New AGMs to replace lead acid?

[rwells36]

In the market for new batteries and I've read reviews on nano-carbon / carbon foam technology.

My current house battery set up is (4) plain Jane lead acid wet 8Ds that take more time to fully charge than I would like (with the 17kw getset while at anchor). We have fridge / freezer / electric induction stove / inverter etc. in board.

Ideally I would / will run the gentset for (4) hours a day to make water regardless so that's my charge window, plus 900 watts of solar.

Question: Assuming 24 hours before battery recharge is needed; is there a way to match the (ideal) rate of charge to the correct battery technology?

[a64pilot]

Best thing may be to have a HUGE charger, or multiple chargers.
However that doesn't shorten your charge time by as much as you might think, but if you go AGM it helps, however AGM are less tolerant of partial charge cycling than traditional LA batteries. Kind of a circular argument
You make water every day? If so then I can't imagine you have a problem, just the earlier you crank the generator the better, get the batteries through bulk and deep into absorption with the generator leaving the panels to top them off. If you have four hour of generator run daily, and you do it early, I can't imagine you have a problem?

Someone will point out correctly that Life-Po batteries would accomplish what your after better than any other

[NewMoon]

Your genset produces lots of AC power, but it can charge batteries only as fast as the battery charger it's connected to can charge. How many charging amps does your charger put out? It could be you need a bigger charger.

Before spending a bunch on AGM's (which I have and like) or a bigger charger, I'd want to know the age and condition of the existing 8D flooded batts, your charger's charging amps, and your amp-hour usage per charging cycle. Without all that info, it's hard to make a good decision.

Do you have a battery monitor (AH meter)? If not, I would install one. You could calculate your AH usage by adding up the AH usage of all your devices over the 24hr period. A spreadsheet makes that a lot easier, as it is likely to be an iterative process. Or you can take the info directly from an AH meter.

Once you know how many AH's you need to replace each cycle, you can figure out how long it would take a given charger to replace them.

[a64pilot]

Originally Posted by rwells36

Question: Assuming 24 hours before battery recharge is needed; is there a way to match the (ideal) rate of charge to the correct battery technology?

If you go with AGM's with similar AH of your current bank, I do not think its possible to have too big a charger. Ideally for a Lifeline battery bank you should have at least .2C charger, which I believe would put you at about 185 amps of charging capacity.
Bigger is better, the battery will only accept what it can, charger cannot be too big, except of course you spent more money on a charger than you had to. This may help
https://www.google.com/url?sa=t&rct=...wvU1vjSROwP_fA

[john61ct]

For me, AGM's only real advantage is when you need to mount horizontal, or in a spot you'd never use a hydrometer. And shorter charge cycle if you were running motors just for that.

Except for Firefly Oasis, which adds the ability to withstand PSOC conditions without the much greater and riskier investment in LFP.

But if you plan to charge from fossil fuel 4 hours early in the morning, followed by sunny days into 900w solar, you're likely to get to full true 100% most days.

So Rolls Surrette FLA IMO, there are others nearly as good too, just make sure you get TRUE deep cycle designed for thousands of 50% cycles, and that usually means 2V or 6V cells, GC2 most common.

I doubt if many starter form factors like 8D, 4D, group 27, 31 etc fit that criteria.

Even a Sam's Club Deka/East Penn golf car 6V is pretty good value, but the Rolls will likely last twice as long if well treated.

[a64pilot]

I'm curious as to what boat he has, it sounds like maybe its a larger boat maybe with lots of people on board?

[rwells36]

Live aboard family of 6 57 LOA

[rwells36]

Originally Posted by john61ct

For me, AGM's only real advantage is when you need to mount horizontal, or in a spot you'd never use a hydrometer. And shorter charge cycle if you were running motors just for that.

Except for Firefly Oasis, which adds the ability to withstand PSOC conditions without the much greater and riskier investment in LFP.

But if you plan to charge from fossil fuel 4 hours early in the morning, followed by sunny days into 900w solar, you're likely to get to full true 100% most days.

So Rolls Surrette FLA IMO, there are others nearly as good too, just make sure you get TRUE deep cycle designed for thousands of 50% cycles, and that usually means 2V or 6V cells, GC2 most common.

I doubt if many starter form factors like 8D, 4D, group 27, 31 etc fit that criteria.

Even a Sam's Club Deka/East Penn golf car 6V is pretty good value, but the Rolls will likely last twice as long if well treated.

Gel Cell is GC2?

[svgertie]

Bigger is not better as chargers go. Charger output should not exceed 25 to 33 percent of total ampacity oh bank being charged. Good luck
Remember what you read here trust but verify.

[a64pilot]

Originally Posted by rwells36

Gel Cell is GC2?

