New battery setup

[mistralf39]

Hi,

Having had our new (to us) boat for a season, we're looking at what we need to do over the winter and upgrading electrics is a high priority.

I have read lots of threads on this subject and have learned a lot but most seem to be bigger boats than ours with much more complicated setups. I would appreciate it if someone could confirm my thinking or (more likely) point out where I've got it wrong!

The boat lives on a swinging mooring and we tend to use her for a few days at a time with the odd full week. We enjoy the luxury of a marina berth when cruising and so most nights, when living aboard, we hook up to the mains overnight. We might occasionally stay "off grid" but I would say we're never living aboard for more than 48 hours without plugging in.

The current boat setup is as follows: She has a Yanmar 2GM20 engine with a 35 amp alternator. 1 lead acid battery for starting (70ah) and one lead acid for house (100ah). When connected to shore power we have a (not very modern) 5amp charger.

We intend to add updated plotter with AIS(B)(Onwa KM12A), wind instrument and a fridge (Isotherm GE80).

My plan is as follows:

Replace house battery with LiFePO4. I'm looking at the Fogstar Drift 230ah as a possible but I'm open to suggestions.
Wire alternator and AC charger directly to starter battery.
Install DC to DC charger between starter battery and new lithium house battery (possibly Victron TR smart 18amp).
Add new 50watt solar panel wired, via charge controller, directly to lithium.

My questions are:
Does this setup seem reasonable/safe?
What about the existing 1/2/off/both switch? Should I get rid and have individual isolators for both batteries?
It would be nice if, in an emergency, I could start the engine using the house battery. I know lithium batteries are not good for starting engines but if the starter battery fails would this be a reasonable thing to do and if so how?
Finally space for the house battery is fairly tight. I think I read somewhere that lithium batteries can be mounted on their side, is this correct?

Thanks in advance for any help/info/criticism .

Ian.

 

[B27]

Your planned use is quite different to mine, but I'd suggest:
Work out your worst case needs in Ah.
Which for you is something like 48hrs with no charging, running fridge and lights etc.
That tells you your usable house bank needed.
Say your fridge is averaging 2A, add in some other bits, you could be wanting say 150Ah.


Then work out how you will replenish that.
Which is either solar, alternator or mains charger.
If you expect to be in a marina at least every alternate night, I would think a powerful mains charger would be a priority. You might want to charge your house battery from its lowest level in 12 hours or so. To put in 150Ah, you might want a charger rated at 25A or more?

If you want the engine to be a major source of charge, then you'll need either a lot of hours or serious current.

Solar, in good weather we find it goes a long way towards providing for the fridge. This week, it's not doing much....

The other big difference between our boats is that I expect a diesel heater to be using some significant Ah in Spring and Autumn. A lot of people start adding in other loads like charging electric outboards, running inverters for toasters and any random home comforts.

So I haven't answered your question, but maybe it helps to define the numbers?

 

[mistralf39]

Thanks for your reply and the advice. I was thinking about swapping out the AC charger for something bigger so adding up the amps and working out worse case scenarios in terms of recharging requirements would certainly seem to be worth the effort.

 

[Neeves]

You need to have a way of measuring when your batteries achieve float - or you will stop charging, say when you use the alternator, too early or too late.

If you need to rely on your alternator to charge up any battery of substance (your desired lithium, 230a/hrs) then a 35 amp alternator, so the engine, is going to need to run for hours. You could schedule to run to a marina, charge from shore power, then go off grid etc - but then your 'amps', not you, determine your schedule. I suspect if your retire to a marina then you need a charger that will provide your needs for your stay, say overnight, AND recharge your house battery.

I might factor in a bigger alternator (as well as the bigger charger).

I hope your wallet is bulging.

When you do your audit of requirements you will find that 12 months later it was inadequate. I strongly believe in a variation on Parkinson's Law that your power (amps) increases to slightly more than you ability to produce same (amps) and any increase in your ability to produce power is soon swallowed by increased usage. Think big!

