Messages

Thanks all for the comments.  They're prompting me to do more research to make sure I understand how it works.

Noah, you're correct about the DC2DC charger "feeding" the LFP battery.  I think of the DC-to-DC charger as a fancy Echo Charger with some differences. The DC-to-DC charger not only charges the LFP battery but also functions as a power supply, regulating voltage and current from the LFP battery to support the house loads. I'll continue to use my Echo Charger to maintain the engine start battery.

Girmann, I'm adding the group 27 battery as a bridge between my existing setup (charger, alternator) and letting the DC2DC charger handle compatibility with the new LFP battery.  I'd either have to change my wiring to charge the engine start battery first (time consuming) or replace the alternator regulator and battery charger to avoid it, then I'd still be concerned about using the LFP to start the engine.  The Epoch 300ah battery peak output is 400 amps for 3 seconds.

That's a good point about BMS shutoff protection.  I'll look into field disconnect or an alternator surge protection.

The DC-to-DC charger is connected to the FLA battery in parallel. It supplies power to the house loads at 12.8V, up to its maximum capacity of 50 amps. This prevents the FLA battery from discharging during normal operation. If current demand exceeds 50 amps (e.g., engine starting), the FLA battery supplements the current. Once the demand drops, the DC-to-DC charger replenishes the FLA battery via the parallel connection.

Regarding battery life, I use full capacity just a few times a season.  I'll get longer battery life because LFP doesn't need to be fully charged like FLA batteries.

Jim, I agree replacing existing batteries would be easiest.  If I didn't enjoy tinkering, I'd just replace the golf cart batteries.  My reason for this post is to vet my plans to avoid unpleasant surprises and costs.  I'll check out "Capable Cruising Guide".

The start battery is charged with a Xantrex echo charger because the battery charger and alternator are connected to the house bank.  I'm adding the group 27 FLA so I can continue to use my charger and regulator and to have a second battery to start the engine.  My old Truecharge 40 charger and ASR-4 regulator don't have a LFP setting and it's not recommended to use the class of LFP battery I'm looking at to start an engine.

Regarding insurance, I talked to mine (Geiko/BoatUS) and they allow LFP batteries as long as they're intended for boats.  The Epoch battery I'm considering (https://www.epochbatteries.com/?rfsn=7030270.54d2cb) is marketed for marine use and is recommended by Rod Collins (Mainesail on this board).

I'll put the group 27 FLA, DC2DC charger and LFP battery in the existing battery area.  There's footprint for more, but I don't want to spend more $$$ than I have to.  As Ted said, the full 300 ah can be used so it's a 50% increase in the usable capacity I have today which is fine for how I use the boat.

The Optima start battery is under the aft berth near the engine.

All,

I'm looking for feedback on a conversion from FLA (Flooded Lead Acid) batteries to LFP (Lithium Iron Phosphate).  I'm considering because it's time to replace my seven year old house bank and four new golf cart batteries will cost around $600.  I estimate upgrade to LFP, including DC to DC charger and other parts, will total between $1000 and $1500 depending on the battery.  Time difference is an hour for new golf cart batteries and a day or two for LFP.

My current system has worked flawlessly for many years so I want to leave it unchanged as much as possible.  I used information from Marine How To (https://marinehowto.com/) and plan to source parts from Rod's affiliate pages.

Let me know what you think.  My goal is to avoid mistakes and help others considering the same change.

Kyle Ewing
DONNYBROOK #1010
 

The part number for the damper plate that came out of my 1990 M25xp was Hurth/ZF 1866050002.

I replaced with the same part number when I put in a ZF10M in 2012. Price then was $140.  The tranny was $1052.

If I remember correctly, you'll need new crush washers. Not a big deal of you have a parts store near where you're doing the work.

Not a direct answer but another data point: I have a 150 amp breaker on my M25xp start battery. It hasn't tripped once in many years.  I sized it based on feedback from this forum and online research.

I'm cross-posting here for visibility.  See pics in parts wanted/for sale.

