LiFePO batteries with external BMS

Is anyone familiar with any brands of lithium batteries, but with external BMS instead of permanently sealed inside?

Victron and Lithionics both have batts that utilize an external BMS (they also have others with internal just FYI).

Victron is the one I would go with. They have an extensive and well integrated eco system to go with it, much larger than Lithionics, pretty much everything you need in a DC system all networked and internet connected if you want.

Just wondering why you want an external BMS?

My thought is that one of the things that goes wrong the most on a boat, and is the most difficult to repair, is the microprocessor board. If all the electronics for a lithium are external, instead of buried under layers of epoxy, then you’d have a more repairable battery system.

MG Energy is my preference. Top notch product, and the original suppliers of Victron's high end offering. And they are much more aggressive on pricing.

makobuilders said:

My thought is that one of the things that goes wrong the most on a boat, and is the most difficult to repair, is the microprocessor board. If all the electronics for a lithium are external, instead of buried under layers of epoxy, then you’d have a more repairable battery system.

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I have not looked at all the brands but Battle Born has a 10 year warranty with the first 8 years full replacement. So I would not be too concerned about the circuit board failure.

Comodave said:

I have not looked at all the brands but Battle Born has a 10 year warranty with the first 8 years full replacement. So I would not be too concerned about the circuit board failure.

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Talked to Battleborn- there have been some internal BMS failures, but nothing of rampant concern. In each case, the battery was warranted and life went on
.

I have the 2 from Costco and have 1 more on the way. It should be here tomorrow. They have a lifetime warranty so if there is a BMS failure they will replace it. I like the Lion lithiums since you can remove the battery terminals and you end up with a flat surface. I have some 3/8”x3/4” copper bars that I will drill and bolt to the top of the terminals so I won’t have cables between the batteries. I am going to put heat shrink on the copper bars between the terminals for insulation against a dropped tool. It should make a very neat install. I can’t install them until after I pull the starboard engine because the crane comes right down in front of the cabinet I am going to install them in. Have the battery tray made and painted. No need for liquid retention like a flooded battery. Waiting to haul the boat now to get started on all the work.

Gonna go with Battleborn- just gotta figure out the rest of the wiring, and confirm that I can eliminate 2 of the 3 8D batteries (1 per engine, plus 1 for the 12kW genset) and instead use the 1 8D to start all 3 engines and parallel the house bank if needed.

Time to start diagramming...

As a point for discussion, LFP batteries with internal BMS's do not communicate any information outside of their cases. Cell unbalance...nope. High cell temperature...nope. High discharge rate (out of spec)...nope. High charge voltage...nope. Low cell temperature...nope. You get the picture.

All of these conditions are handled internally and the operator does not know anything is amiss until the internal contactor opens and the load connected to the battery goes dead or in the case of charging the charging source takes a back EMF surge. Not the way I would design a critical system on my or a client's boat.

CharlieJ said:

As a point for discussion, LFP batteries with internal BMS's do not communicate any information outside of their cases. Cell unbalance...nope. High cell temperature...nope. High discharge rate (out of spec)...nope. High charge voltage...nope. Low cell temperature...nope. You get the picture.

All of these conditions are handled internally and the operator does not know anything is amiss until the internal contactor opens and the load connected to the battery goes dead or in the case of charging the charging source takes a back EMF surge. Not the way I would design a critical system on my or a client's boat.

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Point well taken. I've been also talking to many RV types that have had Battleborn for many years boondocking, and I find a high level of satisfaction with the product. As mentioned, I haven't found any major concerns with their internal BMS having premature or catastrophic failures.

At this point, I've not found any reason to scare me away.

Peter
To continue the discussion: I just finished installing BB batteries in a Sprinter RV.

I did this with my eyes wide open and made sure my client understood my concerns. After talking to several other techs in the RV industry I came to the conclusion that if there is a failure in an RV, the worst that could happen would be a very, very unlikely fire. If the contactor opens, and an RV's operating system goes off line, it is not a big deal unless there is a life safety implication.

On a boat, this is a totally different story that is strongly dependent on the operational environment. For example: at anchor in settled conditions probably not a big concern if the contactor opens on low voltage/low SOC, etc. Entering a pass and dependent on all of your sensors in foul wx could be a huge concern if the contactor opens without warning. Certainly there are work arounds with add on low voltage/high voltage alarms etc. I just can't subscribe to the concept.

Another issue to be aware of, if you want longevity, Lithium batteries do not like to be at 100% for any significant amount of time. If you leave your boat for several days/weeks, the battery should be at 50-60% charge. That is a very different usage model than most of us have. I have left my FLAs plugged in for weeks/months at 100%. FLAs enjoy that, LFPs not so much.

Pau Hana said:

Point well taken. I've been also talking to many RV types that have had Battleborn for many years boondocking, and I find a high level of satisfaction with the product. As mentioned, I haven't found any major concerns with their internal BMS having premature or catastrophic failures.

