AGM to LiFePO4 Batteries

[ElizabethG]

Hi Guys,

I want to upgrade my batteries to lithium (LiFePO4).

I currently have two LifeLine, 4D, 200Ah, AGM batteries.

I'm looking to move up to two, deep cycle, smart, 12v, 4D, at approximately 310Ah batteries.

Here's the problem...

The space in the battery locker is pretty tight. Manufacturers typically vary around the 4D size. It's the width of the batteries that I'm worried about.

If anyone has made this upgrade, can you share the manufacturers name and model number?

I'm really looking for a "drop-in" versus a mini/compact battery, or having to move to a larger locker to fit them in.

(BTW, I'm all set regarding the shore power charger, alternator, and external regulator needed.)

Thanks,

Bill

[Wisail]

Attached is a screenshot as a quick way of downsizing the pic size to post.
Pic shows dc/dc converter, monitor shunt, and lithium batteries. 400 ah fits in the compartment if you place the lead acid starting battery in the compartment next door. Under the settee. My air conditioner is under there but has easily enough room for the starting battery.
Contact me if you want more information about my setup.

[ElizabethG]

Wisail,

Thanks for the post!

So, it looks like you did your upgrade a few years ago. I can't make out the name of the battery manufacturer in your photo.

I'm doing a crash dive in understanding the Lithium technology.

My original thoughts were to set it up like this...

Smart Balmar alternator > external alternator controller (Lithium compatible) > Victron smart 12v, 12/50 shore power charger > Two LiFePO4 batteries in parallel to be used as the house bank and engine start. (No external start battery)

I also find that a lot of folks are using the same setup as yours by using a DC to DC charger and a separate start battery.

I guess I'm trying to figure out the pros and cons of each method...

Bill

[Wisail]

They are Enduro power batteries with internal battery management system. There are numerous other manufacturers producing similar products.
You could get a new alternator and controller and battery charger. I found it just as good and significantly less expensive to use existing charging system going to the starting battery then through the dc/dc converter to the lithium house bank.
It isolates charging one way but creates the ability to jump the starting circuit if something was to happen to the starting battery.
All systems are fed off the house bank and the only load on starting battery is to start the motor.
I have 4 years on the starting battery and expect it to last for many as it doesn’t really get discharged deeply at all.
I’ve been able to use lights, refrigeration, electronics and autopilot for days without charging and no solar or wind generation to augment.

[ElizabethG]

Hi Wisail,

Thanks for the additional info.

For those following along, here is a great article by Rod Collins at Marine How To regarding "drop in" lithium batteries; https://marinehowto.com/drop-in-lifepo4 ... -consumer/

BTW, check out his other articles that are also very informative.

As the article points out, you have to be careful regarding potential "load dump" damage and "DC motor In Rush" such as a windlass motor that pulls a lot of current.

Anyway, going with an AGM to Lithium swap is fascinating.

I hope others will jump in with what they have done.

Bill