Add Lithium To Boat Without A House Bank

[steenbag]

Hi all,

I have a 2000 Monterey 302 Cruiser with 2x gas motors, and 2x dual-purpose AGM batteries. As wired from the factory, it has no dedicated house battery bank, it relies on the dual-purpose batteries for engine start and house loads. It also has shore power (2x 30A) and a ProNautic 1220P battery charger (that charger is currently limited to 20A due to the existing wire and circuit breaker size - I could potentially upgrade it).

After a successful Lithium conversion of our camper earlier this year, I'd like to add lithium to the boat next year. I'm not looking for an inverter system on the boat, just sufficient power (probably 400Ah @ 12v) to stay away from the dock for several days without needing to run the motors to recharge, or needing to jump the batteries to get home (which happens a lot).

What I'm trying to figure out is how to add lithium to the system so both the house and starter batteries can charge from the motors and/or shore power, and also discharge the lithium through the existing wiring (as much as possible) to power the house loads (also assuming the lithium must be disconnected while the engines are starting). I've looked at various isolators and combiners, but I can't figure out a way to make it work without significant rewiring or creating charging loops.

Thanks for any suggestions!

 

[time2roll]

Need to separate the engine system from the house. Yes may need a new fuse panel etc for the house. Move the house circuits to the new fuse/distribution panel and power it with the lithium batteries. Then connect a DC charger to charge the lithium from the engine alternator system. The DC charger will limit the amps to protect the alternator from overload and provide proper charging voltage for the lithium batteries. This is the basic concept.

 

[wpns]

Didn’t someone here have a device that did that (with an override to jump the starter battery from the house battery) recently?

I’ve slept since then, so I honestly don’t remember whether it was in a boat or a van and who it was…

 

[wpns]

The charger is the sterling power bb1260.

Which leads to

https://a.co/d/aXOJZml

You have to do your own research to see if you can figure out if that does what you want.

 

[tpenfield]

Having done a recent upgrade/conversion of my AGM power to some LiFePO4 on my boat, I'll offer these comments . . .

Things to consider and address in replacing AGM's with LiFePO4 (LFP) batteries.

1) Current draw from the batteries during engine starting. There are some LFP batteries that are advertised as being appropriate as a starting battery. 100Amp current rating might be a bit light, but 200Amp might be OK.

2) Charging of the LFP batteries. The LFP's will tend to draw high levels of current during bulk re-charging, so you will want to buffer the charging so as to protect the alternators from damage. A DC-DC converter can provide regulation of charging.

3) If the ProNautic shore power charger has an LiFePO4 setting, then it can effectively manage the LFP batteries while on shore power. Otherwise, you could upgrade it to a model that has the LFP profile.

4) Batteries and DC-DC chargers with Bluetooth would be helpful, as you can monitor/manage things from a smartphone.

 

[mooresolar]

Here a good place to start

Diagrams | Pacific Yacht Systems

Pacific Yacht Systems can design and install exactly what you need, so that you feel safe and enjoy your boat to its full potential. We offer design, installation, service, and support for marine electronics and electrical services.

www.pysystems.ca

 

[MiSh]

Relion battery makes dual purpose starter/marine lifepo4 batteries (HP line). Although I don't have a boat, I do own a couple of their 100ah batteries and they are a quality battery, if not pricey. You might give them a call to explain your charging situation and get some feedback. I'm sure they have encountered this question before. Their customer service is great.

https://www.relionbattery.com/products/lithium/rb300-hp

 

[AnarchyJet]

Find a wiring diagram for your boat and post it up. Might be as simple as finding the circuit that powers your DC panel and putting a DC-DC charger and LPF battery inline. With fuses and disconnects as needed of course.

 

[tpenfield]

Adding a few additional comments . . .

@steenbag - you mentioned that your boat is a year 2000 model. Does it have fuel injected engines (MPI or EFI)? Does it have digital controls?

In the newer boats (not that 25 years old is exactly 'new') the wiring can be quite complex. So, my advice is to simplify your approach to re-fitting/re-wiring the batteries, and don't go too far into the wiring schematic with changes. Keep your focus on/at the batteries.

