LiFePO Batteries ???

[tpenfield]

Also...I highly suggest the 50A DC to DC that Victron just came out with. I just bought one for my trailer.

I would NEVER EVER use Renogy equipment.

I don't see it in your diagram you should add a battery monitor like a Victron Smart Shunt or BMV-712. . . . . Personally, if were to buy a couple batteries today, they would be the Epoch batteries....especially the 460AH ones

The main reason you go with two separate batteries is that each 100AH Lithium will have a 100A BMS so with two in parallel, you will have 200A.

I would have no problem talking on the phone about lithium setups. Been using LiFePO4 for nearly 6 years.

Thanks @bruceb58

Is this the Victron Charger that you are referring to?
https://www.victronenergy.com/dc-dc-converters/orion-xs-12-12-50a-dc-dc-battery-charger#pd-nav-image

Why would you Ever Never buy Renogy? I have their solar panel system, along with a Victron ArgoFET isolator. I saw that Renogy has a DC charger that is designed to work with inputs from both an alternator and a solar panel.

There are many brands of batteries, and I am not sure how different they are. Why do you prefer Epoch?

I have considered LiTime, ExpertPower, and a few others.

 

[bruceb58]

well if under your bed yall be quick to know if sh.. went bad

A lot safer than lead acid batteries under the bed.

 

[bruceb58]

Thanks @bruceb58

Is this the Victron Charger that you are referring to?
https://www.victronenergy.com/dc-dc-converters/orion-xs-12-12-50a-dc-dc-battery-charger#pd-nav-image

Why would you Ever Never buy Renogy? I have their solar panel system, along with a Victron ArgoFET isolator. I saw that Renogy has a DC charger that is designed to work with inputs from both an alternator and a solar panel.

There are many brands of batteries, and I am not sure how different they are. Why do you prefer Epoch?

I have considered LiTime, ExpertPower, and a few others.

The Epoch are better built than any of these other cheap batteries. There are some videos that show how they are built. They also have heaters if you chose to use them for cold weather charging. For example, until recently, LiTime didn't have cold weather protection in their BMS so you could ruin your battery if you tried to charge under 32F or use under 0F. Not a huge problem with boats but definitely an issue for RV use.

The DC to DC charger you linked is the one I would get. It is very efficient(less heat) and it has an adjustable engine startup setting that allows it to detect when the engine is running so to only charge at that point. The Renogy requires a turn on wire. In addition, if you use a Victron battery monitor(definitely should), that allows the two units to talk to each other so you have remote voltage sensing meaning the DC to DC converter will compensate for any voltage drop in your cables. The Victron DC to DC converter has a lot of options to control voltage and input/output current.

Renogy has little to no customer service. I know people that gave up on them when their units failed and just bought something different. I am in a solar group that has one rule that you will get kicked out if you even suggest using Renogy. The panels are likely fine since they are just rebrands of other manufacturers anyway.

Although it won't effect you with that dual purpose MPPT/DCtoDC with only one panel, for many people, the input voltage limit keeps people from putting panels in series or, like me, using high voltage panels. My panels have a Vmp of around 36V. You can buy really inexpensive MPPT solar controllers from Victron or Epoch for your 100W solar panel.

BTW, very easy to overload an alternator using the Victron ArgoFET isolator with lithium batteries. That is why it looks like you are using the DC to DC converter....a very good thing. What is the max output of your alternator?

My 280AH batteries I built weigh around 60#(guestimate based on each cell weighing in at 12# plus my structure. Lithium are the perfect solution for high density power instead of using lead acid for house loads.

 

[bruceb58]

Another BTW...

...When I am not using my trailer, I store them at around 60% state of charge. They self discharge very little and would self discharge even less if I disconnect the Victron MPPT which draws around 25mA.

I bought the Victron IP43 50A charger which also supplies my trailer when I am hooked up to shore power. It has a DC power supply mode that I set at 13.2V which basically keeps my batteries at that 60% SOC if I am on shore power semi long term. The DC to DC power supply has that same power supply mode if you ever need to use it that way...not sure if I know a reason to but it's there if you need it.

Of course all of these Victron units are on the Victron App and they all talk to the battery monitor for remote voltage sensing.

Here is an example of the battery monitor screen

 

[bruceb58]

EDIT: I forgot that the Renogy unit does have circuitry that detects when the alternator is charging. Was thinking of the stand alone Renogy DC to DC converters.

 

[tpenfield]

@bruceb58 . . . any other folks who may know

Many of the Epoch brand batteries say Li-Ion on the case . . .

.
Yet these are marketed as marine trolling motor batteries. A few batteries of different styles clearly say 'LiFePO4'
.

.
So, are they selling Lithium Ion as marine batteries? I would think you'd want exclusively Lithium Iron (not ion).

