Lithium starting battery recommendation? For large rescue boat.

[ccgarnaal]

Lithium starting battery recommendation?
What is the go to brand for lithium starting batteries? Looking for starting batteries for a 13l 800hp marine diesel.
Engine has a 7kw starter so at 24V pulls about 300A for 30 seconds. But recommended lead acid batttery would be 800-1000CCA.

Note: this battery will be used for starting only, It will be connected to a "house battery" trough a smart relay. Which is used for consumers.
When boat is docked battery keys are off and there is 0 parasitic drain.
Still looking for house battery recommendatiosn too. size 50-80Ah, charge current from alternator is 100A max discharge is 60A.

 

[spinningmagnets]

If you buy "affordable" cells they will likely have low current, so you would need a lot of them. If you connect a lot of cells in parallel and series, the bus material becomes a bottleneck to current.

I'd suggest the red Headways, each is the size of two D-cells, 38mm diameter, 120mm long. LiFePO4 chemistry, very fire-safe. 24V would be 8S, and 300A would be 3P, so 24 of them. The threaded ends make assembly easy.

https://batteryhookup.com/collectio...ifepo4-lithium-batteries-25c-200a-super-cells

There are several youtubes where an amp-meter is used when starting a car with an ultracapacitor bank, or also a small lithium battery. A 4-cylinder pulled 200A to start spinning, and then 100A continuous (With the spark removed, the ultracaps could spin it for about 30 seconds).

Here's a pic of 4S / 3P...https://www.facebook.com/groups/KWeldNorthAmerica/?ref=bookmarks

 

[ccgarnaal]

More looking for premade batteries with type approval.
I could build them. But not sure how class approval would like that.
And it would take more then 200A these are 800hp 16l 6 cil diesel engines.
Theoretically it need 250A at 24V but I think at least double that to be safe given the recommended lead acid rating.

 

[BVH]

Just a point to consider if you end up using LiFeP04 cells. I have lots of military and aviation "28 Volt" searchlights up to 2000 Watts in power consumption. I use a 9S configuration of LiFeP04 cells for a nominal 28.8 Volts (3.2 per cell x's 9 = 28.8 ). If your charging system puts out 28+ Volts then you could probably use the 9S configuration to slightly raise Voltage and reduce current. The military systems I have seen, use two regular 12 Volt lead acid batteries in series and the charging systems are putting out 28+ Volts. Pretty much precisely double of an automotive system where charging Voltages are are up to about 14.2-14.4 VDC. I have not had experience with any Marine systems.

You can buy individual LiFeP04 Prismatic, plastic housing cells in capacities of up to around 250 Ah each and these cells are capable of a "2C" continuous discharge so good for a 500 AH discharge. You would need only 9 of these cells to accomplish what you need.

Your 7,000 Watt need is met via: 7,000 Watts / 28.8 Volts = 243 Amps. A 9S/250 Ah pack would provide you up to 500 Amps.

I understand you may not be able to go this way from a liability and insurance standpoint.

 

[john61ct]

You can buy individual LiFeP04 Prismatic, plastic housing cells in capacities of up to around 250 Ah each and these cells are capable of a "2C" continuous discharge so good for a 500 AH discharge. You would need only 9 of these cells to accomplish what you need.

That's insane.

A 50Ah pack will be plenty to crank any size engine, it's just a couple seconds.

Maybe even 20Ah.