Lithium Starter batteries beginning to be promoted and even allowed by Mercury now? huh?

[TommyinMiami]

Starting to see more and more YT videos saying to use a LiFePo4 "Starter Battery" as a drop-in LA replacement and you're good. I even wrote a comment on one video that the system still needs an alternator protector like the Balmar APM-12 AND a smart alternator or a regulator but that it was still best to do an AGM starter battery than a Lithium house battery and tie them together with a DC-DC charger. He wrote back I am wrong that Mercury put out a service bulletin that now they say a Lithium starting battery CAN be used if it meets the specs and it's on certain engines of theirs. He's basically telling the world to go drop in a Lithium Iron battery though which I feel is going to cause a lot of alternators to fry and possibly even some boat fires (he's a boat channel guy). Am I the wrong one? Marine alternators are built for constant on and are smaller voltages than cars a 30 Volt alternator is common and they go up to maybe 65V for larger engines. But still I feel you cant drop in a Lithium Starting battery and thats it. Its resistance is much lower so it will pull all the juice, the BMS can shut the charging circuit, the batteries dont watch the alternator temps, theres no fuses on the wire to the starter or engine, etc. So let me know if Im the one that is wrong here. I want to use Lithium as a drop in starter battery just as much as the next guy but I'm being realistic here.

Here's the technical bulletin:

of 9/26/2022, Mercury has issued Service Bulletin 2022-19 stating that the listed engines will be permitted to use a Lithium Iron Phosphate Battery that is designed for engine cranking, as long as it meets the listed specifications:

-2.1L 75-115hp Fourstroke, ProXS and SeaPro Models
-3.0L 150hp Fourstroke, ProXS and SeaPro
-4.6L V8 and 3.4L V6 175-300hp Fourstroke, ProXS, SeaPro and Verado Models
-2.6L L6 200-400 Pro and Verado Models
-7.6L V12 500-600hp SeaPro and Verado Models.
-NO other engines approved at this time.

Minimum Specs Required:

-Chemistry/Format: Lithium IRON Phosphate designed for MARINE CRANKING USE.
-Minimum Cranking Amps: 800A for 8 second minimum @ 20 Degrees F
-Peak Charge Acceptance: 165A at 20-130 degrees F for one minute
-Max Charge Alternator Size: 150A at 20-130 degrees F
-Max Charge Voltage/Alternator Output: 14.8V
-Reserve Capacity (RC25 @ 80F): 135 Minutes
-Ingress Protection (IP rating): IP67 or greater.

Cautions that use at temperatures below 32F may require additional equipment such as a battery heater.

Bulletin also lists a Relion Battery that has been evaluated and meets the above requirements: RB100-HP.

https://relionbattery.com/products/lithium/rb100-hp

The battery he is telling people to get is the MillerTech Starting Battery:
MillerTech Starting Battery 100Ah
A poster here BentlyJ has posted Cyclenbatt.com makes a starting battery too
Dakota Lithium Dual Purpose LiFePO4 also makes a starting battery and says charges via the alternator

Is it possible that they have special BMSs that limit or regulate input charge values (voltage and/or timeframes) much like a controller would do?
It seems like these charging batteries are whats coming onto the scene next and I think it would be good to know whats what.

 

[Jeremyduckworth]

I know a whole lot of the professional bass guys are running all lithium systems for their outboards and nobody has had an issue a co worker of mines son is on the pro tour and he also is running all lithium batteries starting this year I as well am curious about this I have a 460 Kodiak Ford in my boat and according to Dakota lithium as well as Mtech they have cranking batteries that the BMS systems are rated high enough to use on my engine I'm asking that question here to see what others say because same as you if I can go all lithium I sure would love to.

 

[JCSchwarb]

The existing charging circuit needs to match the LFPs BMS max charging input or the alternator would need to be stepped down. The only issue I foresee is if/when the alternator goes out and the batteries go to 0V, they will need a special LFP pulse to get them to wake up and accept a charge. I would put a DC rated CB or Tfuse from the positive battery terminal to protect from a runaway condition.

 

[wpns]

Bulletin also lists a Relion Battery that has been evaluated and meets the above requirements: RB100-HP.

https://relionbattery.com/products/lithium/rb100-hp

Which lists for $1000.00 Wow!

 

[patrickparrott]

I'm working on this issue for my boat right now. Dakota says that they have changed the upper shutdown limit to accommodate the alternators in the outboard motors and are sending me a replacement battery.

 

[wpns]

I'm working on this issue for my boat right now. Dakota says that they have changed the upper shutdown limit to accommodate the alternators in the outboard motors and are sending me a replacement battery.

No now the BMS allows the battery to overcharge. This is good why?