 

[tpenfield]

Another issue that I'm thinking about as I research LFP batteries . . .

. . . it looks like 140˚F is the maximum temperature to keep/run the batteries. My current battery installation is in the engine bay (like most boats). I am thinking that I'll need/want to mount the LFP batteries in the 'Utility bay' which is more forward in the boat.

Current Battery Layout - Batteries in engine bay:
With 2 engines after running and sitting at the sandbar using accessory power, I'm thinking the temperature in the engine room could approach 140˚F.
.

.
New Battery Layout - Batteries in Utility Bay:
400 lbs. (+/-) less battery in the engine bay and 50 (+/-) batteries more forward in the boat. Batteries positioned to balance the boat (Port-Starboard). There is not enough space in the utility room to place the LFP batteries symmetrically. This layout will do the next best thing and move about 50 lbs more forward in the boat, which should help with forward-aft balancing.


.
This should keep the LiFePO4 batteries (shown in green) in a cooler spot away from the engines.

 

[bruceb58]

LiFePO4 is a Lithium Ion battery. There are many subtypes of lithiun Ion batteries....one of which is LiFePO4.

Lithium-ion battery - Wikipedia

en.wikipedia.org

Go to the Battleborn battery site...one of the pioneers of drop in LiFePO4 batteries. The home page even calls them lithium Ion batteries.

Deep Cycle Lithium-Ion Batteries | Battle Born Batteries

Whether you’re looking to upgrade your batteries to lithium or build a complete power system, we've got you covered.

battlebornbatteries.com

 

[bruceb58]

Since you are worried about the temps of the batteries, you should be equally worried about the temps of the equipment that is charging them and the inverter. All should be operating in an environment less than 140F. Also, the batteries should be as close to the inverter as possible so if you have long battery cables currently going to the inverter, moving the batteries closer to the inverter is desirable.

 

[tpenfield]

Thanks, @bruceb58 . . .

Another question for the electrical gurus in the group . . .

My current design is to use the 3rd circuit from the '2 alternator/3 battery Isolator' to go directly to the DC-DC converter. (Design Option #1 below)

My thinking is that it may be better to go from the battery to the DC-DC converter as the battery will tend to add some 'dampening' to the voltage, rather than directly from the alternator.

The downside is that the battery may be continually charging the LiFePO batteries until the voltage drops at near the LiFePO4 battery voltage (12.8 volts)

Does it really matter if the DC-DC converter is directly connected to the alternator isolator? (Option #1 or #2 ???? - the difference is the red wire)

My concern with 'Option #1' would be if the alternator feed is really a rectified sine wave and not a pure enough DC voltage and the DC-DC converter does not like it.



.
TIA for any comments on the design.

 

[tpenfield]

I think I may have answered my own question. It looks like wiring things up as per 'Option #2' is the preferred way of using an alternator to charge the LFP batteries.

Here is my yet again modified design . . .
.

.
I just got to think about the best way to run the wiring, based on my recent changes to the design and the battery layout.

I am going to limit the alternator charging (to the LFP batteries), so as not to put too much load on the alternators.

 

[bruceb58]

The alternator output has very little ripple...50mV is typical. The DC to DC converter does not care about that. It also doesn't need a battery to dampen voltage. Many DC to DC converters are driven straight off alternators. However, it needs to be a smart alternator to be used without a battery.

Also curious...why do you show a renogy voyager solar controller and the renogy combo MPPT/DCtoDC. Please tell me you aren't feeding the output of the Voyager controller to the Renogy MPPT through that Victron battery isolator. Looks like you have one solar panel driving a cheap PWM solar controller which is then driving an MPPT....that won't work for a variety of reasons.

Out of curiosity, how big are your alternators? Just so you know, if I was using a 50A Dc to DC converter, I would make sure I had at least a 100A alternator. That's the beauty of the Victron DC to DC...you can adjust the input or output current.

Your Pronautic 1230P is a 3 bank charger yet one of the banks will be LiFePO4. I don't think you can designate different chemistry on one of the banks. You may need a seperate charger for the lithium batteries unless you run the same charge profile on the lithium as AGM. The big problem is that you never want to have equalization on with lithium batteries. It will trigger the OVP in the battery BMS and knock them offline...probably when you don't want it to happen.

 

[bruceb58]

The downside is that the battery may be continually charging the LiFePO batteries until the voltage drops at near the LiFePO4 battery voltage (12.8 volts)

The AGM battery will be supplying voltage to the DC to DC converter until:
1) The DC to DC converter detects that the alternator isn't operating...voltage below setpoint.
2) The LiFePO4 battery gets fully charged which is around 14.2V to 14.4V

12.8V is not the LiFePO4 battery voltage. Lithium battery manufacturers use 12.8V as a nominal voltage. Why they picked that voltage is odd actually since a LiFePO4 battery that reads 12.8V is at around 17% SOC.

