LiFePO4 Update - Any Experiences to Report?
- Thread starter jviss
- Start date
Bought a boat last fall with LIFePO4 (4 x ReLion 100ah batteries). PO upgraded the entire charging system to support the installation. I love that the batteries discharge without a significant voltage curve, and that they recharge quickly since I can put high amperage into them. This will also reduce the amount of time it takes to get most of a charge into them while on a generator. Also I appreciate that the internal BMS protects the batteries from a number of damaging situations. Over the winter I had an event which caused the batteries to discharge until the internal BMS shut them down. I was able to charge them right back up without damage. Most other battery chemistries would've been killed by that. I also like the fact that I have 120 lbs of LIFePO4 batteries compared to 560 pounds of AGM batteries to get the same useful amp hours.
Wow, that's awesome! Can you please share the brands of the batteries and other components?
- ReLion LiFePO4 100ah batteries x 4
- Balmar MC-624 regulator
- Balmar SG-200 Battery monitor with shunt and bluetooth
- Balmar 120 amp alternator
- Xantrex Freedom SW2012 shore charger/inverter
- Xantrex Xanbus system control panel
- Bluesea Mini ACR (for Starter battery)
- Balmar MC-624 regulator
- Balmar SG-200 Battery monitor with shunt and bluetooth
- Balmar 120 amp alternator
- Xantrex Freedom SW2012 shore charger/inverter
- Xantrex Xanbus system control panel
- Bluesea Mini ACR (for Starter battery)
Thank you for the quick and complete reply! I'm a bit confused, though. First, you have a 24V regulator and a 12V charger/inverter. How does that work? Also, none of the components except, of course, the batteries, seem to be LiFePO4 specific. Finally, do you know what BMS is in the batteries? Is it one, or one per battery?
Thanks,
jv
Sorry, wrote that wrong, its the Balmar MC-618 12v regulator. Good catch! The BMS internal to the batteries is from the manufacturer, ReLion, but no info beyond that.
A couple of questions.
How is the alternator protected from a BMS dump?
Do the start battery and the LFPs have the same charging characteristics, i.e, are the absorption voltages the same?
Good questions! I'd like to know as well. For the first, some BMS's have an output to enable/disable alternator field current, so they can shut off the alternator before they dump. For the second I'd say no, but what long term damage will that do to the starting battery? Perhaps better a DC-DC charger than an ACR.
The easy one first: My start battery does have similar charging characteristics as the lithiums.
BMS Dump and protection from alternator damage: Not apparent to me how this is set up. I brought in a local Marine Electrical company to have a look at my system and recommend any changes based on issues they see, and educate me on how it is set up. This is a question that I've posed to them and hope to get an answer on this week. ReLion says the following:
"If the BMS disconnects the batteries the alternator may be damaged. To protect your LiFePO4 battery and alternator please be sure to use a compatible high-quality alternator or install a voltage regulator."
I'd consider the Balmar alternator and regulator "high quality", but want assurance that they're set up to protect the alternator from damage. Liv Sailing contacted Balmar during the course of a lithium install and said the following:
"While discussing this issue with Balmar, I was informed that the Balmar alternator would safely shut down if the MC-614 regulator loses power at the same time as the alternator is disconnected from the battery...The power to the external alternator regulator is wired, so the regulator will lose power at the same time as the alternator is disconnected from the battery, which will cause the alternator to shut down safely."
Hopefully my system is wired the same way when the tech looks at it. Otherwise I'm probably looking at them installing a Balmar APM to protect the alternator. APM-12 - Balmar
Curious as to what others have experienced with this regulator and lithiums.
