Adding Lithium capacity to our existing setup

[mrming]

We go on boat holidays with our kids, and find that our current battery power can’t quite keep up with demands on board for more than a day or two.

The engine gets run a fair bit between ports, and we plug in when in marinas, but it would be nice to be able to survive say 3 days at anchor or on a buoy, running the fridge, charging all the gadgets etc.

Our engine has one 65A and one 70A alternator. We currently have a single lead acid battery for starting the engine, and 2 x 110AH AGM lead acid batteries in the domestic bank. There’s a 30w solar panel and a mains Victron charger.

The current batteries are pretty new, and the space they’re in is full, but there’s another candidate space adjacent, under the nav seat. My thought is to fill that space with LiFePo or similar new tech batteries, ideally with integrated BMS. Then install a DC to DC charger and use either the engine or domestic batteries as a buffer to charge the lithium bank.

Is that a reasonable plan? Is there anything I’m missing? I’ve never dealt with lithium type batteries before so could be getting it all wrong.

I appreciate many similar questions have been asked before, but in this case the theory is to supplement rather than upgrade or replace the existing capacity (unless that’s insane) .

Any pointers greatly appreciated. Boat is a Westerly Fulmar with a Beta 28.

 

[dunedin]

For running fridges etc at anchor, personally I would start by adding more solar ahead of more battery.
Appreciate that space is tight on a Fulmar, but 30w is very small these days. Surely you could find space for at least 100w - perhaps in a couple of semi flexible panels (ours are on the sprayhood). And perhaps another one or two moveable semi flexible panels able to be set up when at anchor?

 

[crewman]

There is a promotional piece in the latest PBO on a system called the LE300 Smart battery system (www.bos-ag.com) which seems to fit your needs. Only skimmed the article so far.

 

[sawduster]

My understanding is that lithium and lead acid shouldn't be paired because the charging and discharging profiles are quite different so you wouldn't really be able to have them in one bank when you only have one house circuit. Realistically your best bet long term is to ditch the lead house bank and replace it with lithium - a bit more work than it sounds as it's not really drop in because you'll need to redo a lot wiring, new wiring for the DC-DC charger, fuses etc.

An option could be to have a larger/50Aish DC-DC charger from the engine battery to a lithium battery, then a smaller 10A DC-DC charger from the lithium to house bank. The engine-lithium charger activated on alternator output, then the lithium to house activated on a switch or perhaps a relay so it only activates on alternator off. Your house bank would essentially always be being charged by the lithium battery when not being charged by the alternator so you'd probably want to set it to a pretty low charge profile otherwise your house would always be at 14V+ charging voltages. I'm sure there might be some other downsides I haven't considered that others can offer, but at initial thoughts it might work.

 

[PaulRainbow]

This won't work very well. Best thing to do is to replace the AGM's with Lithium. Connect solar to the Lithium with a controller that has a Lithium profile, or connect to the starter battery. Only charge the engine battery with the alternators or shore power. Charge the lithiums from the engine battery with a DC-DC charger. You'll need to fit a suitable fuse to the Lithiums.

As Dunedin said, more solar would be a great help.

 

[mrming]

There is a promotional piece in the latest PBO on a system called the LE300 Smart battery system (www.bos-ag.com) which seems to fit your needs. Only skimmed the article so far.

This sounds ideal - any thoughts on it @PaulRainbow ?

 

[PaulRainbow]

This sounds ideal - any thoughts on it @PaulRainbow ?

£825.95 for 56Ah ?

 

[Sea Change]

I presume you mean amps rather than watts for your alternators?
The fact that you have two is interesting. By any chance is one of them fitted with anything clever like a charge regulator, which would be able to charge lithium batteries without the need for an expensive, hot, and inefficient DC-DC charger?

(I have limited experience of DC-DC chargers, I've heard that the latest Victron is much better than the old type that I have. But I still think it's best to charge directly from the alternator if possible).

 

[mrming]

£825.95 for 56Ah ?

I only glanced at the pricing at around £400 but I see now that’s only for 1 module (25.6AH). Eek!

 

[mrming]

I presume you mean amps rather than watts for your alternators?
The fact that you have two is interesting. By any chance is one of them fitted with anything clever like a charge regulator, which would be able to charge lithium batteries without the need for an expensive, hot, and inefficient DC-DC charger?

(I have limited experience of DC-DC chargers, I've heard that the latest Victron is much better than the old type that I have. But I still think it's best to charge directly from the alternator if possible).

Yes my mistake - now corrected thanks. I’ll see if there’s a charge regulator - I doubt it but worth a look.

