My battery set-up

[catalinajack]

Your system has been in place for 19 years. My system has been in place for 37 years. Neither fact means anything. This is all preference not the "bible".

I prefer separate house and start battery systems.

There are two G31 batteries for starting the single engine. They also start the generator and power the windlass and bow thruster. There is no 110 VAC charger on the start batteries.

For house, I have 6 golf cart batteries and a 120 amp, 3000 watt inverter/charger.

There is an 100 amp alternator for the start and an 150 amp alternator for the house batteries.

The generator has a 65 amp alternator.

The house and start circuits are totally isolated from each other. A crossover switch allows cross connection in case of problems.

This system has been in place for 19 years without issue.

 

[Bacchus]

How many AGM's do you have in your housebank? I was thinking about going with 400Ah housebank.

My house/start bank is 2 AGM 8Ds with a selector SW.
I have a 3rd 8D for thrusters and a separate gen start.
I have replaced my gen on/off Sw with a 1-2-all so I can easily combine the gen batty to start main of combine weak start/house bank to start gen.
My practice has been to always combine the 2 house/start 8Ds so they are only discharged 1/2 as much as if isolated. My gen is my safety / back-up in case I need it (never have yet)
I'm considering replacing the 2 8Ds w/ 4 6V GCs when I need replacements. That should be approx 400AH with about 200AH useable.
I'm also considering moving main eng start to the thruster bank but that is only a concept at this point.

 

[Bacchus]

Here's a different opinion. I do not see keeping the banks separate as safety critical. My boat has eight golf batteries used as a combined start/house bank. I also have separate start batteries for my generators. If, in the highly unlikely - the aforementioned safety issue - I can either use the generator to recharge the batteries or use jumper cables to start the engines. I once dumbly discharged the house bank down to 20%. The engines started with no hint of struggle. The fact is, it is not right or wrong setting it up either way. Don't be frightened into going to great expense to reconfigure to a set-up that gains you, in my opinion, nothing. Others will disagree with me strongly while many others with a setup such as mine won't. All this, however, presupposes having a generator with its own starting battery.

My thoughts exactly.
Lots of options and none always right or wrong.
Everyone should consider all situations and their options "in case". As long as you have options / back-up and comfortable for your cruising habits and grounds that's what's important. If my cruising grounds and habits were different I might feel very differently.

 

[syjos]

Your system has been in place for 19 years. My system has been in place for 37 years. Neither fact means anything. This is all preference not the "bible".

I stated in my post that I preferred separate systems. Never said it was the definitive configuration or bible.

Since you're touting or boasting about your 37 years, I configured my previous boat, which I had for 15 years, in the same manner. And a number of clients boats too.

Different strokes.

 

[catalinajack]

I stated in my post that I preferred separate systems. Never said it was the definitive configuration or bible.

Since you're touting or boasting about your 37 years, I configured my previous boat, which I had for 15 years, in the same manner. And a number of clients boats too.

Different strokes.

I was not touting. I was not boasting. I was merely saying that the fact was meaningless. My, my, aren't we sensitive.

 

[BruceK]

Here's a different opinion. I do not see keeping the banks separate as safety critical. My boat has eight golf batteries used as a combined start/house bank. I also have separate start batteries for my generators. If, in the highly unlikely - the aforementioned safety issue - I can either use the generator to recharge the batteries or use jumper cables to start the engines. I once dumbly discharged the house bank down to 20%. The engines started with no hint of struggle. The fact is, it is not right or wrong setting it up either way. Don't be frightened into going to great expense to reconfigure to a set-up that gains you, in my opinion, nothing. Others will disagree with me strongly while many others with a setup such as mine won't. All this, however, presupposes having a generator with its own starting battery.

I agree. Baker said something similar recently. The OEM IG set up is 2 8Ds, one per engine, doing everything except the genset. When I first got the boat, as I was realising the batts were not great, I would turn one off overnight so it became start and preserved, and the other house, but "house" got drained, so I figured part drain on both worked better. And of course, genset as back up.

 

[syjos]

I was not touting. I was not boasting. I was merely saying that the fact was meaningless. My, my, aren't we sensitive.

