New Batteries Lifepo4 Conversion

[RDJackso]

We have just purchased a 2001 Heritage East Trawler that is in need of new batteries.

I am looking at Lifepo4 that will fit into my two battery boxes measuring 39-1/2"L X 7-1/2"W X8"D (interior dimensions) with a little extra rise at the top for the cover. I think I can get six of these (https://www.litime.com/products/12v-165ah-bluetooth-lithium-battery?variant=46243099082972), 3 each into each box.

I don't know JS about these things, but I know there are limitations for starting and other high short duration draw needs (bow thruster, windlass, etc). I have not yet had a chance to determine which of the four existing batteries are connected to what, but in general terms I am looking at replacing the four existing batteries with six Lifepo4's hooked up to about 600 watts of solar, which is about all I have room for, a
Victron 3000 watt inverter/charger DC/DC charger, charge controller, shunt, and display.

My question is will these batteries work for what I have in mind, or will I have to mix up the package and wire batteries for specific tasks. I should add that I have a separate battery that is either for the bow thruster or generator start battery...like I said, I haven't had a chance to sort out what is what, and the previous owner used the boat as a floating condo, and really didn't know anything about it's systems, or at least he wasn't sharing.

I am looking for advice as to which batteries to purchase and what difficulties I might encounter trying to wire them up in parallel to achieve the largest wattage and amp hour values I can, and still fit them into the existing battery boxes as, is always the case real estate is limited in my engine room.

Any ideas suggestions would be appreciated.

 

[Jeff F]

In terms of planning, I'd suggest checking to see if fewer bigger capacity batteries could fit. Like instead of six 165ah batteries maybe 3 300ah batteries, or two 400ah batteries. I think in general terms with drop-ins if you can get the same capacity with fewer batteries it's a better approach.

NBD if not feasible.

 

[Comodave]

How long a run is it to the bow thruster? What size cables are there for the thruster?

 

[Jeff F]

Also the requirements for containment are less strict for LiFePo vs LA, I think. The new batteries don't have to go in a traditional battery tray. So mounting options may be opened up with the change in type. I'd be looking around to see where 2 or 3 big drop-ins might fit.

 

[tpbrady]

Litime’s specifies a maximum of 4 of these batteries in parallel. I agree with going with larger batteries, but once you go over about 200AH you need a class T fuse on each battery. Look at the LiTime 320AH mini. It looks like you could get 2 in each box.


Tom

 

[JackConnick]

First things first, you need to figure out exactly what you’ve got and how it’s wired and fused, breakers, etc. If necessary by pulling a cable off of one and trying say the generator. Trace the lines to the equipment, etc. Might be time to have an electrical survey done. You may have an mis-mash of wiring. BTW, lithium and AGM batteries don’t need to be in a battery box, just secured.

 

[SteveK]

Currently with 4 batteries, may have 2 for engine start 2 for house
Yes, find out what you have first

 

[Barking Sands]

Be careful with LiTime. Most models employ Full Charge Protection or FCP for short. Generally, if going budget batteries pick one that can be viewed with the Overkill Solar app in addition to the battery makers official app.

 

[Bud]

Engine room temps can hit 100-140F during runs; reduces cycles ( e.g., from 3000 to 2000). If you plan to hook multiple batteries in parralel or series must be same voltage, amp hour rating and should be same manufacturer. Battleborn was my choice for my house bank.

Bud

 

[Marco Flamingo]

So much of this decision is boat specific that it is difficult to give accurate advice. My experience might be way different than your requirements. That said, JackConnick has the right idea for a starting place. Your existing battery boxes are relics that are not required for LFP. One might think that re-use of the boxes would be easier and cheaper, but usually this really limits choices. You will already be fabricating new cables, bus bars, fuses, etc. Don't worry about fitting inside old unneccessary boxes. They may actually complicate things.

For my install, using fewer larger batteries was also an unneccessary limitation. One might save fabricating a couple cables, but at great cost for utility of the bank. This is really apparent if using the bank as start batteries. You will see people claim that LFP should only be used for house batteries, but never give a rational explanation. They claim that an LFPs used for a starter battery must have a sticker on it that says "starter battery." Yet they use LFP for house batteries and I have never seen an LFP with a "house battery" sticker. So they are already using LFP for an "off label" application by their own reasoning.