 

[mrming]

Thanks all. With regard to more solar, I could do it but it’s tricky to find unshaded space as the boom runs almost to the backstay.

Also this is very much a “once a year” problem so I don’t really want to cover my otherwise nice boat in constructions to hold solar panels.

I could probably get up to 100W without building extra mounting structures though, so I’ll take a look at that.

The power we have works fine for the rest of the season - it’s just on this long annual trip that we’d like a bit more.

First thing I’ll do is draw a diagram of how everything is wired now. It’s an inherited system so I’m not 100% sure of the relationship between the mains charger, solar, 2 alternators and the two battery banks.

If I do replace the domestic bank with lithium, I’ll definitely need a way to charge it from the engine (e.g. via the engine battery as suggested), as it would not be an improvement in the family’s eyes if I say “sorry it’s too cloudy”.

 

[Neeves]

Obvious really - but if you want to reduce engine time and not retreat to marinas you need to increase your solars, 10 fold. This means you will need new MPPT solar controllers. You can cantilever solars off the life lines, with struts to support. But if you want to 'sail' you will not farm many amps if you sail and then anchor in mid afternoon

You need to be able to monitor the battery bank(s). Do you have a shunt? - how often have you run the LA bank below 50% - if often or you do not know - then the LA bank might have been compromised (new or not).

I assume you use gas for cooking and heat water for showers using the calorifier. Your amps demands are then the vessel fridge, electronics and the children's gadgets - maybe if the latter you need power banks (that you recharge every 3 days in the marina).

Your biggest single domestic consumer might be the fridge - and its appetite for amps might be increased by constant opening and closing the door. But an electric icebox that you chill down in the marina and supplement with ice blocks. Look at making the boat fridge more efficient, reduce the temp when in the marina, add computer fans to cool the compressor and remove warm air round the compressor.

You are not alone.

Jonathan

 

[mrming]

Obvious really - but if you want to reduce engine time and not retreat to marinas you need to increase your solars, 10 fold. This means you will need new MPPT solar controllers. You can cantilever solars off the life lines, with struts to support. But if you want to 'sail' you will not farm many amps if you sail and then anchor in mid afternoon

You need to be able to monitor the battery bank(s). Do you have a shunt? - how often have you run the LA bank below 50% - if often or you do not know - then the LA bank might have been compromised (new or not).

I assume you use gas for cooking and heat water for showers using the calorifier. Your amps demands are then the vessel fridge, electronics and the children's gadgets - maybe if the latter you need power banks (that you recharge every 3 days in the marina).

Your biggest single domestic consumer might be the fridge - and its appetite for amps might be increased by constant opening and closing the door. But an electric icebox that you chill down in the marina and supplement with ice blocks. Look at making the boat fridge more efficient, reduce the temp when in the marina, add computer fans to cool the compressor and remove warm air round the compressor.

You are not alone.

Jonathan

Mostly correct assumptions, but there can be a fair bit of motoring between stops so charging from the engine is usually fine. Fridge and gadgets are indeed the main consumers. All lights are LED. I have a battery monitor and have never knowingly run the domestic bank under 50% - the batteries appear to be in good health. There are two issues with covering the boat in solar - one, aesthetics for a once a year trip, and two, we’re in the UK where output will not always be great if it’s overcast.

Hence the thought of adding an extra chunk of battery capacity, charged in the marina or on a long period of motoring, and available to use (almost) fully when anchored or moored.

 

[Sea Change]

If it's genuinely just a one-off the simplest and cheapest thing might be to add a suitcase generator.

And I say that as somebody who loathes the things, and the dusk chorus they produce in popular anchorages.

 

[dunedin]

Thanks all. With regard to more solar, I could do it but it’s tricky to find unshaded space as the boom runs almost to the backstay.

Also this is very much a “once a year” problem so I don’t really want to cover my otherwise nice boat in constructions to hold solar panels.
…..

Then some “roving panels” might be the answer - a couple of c.60 semi flexible panels with 5m leads. Put on board for the summer cruise and pop them on deck or around the cockpit when at anchor. When sailing might be able to keep one up somewhere, or just pop both in the quarterberth till dropped the hook.
We initially had a 100w solid roving panel, but it was too sharp edged and awkward, so replaced with semi flexible. Only issue is latest one is so light I am going to add wood batten on sides to avoid being too flexible.