Jonathan

And I forgot - your biggest single user of amps is your fridge. Look at ways of making it more efficient (lots of threads on this in the forum here, PBO). You can commonly introduce efficiencies cheaply.

 

[TSB240]

Our experienced with two boats used in a similar pattern as yourself is the major consumers are anything driving a motor or incandescent bulbs. Before you invest in new batteries or chargers do a check on your power consumers and replace as many lights as possible with LED. Old wiring and bad connections on masthead incandescent lights showed them to be a major current load.

I was also surprised by the stand by current consumption of my main VHF and one of the biggest culprit for constant parasitic drain was an old car radio/ disc player.
Worth checking your individual electrical item power consumption with an ammeter set in line before you start changing your charging regime or batteries.

Initially we used to preloaded our fridge with prefrozen bottles of water. This would give us at least two days without it needing to be switched on. It used always to be switched off overnight but now with 200 Watts of solar the fridge stays permanently on with our batteries typically in float by 11.00 am most days.

 

[B27]

Our experienced with two boats used in a similar pattern as yourself is the major consumers are anything driving a motor or incandescent bulbs. Before you invest in new batteries or chargers do a check on your power consumers and replace as many lights as possible with LED. Old wiring and bad connections on masthead incandescent lights showed them to be a major current load.

I was also surprised by the stand by current consumption of my main VHF and one of the biggest culprit for constant parasitic drain was an old car radio/ disc player.
Worth checking your individual electrical item power consumption with an ammeter set in line before you start changing your charging regime or batteries.

Initially we used to preloaded our fridge with prefrozen bottles of water. This would give us at least two days without it needing to be switched on. It used always to be switched off overnight but now with 200 Watts of solar the fridge stays permanently on with our batteries typically in float by 11.00 am most days.

Some good points.
High drain items can include car stereos, chart plotters, autopilots, heaters and USB chargers.

We found this summer that 50W of solar would roughly keep pace with our fridge (which is small and very efficient) during sunny weather. But the question is, what minimum input from the solar do you plan for?
We're fairly relaxed about it, because we're not spending much cash on the system, so if we don't get 100% fridge service, we'll go ashore for fresh food and a cool drink. we might expect more if we'd invested hundreds on chargers and lithium batteries.

People have to set their own parameters of what they need, what is nice to have and what they're not bothered about.

 

[Refueler]

Forgive me for this ... but OP has been a forum member since 2015 .... and now posts owned boat for 1 season ....

Surely in that time - a large amount of information would have been amassed ?

Many will understand that I am not a supporter of Li solutions on boats .... preferring to stay with Lead Acid ... why ?

Lead Acid is tried and tested ... can be replaced at any car accessory shop ... petrol station .... and many other outlets ... while Li is via specialised dealers.

Lead Acid when it fails usually will decline in performance - but Li when it fails - usually fails completely - especially those with BMS systems built in.

Back to OP .... why 250 A/hr Li ? For substantially less money - an additional house Lead Acid could be added - a higher output charger - solar as well ... without having to resort to modifications to cater for Li.

That's my view anyway ...

I think the matter of Li vs LA has been distorted by the different needs of Live-aboards ... Long Distance cruisers .... vs general boaters ..

I have my Flak Jacket on ...

 

[mistralf39]

Forgive me for this ... but OP has been a forum member since 2015 .... and now posts owned boat for 1 season ....

Not sure what you're getting at here, we've had this boat for 1 season and the previous one for 12, it had a handheld GPS and handheld VHF with the battery only really starting the engine and running a few led lights so I never really had to think about the battery setup until now. As stated in my original post I have read loads of posts on this subject but very often the information doesn't really fit our situation with many more complex setups.

I take onboard your thoughts on Li versus LA and it's certainly something to consider. I guess one of the attractions with lithium is its ability to be almost fully discharged therefore effectively giving more amps whilst taking up the same amount of space. (If I've understood things correctly).