EDIT: Update on responses from a couple of manufacturers on whether the MC-618, if wired correctly, provides sufficient protection from battery dump:
ReLion:
"That is for sure a quality regulator and alternator so I would say you are good. If you want extra protection again the chance that the battery disconnects you can also look at installing a Alternator Protection Modules - Balmar. "
CDI/Balmar:
"It would be dependent on how the regulator is wired. If you have a switch, such as the Victron Solid State 104, that can take a signal from the BMS to shut down either the field or ignition signal to the regulator, you should be fine. If there is no relay to cut off the regulator then you could damage the alternator when the BMS cuts out. I would recommend getting an APM either way. "
PKYS: (offered three ways to protect the alternator, with the third being as follows)
"... use an Alternator Protection Module like the Balmar APM-12 If the battery disconnects and the voltage starts to spike the APM-12 shorts out the alternator output to stop it working."
So...sounds like an APM-12 is getting installed to protect the alternator.
Last edited:
The Balmar APM is the solution I'm using. From what I learned, BMS dumps are rare, however, they are really damaging. The other solution is the lead the alternator output to the start battery and use a Battery to Battery Charger to charge the LFPs. The problem with this arrangement is the charging current is limited and one of the LFPs benefits, ability to accept a high charge rate, is lost.
True, but that limits your options. The BMS must be able to warn the regulator that it will dump the load and the regulator must be able to act fast enough to cut the field current. This limits options for installation.
The Balmar APM can absorb multiple surges. From the Balmar Website:
(emphasis added)
I saw this on the the data sheet:
That said, a BMS can control an external relay in series with the field current wire, and drop it just before it dumps. I think that's how some of them work.
The Balmar statement is a CYA. And there are trade offs. Yes you can get a BMS that signals the regulator but that drives you into a more expensive solution. If BMS load dumps were a frequent occurrence, then more caution would be needed. However, if the regulator, PV controller, and charger are programmed correctly, a load dump would be a very rare occurrence. Thus we have 2 rare occurrences, a BMS load dump and a failed APM. The combination of both is very very rare. I'll take my chances.
That's fair. I would hope a BMS dump would be rare, or never!
I was designing a system last year, but left it and can't remember everything now. But I recall being disappointed that not everything was "there" yet for LiFePO4. All of these systems, it seemed, Victron, for example, assumed or required a lead-acid battery in the system. One would think that a BMS would emerge that controls the alternator as well, as an integrated system, and then you'd never have to worry about zapping alternator diodes.
Lithionics external BMS will do that, but it’s a seriously pricey installation.
Battleborn is about to release its’ IntelLigence line, with some type of mesh network and CANBus. They own Wakespeed so it’s possible they will be some control interface there.
MIBS 2023 - Battle Born with Dragonfly IntelLigence
Battle Born Batteries is introducing IntelLigence a line of LiFePO4 batteries and accessories that communicate via wireless mesh network
panbo.com
Great, thank you! I used to follow Panbo but it became tedious. Maybe I'll start again.Lithionics external BMS will do that, but it’s a seriously pricey installation.
Battleborn is about to release its’ IntelLigence line, with some type of mesh network and CANBus. They own Wakespeed so it’s possible they will be some control interface there.
MIBS 2023 - Battle Born with Dragonfly IntelLigence
Battle Born Batteries is introducing IntelLigence a line of LiFePO4 batteries and accessories that communicate via wireless mesh networkpanbo.com
Another good source of information is OceanPlanetEnergy.com
The LFP industry is moving to self-contained batteries, poorly named as "drop-ins" which are drop-ins only in size and do not reflect the limitations and specific needs for LFP batteries.
LFP installations appear to moving back from the bleeding edge and cutting edge of technology and into mainstream technology. Increased competition is driving the price down. A good quality 100 ah LFP battery can now be purchased for less than $500. The cost per wh over the life of the battery is now equal to or lower than that of LA batteries.
The LFP industry is moving to self-contained batteries, poorly named as "drop-ins" which are drop-ins only in size and do not reflect the limitations and specific needs for LFP batteries.
LFP installations appear to moving back from the bleeding edge and cutting edge of technology and into mainstream technology. Increased competition is driving the price down. A good quality 100 ah LFP battery can now be purchased for less than $500. The cost per wh over the life of the battery is now equal to or lower than that of LA batteries.
I couldn't make it through more than five minutes or so of this, it's so self-absorbed and tedious, thanks anyway!