Sensitivity has nothing to do with it.

I don't put up with snarky, contentious comments.

 

[catalinajack]

As I said, oversenstive. I wasn't being snarky or contentious but, apparently, whenever someone questions anything you assert, you become combative. This isn't the first time. Grow up.

Sensitivity has nothing to do with it.

I don't put up with snarky, contentious comments.

 

[syjos]

As I said, oversenstive. I wasn't being snarky or contentious but, apparently, whenever someone questions anything you assert, you become combative. This isn't the first time. Grow up.

Only time I get combative is when know it all's and wannabe's post uncivilized comments on any forum.

Such as:

"Your system has been in place for 19 years. My system has been in place for 37 years. Neither fact means anything. This is all preference not the "bible"."

To my post that I started with "I prefer".

You obviously don't comprehend the difference between prefer and assert. And don't realize that your post sounds combative,

Saying things like "My, my, aren't we sensitive." and "Grow up" to me is snarky.

Your turn.

 

[catalinajack]

Pass. I rest my case. As I said, this is not the first time for you. I'll let others judge me and my comments. I'm betting on myself.

Only time I get combative is when know it all's and wannabe's post uncivilized comments on any forum.

Such as:

"Your system has been in place for 19 years. My system has been in place for 37 years. Neither fact means anything. This is all preference not the "bible"."

To my post that I started with "I prefer".

You obviously don't comprehend the difference between prefer and assert. And don't realize that your post sounds combative,

Saying things like "My, my, aren't we sensitive." and "Grow up" to me is snarky.

Your turn.

 

[syjos]

Pass. I rest my case. As I said, this is not the first time for you. I'll let others judge me and my comments. I'm betting on myself.

The defense rests.

 

[RickyD]

With a proper DC system, running the genset can be a rare event. In fact you don't need it at all. The exception being living aboard on a mooring (so not going anywhere) or living in the SE where AC is necessary to support life.

This is really not true if I have understood you correctly. I frequently anchor offshore. My main refrigerator/freezer draws 6.5 amps at 120v. So that is about 70 amps or more running off the inverter. I also have a wine frig in the sun deck. My batteries are needing a recharge every morning and every night. How do I not run my genset or engines? Of course if I always stay tethered to the dock, I should not need a genset.

 

[rslifkin]

This is really not true if I have understood you correctly. I frequently anchor offshore. My main refrigerator/freezer draws 6.5 amps at 120v. So that is about 70 amps or more running off the inverter. I also have a wine frig in the sun deck. My batteries are needing a recharge every morning and every night. How do I not run my genset or engines? Of course if I always stay tethered to the dock, I should not need a genset.

It depends on what systems you have to power, how much battery capacity you have, how much solar you have, etc. In my case, if I add 600 watts or so of solar, I'd only need the genset on cloudy days or when I need AC power for something. If I put in a good size inverter, upped the size of that solar system a bit more and made my house bank bigger, I could reduce generator use to being pretty infrequent.

However, for how I use the boat, other than adding solar at some point, it's not worth making major systems changes to cut down my generator runtime as I only need a generator run specifically for charging if I'm staying in the same spot for multiple days without shore power. A single overnight and then move to the next spot is no problem and the generator only gets run an hour or 2 a day to make hot water and power the stove, microwave, coffee maker, etc. The one change I'm considering is adding a small inverter to power the ice maker, as currently I have to shut it down if I'm away from shore power for more than a few hours (it's 120v only). But I will likely wait until I add solar before I do that, as it'll be a noticeable increase in my daily power consumption (compared to just bagging some ice and throwing it in the freezer at the start of the trip).

Some boats will be easier to minimize generator use than others. Your refrigeration setup will be harder to power than some, but it wouldn't necessarily be impossible (especially considering that fridge definitely isn't drawing that much power 100% of the time). It's just a matter of figuring out how much power you use in 24 hours, how much battery capacity you can reasonably install and how much power you can gather from a solar installation that fits on the boat.