One thing that is different with your approach is that you don't have a 'house' battery bank separate from the engine battery bank. Often with separate battery banks, the engine bank stays as lead-acid (AGM) while the house bank gets change to LFP batteries. This allows you to have the DC-DC charger connected to the AGM bank to provide some level of (what I call) stability for the alternators.

The model year 2000 engines are going to have 'dumb' alternators (probably of the 65 amp variety), so they may not 'enjoy' being connected directly to a DC-DC charger. I had trouble with my boat (2016 model year) when I tried running the DC-DC charger straight from the alternators. You may want to research the best type/brand of DC-DC charger for the application.

You may also need some battery isolators, which your boat probably does not have.

If you do have some electrical diagram information for your boat, it may be best to post it for further input from those following along.

 

[steenbag]

Relion battery makes dual purpose starter/marine lifepo4 batteries (HP line). Although I don't have a boat, I do own a couple of their 100ah batteries and they are a quality battery, if not pricey. You might give them a call to explain your charging situation and get some feedback. I'm sure they have encountered this question before. Their customer service is great.

https://www.relionbattery.com/products/lithium/rb300-hp

I've looked at a couple lithium starters (LiTime makes one, and a couple other car drop-in types I've seen). I'm curious about this type of setup, but the lithium BMS makes me caution. If the BMS were to decide to disconnect for whatever reason while the engine was running, it would destroy the alternator. Also LiTime is pretty explicitly only mentioning outboards on their website, which makes me curious of the reason.

I'm currently looking at the Bank Manager from Clark's Sailing Adventures. Looks like a potentially good solution to get a single house bank attached to one of the starting batteries.

 

[steenbag]

Adding a few additional comments . . .

@steenbag - you mentioned that your boat is a year 2000 model. Does it have fuel injected engines (MPI or EFI)? Does it have digital controls?

In the newer boats (not that 25 years old is exactly 'new') the wiring can be quite complex. So, my advice is to simplify your approach to re-fitting/re-wiring the batteries, and don't go too far into the wiring schematic with changes. Keep your focus on/at the batteries.

One thing that is different with your approach is that you don't have a 'house' battery bank separate from the engine battery bank. Often with separate battery banks, the engine bank stays as lead-acid (AGM) while the house bank gets change to LFP batteries. This allows you to have the DC-DC charger connected to the AGM bank to provide some level of (what I call) stability for the alternators.

The model year 2000 engines are going to have 'dumb' alternators (probably of the 65 amp variety), so they may not 'enjoy' being connected directly to a DC-DC charger. I had trouble with my boat (2016 model year) when I tried running the DC-DC charger straight from the alternators. You may want to research the best type/brand of DC-DC charger for the application.

You may also need some battery isolators, which your boat probably does not have.

If you do have some electrical diagram information for your boat, it may be best to post it for further input from those following along.

The engines are carbureted, and everything is mechanical. I work on everything myself, so I didn't want any computers in the way of that. I'm trying to figure out a wiring diagram (the actual boat wiring is pretty simple), but one of my other side projects for the winter is removing all of the excess wiring that the previous owner added for "stuff" over the years that has since been removed. The alternators are 150A aftermarket units and are externally regulated, which I believe gives me some more options in terms of not frying them while charging lithium, but still concerned about BMS cut-off.

 

[tpenfield]

Some outboard motors are now coming with 'smart' alternators, so they can play nicely with Lithium. Older engines/alternators, not so much.

The design looks challenging. The 150amp alternators are probably a good thing. Look into the Balmar alternator protection module.

I assume that you have a Perko "A, B, Both" switch for your existing batteries? (maybe)

 

[steenbag]

Some outboard motors are now coming with 'smart' alternators, so they can play nicely with Lithium. Older engines/alternators, not so much.

The design looks challenging. The 150amp alternators are probably a good thing. Look into the Balmar alternator protection module.

I assume that you have a Perko "A, B, Both" switch for your existing batteries? (maybe)

I haven't seen these Balmar modules before; that makes me a little more confident in a direct Lithium drop in. I don't think the regulators can handle a full shutdown like this claims to.

As for switches, it has 3 12v switches; Starboard Batt. On/Off, Port Batt. On/Off, and Parallel.