Interesting LiFePO4 question/experiment

Mr Fox

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Aug 31, 2017
204
Marshall 22 Portland, ME
Hello all- I have been handed a new RELiON RB50 battery. So I’m wondering if I can use it in my setup (and honestly I like learning about new things so I’d love it get some feedback and opinions and suggestions). Sorry it’s a long read...

My boat currently has single interstate deep cycle srm-24 on switch posistion 1, and an srm-24 in parallel with an srm-27 on switch position 2. This is how the boat came (she is new to me this year but a 1981 build).

I have 3 small incandescent cabin lights, one 12v fan, gx-2200 vhs/ais receiver, a jabsco electric head, and use navionics on a Samsung rugged 2 waterproof tablet (android version of navionics does correct text on course up view). So my power needs are little.

Boat usually goes for day sails, from a mooring, engine typically is used to leave/enter the mooring field and occasional pickups and supply from dock. I do the occasional overnight with kids on the hook.

The yanmar is the 3gym I believe (it’s the 30 hp with freshwater cooling but I can never remember the model number). It has the stock hitachi alternator (no external regulator). I am comfortable using the conventionally wired 1/2/b/off as is.

My gripe-
The boat has a ton of battery, all mounted far out to starboard along with the 12g fuel tank and 20 gal holding tank. The location of the battery area can not be changed. Ive only got a 20gal water tank to port, so even with the lead ballast all to port she still lists ever so slightly. Not a big deal but yes I notice.

So my thought is is- can I replace the #2 batteries with one of these relions? They have a built in BMS.

Since the #1 battery is used only as a starter, it think it is basically full all the time except due to self discharge. I could start on posistion 1, then switch to both once running. The RELiON is a 12.8 nominal voltage battery that wants 14.2 V - 14.6 V charge voltage. I believe that’s compatible with the lead?

The LiFePO4 would suck up power super fast, but the BMS will take the battery offline once it is full. Perhaps the alternator theoretically/hopefully wouldn't blow its diodes as the lead acid battery is still connected. I’m not sure if this offline action of the BMS is like a hard stop or not.

Could the regulator on the hitachi be relied on to protect the alternator from the hungry LiFePO4? I’m not sure.

My hope-
Once engine is off switch to #2. I now have a 15lb 50amp that can be taken to a low soc without damage, and won’t be damaged from sitting around with a low charge. I have less weight and the start battery will be happy as it’s only starting. I could probably install a monitor for the lifep04 as you can’t tell what’s going on from voltage (right?).

Anyhow it’s a thought- love to hear alternate ideas and feedback. I’m reasonably sure there’s no way it could be this easy or more people would have this set up. :)
 
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jviss

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Feb 5, 2004
6,745
Tartan 3800 20 Westport, MA
I have been handed a new RELiON RB50 battery.
Wow. This line stopped me dead in my tracks. How lucky is that? I'm jealous.

I think @Maine Sail has LiFePO4 batts, so I'm sure when he sees this he will be interested in commenting. He's the resident expert on this.

Odd that you would have an SRM-24 in parallel with an SRM-27, as it goes against all that we know about these systems, but that is exactly what I found on the boat I bought last Fall! (They were new, too, and none the worse for wear. I removed them, charged them, equalized them, and now they await a new assignment.)

Here's my recommendation.

1. Use one, or parallel two of the SRM-24's and use it as an engine starting bank;
2. Install the RB50 as the house bank;
3. re-wire to use the 1/2/BOTH/OFF switch, and add an engine bank ON/OFF switch as a way of selecting "any to any," with normal operation always on "1" and "ON". You can then isolate a bad bank, run the house from the starting bank, start the engine from the house bank. Connect the alternator to the house bank. (There are a couple of threads on this topic, see Maine Sail's: https://forums.sailboatowners.com/index.php?threads/1-both-2-off-switches-thoughts-musings.137615/
4. Add an ACR, Automatic Charging Relay, so when a charging source is present it will close and charge everything.
5. Consider getting your alternator regulator adjusted to 14.3V for the LiFePO4.
 

Mr Fox

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Aug 31, 2017
204
Marshall 22 Portland, ME
Thanks so much for the reply! That seems to make sense, I’ll go over the strategy with the electrician at my yard (as I really don’t know much in this area).

I got super lucky as I picked up 3 of these for a family member’s solar array and it turned out only 2 were needed, so in return for my delivery they decided if I could use the extra I could keep it as opposed to returning it.
 

jviss

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Feb 5, 2004
6,745
Tartan 3800 20 Westport, MA
I got super lucky as I picked up 3 of these for a family member’s solar array and it turned out only 2 were needed, so in return for my delivery they decided if I could use the extra I could keep it as opposed to returning it.
Wow. That's a $700 tip! If you change your mind about using it I'll happily come take it off your hands.

This is for your Rhodes 19? That's a great boat. As kids we used to rent them on City Island in the Bronx, NY, to sail around the end of Long Island Sound. They were the keel versions. No electrical system!
 

Mr Fox

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Aug 31, 2017
204
Marshall 22 Portland, ME
Yeah maybe I should get into battery delivery for my day job!

This is on my new (to me) Marshall 22, my rhodes has zero electric. Both are great family boats.
 

Mr Fox

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Aug 31, 2017
204
Marshall 22 Portland, ME
It's a great little boat for daysailing and overnight camping with a kid. Draws less than 2 feet so beaches are easy. I love Tartans, my uncle has a well maintained 34c on the Chesapeake and I usually help him in the Good Old Boat race down there.
 