 

[RickyD]

Can anyone recommend a really good marine electrician. I really want to go through testing my batteries and charging systems and come up with improvements in charging and storage. I am in Long Beach CA.

 

[mvweebles]

This is really not true if I have understood you correctly. I frequently anchor offshore. My main refrigerator/freezer draws 6.5 amps at 120v. So that is about 70 amps or more running off the inverter. I also have a wine frig in the sun deck. My batteries are needing a recharge every morning and every night. How do I not run my genset or engines? Of course if I always stay tethered to the dock, I should not need a genset.

You either need to go on an energy diet or get used to running the generator a lot or get a beefier DC system (or combo of all three)

If your fridge really consumes 6.5A when running (probably closer to 4.0, but let's go with it), and it runs 50% of the time, you need 9kw of energy just for the frirdge. If you wanted to run solar, you would need eight 100AH batteries and six 300W solar panels. But I doubt your fridge is drawing that much - may want to validate and consider something more efficient.

Chances are you need a bigger reserve battery bank and a means to charge it more quickly. Something like a 1200AH battery bank and 200A large frame alternator with multi-stage regulator to charge when you're underway. You would need to charge off generator - 150A battery charger will still need 4-hours of run time a day.

You're asking a lot of a DC system. It can be done, but you're past the low-hanging fruit. Need a serious and designed system. Or reduce the demand. Or run the generator a bunch. No free lunch here....

Peter

 

[yamabuki]

Battery’s getting older

We have 2 g31 batteries for each engine with their own charger, a separate one each for the the genset and winch and we used to have 6 g31s for our house bank with a charger inverter but 3 died. We don’t live aboard and our cruises are fairly short say weekends or a week at most also we live on watts bar lake with a dock so interlude spends most of the time on shore power. Our batteries are getting to the age where they will need replacing and I will probably stick with g31s for starter batteries and am leaning towards the same for the house mainly due to cost. Any thoughts or advice for replacing the house batts ?

 

[mvweebles]

We have 2 g31 batteries for each engine with their own charger, a separate one each for the the genset and winch and we used to have 6 g31s for our house bank with a charger inverter but 3 died. We don’t live aboard and our cruises are fairly short say weekends or a week at most also we live on watts bar lake with a dock so interlude spends most of the time on shore power. Our batteries are getting to the age where they will need replacing and I will probably stick with g31s for starter batteries and am leaning towards the same for the house mainly due to cost. Any thoughts or advice for replacing the house batts ?

I'm not an expert, but I've not a neanderthal either. Your easiest path will be to replace with the G31s for your house bank. Better would be T105 Golf Cart batteries, but they are 6v and would require some series cabling, plus they are a bit taller than your G31s. Best would be to consider AGMs, then even better to Lithium, but your usage does not justify the cost I suppose.

Given you are mostly shore power or underway, your best bet is to buy a higher quality Group 31. Not sure which ones are best, but would take the time to find the best even at a cost premium. As much as I love Costco, I have not had the best success with their batteries.

Peter

 

[mvweebles]

I'm not an expert, but I've not a neanderthal either. Your easiest path will be to replace with the G31s for your house bank. Better would be T105 Golf Cart batteries, but they are 6v and would require some series cabling, plus they are a bit taller than your G31s. Best would be to consider AGMs, then even better to Lithium, but your usage does not justify the cost I suppose.



Given you are mostly shore power or underway, your best bet is to buy a higher quality Group 31. Not sure which ones are best, but would take the time to find the best even at a cost premium. As much as I love Costco, I have not had the best success with their batteries.

 

[yamabuki]

I probably don’t have the height for 6volt but am thinking that deep cycle might be a better option for the house bank ?

 

[mvweebles]

I probably don’t have the height for 6volt but am thinking that deep cycle might be a better option for the house bank ?

Absolutely. They will probably state some sort of crossover. If you can find some comparison websites, you are looking for fewer, thicker plates.

 

[Capt Dan]

If you are building a new house bank system, why would you install brand new “traditional” flooded lead acid batteries?

Imho, they are antiquated. They do work, but need very careful maintenance to get peak performance.