As far as solar goes, the reason I chose 50w was basically down to physical space. Even a 100w solar panel is a pretty hefty thing to attach to a 27' boat.

I'm very grateful for all answers received so far so thankyou for taking the time to reply.

Ian

 

[PaulRainbow]

Many will understand that I am not a supporter of Li solutions on boats .... preferring to stay with Lead Acid ... why ?

Lead Acid is tried and tested ... can be replaced at any car accessory shop ... petrol station .... and many other outlets ... while Li is via specialised dealers.

Lead Acid when it fails usually will decline in performance - but Li when it fails - usually fails completely - especially those with BMS systems built in.

Back to OP .... why 250 A/hr Li ? For substantially less money - an additional house Lead Acid could be added - a higher output charger - solar as well ... without having to resort to modifications to cater for Li.

That's my view anyway ...

I think the matter of Li vs LA has been distorted by the different needs of Live-aboards ... Long Distance cruisers .... vs general boaters ..

I have my Flak Jacket on ...

I completely agree with the highlighted part above.

I have been asked many times about Lithium and more often than not, i have advised customers of a different solution. Either more batteries, more solar or something else. Several times the boat will sit in a marina all week, on shore power, and just go out for the weekend, or even a day sail. Lithium is, in most of these cases, totally pointless. Never had anyone come back and say they with they went for Lithium.

There are, of course, some cases where Lithium makes sense.

 

[Tranona]

Hi,

Having had our new (to us) boat for a season, we're looking at what we need to do over the winter and upgrading electrics is a high priority.

I have read lots of threads on this subject and have learned a lot but most seem to be bigger boats than ours with much more complicated setups. I would appreciate it if someone could confirm my thinking or (more likely) point out where I've got it wrong!

The boat lives on a swinging mooring and we tend to use her for a few days at a time with the odd full week. We enjoy the luxury of a marina berth when cruising and so most nights, when living aboard, we hook up to the mains overnight. We might occasionally stay "off grid" but I would say we're never living aboard for more than 48 hours without plugging in.

The current boat setup is as follows: She has a Yanmar 2GM20 engine with a 35 amp alternator. 1 lead acid battery for starting (70ah) and one lead acid for house (100ah). When connected to shore power we have a (not very modern) 5amp charger.

We intend to add updated plotter with AIS(B)(Onwa KM12A), wind instrument and a fridge (Isotherm GE80).

My plan is as follows:

Replace house battery with LiFePO4. I'm looking at the Fogstar Drift 230ah as a possible but I'm open to suggestions.
Wire alternator and AC charger directly to starter battery.
Install DC to DC charger between starter battery and new lithium house battery (possibly Victron TR smart 18amp).
Add new 50watt solar panel wired, via charge controller, directly to lithium.

My questions are:
Does this setup seem reasonable/safe?
What about the existing 1/2/off/both switch? Should I get rid and have individual isolators for both batteries?
It would be nice if, in an emergency, I could start the engine using the house battery. I know lithium batteries are not good for starting engines but if the starter battery fails would this be a reasonable thing to do and if so how?
Finally space for the house battery is fairly tight. I think I read somewhere that lithium batteries can be mounted on their side, is this correct?

Thanks in advance for any help/info/criticism .

Ian.

That is a very complicated and expensive way of solving a relatively straightforward requirement. Lithium has a lot of desirable properties IF you either need them or can take advantage of what they offer. The only property that is of any use in your description of what you want to achieve is small size for capacity.

As already suggested the starting point is carry out a usage audit to determine your power usage minus generation over the period expect to be away mains power. that gives you a base for your storage capacity. The only big consumers on your list are the proposed fridge and lights for interior or sailing at night. instruments and even a tiller pilot are low consumers, and you may only use them 9-10 hours a day if sailing. Anyway with small daily engine usage and a bit of solar doubt you will need anywhere near 200ah, probably nearer half that. I have a similar size boat (bit bigger but very simple) and similar 2time away" expectations.

