Victron Smart BMS for Lithium Upgrade?

[shontm]

Has anyone considered using this Victron SmartBMS https://www.victronenergy.com/battery-management-systems/smart-bms-12-200 for a lithium upgrade instead of a DC to DC charger? You’d keep the ACR between starter and thruster batteries (both stay AGM) and isolate the lithium house batteries on the BMS. It seems like it would be a bit simpler and lets you use more amperage from alternator (but still limited) to charge your lithium bank instead of 30-50 amps typical for a DC to DC charger. I had a dockside conversation with an electrician who said this is what he has used for lithium upgrades on other boats.

 

[watson1987]

The purpose of the DC/DC charger is to provide the correct voltage to charge a lithium bank. I don't see this providing any up-voltage to levels required to charge and maintain a lithium battery bank properly.

It might be easier (to be honest, the diagram they show here looks equally complicated - https://www.victronenergy.com/upload/documents/Datasheet-Smart-BMS-12-200-EN.pdf) but I don't think it's the right solution. Also, does this only work with Victron batteries? Those are some of the most expensive available. And for the alternator input it is still limited to 100amps, so the 200amps aspect doesn't matter here (not that we have alternators that can supply that much in our boats anyways)

 

[shontm]

Thanks for the input. It does require the Victron batteries, so you're right that's an added expense -- although cheaper than they used to be. They recommend a charging voltage of 14.0-14.4 so I was assuming that the Volvo Penta D4 alternator wouldn't have trouble with that (I typically see low 14s on my AGMs today). But I'm feeling daunted by all the complexity of going to Lithium and wondering if I shouldn't just replace the existing AGMs and upgrade the solar panel to 400 watts with an MPPT charger. That may be the best way to maximize time on the hook while also allowing me to use max amperage from alternator for recharging in a couple hours between destinations.

Of course, that then begs the question of which AGMs? The cheaper ones it has today (which lasted only 4 years for me) or something higher quality with longer lifespan like Full River (5-7 years) -- but of course cost then gets closer to Lithium, which is why I was investigating that in the first place!

 

[watson1987]

You have to consider the price per usable Ah over the life of the battery, not just the initial upfront costs. Right now, most calculations I see have lithium coming out ahead when you think this way. Given AGMs might only have a few hundred cycles on them compared to thousands on a lithium bank.

I normally see a max high 13s on my D4 today with the Garmin MFD. I know there is some loss between the house bank and the front of the boat where the battery is, but I didn't think it was that high. Where do you see low 14s? Is that from the battery meter gauge on the panel? I can't say I've ever looked at that while running, because, well I'm running the boat 🙂. Voltage aside, the charge profile (voltage changes through bulk, absorption, and float modes) are important as well to make sure you get a full charge, and the alternator is typically not congruent to lithium.

If you just have stock loads on your boat 400W of solar is probably enough to run 'forever' on the hook in weather that you'd want to be out on the hook in. That's been my experience, however, once I turn on Starlink (or my hot water tank), my 385W of solar isn't quite enough to run that all day without slowly dropping 10-20% a day on my system. For me, stock loads include an extra ARB fridge in the rear cockpit, both normal fridges on, AIS TX, and WiFi Router+Cellular Hot Spot system.

 

[shontm]

Thanks again. I have a digital voltage gauge on a USB charger in the 12-volt outlet next to the helm. I've noticed the voltage drops when I have something charging and so I wonder if the Garmin is similarly reading a lower voltage because of the load it draws.

Regardless, I'm coming around to the idea of a DC-DC charger, especially now that Victron makes a 50amp one. When you figure that AGMs must be fully charged and taper quite a bit in absorb stage whereas lithium is happy in partial charge, the slower charge rate might be just fine -- especially when you add a larger solar panel. Looking at the wiring diagram for the R-29, it seems like it could be as simple as (1) replace the Engine-House ACR with the 50 amp DC-DC charger and (2) add a new shore power charger for the house/thruster batteries (the house would use my existing Kisae 2000 watt / 55amp inverter/charger, which has adjustable charging voltages for lithium). Since I'd be going from 4 house batteries to 1 lithium, I'd need to (3) install positive and negative busbars to tidy up everything connected to the 4 batteries today, which would also make it easier to install (4) a shunt for a Victron battery meter to give me more accurate SOC readings. Finally, I'd (5) replace the PWM solar charge controller with a 100/30 Victron MPPT to support a bigger panel and connect that just to the lithium house (and could reuse the unused solar charger wiring to starter battery to run in parallel to house to handle the higher amperage). Am I missing anything important?