PS. According to various articles in YM, need to advise insurers if fit Lithium batteries - and if had a newer boat, BM even suggesting switching to Lithium could be a “major change” impacting RDR/RCD certification. I wouldn’t worry about the latter, but advising the insurance would be worthwhile.
I have just replaced our AGM ships batteries like for like. Worked fine for 12 years so far with solar, so if does and similarly will see me out with this boat.

 

[PaulRainbow]

If it's genuinely just a one-off the simplest and cheapest thing might be to add a suitcase generator.

And I say that as somebody who loathes the things, and the dusk chorus they produce in popular anchorages.

IMO, a generator can be useful (we have a 12kva one powered by a Volvo 2002 !) if you want to to use something power intensive with limited power storage, such as electric cooking etc. But, for actual battery charging you'd have to run a suitcase generator for a very long time.

 

[Carlos Azevedo]

Hi there,

A solar generator might be a good solution to you. I had good experiences with ecoflow but there are several brands and types you can charge with siolar and, or with engine running along way... Most have integrated Lithium batteries and inverters. Maybe a bit pricey but if you count in all... Battery + inverter+ solar panels, they could be a smart option...

 

[PaulRainbow]

Hi there,

A solar generator might be a good solution to you. I had good experiences with ecoflow but there are several brands and types you can charge with siolar and, or with engine running along way... Most have integrated Lithium batteries and inverters. Maybe a bit pricey but if you count in all... Battery + inverter+ solar panels, they could be a smart option...

£1149 for 85ah ?

EcoFlow DELTA 3 Series Solar Generator (PV220W) - EcoFlow UK - EcoFlow UK

 

[PaulRainbow]

We go on boat holidays with our kids, and find that our current battery power can’t quite keep up with demands on board for more than a day or two.

The engine gets run a fair bit between ports, and we plug in when in marinas, but it would be nice to be able to survive say 3 days at anchor or on a buoy, running the fridge, charging all the gadgets etc.

Our engine has one 65A and one 70A alternator. We currently have a single lead acid battery for starting the engine, and 2 x 110AH AGM lead acid batteries in the domestic bank. There’s a 30w solar panel and a mains Victron charger.

The current batteries are pretty new, and the space they’re in is full, but there’s another candidate space adjacent, under the nav seat. My thought is to fill that space with LiFePo or similar new tech batteries, ideally with integrated BMS. Then install a DC to DC charger and use either the engine or domestic batteries as a buffer to charge the lithium bank.

Is that a reasonable plan? Is there anything I’m missing? I’ve never dealt with lithium type batteries before so could be getting it all wrong.

I appreciate many similar questions have been asked before, but in this case the theory is to supplement rather than upgrade or replace the existing capacity (unless that’s insane) .

Any pointers greatly appreciated. Boat is a Westerly Fulmar with a Beta 28.

If the current batteries last 1-2 days and you only need 3 days, an extra 110AH AGM and a 100W solar panel may well get you where you need to be.

If you're not convinced, a Lithium battery and a DC-DC charger, taking out the AGMs.

You could leave one AGM in place and fit the Lithium battery next to it. Connect both batteries to busbars, via seperate fuses and switches. Connect the alternator to the AGM and loads to the Lithium. The Lithium is low resistance so loads will be drawn from her, without barely affecting the AGM (if at all). The charging to the AGM will prevent the Lithium from overloading the alternator. An additional benefit is that if one battery fails you still have power or if you get a Lithium shutdown, same thing, you still have power.

 

[chris-s]

Thanks all. With regard to more solar, I could do it but it’s tricky to find unshaded space as the boom runs almost to the backstay.

Also this is very much a “once a year” problem so I don’t really want to cover my otherwise nice boat in constructions to hold solar panels.

I could probably get up to 100W without building extra mounting structures though, so I’ll take a look at that.

The power we have works fine for the rest of the season - it’s just on this long annual trip that we’d like a bit more.

First thing I’ll do is draw a diagram of how everything is wired now. It’s an inherited system so I’m not 100% sure of the relationship between the mains charger, solar, 2 alternators and the two battery banks.

If I do replace the domestic bank with lithium, I’ll definitely need a way to charge it from the engine (e.g. via the engine battery as suggested), as it would not be an improvement in the family’s eyes if I say “sorry it’s too cloudy”.

We have a similar size boat and upgraded to 300ah of lithium last year (way more than needed but it was a good deal). We have a single fixed 80w panel and two 100watt panels that we leave in the cockpit or placed on the side decks when at anchor or left on the swing mooring. When not needed they get unplugged and moved below.

Running the fridge 24/7 and the usual devices has never caused concern.
As others have suggested, the alternator charges the engine battery and the solar the lithium’s with a dc-dc between them.