At this point, I've not found any reason to scare me away.

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How many of their batteries will you use in parallel for your house bank? Their spec sheet says 100A continuous, do they recommend using them when paralleled with start batteries for engine starting?

sbman said:

How many of their batteries will you use in parallel for your house bank? Their spec sheet says 100A continuous, do they recommend using them when paralleled with start batteries for engine starting?

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My plan is for 6 Lifepo4 batteries to replace the current bank of 6 Lifeline AGM 6V in the house bank. I figure I'll about double the housebank capacity, with the ability to add more later if desired.

To the best of my knowledge, they can be paralleled to the start bank in an emergency; the Precision Circuits LI-BIM 225 includes a way to do exactly that.

As my thruster bank is wholly separate from the start bank in the current configuration, I plan to add the ability to parallel them to the start back.

Pau Hana said:

My plan is for 6 Lifepo4 batteries to replace the current bank of 6 Lifeline AGM 6V in the house bank. I figure I'll about double the housebank capacity, with the ability to add more later if desired.

To the best of my knowledge, they can be paralleled to the start bank in an emergency; the Precision Circuits LI-BIM 225 includes a way to do exactly that.

As my thruster bank is wholly separate from the start bank in the current configuration, I plan to add the ability to parallel them to the start back.

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Peter,


Excellent choice....keep us posted on how well it works. I have 6 lifeline AGMs now and love them and really have all the power I need for an overnight, but not heavy cooking or AC. Not that the Lifepo4s would give me that, but they could give me several nights on the hook.



Also, leaning toward gas cooking.

Seevee said:

Peter,


Excellent choice....keep us posted on how well it works. I have 6 lifeline AGMs now and love them and really have all the power I need for an overnight, but not heavy cooking or AC. Not that the Lifepo4s would give me that, but they could give me several nights on the hook.



Also, leaning toward gas cooking.

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Go gas- first thing we did on our boat! It's nice to cook without the genset running...

I want to be able to extend our time out on the hook with diesel heat, fridge, some inverted loads, etc., for several days without worry.

I got my 3rd battery and today the heat shrink came. Today I finished the battery tray and the bus bars. The Lion Energy batteries have terminal posts that unscrew. They are an M6 thread. So I took the posts off and used a copper bar 3/8”x3/4” and ran them across the terminals. Drilled the copper bars for the M6 bolts and a positive connection on one end and a negative connection on the other end. Then I use adhesive shrink tube to cover the exposed areas of the bus bars. I used clear heat shrink to fashion some covers where the bus bars bolt to the batteries and where the Positive and negative cables will bolt to the bus bars. I made a plywood tray with 1 1/2”x 1 1/2” cleats to hold the batteries secure so they do not wiggle at all. Then an eye screw on each end and a S/S ratchet strap to hold the batteries down. With the bus bars bolted on the terminals on the batteries there isn’t any movement in the batteries, zero. I am pretty happy with the setup. I will put some 1 1/2” rigid insulation under the battery tray since it will be in a cabinet above the engine room. The Lithium batteries will shut off charging at 111 degrees so I want to keep them cool. I have a 50 mAmp fan that will install on the upper vent and blow warm air out of the cabinet and a low vent will let cool air in. I will just let the fan run during the summer when the boat is in the water and turn it off during the winter.

I just previewed the photos and they are loaded upside down. I edited them on my ipad so they were upside down and they still uploaded upside down on this post. Since I have already disassembled the batteries these photos are the best I can do. Sorry.

I just bought two 100ah battle born batteries and a sterling BB1260 dc to dc charger. Total cost delivered is $2093 with a veterans discount directly from Battleborn. I will add another battery later if all goes well.

Bud

Pau Hana said:

My plan is for 6 Lifepo4 batteries to replace the current bank of 6 Lifeline AGM 6V in the house bank. I figure I'll about double the housebank capacity, with the ability to add more later if desired.

To the best of my knowledge, they can be paralleled to the start bank in an emergency; the Precision Circuits LI-BIM 225 includes a way to do exactly that.

As my thruster bank is wholly separate from the start bank in the current configuration, I plan to add the ability to parallel them to the start back.

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I just ordered a 120 amp Balmar alternator kit. It comes with the 614 external regulator and 2 temperature sensors, battery and alternator. The list price is about $1200. I found it several places for about $1000. Defender had it for $879 but if you join Defender First for $50 then the cost was $817. So I saved more than the $50 on the one item and the membership is good for the next year. I was concerned about the BMS shutting off the batteries whether for temperature or because they are fully charged. I called Lion Energy asked them about it. They said I could use a DC to DC charger. So I called Balmar. They said that the lithium batteries would definitely shutoff and that it would definitely damage the alternator. They recommended an alternator protection device. It goes across the positive and negative terminals on the alternator. Simple solution that costs about $70. I ordered the Sterling one from marinehowto.com.

