LiFePO4 Starting Battery Alternator Charging

[Tcheairs]

Just bought a group 34 LiFePO4 lithium battery in hopes of using it to start my Crusader 350 and also run house items at anchor. The advantage of the lithium is that it can be completely discharged and brought back to life. We have frequent power outages at my marina in cold weather and I've been eating AGM batteries regularly.

Guess I should have asked this question before I bought it. It was EXPENSIVE. I have not installed the battery yet as it is returnable if not having been installed.Has anyone had any experience with lithium as a starting battery given that it will be charged by an engine alternator when en route? I've since heard it might cause a problem with the internal charging software in the LiFePO4.

Thanks

[wholybee]

Originally Posted by Tcheairs

Just bought a group 34 LiFePO4 lithium battery in hopes of using it to start my Crusader 350 and also run house items at anchor. The advantage of the lithium is that it can be completely discharged and brought back to life. We have frequent power outages at my marina in cold weather and I've been eating AGM batteries regularly.

Guess I should have asked this question before I bought it. It was EXPENSIVE. I have not installed the battery yet as it is returnable if not having been installed.Has anyone had any experience with lithium as a starting battery given that it will be charged by an engine alternator when en route? I've since heard it might cause a problem with the internal charging software in the LiFePO4.

Thanks

What battery did you buy, and was it advertised as a starting batter?

[Tcheairs]

Group 34..looks just like any other starting battery with the top posts

[sogin]

Originally Posted by Tcheairs

Just bought a group 34 LiFePO4 lithium battery in hopes of using it to start my Crusader 350 and also run house items at anchor. The advantage of the lithium is that it can be completely discharged and brought back to life. We have frequent power outages at my marina in cold weather and I've been eating AGM batteries regularly.

Guess I should have asked this question before I bought it. It was EXPENSIVE. I have not installed the battery yet as it is returnable if not having been installed.Has anyone had any experience with lithium as a starting battery given that it will be charged by an engine alternator when en route? I've since heard it might cause a problem with the internal charging software in the LiFePO4.

Thanks

Relion sells a series designate as HP e.g. 100HP and these can be used as a starter battery

[Calaban-Alleria]

The group 34 really just refers to the physical dimensions of the battery.

You need to look deeper into the manufactures specs, and the current demands of your engine when starting. I would be concerned of the surge and continuous current capability of the internal battery management system of your battery being exceeded by the demands of the starting and frying the power FETs inside the BMS of your battery.
Worse it might handle the surge some random number of times - until it doesn't - then you are stranded.

[SV_BlueTurtle]

I setup my previous boat with a LiFePO4 battery as my starting battery, but you can’t just drop one in as a replacement for a FLA/AGM battery. You need to ensure the battery can provide the requisite CCA, and you need to ensure that the alternator is properly regulated.

Is the rest of your battery bank lithium? Is this your only battery?

Lithium generally requires a charger that can handle the profile specified by the manufacturer - usually 14.4V for 0.3C. You also need to ensure that the battery is fused properly (at the battery), and that the cables are rated for the battery. If you just hook a traditional alternator up to it, you’ll run the risk that it will kill the battery and the cook the alternator. The BMS could also disable it, leaving you without any way to start your engine.

Also, don’t run house loads off of your starting battery, as you can drain it and be left stranded.

[wholybee]

Originally Posted by Tcheairs

Group 34..looks just like any other starting battery with the top posts

That just means what the physical dimensions are. Most Group 34 LFP batteries are not appropriate for starting and will likely be damaged if you use them for that. There are some that are specifically sold as starting batteries. So, to answer your question, we really need to know exactly what you bought.

[Tcheairs]

This is what I have. The "fine print" says that the BMS with cut out any over charge source. I bought it from Walmart.com and it has a guarantee, so it think it's worth a try as a dual purpose 12v power supply. I primarily like the fact that it is "advertised" as being rechargeable even from 0 voltage.

cut and paste this for more info and please comment.

https://bansheebatteries.com/product...lifep04-800cca

[SV_BlueTurtle]

Please make sure you have installed that battery correctly. You need, at minimum:

- an appropriately sized fuse within 7" of the battery itself, unless the wire is run through conduit or a sheath, which means you can extend the run 72" before a fuse is needed
- properly sized wires (likely 4/0 AWG, larger than what you'd use for an AGM, depending upon how far the battery bank wires need to run to reach your intended charger/inverter/etc.)
- some way to regulate your alternator if you're using it to charge this battery directly
- a charging profile specific to that battery - this will not be the same as an AGM/FLA

LiFePO4 batteries are not drop-in interchangeable with AGM batteries, even if they share the same physical dimensions.

