Lithium again...

Lightwave395

Lightwave395

Well-Known Member
Joined
14 Aug 2016
Messages
2,961
Location
Me in Cowes, Boat down in Southern Brittany
Visit site
I've searched the forum and read myself into a stupor about lithium and apologise for this repetitive but hopefully simple question...?

My house Gel batteries are seemingly fading and I'm pondering on their replacement.

I'm aware of the slowly decreasing prices of Lithium but also the dangers of buying some obscure, cheap brand (or non-brand).
I'm also aware from reading on the forum of the cost of proper alternator / engine start / DC - DC charger / Lithium etc to 'do it properly'

Engine is a VP md2040 with a modest 55A alternator with the basic V belt - I've looked at upgrading that to a ribbed belt and fitting the new 90A alernator I have but that belt conversion alone is north of £700

I could just replace my house batteries with SLA to keep it simple as we're marina based and our 12v power needs are modest with only the odd spring and summer nights at anchor and a relatively modest cruising range.
I'm wondering if it might be practicable to fit one or two Lithium batteries (maybe 200ah) connected only to my as yet unfitted 200w solar panel and my existing Sterling Ultra 12/50 mains charger (which does have a Lithium profile setting) leaving the recent 100ah SLA engine start battery connected to the alternator

I would need to keep any initial foray into Lithium as simple and budget friendly as possible for this year at least

Or do I just replace the fading house batteries with a couple of new SLA's
 
Lightwave395 said:
I've searched the forum and read myself into a stupor about lithium and apologise for this repetitive but hopefully simple question...?

My house Gel batteries are seemingly fading and I'm pondering on their replacement.

I'm aware of the slowly decreasing prices of Lithium but also the dangers of buying some obscure, cheap brand (or non-brand).
I'm also aware from reading on the forum of the cost of proper alternator / engine start / DC - DC charger / Lithium etc to 'do it properly'

Engine is a VP md2040 with a modest 55A alternator with the basic V belt - I've looked at upgrading that to a ribbed belt and fitting the new 90A alernator I have but that belt conversion alone is north of £700

I could just replace my house batteries with SLA to keep it simple as we're marina based and our 12v power needs are modest with only the odd spring and summer nights at anchor and a relatively modest cruising range.
I'm wondering if it might be practicable to fit one or two Lithium batteries (maybe 200ah) connected only to my as yet unfitted 200w solar panel and my existing Sterling Ultra 12/50 mains charger (which does have a Lithium profile setting) leaving the recent 100ah SLA engine start battery connected to the alternator

I would need to keep any initial foray into Lithium as simple and budget friendly as possible for this year at least

Or do I just replace the fading house batteries with a couple of new SLA's
Click to expand...
You could fit a couple of 100Ah lithium batteries. They would need a fuse each and an isolator each. Wire them with equal length wires to a +ve and a
-ve busbar. From here you can connect your MPPT for solar, your distribution board loads etc. You may also want to add an isolator to the distribution board and install the bilge pump on an essential services board with its own isolator. This allows you to isolate all normal loads of the distribution board but have blilge pumps still energised as well as solar. Instead of isolating the batteries when you leave the boat, you isolate the distribution board. This leaves the lithium batteries and solar with bilge pump, etc still live.
 
fredrussell said:
With that in mind, just stick with AGMs.
Click to expand...
You can expect up to 10 times the life out of lithium. I think it's so cost effective now that its a no brainer to make the change. The upgrade of the electrics is a one off cost, never to be repeated. Adding fusing to each battery and an isolator is good practise on any installation. I have seen people install lithium without this but it won't meet any relevant standard. Something that could be important in the event of an electrical fire and an insurance claim.
A DC/DC charger and smart shunt would also be needed.
A friend has lithium on his boat. The lithium was installed by the previous owner over 10 years ago. They are liveaboards and run charters.
Those batteries have been hammered. Used really hard. They are still in daily service.
Usable watt per £ there is no comparison that lithium is more cost effective.
If you have no plans to keep the boat then just swap for lead. If its a keeper then lithium everytime.

I think one of the very noticeable improvements when you install lithium, even on a boat with modest power requirements, is never suffering voltage sag. Electronics get the higher voltage they like. The fridge doesn't trip out in the middle of the night. You don't worry about getting the battery charged. You can discharge far lower than you can ever do safely with lead
 
PaulRainbow said:
How many batteries do you have, how big, room for more ?

What are "modest" power needs ?
Click to expand...
Currently I have 3 X 100ah 'Photonic Universe' gel batteries, each physically 325mm L X 170mm W X 215mm H all comfortably sitting together, I haven't done an exact power calculation but subjectively we might once in a while anchor for one, no more than two nights with a fridge (continuous), electric loo (occasionally !), water pump and LED lighting on, when sailing it's an autopilot and usual Nav instruments for maybe 6 - 8 hours max (less for the pilot as I enjoy steering...
 
Ok, here's what I did, being in a similar situation to you:-

I replaced my gel batteries with a single Ecoworthy 280ah LifeP04 battery, Great value at just over £300, and the bluetooth app is good.

Having bench-tested it at home, I decided to install it as follows:

I have a mains charger ONLY charging the lithium battery (you can buy a 20a charger from Ecoworthy as a bundle with the battery, that will do the job).

I ONLY charge the engine battery from the alternator (I removed the switch diode and wiring to the house battery).

I have found that to work perfectly. The engine battery only gets used to start the engine, and is replenished by the alternator. The lithium battery is charged when in a marina, and a fully charged battery lasts us 3 or 4 nights at anchor with no problem.

We used it like that all last summer, and have no plans to change it, as it works perfectly and is simple to install and manage.

