Lithium house bank project

[tiltrider1]

I have a 1060 AH Lifepo4 bank. Yesterday I pulled 40amps for 6 hours and 20 amps for 8 hours. It took me 5 hours at 100AH charging to get back to full. These numbers don’t exactly add up because I am not monitoring very carefully plus I still have heavy demand even while charging. I am again pulling 40 amps today. I am experimenting with how hard I can hammer the bank. My 1400 AH lead acid would have been down to 12.0v with this much use. So far I have not been down to 13.0v. This is not exact science. It is a test run to see what I can expect from LiFePo4. I do not normally spend a day watching 10 hours of TV with the wife surfing the Internet. So far I find my self more comfortable with the LiFePo4 batteries than my old lead acid batteries.

 

[Delta Riverat]

Yeah Baby!

If your bank works, don't fix it. But when it's time...do you really want to install more heavy low capacity clunkers...

Or something much better -

 

[Delta Riverat]

Hooked all the grounds up today and everything that wasn't working is working now. Aft bilge pump (the important one) and the 12 volt cigarette socket in the saloon (not so important but gets lots of use)

When I left the boat yesterday, the batteries were at 13.2. No charge overnight. Was on for 4 hours, lights on, recharged my flashlight and when I was done the batteries were still at 13.2. No big loads except the drawer fridge on the fly for 24 hours, but hey, it's hot here now and the beer is ice cold -

Now on to the engine panel, get the new lead-acid charger connected and the bridge solenoid wired and verified and then we'll be ready for some boat rides.

Soon I hope to have as much confidence in my starter batteries as I do in the LiFePO4 house bank. And soon after the house bank will grow to 880 AH. I can run House 2 (600AH) dry and switch to House 1 for another 280AH. Sort of a safety zone -

 

[SteveK]

I can run House 2 (600AH) dry and switch to House 1 for another 280AH. Sort of a safety zone

If I may, based on nothing specific, as long as you have a shunt and/or other monitors consider keeping just one bank to more easily monitor SOC, better control over charging. With LFP you do not need that extra safety net we needed with FLA

 

[Delta Riverat]

Good idea, but that would not be easily done.

However, in a way it is already. This whole project started with the idea of (2) 300AH batteries for the house and that is what is in there now. During the process I found out that what I thought was a generator battery was not. It was simply bridged over to the starboard house battery, House 1 on the helm switch. Now it is bridged over to House 2, the one in the toolbox enclosure and the shunt for the monitor is also in there keeping track of both batteries.

I bought the third Li Time battery (280 AH) after I found there was no generator battery and that will be the new House 1 after I get the other dead 4D lead-acid out of there.

 

[CMS]

I see a lot of LFP banks lacking overcurrent protection…

 

[Delta Riverat]

I installed a Blue Sea Systems 250A terminal fuse on each battery. In addition the BMS will limit continuous current to 200A.

 

[luna]

ABYC’s E-11 requires the overcurrent protection device at the battery to have an Amperage Interruption Rating equal to the battery manufacturer’s short circuit rating or 20,000 Amps @ 125 V.

Blue Seas MRBFs have an AIC of only 10,000 amps @ 12 V. which is likely fine for small LA banks, but typically not for LFP.

You may want to consider a Class T, or perhaps a NH fuse to comply with ABYC.

 

[tiltrider1]

Just so people understand, most fuses are installed to preserve the wire simple as that. However, as you get in to larger battery banks, you end up with enough power that the bank can melt down the fuse and jump across the gap. You need a fuse that is capable of withstanding the destructive power of your bank. T class fuses are usually rated for suck applications but, you need to match the fuse up not just to your wire size but also the destructive capability of your bank.

 

[Barking Sands]

On the Epoch 460 there is a 500amp, 50k AIC rated fuse inside each battery. Then I have 250 amp MRBF on each positive terminal.

 

[Delta Riverat]

According to Li Time, the BMS is good for 200A continuous and 800A for 5 seconds. I think the 250A fuse will melt long before the 5 seconds.