If you don’t want to take the plunge into the future of Lithium, which are dollar for dollar cost effective, smaller, lighter, hmm, no downside...

You might look at Absorbed Glass Mat as a middle ground. More useable power, faster charging, no maintenance, no toxic fumes while charging.

There are a lot of modern systems out there that are easier, more efficient alternatives.

All that being said, flooded lead acid systems do work. They are just shorter lifespan and maintenance hungry.

Dan

 

[syjos]

Wet cell batteries are the most amps/$. I can buy two sets of wet cell golf cart batteries for what an AGM bank costs. Wet cells may not last as long but the lower price allows replacing more frequently.

I don't know how long AGM deep cycle batteries last but I usually get 6 to 7 years out of my 6 X $100 Costco wet cell Golf Cart Batteries.

If the wet cell batteries are hard to access to check and water, then AGM makes sense.

And if space and weight is an issue, lithium batteries are dropping in price and are the superior battery technology. Lithium battery prices are getting competitive to an equivalent AGM battery bank since less lithuim batteries are required as AGM.

 

[mvweebles]

If you are building a new house bank system, why would you install brand new “traditional” flooded lead acid batteries?

Imho, they are antiquated. They do work, but need very careful maintenance to get peak performance.

If you don’t want to take the plunge into the future of Lithium, which are dollar for dollar cost effective, smaller, lighter, hmm, no downside...

You might look at Absorbed Glass Mat as a middle ground. More useable power, faster charging, no maintenance, no toxic fumes while charging.

There are a lot of modern systems out there that are easier, more efficient alternatives.

All that being said, flooded lead acid systems do work. They are just shorter lifespan and maintenance hungry.

Dan

I was going to suggest the same thing - LiFePO4 are, over the long run, a better value. But sounded like usage of a house bank for OP is incidental. The CCA of either AGM or Flood Acid make them preferable for engine starting applications, so he would need some sort of DC-DC charging bridge between the engine start batteries and the lithium (or a separate charger altogether). So while I don't disagree with your statement - I am upgrading to LiFePO4 for house, just didn't sound like the OP's usage would justify the change, especially given the upfront cost of lithium batteries ($1000/100A battery or thereabouts vs $150/100A for Lead Acid).



Peter

 

[rslifkin]

Decent AGMs may last longer than cheap flooded, but good flooded batteries will out-last most AGMs. Depth of discharge limits are about the same in practical use. AGMs can support higher charge and discharge limits, but not everyone needs that relative to the size of their bank. And good flooded batteries are cheaper than good AGMs, particularly with a somewhat longer lifespan.

In my case, I chose AGM. But if I had the space / weight capacity for a larger house bank and didn't mind dealing with ventilation, watering, etc. I'd probably be running flooded batteries.

If you want a sealed battery with a long lifespan, a good quality gel can do that, but they're more sensitive to charge voltage and only a little better than flooded about high charge and discharge rates. And good ones are pricey.

 

[mvweebles]

My main refrigerator/freezer draws 6.5 amps at 120v. So that is about 70 amps or more running off the inverter. I also have a wine frig in the sun deck. My batteries are needing a recharge every morning and every night. How do I not run my genset or engines? Of course if I always stay tethered to the dock, I should not need a genset.

RickyD - here is a decent calculator from Renogy, one of the larger names in solar. Gives you an idea of how to size a solar system, the only practical replacement to an internal combustion engine for generating power.


https://www.renogy.com/calculators#tab_battery


Assuming 8-hours of run time for your fridge, and 5-hours of sunshine per day (I know, sun shines longer, but on average for solar, rule of thumb is five full hours to offset low-angle times), you would need 4-5 full sized panels, and 1000 AH of battery capacity (though doesn't say if that's usable battery capacity such as LiFePO4 or Firefly AGMs vs flooded batteries which would only have 50% usable, so need to double the capacity). .

 

[yamabuki]

Thanks a lot, I am leaning towards good quality maintenance free g31 for the house and also for the engine start as I think for our limited use and cost per amp is probably the best choice, as both sets have a fairly good “smart” charger we may get some good use from them,thanks again.