GC2 is a wet cell 6V golf cart battery. Likely the most battery you can get for the money. There are better, but usually at a much higher cost, golf cart batteries are very widely available as well. Downside is you have to water them, although there are caps that will allow automatic or nearly so watering

[a64pilot]

Originally Posted by svgertie

Bigger is not better as chargers go. Charger output should not exceed 25 to 33 percent of total ampacity oh bank being charged. Good luck
Remember what you read here trust but verify.

I think he has around 900 AH bank. So how big a charger do you recommend?
What would happen if charger was twice as big?

[bradfordharley]

I just went through the same exercise replacing my battery bank. Lots of the decision points come to preference and opinion and I'm happy to share mine...
I replaced 4 GC2 (6v golf cart batteries) with another 4 lifeline 6CT batteries; Same footprint as the GC2, just 3" taller with an extra 80ah (@6v) than the GC2's. Here was my thought process:
1. I wanted zero maintenance due to the location of the battery box and my lack of desire to maintain the batteries. This is a choice, and while I like maintenance, I have fixed time and would rather spend the time on other projects.
2. I don't think Lithium of any chemistry is really ready yet. This was a hard choice as I'm an engineer by schooling and would really enjoy the whole Lithium DIY concept. That said, it's not the best use of my time with other projects pending, and I strongly believe the next 3-5 years will transform the market from a safety and price perspective.
3. I looked at carbon foam, and it appears that technology and equivalents are only available in group 31 or 26 which is a bad form factor for my particular battery box. I love the concept though, and there are great articles out there on practical sailor and panbo.

The above left me with AGM. I chose lifeline as I wanted quality, and the comfort that it would last years on my pending cruise. I'm assuming the next set will be a variety of lithium.

Check out the manual from lifeline which I've linked below. It has a good description of charging. I agree with previous posters that you as much charge current as possible. I have 125amps out of my inverter and a 125 amp alternator which I may upgrade/go dual.

http://lifelinebatteries.com/wp-cont.../12/manual.pdf


Good luck with the project.

Brad

[W3GAC]

We lived aboard in Caribbean on 46' ketch, with 8kw gen, 500ah of AGM, no solar/ wind... all OK with 40 minute gen run in morning and evening. But our frig/ freeze was holding plate technology via large 120v compressor, so the major on-going load load of refrig was done with battery involvement. The 40 min gen runs coincided w/ high energy loads of food prep/ toaster, microwave, coffee making, hair drying, air-conditioning (sometimes in evening).
Sometimes with batteries, bigger isn't always better. Consider diving bank and only using amount of batteries needed. Easier to bring down to 50% and all the way back up... than bring whole bank up from 75% to full. Wasn't mention if you have/ use battery monitor. I consider batter monitor/ tracking ah loading and charging dynamics one of the most important instrumention on board. Can't manage what you don't measure.

[a64pilot]

Now just for sake of argument, a Lifeline battery is an AGM, most AGM's need regular charging to 100% capacity, if you can't or don't want to do that, then maybe another battery is a better choice, say Golf Cart batteries.
Now if you are to believe Mainesail, ( I do) then you assuming properly sized charging equipment around 6 hours to fully recharge a Lifeline battery.
If he is running a generator for four hours daily and does so in the morning, then with Solar he ought to be able to get to 100% SOC every day, assuming the Solar has excess capacity, meaning that as long as house loads are not absorbing all of the Solar output.

But running a generator for an hour or so daily, will kill a Lifeline pretty quick, and they are not cheap, that is a waste of a lot of money, especially when an inexpensive golf cart battery would hold up better for a whole lot less money

[rwells36]

Originally Posted by a64pilot

Now just for sake of argument, a Lifeline battery is an AGM, most AGM's need regular charging to 100% capacity, if you can't or don't want to do that, then maybe another battery is a better choice, say Golf Cart batteries.
Now if you are to believe Mainesail, ( I do) then you assuming properly sized charging equipment around 6 hours to fully recharge a Lifeline battery.
If he is running a generator for four hours daily and does so in the morning, then with Solar he ought to be able to get to 100% SOC every day, assuming the Solar has excess capacity, meaning that as long as house loads are not absorbing all of the Solar output.

But running a generator for an hour or so daily, will kill a Lifeline pretty quick, and they are not cheap, that is a waste of a lot of money, especially when an inexpensive golf cart battery would hold up better for a whole lot less money

Refrigerator is 8 amps (doesn't run 24x7) mini freezer is 4 amps. These two appliances represent the power consumption outside of the genset running (4 hours for water-maker)

Rounding off to 10 amps (both appliances) x 120v = 1200 watts less 10% for DC-AC conversion means I'd need 1230 watts to break even.

In other words I'm taking out 10 amps per hour and replacing it with about 7.5 via 945 watts of 24v solar for a net loss of 2.5 amps per hour x 20 hour = 50 amps (accounting for 4 hours of genset time).

50 amp loss in 20 hours is low so I will estimate another 50 amps for other energy needs for a total deficit of 100 amps. Check my math guys; that doesn't seem like a lot to make up each day to me.