Move to lithium yet?

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pcatterall

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Following my battery test and your advice on this I conclude that our 2x70 ah domestics need replacing.
We are considering retaining the lead acid starter and using a dc dc charger. We have up to 200w of solar.
An important issue is that yacht is in group ownership and some members don't always follow rules about how to use and leave things. I would rather let them ruin a couple of LA than lithium bats.
In general what does the team think about the general idea lead/ lithium mix and potential for misuse by this and other numpties?
An idea about overall cost would be great to!
 
pcatterall said:
Following my battery test and your advice on this I conclude that our 2x70 ah domestics need replacing.
We are considering retaining the lead acid starter and using a dc dc charger. We have up to 200w of solar.
An important issue is that yacht is in group ownership and some members don't always follow rules about how to use and leave things. I would rather let them ruin a couple of LA than lithium bats.
In general what does the team think about the general idea lead/ lithium mix and potential for misuse by this and other numpties?
An idea about overall cost would be great to!
Click to expand...
What do you mean by "lead/lithium mix". LA engine battery and LFP domestics, or something else ?

If you mean engine/domestics, there is no mix, as such. Both are independent systems, one may charge the other, via the DC-DC charger, but they still remain independent. It's actually harder to harm a properly installed/setup LFP system than it is LA, the BMS will protect the LFP from most things, LA has virtually no safeguards. Cost will depend on what you want/need to install and who is going to install it.
 
Thanks. I meant what I thought was fairly common practice. Having.a LA starter and lithium domestics. Charging the starter would utilise the existing set up and then the lithium is charged .via a dc-dc charger.
My concern about simplicity.is that crew are familiar. with LA but.not.lithium. I.understand.that lithium bats should not be left for .long periods.fully charged so that's the first thing they may cock up. Also it is always nice to.have you starter battery ready to. go at any.time!
 
pcatterall said:
Thanks. I meant what I thought was fairly common practice. Having.a LA starter and lithium domestics. Charging the starter would utilise the existing set up and then the lithium is charged .via a dc-dc charger.
My concern about simplicity.is that crew are familiar. with LA but.not.lithium. I.understand.that lithium bats should not be left for .long periods.fully charged so that's the first thing they may cock up. Also it is always nice to.have you starter battery ready to. go at any.time!
Click to expand...
If it's properly installed and setup there's nothing to do except turn he batteries on/off.

Alternator charges engine battery, then the LFP via a DC-DC charger.

Solar would usually charge the LFP, but as your boat is in Spain i would connect the solar to the engine battery.

Fit a Victron DC-DC charger and connect the remote wire to the load side of the domestic isolator, that way the DC-DC charger will be off when the crew leave the boat (switching the domestic isolator off), so the solar won't hold the LFP at full charge while you're away, but will keep the engine battery fully charged.

They should be able to remember to turn one switch on/off ?
 
It would be good to know a few things:
- how long do you plan to keep the boat?
- do you keep it on a berth with a charger plugged in?
- do you do a lot of motoring and stay in marinas a lot?
- what do you need to power from the batteries?
 
If you set the voltage correctly on the charger then the harm done in keeping LFP on charge is minimal. It’s unlikely you’d notice the degradation even after several years. This advice is mostly a hangover from when LFP was exceptionally expensive.

It’s still good advice, but it’s really not an issue if you leave them on charge at a suitable voltage. When we’re in marinas we often go for a month at a time at 100% with the charger on 24/7. No drop in capacity after 3 years.
 
lustyd said:
If you set the voltage correctly on the charger then the harm done in keeping LFP on charge is minimal. It’s unlikely you’d notice the degradation even after several years. This advice is mostly a hangover from when LFP was exceptionally expensive.

It’s still good advice, but it’s really not an issue if you leave them on charge at a suitable voltage. When we’re in marinas we often go for a month at a time at 100% with the charger on 24/7. No drop in capacity after 3 years.
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With LA there was pretty much a one size fits all for charging routines, but I see LFP benefiting from different regimes, depending on the usage pattern of the owner/boat.

Like you, we live aboard, so the solar controller is set to fully charge the batteries and then a float voltage that keeps them at about 98%. I want to keep them pretty much fully charged so i have the maximum power for when the Sun goes down. But something different would be better for, say, a weekend sailor. Still fully charge the batteries, but set the float voltage a little lower, so as to maintain about 90% SOC. He'll arrive at the boat with plenty of power, without stressing the batteries.

During the Winter we don't get enough solar yield to fully charge the batteries. I don't want the mains charger to fully charge the batteries, because that leaves nowhere for tomorrows solar yield to go, i want all of the solar yield there is. So, the mains charger (Victron Multiplus 2) is set to charge when the SOC falls to 50% and stop charging at 60% SOC. This keeps the batteries at an ideal SOC, but allows plenty of room for solar yield. For a boat left unused for the Winter something slightly different would be better, likely no mains charging at all, rely on solar to keep the batteries at a suitable SOC, obviously subject to location and amount of solar.
 
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All very sensible Paul. I said what I said as OP was worried that the other owners may not follow procedure or forget to switch on/off something. I just wanted to let them know that best practice is good but the LFP are very unlikely to suffer much if anything happens. In their position I may do a lot of things differently than my own boat in order to make it easier for all rather than protecting against loss of 1% capacity after 5 years.
 
lustyd said:
All very sensible Paul. I said what I said as OP was worried that the other owners may not follow procedure or forget to switch on/off something. I just wanted to let them know that best practice is good but the LFP are very unlikely to suffer much if anything happens. In their position I may do a lot of things differently than my own boat in order to make it easier for all rather than protecting against loss of 1% capacity after 5 years.
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I agree, no criticism of your original post (y)
 
Hi Peter, we met many years ago at Fiddlers Ferry, I think you had some sort of motorsailer at the time.
This might interest you, seems like a decent bargain till Tuesday, 200ah for 243, cheaper than equivalent usable capacity than AGM. I already have a Renogy DcDc charger so might take the plunge.
Pardon our interruption...

Opinions welcome.
 
ridgy said:
Hi Peter, we met many years ago at Fiddlers Ferry, I think you had some sort of motorsailer at the time.
This might interest you, seems like a decent bargain till Tuesday, 200ah for 243, cheaper than equivalent usable capacity than AGM. I already have a Renogy DcDc charger so might take the plunge.
Pardon our interruption...

Opinions welcome.
Click to expand...
The spec on those is terrible, not with a bargepole.

Pay the extra £100 and get 230Ah of much, much better quality battery.
 
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