[Tcheairs]

Originally Posted by SV_BlueTurtle

Please make sure you have installed that battery correctly. You need, at minimum:

- an appropriately sized fuse within 7" of the battery itself, unless the wire is run through conduit or a sheath, which means you can extend the run 72" before a fuse is needed
- properly sized wires (likely 4/0 AWG, larger than what you'd use for an AGM, depending upon how far the battery bank wires need to run to reach your intended charger/inverter/etc.)
- some way to regulate your alternator if you're using it to charge this battery directly
- a charging profile specific to that battery - this will not be the same as an AGM/FLA

LiFePO4 batteries are not drop-in interchangeable with AGM batteries, even if they share the same physical dimensions.

I appreciate your trying to be helpful, but did you read the specs I sent in the link?

[Tcheairs]

This battery will be charged with a NOCO Genius which has a LifePO04 BMS function. Don't know how you insert a fuse into a 2awg battery cable. But I'm sure someone out there does

[SV_BlueTurtle]

I did, yes - and everything I said is relevant. Wire fusing is per ABYC E-13 specifications. Wire gauge is determined by resistance, voltage drop, and current. Alternator regulation and charging profile are essential for any lithium installation.

With respect, you do not appear to understand what you're doing here - yes, lithium batteries can be more deeply discharged (realistically to 20%, not 0%), but there are important things that need to be considered when switching to a LiFePO4 bank that you are not responding to.

Specifically, you need to understand the differences in charging profile between FLA/AGM and LiFePO4 batteries. A lithium battery does not sulfate, requires a higher bulk absorption voltage (usually around 14.4V), held at that rate for a different time (0.3-1.0C, depending upon battery, and which needs to be specific to the battery), and does not go into float like a traditional battery does. Once again: if you just drop this battery -- which I do see a UL rating for, let alone a proper specifications sheet -- into your boat, you will (at best) experience charging problems.

Also, you will almost certainly create an insurance issue if you do not properly install (fusing, wiring, charging, etc.) this battery, meaning you need to ensure that this battery is installed per ABYC standards.

I'm not trying to be a jerk, but converting to lithium requires more than a budget lithium battery that happens to fit the space in which your AGM bank used to be in.

[SV_BlueTurtle]

Originally Posted by Tcheairs

Don't know how you insert a fuse into a 2awg battery cable. But I'm sure someone out there does

You need to know the amperage of the load, the ampacity of the wire, and the AIC of the bank. Typically you'll use a high-quality MRBF fuse on the battery if sized appropriately, or a fuse block.

[Tcheairs]

Originally Posted by SV_BlueTurtle

I did, yes - and everything I said is relevant. Wire fusing is per ABYC E-13 specifications. Wire gauge is determined by resistance, voltage drop, and current. Alternator regulation and charging profile are essential for any lithium installation.

With respect, you do not appear to understand what you're doing here - yes, lithium batteries can be more deeply discharged (realistically to 20%, not 0%), but there are important things that need to be considered when switching to a LiFePO4 bank that you are not responding to.

Specifically, you need to understand the differences in charging profile between FLA/AGM and LiFePO4 batteries. A lithium battery does not sulfate, requires a higher bulk absorption voltage (usually around 14.4V), held at that rate for a different time (0.3-1.0C, depending upon battery, and which needs to be specific to the battery), and does not go into float like a traditional battery does. Once again: if you just drop this battery -- which I do see a UL rating for, let alone a proper specifications sheet -- into your boat, you will (at best) experience charging problems.

Also, you will almost certainly create an insurance issue if you do not properly install (fusing, wiring, charging, etc.) this battery, meaning you need to ensure that this battery is installed per ABYC standards.

I'm not trying to be a jerk, but converting to lithium requires more than a budget lithium battery that happens to fit the space in which your AGM bank used to be in.

No offense at all...I appreciate your technical expertise and input.

[NorthCoastJoe]

Seems to me you need to figure out why your AGM batteries are not lasting.

To install a LiFePO4 battery you need to do quite a bit of reworking your charging system.

You cannot use your alternator as it is now. You will need to go with an external regulator and program it for LiFePO4 batteries.

Your shore power charger needs to be comparable also.

I think your cheap LiFePO4 will be far more expensive than you think.

Again what is killing your AGM batteries? Try shutting off the battery when you leave the boat. Leave nothing turned on. My Pearson 30 has 2 Costco marine batteries that have lasted over 5 years. Somewhere you have a problem and changing to a LiFePO4 battery is not going to solve the problem.

I hope you find your vampire draw and solve the problem.