This is where using multiple LFP batteries really makes a difference. Just like you can join two 12V LFP to produce 24V, you can join two 160Ah LFP to produce a 320Ah bank. I think most people (including all manufacturers) are okay with that rational addition. Some people (including manufacturers) understand that one can also add the rated short-term current production of LFP batteries. For instance, the batteries you have posted have an 800 amp rating for one second. Three of them could produce 2,400 amps for one second. If in two banks of 6, as you propose, they could produce 4,800 amps for one second (properly cabled and fused.) Even without knowing your engine(s), I would guess that is way more than the millisecond amperage you need as a starter bank, thus simplifying the installation.

TpBrady proposed using 4 LiTime 320Ah minis to fit the existing boxes. They each have a max discharge rating of 1,000 amps for one second, for a starter bank of 4,000 amps, i.e., slightly less. Using even larger batteries, like two of the 400Ah batteries mentioned above, can be even worse because their momentary discharge rating is 250A each. A bank of two is only 800Ah "house" and 500 amps "start," not enough for most diesels. Sure, you save some on cables for the LFP, but at the huge cost of a smaller house capacity and having to retain or install an additional bank to help start the engine(s).

In addition, having 6 LFP means having 6 independent BMSs. When charging directly to the batteries, you will be well within their maximum charging acceptance rate and even should one drop out from an overcurrent shutdown or cell imbalance, you have the protection of the 5 other BMSs. Not true if only using 2 batteries. For that system, people often add lead batteries and conversion devices that choke down the charging ability of the alternator.

Lots to think about. And that isn't even looking at connections and fuses.

 

[RDJackso]

First things first, you need to figure out exactly what you’ve got and how it’s wired and fused, breakers, etc. If necessary by pulling a cable off of one and trying say the generator. Trace the lines to the equipment, etc. Might be time to have an electrical survey done. You may have an mis-mash of wiring. BTW, lithium and AGM batteries don’t need to be in a battery box, just secured.

Jack - Good advice. I have built my share of custom cars and have installed the wiring systems from scratch. One circuit at a time.

That is my intent here as well, but I am anxious to learn of my options with the LeFiPO4's.

I definitely have a mis-mash of wiring as it would appear that a whole team of ham fisted mechanimals have had their way with the engine room. It definitely needs sorting. When I am finished, it will look like a single line diagram.

That said, I am looking to fast track the parts purchase so that I can take advantage of the federal tax credits that are set to expire on Dec, 31.

I know I will need multiple fuse protection(s), increased conductor sizing and probably multiple solar charge controllers as well, but I am hoping for guidance on the most reasonable approach.

I am not opposed to removing the battery boxes, but I do like the tidy look as they fit into the engine room where a parallel installation of 8D's would not. Well, that's probably not entirely accurate, enough dead Benjamins can usually solve most installation challenges, but sometimes a guy needs to know when to say when, no?

This is a relatively small boat (36', 41'9" including the bow pulpit and swim platform), and the lower aft stateroom coupled with a down galley and day head complicates matters, making the engine room short in length. This is the primary motivation for staying with the battery boxes, although I am fairly certain the lids are going to be history.

Are my ideas making any sense? I like what I am hearing from everybody. Marco Flamingo, I like the direction you are pointing me. I am on the fence regarding the LiTime brand, but nearly all of these new batteries are coming from China or Taiwan, or Viet Nam. Six one, half dozen in the other I'd recon, but I will admit that I might be talking out my a$$. So, there's that.

 

[SteveK]

Have you considered the 25% off the epoch battery ends Dec 2nd

 

[Jeff F]

Be careful with LiTime. Most models employ Full Charge Protection or FCP for short.

I haven't followed closely, but followed your earlier discussions here on FCP. Agree it can be a problem.

General question: wouldn't that concern be specific to alternator charging? If the bank is not directly connected to the alternator should the OP, or anyone, care?

