Advice boat installation

[nilsson_lina]

Hi all,
I recently found this forum and it seems great. I've been searching and not found answers to all my questions. So I thought perhaps I could reach out and ask for some advice.

My house batteries on my boat are going bad. I need to replace them the coming months. So I thought I should install Lithium instead. But I understand there are a few things I need to consider and do to make it a safe but still easy installation. That is where I hope to get some advice from this forum.

A few details about my ideas and needs:

• I want to keep my starting batteries and only change the house bank to lithium
• I don't plan to have a lot of solar, only a few panels at the moment. (not included in the schematic below)
• I want to add approx 4 x 200Ah Lithium batteries that are reliable and safe (i don't want to build them myself.
• The charger I have has a lithium profile
• The alternators I have are "stupid" not regulated

Below you see the setup I have today.

If I change the house battery bank to Lithium. What do I need to do with this configuration to make it a safe and reliable system?
Especially thinking about the setup with the alternators and the combination with my old starting batteries and new lithium batteries.

What would be your best configuration and advice?

Thanks in advance

 

[Supervstech]

In theory , the dumb alternators can burn out trying to satisfy the spike demands of a house lithium battery… you should replace the isolators with dc to dc chargers, or at lease install them between the isolators and the house bank.

 

[nilsson_lina]

In theory , the dumb alternators can burn out trying to satisfy the spike demands of a house lithium battery… you should replace the isolators with dc to dc chargers, or at lease install them between the isolators and the house bank.

Thanks for your advice.
Sounds pretty straightforward.

Would you say that dc-dc charger is s better alternative than changing alternators to regulated ones?

 

[Browneye]

Thanks for your advice.
Sounds pretty straightforward.

Would you say that dc-dc charger is s better alternative than changing alternators to regulated ones?

Yes. Starting batteries should not be parallel connected to lifepo4 house batteries. And starting batteries should be lead acid for high amp starting. Keep the starting and house circuits separated, skip the isolators. Once I figured out I could just take the isolator out of the Winnebago it made accommodating the lifepo4 charging and maintaining requirements a lot easier to address.

Start with an energy audit to assess what your actual needs are, then assemble your components to suit. Without knowing what you need to run, like refers, heaters, appliances, etc., it's difficult to select the right components and capacities. All depends on how much you plug in and how much you want to run a genset.

Will has some tested off the shelf battery recommendations at varying price points.

Now is a good time to assess power needs, wiring layout and componentry, inverters, chargers, etc.

 

[nilsson_lina]

My energy needs aren't really changing. So no need to change inverters or chargers unless I have to, for it to work well.
If I'm motoring I want to "use" that energy as much as possible to charge the batteries, to minimize generator time.

Is this what you are suggesting? See the changes in red below

• No change to the alternators
• Remove isolators and add a dc-dc 12v charger for the house batteries, like a victron 30A charger
• Charge only house batteries from the chargers I have, using their lithium profile
• Starting batteries will be charged directly from alternators

If this is what you suggest I have a question (and please excuse if I'm not understanding this correctly)
- Won't this setup be slowing down the charging to the house battery when motoring?

I thought of an idea, and please feel free to say if this is a bad idea.
What if I add external regulators to the alternators, for them to preform at their best, and charge house and starting batteries using isloators to separate them? Bad idea? Maybe that is still considered to be in parallel?
And if needed, add a dc-dc charger from house to starting batteries, to use when house are being charged from generator or shore power.
(In this alternative the isolators could also be removed if it's not recommended to have them, and let the alternators only charge house batteries. But then the dc-dc charger between house and starting is required.)

Like this...

 

[Browneye]

Hopefully some of the more seasoned installers will come along here with more suggestions.
Appears your goal is to utilize the alternator's full capacity to charge your house batteries, and I'm not familiar with modifying them to work with lifepo4. I do know that lfp batteries have such low internal resistance that they'll pull whatever your alternator(s) can output, and especially at idle can overheat them, actually burn them out. Hence a way to regulate them. What have you found for a proper external regulator?

We have another current thread here where the poor guy has burned out 4 expensive alternators trying to get his system to work.

The victron orion is an excellent product, and you might even be able to use a couple of them. Your first diagram is a more common way to do this, the latter has it going the wrong way - they should turn on when your engines run to charge the house bank. Your starting batteries are already connected for charging. In most instances the starting circuit/setup is left alone and new lfp configuration for house loads with their own proper charging parameters.

What kind of chargers are already installed? What are their charge profiles? Some of them can work with lfp, but generally ones specifically designed for such are recommended. Chargers for lead-acid batteries tend to charge at too high of voltage and don't terminate when lfp gets full, and thus over-volting them.

My mobile installation is in a Winnebago, 8.1L GM V8 with the same two starting SLA's, isolated from the house circuit. The old isolator combiner would connect house and starting when the ignition turned on. And as-built had the generator wired to the house side, it was moved over to the starting side. I installed a separate 100W solar panel and controller for the starting batteries with a SLA charge profile - to keep them topped up during storage.

The house side got 600W of solar and lfp charge profile controller, a victron orion charger for when driving, and a 12V converter/charger that can be manually turned on for charging when plugged into shorepower or generator running.

Without knowing your consumption when not running, it's difficult to assess how many charging amps might be required to put back what you used. If you're installing 800Ah of capacity, then 60A of dc-to-dc charging might take more than 12-15 hours to recharge a depleted house bank. Generally the target is to start with mostly full charge when parked and using them.