Just looked it up and at 3X rating (750A) the fuse will melt in 1 second.

 

[luna]

The trip delay curve has nothing to do with the fuse’s amperage interrupt ability.

In the case of a full on battery short circuit where your LFP battery will deliver 1000s of amps, the 250 amp fuse blows open almost instantly but the plasma in the fuse or the remaining fuse parts provide continuity and the current still flows. The BMS is undoubtably no match for this amount of current and is rendered inoperable.
The only thing that is stopping your 2/0 battery cable from becoming a very large red hot heating element is the Class T fuse with its higher AIC.

Unless your LI Time batteries have a fuse embedded like the 50,000 AIC. rated fuse of Barking Sands Epoch batteries, you should consider a Class T or better fuse.

 

[Delta Riverat]

There is a class T fuse (400A) already installed. I found it while down in the engine room a couple weeks ago. I have a replacement in the toolbox now in case it blows. Also a box of the 250 amp terminal fuses.

The battery spec for internal resistance is <40 milliohms. Google shows 2-20 typical. So lets use 10 for fun. At 13 volts the max current even w/o a BMS is 1300 amps on a dead (zero ohm) short.

The fuse has an interrupt rating of 10,000 amps at 14 volts. Yes I know about arcing and plasma, Pops was an electrical engineer at Detroit Edison (now DTE energy). The fuse has to be able to quench the arc. Somewhat more difficult at 2000 volts.

I feel confident in the fuse rating as I don't see 10,000 amps happening ever.

 

[luna]

I see that you now acknowledge the existence of a 400 A class T fuse in the circuit. That’s great!

Understanding that you found it in the ER a while ago and you just installed 3 LFP batteries, you should ensure it is within 7” or 42” if sheathed, of the battery post.

 

[Delta Riverat]

Today I can say that House 2 is done;

Just need to put the lid back on. But that was not the main effort today;

The start charger is on and works -

Don't worry, I'll clean up that wiring tomorrow when I install the solenoid jumpers, the 12V feed to the solenoid (helm switch is wired to ground) and see how overnight does on the start batteries. All went well, no arcing-sparking or blown breakers, I flipped the switch and went back down to the engine room and found all settings correct (defaults for flooded) and the charger jamming 40 amps (20 to each side) to the batteries. Left the boat with the charger running.

Looking forward to my visit tomorrow to see how the overnight went.

 

[Delta Riverat]

When I returned the Xantrex showed ready and charge under 10%, float mode, less than 4 amps. When I lifted 1 ground decreased to less than 2 amps. Perfect. This charger is for the 2 start batteries currently two sets of 2 6 volt golf cart batteries in series. Yeah deep cycles used for starters...but hey, they work. These golf cart batteries continue to amaze me as I have been guilty of serious abuse.

I let them dry up once. Seriously dry as in I put a gallon of distilled water in one and a half gallon in the other to fill them up. Then charged and they worked fine. Just recently as this project tells the 10 amp charger failed and they went flat as in not being able to crank the engines.

Now that I have a capable charger installed, a couple equalizing cycles will be done. I have destroyed batteries before with far less abuse than described above. When I need replacements I'll get 4 new 6 volt GC batts, which have the additional benefit of being 60 pounds each a manageable weight for me to handle alone.

 

[Delta Riverat]

It was a good day and a bad day. The good part was I connected the start batteries 500A combiner to the helm switch and started the engines.

The bad news is both start batteries would do nothing but click the solenoid alone. So I also need new start batts. Three one hour equalizing sessions with the new charger didn't work. But at least the combiner works!

Also found that all the batteries that came with the boat are from 2017 so not much surprise they are shot.

Yeah maintenance...this battery / inverter / charger / isolater project is up to 6 grand now. These old boats.

 

[Delta Riverat]

Today I installed the last of three Li Time batteries, the 280 AH on House 1. Also connected to it's charger the Progressive Dynamics 60A. Charger started charging, voltage kept going up, all is well.