Not trying to start a debate, just curious. The answer might be relevant to the OP.

 

[Barking Sands]

I haven't followed closely, but followed your earlier discussions here on FCP. Agree it can be a problem.

General question: wouldn't that concern be specific to alternator charging? If the bank is not directly connected to the alternator should the OP, or anyone, care?

Not trying to start a debate, just curious. The answer might be relevant to the OP.

Litime has a Facebook group that I do frequent. If you go to the Litime group this is the first post on there. And this indicative of about every fourth post there. You can get around it by lowering the chargers absorption voltage to just under the FCP threshold. Usually 13.9 volts. But this compresses the operating envelope and may cause other issues. if you have a single battery you wouldn't care and wouldn't even know. But the picture below shows what most people get with more than one battery in parallel.

 

[RDJackso]

Have you considered the 25% off the epoch battery ends Dec 2nd

They are a bit outside my price range.

All I really want to do is run my refer off the inverter 24/7 (when not on shore power on generator), an occasional cup of coffee, likewise a toaster and microwave to warm up a burrito.

I have a good northern lights genset that handles the heavy loads, air conditioning and hot water (that is also plumbed to the Cummins 6bt).

I have no intention of trying to go full solar, but I do want to overkill the basic needs as described above. We will be mostly cruising the AICW anchoring out in some of our favorite haunts. But we like our adult beverages cold...

 

[tpbrady]

Sands

I have 3 Litimes in parallel and over 4 months I never saw more then 3% difference in SOC when discharging. I believe the imbalance you showed the picture of occurs when both batteries went into FCP and when the charging source was removed, only one of them assumed the load. After some period of time the other one came back on line. I saw FCP early on (before this discussion started) and adjusted my charging system to stay out of it.

Tom

 

[Delta Riverat]

The LiTimes should work well and they look to an excellent fit for your boxes, ie the most capacity that will fit in the space.

The FCP is a real thing and the big issue is the .3 volt drop at the terminals when it goes active. In a parallel build the FCP batt will not discharge until the others go down .3 volts. Then it will connect and drive the loads as well as charge the other batts on the line. So, eventually it will all even out.

Are all these batts parallel or are 3 on one side of the house switch and 3 on the other?

The new Victron inverter/charger should be able to manage this issue well.

Yeah 6 x 165 will make a nice house bank -

 

[Barking Sands]

Sands

I have 3 Litimes in parallel and over 4 months I never saw more then 3% difference in SOC when discharging. I believe the imbalance you showed the picture of occurs when both batteries went into FCP and when the charging source was removed, only one of them assumed the load. After some period of time the other one came back on line. I saw FCP early on (before this discussion started) and adjusted my charging system to stay out of it.

Tom

Yes, that's the remedy. And you can operate that way with the reduced absorption. I operated that way for almost 2 years. But all things equal, knowing what I know now, I'd prefer to buy and recommend non-fcp batteries. At the very least, share that FCP exists and help make up for the fact that no manufacturer that produces batteries with fcp discloses the presence of fcp nor the parameters to circumvent it.
But with a little experimentation its not hard to figure out the threshold and plan for it. I just dont want it to be a suprise. I have seen quite a few get that initial surprise in the form of damaged equipment. Sometimes even more than once before FCP was figured out.

 

[SteveK]

They are a bit outside my price range.

All I really want to do is run my refer off the inverter 24/7 (when not on shore power on generator), an occasional cup of coffee, likewise a toaster and microwave to warm up a burrito.

I have a good northern lights genset that handles the heavy loads, air conditioning and hot water (that is also plumbed to the Cummins 6bt).

I have no intention of trying to go full solar, but I do want to overkill the basic needs as described above. We will be mostly cruising the AICW anchoring out in some of our favorite haunts. But we like our adult beverages cold...

Understood. 6-135Ah is almost 1000Ah of house bank, probably twice what you need as described. I have 800Ah and cook with electric stove/oven in addition to what you mentioned and can go 2 days.

 

[RDJackso]

The LiTimes should work well and they look to an excellent fit for your boxes, ie the most capacity that will fit in the space.