Sterling Power 12V or 24V - Alternator Protection Device

Comodave said:

I just ordered a 120 amp Balmar alternator kit. It comes with the 614 external regulator and 2 temperature sensors, battery and alternator. The list price is about $1200. I found it several places for about $1000. Defender had it for $879 but if you join Defender First for $50 then the cost was $817. So I saved more than the $50 on the one item and the membership is good for the next year. I was concerned about the BMS shutting off the batteries whether for temperature or because they are fully charged. I called Lion Energy asked them about it. They said I could use a DC to DC charger. So I called Balmar. They said that the lithium batteries would definitely shutoff and that it would definitely damage the alternator. They recommended an alternator protection device. It goes across the positive and negative terminals on the alternator. Simple solution that costs about $70. I ordered the Sterling one from marinehowto.com.

Sterling Power 12V or 24V - Alternator Protection Device

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The bms will shut off the battery because of over temp? How about the battery temp sensor from the Balmar regulator cant that be set up to a temp less than the BMS shutoff temp? Just wondering I could be missing something.

Bud

Bud said:

The bms will shut off the battery because of over temp? How about the battery temp sensor from the Balmar regulator cant that be set up to a temp less than the BMS shutoff temp? Just wondering I could be missing something.

Bud

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My batteries (Lion Energy) will shutoff at 111 degrees. Other brands may have a different shutoff temperature but I think that all the lithium batteries have a shutoff temperature. I am going to install them in a cabinet in the salon and put vents both high and low. I am going to insulate under the batteries to keep heat from the engine room from coming up into the cabinet. Also I will put a 50 mAmp fan exhausting hot air out the top vent. I am not sure if the temperature sensor for the batteries is adjustable or not. Balmar said that the 614 regulator will derate the alternator by 20% if you program it for lithium batteries. I was going to derate the alternator anyway so that is taken care of. They recommended the alternator protection device that will stop the alternator from being damaged when the BMS turns the batteries off. So that is a really simple fix. I had imagined a much more complicated fix.

I think insulating your battery compartment from the engine room heat is a good idea. Just keep in mind that the batteries themselves will generate little to no heat, assuming you are charging and discharging in the .5C and below range, and that unlikely to be exceeded in a house bank setup. Given the efficiency of LFP (95-98%), the don't heat up the way lead acid does. Ambient heat is what you need to keep them away from, and your insulation should do that nicely.

twistedtree said:

I think insulating your battery compartment from the engine room heat is a good idea. Just keep in mind that the batteries themselves will generate little to no heat, assuming you are charging and discharging in the .5C and below range, and that unlikely to be exceeded in a house bank setup. Given the efficiency of LFP (95-98%), the don't heat up the way lead acid does. Ambient heat is what you need to keep them away from, and your insulation should do that nicely.

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Yes, that is my plan along with active venting. Hopefully they will not get too hot.

Comodave said:

My batteries (Lion Energy) will shutoff at 111 degrees. Other brands may have a different shutoff temperature but I think that all the lithium batteries have a shutoff temperature. I am going to install them in a cabinet in the salon and put vents both high and low. I am going to insulate under the batteries to keep heat from the engine room from coming up into the cabinet. Also I will put a 50 mAmp fan exhausting hot air out the top vent. I am not sure if the temperature sensor for the batteries is adjustable or not. Balmar said that the 614 regulator will derate the alternator by 20% if you program it for lithium batteries. I was going to derate the alternator anyway so that is taken care of. They recommended the alternator protection device that will stop the alternator from being damaged when the BMS turns the batteries off. So that is a really simple fix. I had imagined a much more complicated fix.

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I understand now, the device across the altenator acts as a alternative load for the alternator when and if the battery bms shuts the battery off for full charge or temp.

Bud

Bud said:

I understand now, the device across the altenator acts as a alternative load for the alternator when and if the battery bms shuts the battery off for full charge or temp.

Bud

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Yes, that is my understanding. Marinehowto.com has them.

Comodave said:

Yes, that is my understanding. Marinehowto.com has them.

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I am starting out using a dc to dc charger goes between the start batteries and house lithiums so the lithiums could shut off for temp but the start batteries will still be a load for the alternator, so not a problem. Good to know though because I am sure my system will evolve.

Bud

Bud said:

I am starting out using a dc to dc charger goes between the start batteries and house lithiums so the lithiums could shut off for temp but the start batteries will still be a load for the alternator, so not a problem. Good to know though because I am sure my system will evolve.

Bud

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What do you expect the LFP batteries to shut off for temp? Will they be in the engine room exposed to engine heat?

Comodave said:

Yes, that is my plan along with active venting. Hopefully they will not get too hot.

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I think you may find that the active venting is not required, provided you keep engine room heat away from them. The batteries themselves won't warm up in any appreciable way.