Mr Fox

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Aug 31, 2017
204
Marshall 22 Portland, ME
Could re-wiring the battery switch to be a use switch, with the alternator directly wired to the start battery and a sterling dc-dc charger programmed to the correct parameters for the RELiON rb-50 work?

Again fully aware this may not cut the mustard.
 
Feb 26, 2004
22,760
Catalina 34 224 Maple Bay, BC, Canada
Could re-wiring the battery switch to be a use switch, with the alternator directly wired to the start battery and a sterling dc-dc charger programmed to the correct parameters for the RELiON rb-50 work?
with the alternator directly wired to the HOUSE battery

Why do certain folks think that the start bank ever needs anything?
 

Mr Fox

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Aug 31, 2017
204
Marshall 22 Portland, ME
My thought being since the house will be the LifeP04 with the BMS, once full the BMS would take the battery offline and blow the diodes on the alternator. Wiring the alternator to the start battery which is a flooded battery would avoid this potential problem.
 

jviss

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Feb 5, 2004
6,745
Tartan 3800 20 Westport, MA
My thought being since the house will be the LifeP04 with the BMS, once full the BMS would take the battery offline and blow the diodes on the alternator. Wiring the alternator to the start battery which is a flooded battery would avoid this potential problem.
Do you have a link to a manual for the RB50 and BMS? I was only able to find a data sheet, and nothing about the BMS taking the batt off line.
 
Oct 2, 2008
3,807
Pearson/ 530 Strafford, NH
Hamilton Marine just did a video on basic boat wiring which may answer your question. As for the trim look for something heavy for the port side. [anchor, food, drinks, water] I had lead bars that we added once to a smaller boat. Don't know if that made any difference other than the drinks didn't slide off the cockpit table.
 
Feb 6, 1998
11,667
Canadian Sailcraft 36T Casco Bay, ME
Could re-wiring the battery switch to be a use switch, with the alternator directly wired to the start battery and a sterling dc-dc charger programmed to the correct parameters for the RELiON rb-50 work?

Again fully aware this may not cut the mustard.
Hard wire your alternator (NOT THROUGH THE BATTERY SWITCH) directly to the start bank and keep start bank on SW position #2
Install the Relion as bank 1
Install a Sterling *BB1230 and feed it from start bank to house bank and use the "key on" excite feature. (alt must be able to produce more than 40A when hot)
Set Sterling BB1230 absorption time to ZERO or less than 20 minutes
Set Sterling voltage to 14.0V - 14.2V
DO NOT FLOAT & DO NOT let the battery discharge below 12.0V
DO NOT use the temp sensor, that is for lead acid only
Install an LVD for house load panel set to 12.2V

For more insight into LFP on boats:

LiFePO4 On Boats


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Aug 22, 2017
1,609
Hunter 26.5 West Palm Beach
...
The yanmar is the 3gym I believe (it’s the 30 hp with freshwater cooling but I can never remember the model number). ...
A 22' sailboat with a 30hp Yanmar??? Is that correct?

I don't know the Marshal. Maybe that is a super rugged little boat that is designed for such a big motor. It just sounds like a lot of motor for a 22.
 

jviss

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Feb 5, 2004
6,745
Tartan 3800 20 Westport, MA
Install a Sterling *BB1230 and feed it from start bank to house bank and use the "key on" excite feature.
I'm a little confused. Can the BB1230 operate off DC, i.e., not in the presence of shore power?
 

jviss

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Feb 5, 2004
6,745
Tartan 3800 20 Westport, MA
A 22' sailboat with a 30hp Yanmar??? Is that correct?

I don't know the Marshal. Maybe that is a super rugged little boat that is designed for such a big motor. It just sounds like a lot of motor for a 22.
The standard engine for new Marshall 22's is the Yanmar 3YM20, which is 20hp. I've seen Marshall 22's with anything from 16 to 30hp, and a wide variety of engines, gas and diesel.

These are big boats for their length. The beam on this is 10'2" and displacement 5,660 lb.
 

Mr Fox

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Aug 31, 2017
204
Marshall 22 Portland, ME
A 22' sailboat with a 30hp Yanmar??? Is that correct?

I don't know the Marshal. Maybe that is a super rugged little boat that is designed for such a big motor. It just sounds like a lot of motor for a 22.
I confirmed it is a 3gm30f, so I believe it's 27 hp. These boats are incredibly robust, there's no mechanical fasteners in the deck to hull joint (its essentially a monocoque) and the fiberglass lay up is really well done. Imho the marshall catboats are the definition of new england rugged - but I may be a little biased :)
 
Feb 6, 1998
11,667
Canadian Sailcraft 36T Casco Bay, ME
I don't have a good manual, but the people at region informed me that the BMS will take the battery off line when it is full. The specs are here, which included the voltage, current and temperature disconnect and reconnect thresholds. https://ceb8596f236225acd007-8e9532...n.com/docs/product/Relion-Data-Sheet-RB50.pdf
The internal BMS switch will open the circuit when any internal cell, there are four cells, exceeds the 15.6V limit. You NEVER want to have the BMS disconnect on low or high voltage. If the BMS ever disconnects the battery you have serious issues. It is up to you to set your charge sources carefully to not stress the cells and drastically shorten cycle life. I see LiFePO4 batteries destroyed rapidly by incorrect charging all the time. The BMS in the Relion is catastrophic protection not "battery cycle life management"..
 
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Mr Fox

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Aug 31, 2017
204
Marshall 22 Portland, ME
(alt must be able to produce more than 40A when hot)

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I will test the alternator to see if that is possible.

Maine Sail thank you, the parameters for the sterling are much appreciated and will remove anxiety and costly guess work if I can confirm my alternator is up to task (or that I can install one that is).