I have just rewired it and my charging/battery is alternator charging through a BEP Marine VSR switch cluster (does away with the 1,2,both) 2*95ah AGMs for house and a high power 28ah AGM start. The latter is not essential - I used it so that I could fit all 3 into a small existing area. The switch cluster allows combining to start the engine from the house bank. Mains charging is a simple single output 15A to the house bank. The photos show the batteries before final wiring - just connected to test the engine and 12V distribution. The second photo shows the switch cluster and the battery monitor. The AGMs were the biggest capacity I could get in the vertical space. Through choice I would have liked 2*115.

In your situation I would look to find space for 2*115 AGMs - they do not have to be in exactly the same space, but preferably close together. Your battery start is perhaps on the large side, but only look to using a much smaller one if it makes increasing the house bank easier as it was in my case. You have a limitation with your small alternator. It will do OK with AGMs except if trying to charge from near fully discharged when it will be slow getting them up, but to inadequate for lithium. Likewise your mains charger.

The key to getting the best out of your battery capacity is making sure you start your weekend with fully charged batteries. Easy if plugged into mains in a marina, but on a swinging mooring suggest you add another lot of solar to supplement the fixed solar. I don't need this as I have shorepower.

This suggestion is far simpler and a fraction of the cost of going lithium and more than adequate for your needs. The only barrier at the moment is finding space to fit the 2 big batteries. Without knowing the layout of your boat not possible to make suggestions, but rare that such space cannot be found.

 

[Slowboater33]

Tranona. Hi read your reply with interest. Just got myself a Barbican 30 with 2 100ah batteries and looking to fit a seperate engine start battery using existing for house. You mention a 28ah start battery. Do you find that enough for your needs. I'm assuming it's quite small in size which is what I am after as space a premium. My engine 18hp beta.
Cheers

 

[Refueler]

Not sure what you're getting at here, we've had this boat for 1 season and the previous one for 12, it had a handheld GPS and handheld VHF with the battery only really starting the engine and running a few led lights so I never really had to think about the battery setup until now. As stated in my original post I have read loads of posts on this subject but very often the information doesn't really fit our situation with many more complex setups.

I take onboard your thoughts on Li versus LA and it's certainly something to consider. I guess one of the attractions with lithium is its ability to be almost fully discharged therefore effectively giving more amps whilst taking up the same amount of space. (If I've understood things correctly).

As far as solar goes, the reason I chose 50w was basically down to physical space. Even a 100w solar panel is a pretty hefty thing to attach to a 27' boat.

I'm very grateful for all answers received so far so thankyou for taking the time to reply.

Ian

My apologies .... the 'sense' of the post gave impression of first boat.

As to fitting situation - I totally understand and is why I posted about Li vs LA ..... the 'waters' get extremely muddy when dedicated long distance sailors start posting ... the original modest needs get waylaid.

 

[Refueler]

Tranona. Hi read your reply with interest. Just got myself a Barbican 30 with 2 100ah batteries and looking to fit a seperate engine start battery using existing for house. You mention a 28ah start battery. Do you find that enough for your needs. I'm assuming it's quite small in size which is what I am after as space a premium. My engine 18hp beta.
Cheers

Be careful in choice of small A/hr battery if you go that route ... Tranona has obviously chosen wisely ..

A small diesel engine STILL has high compression to overcome for a starter ... so the average lawn tractor battery may start the engine if fully charged and on first key turn ... but if reluctant to start - will soon be too discharged to provide the necessary ooomph.
Backup from house system will then be demanded.

 

[PaulRainbow]

Hi,

Having had our new (to us) boat for a season, we're looking at what we need to do over the winter and upgrading electrics is a high priority.