Also, has anyone with an inboard diesel had problems with the port lazarette getting too hot for lithium? There is a wall with some minimal insulation separating it.

Finally, any recommendations on batteries? I'd want a built-in BMS with all the usual protections (overcharge, over discharge, short circuit, overcurrent, high & low temp cutoffs). Ideally, it would have a SOC display and the ability to set max charge to 60-80% for when it's sitting for winter months unused (although I haven't really seen the latter -- perhaps I could do some sort of relay tied to the Victron battery monitor?).

 

[watson1987]

I've done basically everything you've described with my lithium setup. The big difference is that I stuck with 4 Group 31 batteries. You might want to consider going with 2 smaller batteries instead of a large one, to remove a single point of failure in the system.

Are you sure your Kisae supports Lithium? Mine didn't, but mine was from a 2018 boat, I have a Victron Inverter/Charger now, which has a trickle charging output that I use for the Engine/Thruster, which means that I don't need to add a separate charger. However, another option is to continue to use your Kisae as a 12V source, and have it feed into your DC/DC chargers just like your alternator does. The downside of this is that you run into the same problem where you won't be able to charge at full speed because your Kisae is likely going to go into float/absorption quickly when it sees your charged Engine/Start.

I recently added a Wifi temp gauge in my engine bay and have only noticed the ambient temperature rise of 10-20*F. Maybe I'll dry to move it around to see if there are any hot spots, right now I have it mounted at the back of the engine compartment about 1 foot from the engine.

 

[shontm]

What brand did you go with for your Group 31s? I have a new Kisae because the 3-year-old one crapped out and they replaced at a discount. As a charger-inverter, it has a single pair of DC wires that connect directly to house batteries for both inverting and charging and so I don't think I could run through DC-to-DC charger (plus that has engine shutdown detection so it won't charge when alternator isn't running). I'll probably just go with a dedicated 25amp Victron charger dedicated to starter/thruster -- pricy but nice to monitor on bluetooth with all the other Victron gear I plan to buy. https://www.victronenergy.com/chargers/blue-smart-ip67-charger-waterproof

 

[watson1987]

LiTime - https://www.litime.com/products/litime-12v-100ah-lithium-lifepo4-battery

If I did it again I'd go with 2 instead of 4, but the sizes that were offered back in 2021 didn't work out. For the same volume of space, you should get more total capacity with 2 instead of 4.

Make sure your Kisea has a temperature cut-off for Lithium to prevent charging under 0*C

And you're correct about the Inverter/Charger. I forgot when I temporarily had this as my setup before my Kisea also crapped out too 🙂 I also changed the on/off rotary switch coming from the inverter/charger to an ON/OFF/ON, so that in the second ON position it was behind the DC/DC chargers to draw off the batteries directly for inverting. Going with a separate charger from the start is the smart move.

 

[Submariner]

Make sure your Kisea has a temperature cut-off for Lithium to prevent charging under 0*C

The Lithionics 320ah LFP battery I installed has an internal thermal blanket. The BMS keeps track of the temperature. When it gets below 40 degrees it powers on the thermal blanket to keep the cells above freezing. The data sheet says I can use the battery down to a -4 degrees Fahrenheit, discharge and charging.

I know the Dakota G31 320ah dual-purpose battery also supports cold weather usage.

From Dakota's website.
" -20°F min, +150°F max optimal operating temps (battery performs well down to -20°F). Internal even-heat technology allows for charging below 32°F. BMS high temp cut off at 167°F / 75°C.."

If you're a cold weather boater like I am, look into this before purchasing batteries as most LFP batteries don't have thermal blankets.

 

[Submariner]

Finally, any recommendations on batteries? I'd want a built-in BMS with all the usual protections (overcharge, over discharge, short circuit, overcurrent, high & low temp cutoffs). Ideally, it would have a SOC display and the ability to set max charge to 60-80% for when it's sitting for winter months unused (although I haven't really seen the latter -- perhaps I could do some sort of relay tied to the Victron battery monitor?).

