The Rules of LiFePO4: The 3 Most Common Causes of Failure and General Guidelines for Long Term Use

[SteveK]

Will Prowse makes sense to me on any videos I have watched. This one surprised me a little as I actually do as he says to do. That is I charge to 100% and use the batteries, then the program to recharge kicks in on the inverter/charger when it gets to 12.8. I expected early demise with my process as I cycle daily with the fridge and a few other draw items on the house batteries running on the boat.
View HERE

 

[SteveK]

LiFePO4 Charging Guidelines: What is 100%? What is 0%?! How to Balance??​

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[HeadedToTexas]

Great stuff. Makes sense. I feel so low tech with my AGMs!

 

[Frankdog]

Great stuff. Makes sense. I feel so low tech with my AGMs!

Lead batteries still have there place in boat applications in fact due to the low tech management of them its a plus not a neg.
i use to own a renewable energy business for 20 years and was a Victron distributor and installer for about 15 years of this in later years we secured a BYD distributorship for there Lithium battery products. after purchasing our boat i wrestled with the idea of converting to Lithium Iron Phosphate as i use to preach it day in day out in my old business.(land based applications) given the safety profile i decided to stay with lead mainly due to my low power demands and when i am steaming i have power from main engine any way plus have a generator backup.

 

[Barking Sands]

Here is an article and a video on a Tesla with LFP and how much degradation after 110k miles.

Tesla Model 3 Owner Reveals Surprising LFP Battery Degradation After 110,000 Miles

The car has been regularly DC fast charged to 100%, but the degradation level is minimal.

insideevs.com

 

[TBill36]

Maybe a little off-topic but is heat management an issue with LP battery and system placement. I'm planning on installing 2 300 AH 12v LPs and a Victron 3000 kw with 120 amp charger. It will be in the living area and not engine room, but inside a closet or under the stairs. Both areas are enclosed with no ventilation so if heat build-up is an issue, it will need to be dealt with. Any guidance appreciated.

 

[Barking Sands]

Maybe a little off-topic but is heat management an issue with LP battery and system placement. I'm planning on installing 2 300 AH 12v LPs and a Victron 3000 kw with 120 amp charger. It will be in the living area and not engine room, but inside a closet or under the stairs. Both areas are enclosed with no ventilation so if heat build-up is an issue, it will need to be dealt with. Any guidance appreciated.

The inverter will get quite hot. The batteries not so much. If you can keep the two separated a bit that would be good.

 

[Marco Flamingo]

I've looked into the heat issue for LFP. I know the charge profile for lead acid changes quite a bit for heat, using an algorithm that changes the charge voltage by over 1/2 volt from 30F to 100F. Haven't found anything like that for LFP, only to keep them above freezing for charging and below 130F for long life. From what I've read, merely charging LFP produces less heat even though they can generally accept more current.

A charger in the same closed-in space as the LFP might get you up to the 130F area. The other possible heat generation issue is a less than perfect connection. I've seen a couple pictures on the web showing the terminal area of an LFP melted. Apparently, the material used for lead acid batteries is more heat tolerant than the material (thermoplastic?) used for LFP.

A loose connection would be an issue regrardless of battery location, but confined heat from whatever source also "de-rates" the current carrying ability of the cables. Most are familiar with "engine room" heat de-rating for electrical cables (and that effects fuse choice), but it is actually based on the ABYC assuming that every engine room is hot. Digging deep, one can find just what the ABYC considers to be an average ER temperature. An unvented battery/charger closet would likely reach that temperature.

LFP batteries don't require the air circulation of lead acid for explosive gasses, but still can benefit from circulation. Same is definately true for a charger/inverter, as it has a heat sink that really benefits from circulation.

It is odd that LFP batteries still carry the stigma of "uncontrolled fire hazard" by the uninformed sky-is-falling crowd. When I installed a LFP battery next to a dedicated inverter, I put the  inverter inside of a vented metal cabinet for fire protection, not the battery. Same would be true for a charger.

 

[TBill36]

Is it standard practice to have the inverter in the engine room? It's simple enough for me to place it there and have the batteries on the other side of a wall that's in the cabin environment. Could place everything in the engine room, but thought better to have the batteries in a cooler environment.

 

[SteveK]

Is it standard practice to have the inverter in the engine room? It's simple enough for me to place it there and have the batteries on the other side of a wall that's in the cabin environment. Could place everything in the engine room, but thought better to have the batteries in a cooler environment.

The ER usually is the only space for it. It is only OK for diesel, not gas boats BTW. If it is possible outside the ER that would be my choice if installing a new setup.

 

[fryedaze]

Will Prowse makes sense to me on any videos I have watched. This one surprised me a little as I actually do as he says to do. That is I charge to 100% and use the batteries, then the program to recharge kicks in on the inverter/charger when it gets to 12.8. I expected early demise with my process as I cycle daily with the fridge and a few other draw items on the house batteries running on the boat.
View HERE

Steve, keep in mind that a lot of these batteries are spec'ed at 4000 full cycles. That almost 11 years if you do a full cycle each day..

 

[fgarriso]

This may be helpful.

Standards and Practices of DC Marine Wiring | West Marine

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