Lithium Conversion Question

[coffeytime]

Maybe I suck at searching, but can't find an answer to this. Feel free to point and laugh.

We have a 1985 PT38 Sundeck. We love her and want to upgrade the electrical system to allow for extended stays away from the dock.

Our current setup is a 2 bank house battery made up of one 200 Ah AGM battery per bank. We would like to convert to a single bank of LiFePO4 made up of two 460 Ah batteries. We have two engines with alternators connected to two Sure Power Model 703 (70 amp) Battery isolators. These are set to charge 3 batteries, Bank 1 , Bank 2 and the Starter Battery. We are concurrently replacing our old 1000w Inverter charger with a MultiPlus II. We also have a genset.

My question is this. If I connect both start batteries (1 4D AGM for the engines and one flooded 12v for the generator) to the trickle charge output from the MultiPlus, Can I remove the Battery Isolators and replace them with 2 DC-DC Battery Chargers integrated with the Multiplus through a Lynx Shunt?

Let me know if I have not been clear or if more information is needed.

Thanks.

 

[READY]

I am not sure I am clear but will toss out some comments
1) the trickle charge off the MP will not supply a lot of charge current. If you deeply drain them you may need a plan B
2) The trickle charger I don't think can charge both those start batteries properly since they have different charging profiles
3) Are you planning to charge the house LFP bank off your existing alternator? You need to consider managing that.

I think the most simple solution (but not the best) would be just replace your house bank with LFP and charge them off either the MP on shore/generator or through a DC to DC to protect the alternator. Keep the start setup as is.

 

[coffeytime]

Thank, @READY. I understand your comment about the trickle charge only. With that in mind, I can keep the start battery connected to to Battery Isolaters. Then the question is, can I safely connect two DC-DC Battery Chargers to the two Battery Isolators? Or should I remove the Battery Isolators and connect the battery to both Alternators? Is it possible to connect the the two Alternators together to charge the Start Battery?

 

[Bmarler]

Hmm, always lots of choices with twins and battery chemistries.
I might think about this: set one alternator up for starting duty. One battery to start both engines fed by one alternator. Connect the genset battery via an automatic charge relay. Get rid of the isolators.
For the other alternator, change it out for one with external regulation and high output. Use this for the lithium house bank. I’m not familiar with how the multiplus charges, but I’d think you would set it with a lithium charge profile and either use a dc to dc for the start bank or a smaller, dedicated charger, whichever makes more sense.

 

[Mambo42]

If you change to LiFePO4 you will need a different regulator for your alternators and once you have that different regulator you cannot charge the start bank with those alternators.

I had roughly the same set up, but then even changed to 24 V for the house bank. The start batteries however are still 12 V though. So I added a second (24V) alternator to each engine, while keeping the 12 V alternators to charge the start batteries. I added a switch on the helm (via the allowed to charge switch on the BMS) to those 24 V alternators so that I can switch them on or off as required.
As others have stated, a trickle charger won't be enough to charge the batteries, but instead you can add a 110 V (or 220V) 12 V 25 A Victron charger. That one can be connected to the output of the Multiplus, which will then charge the start batteries. Unless you have eg a bow thruster or wind lass also connected to the start batteries that charger should be capable of recharging the start batteries.

Another solution would be to have one alternator on one engine charge the LiFePO4 bank and the other alternator on the other engine charge the start batteries. That is assuming that you run on two engines or can switch them on when necessary. As a back up I would then add the Victron charger via the Multiplus to charge the batteries if you would be on one engine.

 

[SteveK]

Do not connect engine start and GEN start batteries together as one bank. Leave them isolated.
You have 2 mains, 2 ALT, plus a GEN.
The 70A trickle charger will remain for start batteries only. The multiple plus for new LFP bank off GEN and shore.
Yes to dc2dc from engine start batteries up to 80% max of ALT Amp output.
That is what I have done and works great.

 

[READY]

Whatever way you go I would suggest monitoring your alternator temps. Victron has a Bluetooth sensor that can do this. I would include a CerboGX for controlling and monitoring.

Lots of options so you should start with a block diagram. Those batts are able to output a lot of current so wire gauge and fusing is not trivial. As suggested you may want to go 24 or 48 for the house.

 

[Mambo42]

Whatever way you go I would suggest monitoring your alternator temps. Victron has a Bluetooth sensor that can do this. I would include a CerboGX for controlling and monitoring.