I have read lots of threads on this subject and have learned a lot but most seem to be bigger boats than ours with much more complicated setups. I would appreciate it if someone could confirm my thinking or (more likely) point out where I've got it wrong!

The boat lives on a swinging mooring and we tend to use her for a few days at a time with the odd full week. We enjoy the luxury of a marina berth when cruising and so most nights, when living aboard, we hook up to the mains overnight. We might occasionally stay "off grid" but I would say we're never living aboard for more than 48 hours without plugging in.

The current boat setup is as follows: She has a Yanmar 2GM20 engine with a 35 amp alternator. 1 lead acid battery for starting (70ah) and one lead acid for house (100ah). When connected to shore power we have a (not very modern) 5amp charger.

We intend to add updated plotter with AIS(B)(Onwa KM12A), wind instrument and a fridge (Isotherm GE80).

My plan is as follows:

Replace house battery with LiFePO4. I'm looking at the Fogstar Drift 230ah as a possible but I'm open to suggestions.
Wire alternator and AC charger directly to starter battery.
Install DC to DC charger between starter battery and new lithium house battery (possibly Victron TR smart 18amp).
Add new 50watt solar panel wired, via charge controller, directly to lithium.

My questions are:
Does this setup seem reasonable/safe?
What about the existing 1/2/off/both switch? Should I get rid and have individual isolators for both batteries?
It would be nice if, in an emergency, I could start the engine using the house battery. I know lithium batteries are not good for starting engines but if the starter battery fails would this be a reasonable thing to do and if so how?
Finally space for the house battery is fairly tight. I think I read somewhere that lithium batteries can be mounted on their side, is this correct?

Thanks in advance for any help/info/criticism .

Ian.

Ref the 1-2-both switch, i would wire as below, which give emergency engine starting and the ability to run all services and the engine from either bank in the case of an emergency.

 

[Tranona]

Tranona. Hi read your reply with interest. Just got myself a Barbican 30 with 2 100ah batteries and looking to fit a seperate engine start battery using existing for house. You mention a 28ah start battery. Do you find that enough for your needs. I'm assuming it's quite small in size which is what I am after as space a premium. My engine 18hp beta.
Cheers

You can see it on the right in the photo. It is an Odyssey normally used on small racing cars. Yes more than adequate with a CCA of 1100A. My beta is a 30. Thee other main supplier is Red flash which I have used in the past. I had one in my Morgan from new. Changed it last year after 19 years. If used only for engine start the battery has an easy life especially if you use a split charge system so it is always fully recharged after use. Downside is price. I think that size is close to £200 now but worth it if space is an issue - you can mount it in any orientation so could fit over the gearbox for example as done on racing cars or on the side panel of an engine bay.

An alternative cheaper way is to use a 50ah car battery such as is used on small cars like Citroens and Honda Jazz. Not as compact but well capable of starting the beta.

 

[lustyd]

I'm looking at the Fogstar Drift 230ah as a possible but I'm open to suggestions.

In case you had not noticed, the 280Ah and 300Ah are identical cases. I just got the 300Ah which was pricey but the capacity per volume was great.

Finally space for the house battery is fairly tight. I think I read somewhere that lithium batteries can be mounted on their side, is this correct?

Fogstar explicitely state they can be any orientation. They also allowed me to cut off the handles to reduce overall length to (I think!) 245mm rather than the 280 with the handles without affecting warranty. This was because their website had the shorter measurement by mistake at the time, but it was easy and safe to do if you need to.

We went from 2x110Ah AGM for a usable capacity of about 44Ah to 1x300Ah for a total usable of about 240Ah. It took 11 hours to fully charge on a 30A Victron charger but it's not often we deeply discharge. There were a lot of other faffy changes needed too, but overall we're happy with the swap. It takes some getting used to with the charge regime and leaving it without fully charging. For our use, the solar fully charges between visits very gently and I might end up switching off the solar as a result, but we're marina based so a quick charge when we arrive is doable.