***

I'm decluttering and am offering for free my original, delaminated rudder from a 1990 fin keel Catalina 34.  Boat has always been in fresh water (Lake Michigan).  Rudder may be useful to someone who has a boat with a bent rudder shaft who needs a straight rudder to rebuild. 

Foam is water logged with delamination at the bottom.  I tried drilling holes to dry over winter and filling with expandable foam for first two years I owned Donnybrook before replacing with a new elliptical rudder.  It's sat on my cradle since.

Free for pickup in Chicago Northwest side (60625 zip) or will deliver/meet a reasonable distance for gas money.

CONSIDERATIONS:  Even though boat was fresh water sailed, I don't know condition of the grid welded to the shaft.  Holes for steering quadrant and tiller cap may not align to another boat.

I'm decluttering and am offering for free my original, delaminated rudder from a 1990 fin keel Catalina 34.  Boat has always been in fresh water (Lake Michigan).  Rudder may be useful to someone who has a boat with a bent rudder shaft who needs a straight rudder to rebuild. 

Foam is water logged with delamination at the bottom.  I tried drilling holes to dry over winter and filling with expandable foam for first two years I owned Donnybrook before replacing with a new elliptical rudder.  It's sat on my cradle since.

Free for pickup in Chicago Northwest side (60625 zip) or will deliver/meet a reasonable distance for gas money.

CONSIDERATIONS:  Even though boat was fresh water sailed, I don't know condition of the grid welded to the shaft.  Holes for steering quadrant and tiller cap may not align to another boat.

Thanks, Noah, Ron and MooseDriver.  I use plastic storage bins but typically put them under settees or in lazarettes. 

The "submarine laundry bag" idea is what I'm looking for!  It pointed me to "bunk bags", "foldable fabric bin" and "wall hanging organizer bag".  They'll add color and texture and can be stowed away when not needed.

There's a huge selection on Amazon and other sources so I'm interested in what others have used given our boats' dimensions.

I'm looking for ways to add clothes storage to the cabinet tops in the v-berth. The problem I'm trying to solve is living out of bags when staying on the boat for a few nights or longer. I didn't see anything in the wiki.

What have others done to that area? It could be as simple as adding plastic milk crates or basic shelves.  I need something that'll be secure when under way but doesn't feel like it's filling up the space like a cabinet would.  It'll also need to support air circulation to minimize "boat smell" on clothes, which is an advantage of keeping clothes in a bag.

 

Assuming you have two batteries separated by the 1-2-Both switch, can you reproduce the problem with each battery individually? When unable to start, does moving to BOTH position help?  That test will eliminate issues from either battery to the switch.

If you haven't already, physically try to move/wiggle then tighten all the battery connectors between the engine, switch and battery, including those at the battery switch. Look for loose battery lugs.
 Sometimes a loose connection will still show voltage but not let enough current flow.

Only then would I replace parts.

Ted is correct. My current yard in Chicago (Crowley's) includes cradle storage and movement in the fee as most boats store on cradles. The yard I'm looking at (Southport in Kenosha) is about half cradle so they charge a cradle fee with lower storage so overall price is comparable.

If I move, I'm leaning toward renting jackstands and selling/donating my current cradle.

Are the benefits of a 34 year old cradle worth the time and expense to truck it 80 miles to another yard?

I'm considering switching winter boat yards from Chicago south side to Kenosha.  If I do, I need to make a decision about shipping my cradle or using jack stands.  My cradle is the original four pad shipping cradle and is showing it's age.  The yard I'm considering charges a "cradle handling fee" that's essentially the same as jack stand rental.

I expect strong winds being on Lake Michigan.
 

My Webasto 16k BTU cools all cabins in my 1990 on the hottest Chicago summer days.  I use it at Marina's but read it'll run on a Honda 2000 if I add a soft start circuit.

@Andy, she's never been on the boat. I'm guessing up the stairs will be easy and going down tricky...

I did a lot of projects during Covid and, after 20 years, have Donnybrook more or less where I want her.  There always more I could do, but don't make sense right now.