Battery Selection?

[Kevin84]

I'm considering replacing my house battery bank. It currently has a single 12v deep cycle battery. These are what I'm considering as a replacement. I want to use 4 of the 400ah batteries. They will be going into a Catalina 38 with the Universal M25. Thoughts?

http://m.westmarine.com/aHR0cDovL3d3...dW09NTA1NDQ%3D

[goboatingnow]

for that price, I'd buy LiFerrous , I suggest refocusing in good quality flooded, open cell standard lead acid batteries, AGMs have no real advantage on most boats.

I also suspect if you are going from a single battery to 1000Ah of 12v capacity you'd need to look at charging sources very carefully . Batteries should be installed as part of a system not just considered on their own.


dave

[Kevin84]

Originally Posted by goboatingnow

for that price, I'd buy LiFerrous , I suggest refocusing in good quality flooded, open cell standard lead acid batteries, AGMs have no real advantage on most boats.

I also suspect if you are going from a single battery to 1000Ah of 12v capacity you'd need to look at charging sources very carefully . Batteries should be installed as part of a system not just considered on their own.

dave

Sorry, should have mentioned that. I'm upgrading my entire electrical system. The mast is getting rewired now abd I'm adding solar and a new alternator. Why standard lead acid though?

[goboatingnow]

Unless you can use the specific AGM good characteristics, like high charge acceptance, and low leakage current, thats fine, few boats need that , but you get the bad AGm characteristics, like sensitivity to charging, requirement to periodically bring to full charge, no ability to replace electrolyte, etc

dave

[Amnesia II]

Originally Posted by Kevin84

I'm considering replacing my house battery bank. It currently has a single 12v deep cycle battery. These are what I'm considering as a replacement. I want to use 4 of the 400ah batteries. They will be going into a Catalina 38 with the Universal M25. Thoughts?

MASTERVOLT AGM 6 Volt Batteries at West Marine

I have to say 4 x 400 ah batteries seems rather large on your C38 with the M25 motor...that's 1600ah which in my estimation will require an alternator of huge proportions to effectively recharge that bank!

I have a bank of AGMs 800ah being recharged by an Electromaax 180 amp alt backed up by 3 x 200 W solar panels and find that very satisfactory.

I recommend you read up on some of 'Mainsails Musings' on batteries and charging!

[Kevin84]

Originally Posted by Amnesia II

I have to say 4 x 400 ah batteries seems rather large on your C38 with the M25 motor...that's 1600ah which in my estimation will require an alternator of huge proportions to effectively recharge that bank!

I have a bank of AGMs 800ah being recharged by an Electromaax 180 amp alt backed up by 3 x 200 W solar panels and find that very satisfactory.

I recommend you read up on some of 'Mainsails Musings' on batteries and charging!

That's why I'm asking! I just wasn't sure if two would provide the power I need while offshore.

[btrayfors]

I believe those who responded thus far have missed the point.

Four 260AH 6-volt AGMs in series/parallel will yield 520AH @ 12VDC.

That's a very healthy-sized house battery bank for a Catalina 38.

I certainly agree with the comments re: checking out flooded LA batteries first. They're MUCH cheaper and, for most cruisers, are a better deal than AGMs.

However, it depends very much on your intended use of the boat: dockside most of the time? Weekend cruising with occasional longer cruises? On anchor/mooring most of the time? Full-time cruising? Intended cruising ground? etc., etc.

You should take these factors into account BEFORE upgrading your solar/alternator/charter-generator/battery system.

Bill

[DeepFrz]

That is not 1600 amp hrs, it is 800 amp hrs at 12 volts.

[DeepFrz]

Ah, so they are 260 amp. hr. batteries and not 400 so Bill's calculations are right. So where did the 400 amp. hr. come from?

I would still follow the caution on using AGM. I second the suggestion to read Main Sail's musings on batteries.

[Kevin84]

Originally Posted by btrayfors

I believe those who responded thus far have missed the point.

Four 260AH 6-volt AGMs in series/parallel will yield 520AH @ 12VDC.

That's a very healthy-sized house battery bank for a Catalina 38.

I certainly agree with the comments re: checking out flooded LA batteries first. They're MUCH cheaper and, for most cruisers, are a better deal than AGMs.

However, it depends very much on your intended use of the boat: dockside most of the time? Weekend cruising with occasional longer cruises? On anchor/mooring most of the time? Full-time cruising? Intended cruising ground? etc., etc.

You should take these factors into account BEFORE upgrading your solar/alternator/charter-generator/battery system.

Bill

Intended use, for now full time liveaboard at a marina with regular weekend use and occasional week too two week trips away from shore power. Then in 3 to 4 years full time cruising. I'm not in a rush to upgrade them right now. The boat is on the hard in Massachusetts. But I am planning on sailing her down in the spring on the outside. So I need to have at least the batteries sorted by then.

[Kevin84]

Originally Posted by DeepFrz

Ah, so they are 260 amp. hr. batteries and not 400 so Bill's calculations are right. So where did the 400 amp. hr. come from?

I would still follow the caution on using AGM. I second the suggestion to read Main Sail's musings on batteries.

No, I'm considering the 400ah batts.

[mitiempo]

If you go with Agm batteries their life will be severely compromised if not fully charged very regularly. Offshore cruisers use their batteries to 50% and charge with alternator to 80-85% as the last 15% takes many hours. Solar and or wind gen will take care of the last 15% but neither can be relied on to charge them fully regularly - say twice a week. Agm batteries rarely will outlast a good flooded bank that is maintained - flooded batteries are much more tolerant of undercharging than Agm batteries.

This link from MaineSail is well worth reading before buying Agm batteries.
AGM Batteries - Making The Choice - SailboatOwners.com

800 AH is a large bank but if you have the room it can mean cycling down to 60 or 70% instead of 50% and that will extend the life of any battery.

[Kevin84]

Originally Posted by mitiempo

If you go with Agm batteries their life will be severely compromised if not fully charged very regularly. Offshore cruisers use their batteries to 50% and charge with alternator to 80-85% as the last 15% takes many hours. Solar and or wind gen will take care of the last 15% but neither can be relied on to charge them fully regularly - say twice a week. Agm batteries rarely will outlast a good flooded bank that is maintained - flooded batteries are much more tolerant of undercharging than Agm batteries.

This link from MaineSail is well worth reading before buying Agm batteries.
AGM Batteries - Making The Choice - SailboatOwners.com

I appreciate it!

[btrayfors]

OK. Four 400AH six-volt batteries in series/parallel = 800AH total capacity. That's a LOT.

It's way overkill for marina living and part-time cruising.

Save your money. Go with flooded LA batteries. From what you've described thus far, four six-volt golf-carts (about 450AH) would be more than enough, unless you have a HUGE energy budget. These would set you back about $400-$500 total.

But you also need to consider charging means and requirements. Not much required for marina living and occasional trips, but for long-distance cruising and, especially, if you plan to fit AGMs you'll need to beef up all charging means....alternator, battery charger, on-board generator, solar panels, etc.

Bill

[DotDun]

I agree with others. 800AH is a lot of battery.

If you are truly set on spending $2400 on batteries, I would look at LifePO4. But I value money so for your needs I would suggest (4) T-105s (or 6 if you really think you need to go big) will fit your needs at a cost of ~$100 each. Beat the crap out of 'em, they just keep ticking.