The FCP is a real thing and the big issue is the .3 volt drop at the terminals when it goes active. In a parallel build the FCP batt will not discharge until the others go down .3 volts. Then it will connect and drive the loads as well as charge the other batts on the line. So, eventually it will all even out.

Are all these batts parallel or are 3 on one side of the house switch and 3 on the other?

The new Victron inverter/charger should be able to manage this issue well.

Yeah 6 x 165 will make a nice house bank -

The batteries will be 3 in parallel for the house and 3 in parallel for the engine, genset. I am actually thinking of some sort of switch that would allow me to link the entire system in parallel if needed. The bow thruster is on a separate battery and I'm not really certain that the demand is suitable for LiFePO4's, although these combo batteries may work for that purpose as well.

 

[RDJackso]

Understood. 6-135Ah is almost 1000Ah of house bank, probably twice what you need as described. I have 800Ah and cook with electric stove/oven in addition to what you mentioned and can go 2 days.

Like horsepower, I tend to lean toward the notion that if a little is good, a lot is better...

 

[tpbrady]

9

 

[RDJackso]

So...after extensive research, the Luddite in me comes to center stage!

The whole LiFePO4 debate is nothing if not exhausting. BMS, increased alternator requirements, special programmable voltage regulators, increased conductor sizing, draw issues with high current over extended time periods (say, for example bow thruster and anchor windlass), incompatibility issues with FLA or AGM start batteries necessitating special charging considerations...the list is endless. And, most of the LiFePO4 batteries are made in in China. If they take a trip south, then what?

All I want to do is keep my beer cold running my 120VAC refrigerator off of my new Victron 3000 watt inverter charger with limited genny use while on the hook. Solar will come, later...

My existing DC electrical system is constructed as follows from the factory: Two group 31 FLA house batteries in a 8"W x 10"D x 39" L battery box on the port side of the engine bay located between a 210 gal FRP over iron fuel tank and a Northern Lights 8KW generator FWD and a Cummins 6BT5.9M midship, and; two group 31 FLA engine start batteries in an identical battery box in a mirror image location on the starboard side of the engine bay with a separate group 31 FLA in a single battery box located just aft of the engine start batts and dedicated to the generator. Whew, that's a mouthful.

The batteries in the port side box are wired in parallel and charged by the battery charger (and possibly the engine alternator, I have yet to fully trace the wiring). The batteries in the starboard engine start box are also wired in parallel and are charged by the engine alternator and the battery charger. The stand alone generator battery is charged by the generator alternator.

That's all the batteries on the boat!

So I purchased 7 new Odyssey ODX 31 105Ahr deep cycle batteries that I intend to uses as follows: One each for the engine, generator and bow thruster/windlass (combined on single battery) and 4 batteries wired in parallel for the house. The dedicated bow thruster/anchor windlass battery will be mounted forward close to the BT/AW and charged by a Victron 50 amp DC/DC charger connected to the engine start battery. My thinking is that neither the bow thruster nor windlass will likely ever be used without the engine running. I am debating with myself as to the merits of wiring the genny batt and engine batt in parallel just to have a little extra oomph with the battery switch selected to both. This might also eliminate the need for an additional battery switch. But I can see the merit of having the genny batt stand alone, if all else fails I could probably get enough juice from the inverter charger running on the genny to start the boat.

I am also adding a Victron Cerbo GX, Victron Touch Screen 50, and Victron Smart Shunt to the mix in addition to various fuses battery switches and the like not to mention increasing cabling sizes as required by length of run, then going up a size for yucks.

I am intentionally leaving out most of the installation details as I don't care to bore the forum with minutia, but I will say that these batteries are small, but beasts...they weigh in at 77lbs each. They are made in the good old USA, and I bought them from a friend who happens to manage our local O'Reilly's Auto Parts store, so if I have problems with warranty, I have nearly immediate recourse without having to work it out with someone in a foreign land.

400 or 600 watts of solar (whatever I can fit) is coming with 2 or 3 charge controllers.

At the risk of self flagellation, I offer this post for comments. Be gentle...