "install Lithium instead"
I have been using AGM's for the house bank and I have been pleased so far. I destroyed one of them through overcharging. The particular setup was that the voltage sensing wire of one of my alternators was connected to the starter set, while the charging lead to the house set. The alternator increased house voltage to 38V (on a 24V system) since it was getting no feedback and short circuited one of the cells. You may want to be more careful than me in sorting out the alternator leads or install some overvoltage protection. By the way, that particular alternator, a Delco 22SI, was producing 38V x 80A = 3kW during this experiment which I thought was impressive.

Below is my understanding of battery technologies is, you choose your poison:

Wet cells... robust but need water and one day you will forget
AGM... current standard but more sensitive to PSC than the others
Lifepo4... already price competitive but more complicated charging

One issue I learned recently is that Lifepo4 is not optimal for engine starting. It is nice to be able to start your engine from the house or thruster bank in case of emergency. Once I had forgotten to add water to the starting set and one of the batteries exploded. I just took one of the thruster batteries and moved it to the engine bank. Quick and easy. You will not have this redundancy with lithium, which is a consideration on a boat.

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Old 17-02-2023, 06:42   #24
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Re: AGM as house Bank

Honestly LifeP04 is now so cheap you can't not consider them for house bank. 200 amp hrs at $650US.
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Old 17-02-2023, 07:08   #25
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Re: AGM as house Bank

I've been on two 8D AM's for my house bank for 8 years now, no problem but then again, I have 450 watts of solar that keep them charged back to full by noon.
I know that the battery chemistry for lithium has changed for the better, but is the risk of fire still there? That and the cold sensitivity scares me off of lithium, at least for now. I do like the weight savings aspect though.
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Old 17-02-2023, 07:24   #26
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Re: AGM as house Bank

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Originally Posted by smac999 View Post
any brand name lithium battery has a float voltage listed. many boats are plugged into a dock 360 days a year and are now getting lithuim. which will sit at 100% except the 2 weekends a year the boat is used. time will tell I guess.
Why on earth would somebody who kept a boat at the dock most of the time spend the premium for a Lithium installation??? Other than having bragging rights at the yacht club bar?

For some people, in some usage situations, LiFePO makes great sense. But they are not for everybody...
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Old 17-02-2023, 07:35   #27
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Re: AGM as house Bank

Most posted questions omit how the boat is used so the answers usually don't address the nuances/pros-cons for different lifestyles.

We used AGMs as recreational boaters for years with our boat in a marina and going out for a day, weekend, or week at a time.

When we started cruising full time we came to hate the AGMs because-

1. 50% or less of capacity is usable.

2. Degrade fast if you don't charge to 100%

3. Charging to 100% requires a long time in float mode, no problem on shore power or if your solar/wind keeps up with your usage, but a big, expensive PIA when living on the hook and charging by generator.

4. Related to #3, AGMs only accept full charging capacity (200amps for our setup) in Bulk mode and for our 1200ah house bank that translated to a routine of 2 hours in Bulk mode, 2 hours in Absorption mode, and 4 hours in Float mode to get to 100%, so our generator was running for FOUR HOURS with hardly any load on it. A terrible, painful waste but when I cut back on doing so one of our batteries failed and we got by with 800ah for a year until upgrading to lithium.

Swapping out the AGMs for lithium changed our cruising life for the better as we can now use 80% or more of capacity and charge 200amps full blast using our generator only 1-3 hours depending upon our preference as they don't need to be charged to 100%.

But if you don't cruise full time, you don't really need lithium, just about anything will do.
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Old 17-02-2023, 07:44   #28
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Re: AGM as house Bank

Our 1985 Catalina 30 has a single bank consisting of two G27 AGM batteries with 98Ah each. Charging is handled by two 175W Renogy flexible solar panels with a Renogy MPPT controller and the occasional use of the engine alternator while motoring. If we were blue water sailing the bank would be bigger, but I'd stay with AGM.

Lithium batteries are NOT a 'drop in' replacement for FLA, and in older boats it costs a LOT to change the wiring / charging / monitoring systems to what is required by lithium, and to my knowledge it is not usually worth it on its own.
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Old 17-02-2023, 10:28   #29
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Re: AGM as house Bank

In rebuilding Mustang Sally, I removed the Four + Start wet cell batteries and put in five AGMs + one more for Start (all deep cycle). I also removed the propane system and put in an inverter, induction-dual-cooktop and a convection microwave oven (all gimballed). And then I purchased Balmar’s 150 amp alternator with smart box as an upgrade for my Yanmar 3ym20’s 80 amp alternator (and will install it someday). Yes, I expect when all is done, charging at the full 150 amps will give me a 16hp Yanmar. Hope it all works out ok.
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Old 17-02-2023, 10:51   #30
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Re: AGM as house Bank

Sorry for the divergent thread, but:

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In rebuilding Mustang Sally, I .... put in five AGMs . I also .... put in an inverter, induction-dual-cooktop and a convection microwave oven.
What size and Ah are your AGMs? What kind and output inverter did you use? Is the house bank up to the draw of the induction cooktop? We have a dual burner induction cooktop as well (not gimbled) but I don't have an inverter for it.

Quote:
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I purchased Balmar’s 150 amp alternator with smart box as an upgrade for my Yanmar 3ym20’s 80 amp alternator
What is a 'smart box'? An external regulator? Did you get a serpentine conversion kit, or go dual belts? Do you think you will have any issues getting the new regulator and belt to fit your current space?
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