Very simple and cheap install, and if you decide that you want to be able to charge the lithium from the alternator, just fit a small B2B charger later.
 
Bobc said:
Ok, here's what I did, being in a similar situation to you:-

I replaced my gel batteries with a single Ecoworthy 280ah LifeP04 battery, Great value at just over £300, and the bluetooth app is good.

Having bench-tested it at home, I decided to install it as follows:

I have a mains charger ONLY charging the lithium battery (you can buy a 20a charger from Ecoworthy as a bundle with the battery, that will do the job).

I ONLY charge the engine battery from the alternator (I removed the switch diode and wiring to the house battery).

I have found that to work perfectly. The engine battery only gets used to start the engine, and is replenished by the alternator. The lithium battery is charged when in a marina, and a fully charged battery lasts us 3 or 4 nights at anchor with no problem.

Very simple and cheap install, and if you decide that you want to be able to charge the lithium from the alternator, just fit a small B2B charger later.
Click to expand...
I was thinking along the same lines with that same battery - 2 X SLA 110 / 120 batteries will cost me over £200 and I could already have (I think) a mains charger, would hopefully just need to change the profile or just sell it and replace it - do you have any solar ?
 
Lightwave395 said:
I was thinking along the same lines with that same battery - 2 X SLA 110 / 120 batteries will cost me over £200 and I could already have (I think) a mains charger, would hopefully just need to change the profile or just sell it and replace it - do you have any solar ?
Click to expand...
Ebay listing

This is what you need, plus an isolator and fuse.

I had 3 x 110ah gel batteries, and this gives nearly TWICE that capacity,
 
In your case a simple install makes sense - pretty much as you describe it - solar (assuming the MPPT controller can be suitably programmed for lithium) and shore power to the Lithium and no complexity between alternator and LFP .

You can get one 200ah or 300ah LFP a lot cheaper than 2 separate batteries and then only need one fuse and cable etc but think about redundancy and if the loss of the house battery would be a major problem ... If so then spend a bit more for two separate LFP. But as Geem says, basically fuse the LFP properly, make sure there is a rotary cut off switch of suitable size for the battery and run + and - to separate busbars and connect the charge sources to those bus bars.

Maybe check out Will Prowse' channel on U-tube to se if there is a review of your chosen LFP brand - there are many and some well known brands I could never recommend based on experience fitting so many of these things
 
In this situation (almost exactly the same, down to the engine!) we fitted 1 300Ah Fogstar Drift battery. I had to cut the plastic handles off to fit it in the box but totally worth it given the huge capacity boost. This also gave me space in the battery box to add fuse and a couple of other components as I only have one battery where before there were two.
Adding in a B2B later is pretty easy and cheap, just don't forget to remove any VSR or split charge relay currently fitted (MD2040 usually has a relay, mine for some reason had both!)
Beware of larger alternators, heat will potentially limit output anyway. We get ~30A from ours on the MD2040 despite the higher rating.
 
Lightwave395 said:
I guess if I went with the marginally cheaper option of one big Lithium then for emergency redundancy I could just have a changeover switch to the 100ah engine start battery
Click to expand...
Most of the things that would take one lithium battery offline would take both of them offline: i.e. low voltage, over current.

A single lithium battery and some form of changeover to the start battery sounds like a good plan. But it would be best, IMHO, if you make it so that you can't put them in parallel.
 
Sea Change said:
Most of the things that would take one lithium battery offline would take both of them offline: i.e. low voltage, over current.

A single lithium battery and some form of changeover to the start battery sounds like a good plan. But it would be best, IMHO, if you make it so that you can't put them in parallel.
Click to expand...
I guess some kind of 'break before make' changeover switch/breaker
 
I would not fit 2 batteries, i'd pay the little extra and have a Fogstar Drift, rather than Eco-Worthy. Connect that to a fuse, then the isolator, then to the domestic systems. Connect the solar directly to the LFP, same with the mains charger, use Victron for both, generally more configurable and have Bluetooth.

Keep the engine separate, with it's own isolator, if you find you need it you can easily add a DC-DC charger later, Victron again.

I would fit a parallel switch between the load terminals of both switches. If there was a problem with the LFP, isolate it and close the emergency switch, everything works from the engine battery. If the engine battery won't start the engine close the emergency switch, start the engine, turn the emergency switch off. Chances are the LFP can start the engine without upsetting the BMS. Use an emergency switch with a removable key, don't leave the key in so no-one can turn it on accidentally.
 
Sea Change said:
Most of the things that would take one lithium battery offline would take both of them offline: i.e. low voltage, over current.

A single lithium battery and some form of changeover to the start battery sounds like a good plan. But it would be best, IMHO, if you make it so that you can't put them in parallel.
Click to expand...
Out of interest, why ?
 
Sea Change said:
Most of the things that would take one lithium battery offline would take both of them offline: i.e. low voltage, over current.

A single lithium battery and some form of changeover to the start battery sounds like a good plan. But it would be best, IMHO, if you make it so that you can't put them in parallel.
Click to expand...
Dont forget things like bad connectors on the bms, bad connections on the cell terminals, failed bms.
From my recent experience on the Winston battery installation that I have been trouble shooting, corrosion can be an issue, even though the boat is very dry. What looked perfect at first glance wasn't when the connections were disassembled.
A second battery allows you to take one off line to check these thing periodically without going dark. A failed battery can easily be isolated and you carry on on the remaining battery or batteries
 
You must log in or register to reply here.

Other threads that may be of interest

geem
Lithium battery system lessons
Replies
10
Views
313
migs
M

Share this page

Top