Then I started the engines, each on it's own battery, no sharing needed. That works well.

Lastly I tested inverter-charger on all and it charges all. Tested the PD charger on all and it charges all.

The LiFePO4 is complete -

As far as charging at the dock is concerned. Next will be the alternators and regulators as well as "does the generator even work"...I know it starts and runs, but actually generate electricity? Needs verification.

 

[HeadedToTexas]

Great story, Delta. I’ll be following along. I am in the “if it ain’t broke…” situation right now, but my 800 amp hour AGM bank delivers well less than that already and a battery upgrade is only a season or so away.

My Xantrex Freedom SW 3012 has been faithful and effective and provides all the power and charging I have needed. It is also configurable for LiFePo batteries, but its interface is dated and Xantrex offers no upgrade to integrate with other platforms that might improve the interface.

It seems like anyone going to all the trouble of replacing batteries, adding DC to DC chargers, and generally revamping the boat’s electrical system should also be upgrading the inverter/charger at the same time, yes? In terms of reliability, understandability, and safety, “all Victron” appears to be the way to go, though that might change in the coming years. Am I reading that right?

 

[tiltrider1]

Great story, Delta. I’ll be following along. I am in the “if it ain’t broke…” situation right now, but my 800 amp hour AGM bank delivers well less than that already and a battery upgrade is only a season or so away.

My Xantrex Freedom SW 3012 has been faithful and effective and provides all the power and charging I have needed. It is also configurable for LiFePo batteries, but its interface is dated and Xantrex offers no upgrade to integrate with other platforms that might improve the interface.

It seems like anyone going to all the trouble of replacing batteries, adding DC to DC chargers, and generally revamping the boat’s electrical system should also be upgrading the inverter/charger at the same time, yes? In terms of reliability, understandability, and safety, “all Victron” appears to be the way to go, though that might change in the coming years. Am I reading that right?

When I converted to LFP i was able to use my existing Inverter/charger as it could be custom programmed. I wouldn’t be surprised if your xantrex is the same. The only other changes I needed to make was moving the alternators from the house bank to the start bank and replacing my smart ACR with a Dc to Dc charger. In my case it took two Dc to Dc chargers for a total cost or $500.

The LFP batteries were $400 cheaper than the FLA batteries so the project only cost me $100 more except that the FLA’s weigh 125# x 8 which means I would have needed to pay for some One to physical move them. At this point I feel like the conversion costs were zero.

 

[Delta Riverat]

The Victron Multiplus would have been my first choice of inverter/charger, but I would have had a problem mounting it under the settee and there is no room in the engine room. The Xantrex is smaller and lighter and fit the space nicely.

Yeah as far as cost goes, LiFePO4 prices continue to decline as volume increases. The (2) 300 AH units I bought a year ago cost a grand each. They are now $720. Amazing!

 

[dhays]

It seems like anyone going to all the trouble of replacing batteries, adding DC to DC chargers, and generally revamping the boat’s electrical system should also be upgrading the inverter/charger at the same time, yes? In terms of reliability, understandability, and safety, “all Victron” appears to be the way to go, though that might change in the coming years. Am I reading that right?

I am not sure. Given the great information these folks are providing and reading some of Rod Collins recent articles it has me thinking that I may be able to do some piecemeal progression.

Reuse the equipment that will meet requirements to get a good, affordable, system now rather than waiting until I can/feel like spending the money on a "perfect" system.

 

[Barking Sands]

One of the main concerns for success with drop in batteries, especially newer ones that have certain features (like the latest Litime or Epoch and others), is the ability to set custom charge profiles for absorption and float. Especially if you have batts in parallel. If you have an inverter charger that has direct settings for those parameters you can definitely do piecemeal. Chargers that have lifepo4 presets and no ability to change them IMO are no good.

One other thing I have learned along the way...if you want to go 24v or 48 volt...buy your batteries in the voltage you want to run. Running Lifepo4 in series can be pretty frustrating over time. 4 in series is a nightmare.