What kind of vessel is this? 80A alternators seem small for a pair of diesels in a motoryacht. And a sailing yacht generally has just one engine.

 

[nilsson_lina]

Appears your goal is to utilize the alternator's full capacity to charge your house batteries, and I'm not familiar with modifying them to work with lifepo4. I do know that lfp batteries have such low internal resistance that they'll pull whatever your alternator(s) can output, and especially at idle can overheat them, actually burn them out. Hence a way to regulate them. What have you found for a proper external regulator?

That was one of the hopes to utilize the alternators. The regulators I've been looking at are Mastervolt Alpha pro III or the Balmar retrofit-kit with MC-614 Regulator Kit.

What kind of chargers are already installed? What are their charge profiles?

I have two cristec Ypower, one 60A and one 40A, they have lithium profiles. The 60+40A chargers are doing a fairly good job keeping the batteries charged when running the generators for 4-6h per day. We live on the boat 9 months of the year so the batteries are being used daily.

If you're installing 800Ah of capacity, then 60A of dc-to-dc charging might take more than 12-15 hours to recharge a depleted house bank. Generally the target is to start with mostly full charge when parked and using them

Yes, that is a long time. That's why I was thinking it might be better to charge the house with more amps directly from the alternators instead of limiting the charging capacity by a "small" dc-dc charger. But maybe a stupid idea To charge the starting batteries a smaller charger would be needed since it's a smaller bank. But we don't plan to fully charge the house with the alternators, just want to utilize the energy they generate in an efficient way.

What kind of vessel is this? 80A alternators seem small for a pair of diesels in a motoryacht. And a sailing yacht generally has just one engine.

Oh, sorry I have two 120A alternators, I updated the pictures.

 

[Browneye]

We need some more well versed installers opinions here...
@Lt.Dan
@12VoltInstalls
@time2roll
@sunshine_eggo
@John Frum - looks like smoothjoey changed his name.
@HRTKD

 

[time2roll]

I like alt 1. I would add an isolator off the 25a charger to maintain both the Engine start and the generator start battery. Probably 10 amps is plenty.

I would probably skip the extra regulators for the alternators. Existing should be fine for the FLA and the DC-DC will control voltage to the LFP. Can be added later is something needs improvement.

 

[Goboatingnow]

Thanks for your advice.
Sounds pretty straightforward.

Would you say that dc-dc charger is s better alternative than changing alternators to regulated ones?

Change the alternator to handle Li charging and then use a small dc dc converter to trickle charge the starter from the li.

Doing the reverse means expensive high power dc dc units or throwing away the alternator current.

 

[nilsson_lina]

Change the alternator to handle Li charging and then use a small dc dc converter to trickle charge the starter from the li.

Doing the reverse means expensive high power dc dc units or throwing away the alternator current.

That was one of the ideas with alternative 2 that I was looking for feedback on, if it was a bad or good idea sounds like you are in favor of that idea

 

[Goboatingnow]

That was one of the ideas with alternative 2 that I was looking for feedback on, if it was a bad or good idea sounds like you are in favor of that idea

Yes it’s far superior to the reverse option , configure all charge sources to connect directly to the li bank. This makes best use as the Li bank needs the most charging. Charge the starter with a cheap dc dc trickle charger and simply regard the Li power as the system power bank.

 

[time2roll]

Change the alternator to handle Li charging and then use a small dc dc converter to trickle charge the starter from the li.

Doing the reverse means expensive high power dc dc units or throwing away the alternator current.

I read in the boating world... that LFP can draw the alternators at full capacity and burn them out.

Recently read a post here of a boat that went through four alternators and was asking for help.

The DC-DC is generally to limit current into the LFP battery. Where as the FLA direct on the alternator is not an issue.

 

[Goboatingnow]

I read in the boating world... that LFP can draw the alternators at full capacity and burn them out.

Recently read a post here of a boat that went through four alternators and was asking for help.

The DC-DC is generally to limit current into the LFP battery. Where as the FLA direct on the alternator is not an issue.

Alternators only burn out on li because the stock alternator regulator is from a car and is not designed to charge any battery , it’s designed to act as a fixed voltage power supply.

In any Li install your charge sources should all be Li compatible

Change the regulator and that fixes things , what’s not good is a half arsed solution to get around the stock alternator issue.

You’ll also need to ensure the lithium dc dc charger stops when the alternator stops.

I

 

[Rocketman]

The YouTube channel “Gone with the Wynns” a couple of months ago upgraded their marine alternators to work very well with their lithium bank. The episode is “This changes everything”.

That would be the best - if you can afford it. The alternator is controlled by an external regulator that watches alternator temp, battery voltages, etc. to provide maximum charging without causing problems.

Then use a dc-dc charger to charge the starter battery. Wakespeed (if I am remembering correctly) is another regulator that can work well.

Remember to have a really good shunt based battery monitor.

Good Luck

 

[nilsson_lina]

The YouTube channel “Gone with the Wynns” a couple of months ago upgraded their marine alternators to work very well with their lithium bank. The episode is “This changes everything”.

That would be the best - if you can afford it. The alternator is controlled by an external regulator that watches alternator temp, battery voltages, etc. to provide maximum charging without causing problems.

Then use a dc-dc charger to charge the starter battery. Wakespeed (if I am remembering correctly) is another regulator that can work well.

Remember to have a really good shunt based battery monitor.

Good Luck

Thank you. Will check the video.
I have a Mastervolt mastershunt 500 that should work.