Here is a chart for LiFePO4 battery voltages:

 

[tpenfield]

Got it. I’m thinking with all the isolators and converters that the net voltage from the alternators might not be quite high enough for the 100% charging level.

Time will tell. . .

 

[bruceb58]

Got it. I’m thinking with all the isolators and converters that the net voltage from the alternators might not be quite high enough for the 100% charging level.

Time will tell. . .

Won't matter for the DC to DC converter to lithium...one bit. It's the whole reason you use a DC to DC converter. Personally, I would ditch the 2 alt/3 battery isolator and just have each engine charge it's own battery with a manual switch and/or and ACR to combine if needed. Never really understood why people use diode based isolators. The Victron one has no(basically none) voltage drop since it's FET based but really not needed here.

You could actually use the solar panel to keep your AGMs charged. The DC to DC converter will come on once the AGMs reach full charge and that solar energy would go to the lithiums at that point. The DC to DC converter will work for when the engines or running and/or once the AGMs gets charged

 

[tpenfield]

The alternator output has very little ripple...50mV is typical. The DC to DC converter does not care about that. It also doesn't need a battery to dampen voltage. Many DC to DC converters are driven straight off alternators. However, it needs to be a smart alternator to be used without a battery.

Also curious...why do you show a renogy voyager solar controller and the renogy combo MPPT/DCtoDC. Please tell me you aren't feeding the output of the Voyager controller to the Renogy MPPT through that Victron battery isolator. Looks like you have one solar panel driving a cheap PWM solar controller which is then driving an MPPT....that won't work for a variety of reasons.

Out of curiosity, how big are your alternators? Just so you know, if I was using a 50A Dc to DC converter, I would make sure I had at least a 100A alternator. That's the beauty of the Victron DC to DC...you can adjust the input or output current.

Your Pronautic 1230P is a 3 bank charger yet one of the banks will be LiFePO4. I don't think you can designate different chemistry on one of the banks. You may need a separate charger for the lithium batteries unless you run the same charge profile on the lithium as AGM. The big problem is that you never want to have equalization on with lithium batteries. It will trigger the OVP in the battery BMS and knock them offline...probably when you don't want it to happen.

Thank you for the continued comments. Very helpful.

I won't tell you that I am feeding the MPPT through the Voyager controller . . . since it has not happened yet.

I am trying to re-use as much of the OEM components and wiring, since it may open a can of worms, if I change too many things.

As for the solar panel, it currently charges the 3 battery banks. I designed it to be more of a maintenance system than a re-charging system, since the engines can certainly do the re-charging. The boat sits on a mooring and when we use the boat, we are usually anchored at the sandbar for 4-6 hours or until the beer runs out.

I could run the DC/MPPT charger in parallel with the voyager, if that will remedy the issue of running through 2 controllers in series to charge the LiFePO. So, the Voyager/ArgoFET combo can do just the AGM batteries and the DC-DC/MPPT can to do the LiFePO4 batteries.

In my experience the 100 watt solar panel puts out about 60 watts as indicated by the Voyager controller. I could do a panel upgrade to 150 or 200 watts, if needed.

I was planning on using the liFePO charging profile on the ProNautic, since most of its 'work' will be to charge the LiFePO bank while at a slip on shore power for overnights, etc. I'll have to do a little bit or research into 'equalization'

I believe the alternators are old-school and about 70 amp rating. That is why I was planning on a 30amp DC-DC converter so as not to take too much from the alternators is a peak load situation. since the alternators are old-school, I believe I should do the 'Option 2' (connect at the battery) for stability.

I'll be making a few more changes to the design. . . .

 

[tpenfield]

@bruceb58 and any others . . .

Here are a couple of approaches to the solar and alternator charging.

Option 1 . . . parallel controller paths for AGM and LFP

.
Option # 2
Single MPPT converter to charge all batteries through the 3-bank isolator

.
.
Or perhaps a third option parallel MPPT solar controller and MPPT DC-DC converter.

 

[tpenfield]

Leaning towards this configuration . . .

• Separate MPPT controllers for each battery type to charge from the solar panel. (discard the PWM 10amp controller)
• Either engine can charge the LiFePO4 bank via the DC/MPPT converter.
• The AGM batteries charge directly from the engines.

Budget is in the $1,600 range with the additional controller.
.

 

[bruceb58]

You can't run two different solar controllers off one panel, especially MPPT controllers.

 

[tpenfield]

You can't run two different solar controllers off one panel, especially MPPT controllers.

Ok, so what solar panel & controller configuration would work for this situation?

That‘s what I am trying to achieve.

Thank you.