 

[lustyd]

As already suggested the starting point is carry out a usage audit

I would only consider this if I wasn't sure I could meet minimum needs. Lithium makes this kind of thing pretty obsolete as the leaky bucket becomes a leaky bathtub. Even with lead, people fitted what would fit in the boat as a general rule so talk of power audits was a waste of time

The only big consumers on your list are the proposed fridge and lights for interior or sailing at night. instruments and even a tiller pilot are low consumers, and you may only use them 9-10 hours a day if sailing. Anyway with small daily engine usage and a bit of solar doubt you will need anywhere near 200ah

Our fridge, from warm, will chew through 60Ah overnight to get it and contents down to temperature and make some ice. That will destroy a 200Ah lead bank before leaving the mooring.

 

[B27]

300Ah of fogstar is £800?
Seems a little crazy that a marina based boat needs £800 of batteries.
It would have been cheaper to get a more efficient fridge.
Or switch it on while still in your marina?
Having loads of battery capacity doesn't always help, at some point you have to generate the energy you use.
So it's still good to have a fair idea of where your Ah are going.
Unless you are looking for extreme cycle life, most people would reckon the useful capacity of two 110Ah batteries is around 110Ah, but you can discharge below 50% a few times a year and not lose much life.

 

[Refueler]

I would only consider this if I wasn't sure I could meet minimum needs. Lithium makes this kind of thing pretty obsolete as the leaky bucket becomes a leaky bathtub. Even with lead, people fitted what would fit in the boat as a general rule so talk of power audits was a waste of time

Our fridge, from warm, will chew through 60Ah overnight to get it and contents down to temperature and make some ice. That will destroy a 200Ah lead bank before leaving the mooring.

I have to agree that most people I reckon fit what they can get into space available.

On the fridge subject ..... I had a direct lesson in this few days ago ...

My house bank is 2x 75 A/hr ... gives about 75 A/hr real use ... (50%) but only if charged up very soon after ... as 50% on a Lead Acid is pushing the limits ... having consumed a few ... I stupidly left the fridge on high rate - thinking the mains power via pair of trickle chargers would be ok through the night. Got up in the morning to find my house bank down .... switched off system ... voltage rose to ~10V ... UGH !! Switched on system - dropped to 5V.

Yard guy brought on his test gear and indications were as long as I charged right away - I should get away with it ...
We started the engine and bank soon started recovering.

Due to bad wind direction - most of sail back to home port used engine - batterys were well charged ... shore power then connected ... chargers swapped to higher output units ... all appears I have been lucky.

Looks like I shall be fitting one of my Voltage Cut-out units ....

 

[lustyd]

300Ah of fogstar is £800?
Seems a little crazy that a marina based boat needs £800 of batteries.
It would have been cheaper to get a more efficient fridge.
Or switch it on while still in your marina?
Having loads of battery capacity doesn't always help, at some point you have to generate the energy you use.
So it's still good to have a fair idea of where your Ah are going.
Unless you are looking for extreme cycle life, most people would reckon the useful capacity of two 110Ah batteries is around 110Ah, but you can discharge below 50% a few times a year and not lose much life.

Assume you're replying to me. My fridge is very efficient once cool, but from warm it just takes power to get down to temperature. Most people probably don't realise how much.
We're a marina based boat while home, but occasionally are away for a few months. This has nothing at all to do with battery capacity though. We need a couple of weeks in British "Summer" while using the battery for fridge and Starlink among other things.
The cost of the 230Ah Fogstar is the same as two quality AGMs. The difference in capacity is normous so Lithium was a no brainer from the start, I actually thought the replacement AGMs would be a silly move given the cost per USABLE Ah. I added the £200 to get up to 300Ah as it was peanuts for the extra usable power over the life of the battery.

I've always seen 80% discharge recommended for lead, and the number of duff leads after short lives would seem to suggest even that is optimistic.