The Wakespeed controller, which is made for Lithium batteries has a temp sensor and that should be attached to the part of the alternator that becomes the hottest during operation. When the set temperature is exceeded the wakespeed will then lower the output or even shut it down.
It is indeed very important to monitor the temperature and mostly during low rpm and high output, since cooling of the alternator is then at its lowest.

Connecting the wakespeed is however something for a specialist. Yes you can try to do it yourself, but one mistake and the wakespeed is toast, then you can buy a new one and they are not cheap.
Also Balmar has a controller for lithium batteries, but apparently has a lot of problems. Wakespeed also has a lot of problems, especially when you combine them with non Victron batteries and BMS.

 

[READY]

I have experience with both wakespeed and balmar. Highly prefer the Wakespeed. It is sophisticated but not beyond someone with the knowledge to DIY an LFP install. Of course it assumes the DIY person really understands what they are doing. Taking a system level approach is critical.

If someone is considering just "dropping in" LFP they are in for some potential serious issues not the least maybe risk of fire and compromising their insurance.

I have done conversions on my boat and Airstream trailers. Doing it right is not trival. Not rocket science but neither is it for folks who really don't want to gain a deep understanding. More than just watching a few online videos.

 

[tiltrider1]

If someone is considering just "dropping in" LFP they are in for some potential serious issues not the least maybe risk of fire and compromising their insurance.

These are urban myths. We know LFP is not a fire risk and we have seen no proof of any insurance issues.

 

[READY]

I was referring to Fire risks from wiring issues. Agree that LFP batteries are very low fire risks. But wiring these even though low voltage requires proper attention due to the high currents.

Many insurance policies do have clauses about modifications and workmanship. I dont have a specific example but I dont think insurance carriers would roll over on a claim if they could clearly show the loss was (just a theoretical example) directly the result of a fire from running 400+ amps through 20 feet 12 gauge wire and no fusing (installed by the DIY owner). Certainly cannot know for sure but I would not want to be in that position.

 

[tpbrady]

As far as regulators go, I find Wakespeed to require much more controlled conditions. First, you really do need a shunt connection. Second don’t use a battery isolator, it could screw up how it measures voltage. Do use a battery it can communicate with and it should work wonderfully. Balmar’s MC-618 works fine as far as I am concerned and is not as finicky as the Wakespeed. I do recommend you get the complete kit with Bluetooth. If you are good at Morse code, the screwdriver works just fine.

Tom

 

[Mambo42]

These are urban myths. We know LFP is not a fire risk and we have seen no proof of any insurance issues.

I actually had to show an invoice of a qualified Victron installer before the insurance would accept the installation and give me coverage. My insurance does not allow DIY lithium projects. So my advice is: check with your insurance if you are allowed to DIY Lithium. You could be in for a nasty surprise once it is installed and you did not check with the insurance.

 

[coffeytime]

Thanks for all the input. I definitely understand the importance of fusing and wire size. I do have a CerboGX and display as well as the remote for the Multiplus. My current thinking is this.
Replace the battery isolators with 2 dc-dc chargers with one connected to the start battery and programed as such and one connected to the new house bank. By using the dc-dc charger on the start bank, I will be able to monitor and control the charge profile through the Cerbo, right? In the future, I may install another dc-dc charger with two solenoids connected to a dpst 1no 1nc relay to allow me to switch from the start battery to the house bank when the start battery is full. Or ideally, program it to do so automatically.
I have an electrician lined up to help with this install.
Being from 1985, there is a lot of cleanup to be done. There was not a fuse or battery switch at all on any of the batteries. I am going to try and remove all of the things that have been scabbed on and place them on fuse protected circuits.
I would also like to install temp sensors on the alternators. What is the preferred device for that? The Victron Bluetooth Dongle?

 

[READY]

I believe you may get a bolt on temp sensor (hardwired) with the MP but if not the little $40 Victron stick on BT sensors are very handy.

 

[Portage_Bay]

I actually had to show an invoice of a qualified Victron installer before the insurance would accept the installation and give me coverage. My insurance does not allow DIY lithium projects. So my advice is: check with your insurance if you are allowed to DIY Lithium. You could be in for a nasty surprise once it is installed and you did not check with the insurance.

Which insurance carrier?

 

[coffeytime]

@READY Are you thinking of this one? I have never set up a Victron system. Since this is a battery monitor and I would be connecting it to the alternator, would I set it up as a separate "battery"?