 

[Delta Riverat]

Went to the boat and worked on the fridge project. Left the 8 amp engine room blower on for 24 hours as well as the lights. Beat a hasty retreat yesterday and forgot a few things. Batteries were at 13.2.

Yeah baby! Top fridge still cold, blower still running, no chargers on and 13.2. The power of a 880 AH house bank -

Yeah I don't like fixed chargers either, typically set to max. The PD charger is meant to be a backup, it even has a plug for disconnect. But it does work and I used it today while I was working for 4 hours and got the house bank up to 13,4

Always good to have a backup. I have the Xantrex set for lower levels. It's pretty small too (60 amp) would take 15 hours to fill up 900 AH of batts.

 

[Delta Riverat]

Today I added a Victron argo diode isolator to the output of the PD 60A fixed (14.6 and 13.6) volt charger. The voltage drop across the diodes which they spec at .3-.45 works perfectly to reduce the output for the batteries. Tested and verified a .4 volt drop. Unit just gets warm dissipating 24 watts, no problem.

And now I can leave that charger on full time and not worry as the batts will see a constant current breakpoint of 14.2 volts and the float will 13.2.

Yeah, nobody likes diode isolators because of the voltage drop, but for this application a voltage drop is exactly what is needed -

 

[Barking Sands]

Today I added a Victron argo diode isolator to the output of the PD 60A fixed (14.6 and 13.6) volt charger. The voltage drop across the diodes which they spec at .3-.45 works perfectly to reduce the output for the batteries. Tested and verified a .4 volt drop. Unit just gets warm dissipating 24 watts, no problem.

And now I can leave that charger on full time and not worry as the batts will see a constant current breakpoint of 14.2 volts and the float will 13.2.

Yeah, nobody likes diode isolators because of the voltage drop, but for this application a voltage drop is exactly what is needed -

13.2 float may be a bit low depending on exact details. That could bring you down in soc well below 50% under some conditions.

 

[Delta Riverat]

Made a addition, connected 1 output of the Argo diode to House 1 and the other to House 2. Lower current means lower voltage drop. Argo diode did not get as warm as with all 60A going through 1 output. Left it running when I left yesterday, looking forward to seeing the results.

 

[Delta Riverat]

Me thinks this argo-diode thing is perfect with the PD fixed 60a charger.

Went back today and the house bank was at 13.2. Went down to the engine room and the lead-acid starters were idling and so was the house. The charge wizard was short blinking, it had timed out. The PD charger tries real hard not to over charge, it will hold the bulk for 8 hours and will fold back after even if target voltage not met. So I pushed the button and the long blinking started as well as the fan and the heat sink got warm as well as the argo-diode and sure enough, 60A was going to the batteries. Some 4 hours later the house bank was up to 14 volts when I was leaving and just to check, I shut down the PD and booted up the Xantrex which I lowered the settings on and also set for 100A. It started in absorb and the current was 20A.

That made me smile and then I shut everything down and left. Going to run the house bank down now to 12V before I recharge, give 'em some "life in the middle"

 

[Delta Riverat]

Returned today and found the house bank at 13.2. Turned on the ER blowers and spiffed things up a bit down there (always good to turn on the blowers when working in the ER) while the Admiral was doing her cleaning thing above deck. This is the end of the "lithium house bank project" and the beginning of the Balmar MC-618 project.

Everything on that board is new except the main ground bar and the AC outlet (which has been relocated and re-wired) and of course the defunct next step regulator. The MC-618 is on the boat in a box and I intend to do the pre-programming thing on the bench with a battery before I even mount it. Followed by carefully taping and labeling each wire going into the dead box before removing said dead box. Not to mention I don't even know if the alternator still works.

But I have a brand new Balmar on hand and a place to mount it too. A big place, cool that these things are so small -

 

[luna]

Are the 2 10ga red conductors spanning? between the 2 Argofet? B+ posts and the Xantrex 40 A charger unprotected? (not fused)