 

[coffeytime]

Thanks again for all the information. One thing I will ask here is this. In order to get my inverter/charger out of the engine room, the best location is going to be a hanging locker in the aft stateroom. My wife, rightly asked, "Is this going to make noise?". The locker will contain the Multiplus, Lynx modules, up to 4 MPPTs, and a Cerbo unit. My guess is that the "hum" from the Multiplus won't be noticeable at night since there is no real draw on the system.

 

[tiltrider1]

Generally, inverter/chargers make noise. The cooling fans make most of the noise when charging. They also hum most of the time. For this reason I located mine in the engine room away from the bedrooms.

I would be careful what you promise your wife.

 

[Mambo42]

Which insurance carrier?

That is Pantaenius, a very large insurer in Europe. Problem is that I did not even know I had to send the invoice. Upon renewal at the end of the year I told them what was new on the boat and that is when they asked for the invoice of an certified Victron electrician.
So anyone wanting to do DIY, just make sure you check first with your insurance whether they allow it or not. Better safe than sorry I would say.

 

[Portage_Bay]

That is Pantaenius, a very large insurer in Europe. Problem is that I did not even know I had to send the invoice. Upon renewal at the end of the year I told them what was new on the boat and that is when they asked for the invoice of an certified Victron electrician.
So anyone wanting to do DIY, just make sure you check first with your insurance whether they allow it or not. Better safe than sorry I would say.

Thank you.

 

[coffeytime]

Generally, inverter/chargers make noise. The cooling fans make most of the noise when charging. They also hum most of the time. For this reason I located mine in the engine room away from the bedrooms.

I would be careful what you promise your wife.

I thought that locating in the engine room was not allowed. That is why I was looking for another location. I could lay it on its' side in my settee. The issue here is that there are two heat exchangers there as well for cabin heat, one from the engine and one from a Webasto. My thought there is cooling. I guess that I will install a external fan. Got to get my sleep. Also, if mounting it on its side, would I still use the included bracket? or is there another solution?

 

[SteveK]

That is Pantaenius, a very large insurer in Europe. Problem is that I did not even know I had to send the invoice. Upon renewal at the end of the year I told them what was new on the boat and that is when they asked for the invoice of an certified Victron electrician.
So anyone wanting to do DIY, just make sure you check first with your insurance whether they allow it or not. Better safe than sorry I would say.

Mind sharing what is a certified electrician.
What course certified them?
Or is it like here, you become a ABYC member which gives access to guidelines.

 

[SteveK]

Inverters cannot go into a gas engine room. They are usually not spark proof, as explained to me.
Diesel engine room no problem.

 

[tiltrider1]

Steve is correct and I assumed that you had a pair of Leman ford diesels. If I assumed wrong and you have gas engines then you are correct and need to explain to your wife why a little hum is more desirable than a potential large explosion. While the explosion risk from an inverter would be extremely low it is more risk than I am willing to take.

 

[tiltrider1]

That is Pantaenius, a very large insurer in Europe. Problem is that I did not even know I had to send the invoice. Upon renewal at the end of the year I told them what was new on the boat and that is when they asked for the invoice of an certified Victron electrician.
So anyone wanting to do DIY, just make sure you check first with your insurance whether they allow it or not. Better safe than sorry I would say.

I believe this is a case of DIY concern and not so much a LFP concern. I wouldn't be surprised if you got the same request for installing a Hydraulic heating system.

 

[Mambo42]

I believe this is a case of DIY concern and not so much a LFP concern. I wouldn't be surprised if you got the same request for installing a Hydraulic heating system.

Many insurers just don't understand the difference between LiFePO4 and Lithium Iion (e.g. Tesla power pack), so they want to be sure there are no risks. They have heard somewhere that it is dangerous and then they want to cover themselves.
Good part is that, once I sent them the invoice, they simply accepted the addition to my boat, they did not question it, they did not say it was prohibited.

I did not get the question when I informed them I had installed stabilizers or new engines, they could not care less if I had done it myself or not. I just sent the proof that I had bought and installed them and that was enough, no questions about certification of the mechanics.

 

[SteveK]

I wonder what they would say if you replied, write on my policy if a faulty installation is proven the cause of a claim, then not insured. I am sure that test is used on all claims anyway.

 

[tiltrider1]

The insurance company never actually stated LFP as an issue. They asked what was new and you gave them an answer that was new to them. If you had just said new batteries and never mentioned the switch between chemistries there probably would have been no further discussion. In the end the insurance company didn’t have an issue with LFP. Their issue was with DYI electrical upgrades.