For offseason storage, I run my LFP house battery down below 90% SOC. I have a 250amp breaker, which could be a disconnect switch in front of a T-class fuse. I flip the breaker which completely isolates the LFP from the boat. Then I parallel the engine and house which puts all 12volt loads on the boat off the engine battery, which is fed by a 20amp Kisae battery charger. I also then disable my Victron solar controller (set it Charger Disabled) as it's configured for LFP and not AGM.

Lithionics's says ideally, it should be 50% SOC, but as long as it's >20% and less than 95% it's plenty good enough.
Also note, the 250amp breaker I have came with the 320ah Battery and is required as part of the UL rating. The internal BMS has 2 wires that connect to that external breaker which lets the BMS trip the external breaker providing for double disconnect protection should it be necessary. The breaker also has an AIC rating over 100,000 amps.

For a battery recommendation on LFP, I'd say Lithionics for sure, or Dakota.
I've got 3 seasons on my Lithionics battery now, and I use the heck out of it. We run the inverter daily on the boat. 25% SOC, turn on the espresso machine and make latte's and pull 100 amps at 12volts, weigh the anchor, and head home without issues. The BMS on the Lithionics battery I access via bluetooth, which also gives me a second battery monitor to compare against the Victron BMV712.

LFP conversion on an NW edition R27-OB

House Battery-Lithium | LetsGoChannelSurfing

www.letsgochannelsurfing.com

 

[shontm]

Thanks, Martin. I have a few more questions after reading your posts and a few videos.

1. I like having the emergency parallel switch in the event I ever had a dead starter battery and needed to start off the house. (I have an R29 with the Volvo D4.). Is that a reason to get the dual use battery? Or could I still parallel a traditional lifepo4 to start in an emergency?

2. As noted above, I’m contemplating a second AC battery charger for the starter/thruster (and would use the kisae inverter/charger for the lithium house). But after reading how the Victron dc-dc charger uses a voltage reading to detect whether to charge, I think it wont be able to distinguish between the alternator (when I want it on) and the ac charger (when I want it off). How do you keep the dc-dc from charging when on shore power?

3. Why didn’t you keep the ACR from engine to thruster on your setup and replace with another dc-dc given both batteries are AGM?

 

[shontm]

Related to 1. Would I blow my t-class fuse trying to start off the house and/or have to install an oversized one which kind of defeats the purpose? Again, this is only for an emergency - not planning to regularly start in emergency parallel.

 

[shontm]

Sorry for the replies to myself, but I keep thinking about this. 🙂

On 2, why not install the dc-to-dc charger on the other side of the engine switch? I keep that off when on shore power and that would ensure the dc-to-dc charger isn't trying to charge the house batteries at the same time as the ac chargers. But when running, it would be connected and could do its job.

 

[Submariner]

Thanks, Martin. I have a few more questions after reading your posts and a few videos.

1. I like having the emergency parallel switch in the event I ever had a dead starter battery and needed to start off the house. (I have an R29 with the Volvo D4.). Is that a reason to get the dual use battery? Or could I still parallel a traditional lifepo4 to start in an emergency?

2. As noted above, I’m contemplating a second AC battery charger for the starter/thruster (and would use the kisae inverter/charger for the lithium house). But after reading how the Victron dc-dc charger uses a voltage reading to detect whether to charge, I think it wont be able to distinguish between the alternator (when I want it on) and the ac charger (when I want it off). How do you keep the dc-dc from charging when on shore power?

3. Why didn’t you keep the ACR from engine to thruster on your setup and replace with another dc-dc given both batteries are AGM?

1) This is where shopping for a LFP battery one should look beyond the price. Some LFP batteries are only rated to 100 amps of continuous load, and aren't recommended to ever be used for emergency engine starting. The Lithionics battery I have supports 150amps continuous to a max of 230 amps, and can be used to emergency start my engine. (1200 amps for 1 second). The answer to your question is dependent on the LFP battery you choose. The 320ah Li3 battery I selected was about 1/3 more expensive than similar in a Dakota battery at the time. I'm also a cold weather boater so being able to charge LFP below freezing temperatures was important to me. The Li3 battery has a thermal blanket allowing it to operate normally down to -4 degrees F. A lot of LFP batteries don't have this feature. Names like "dual-purpose" to me are marketing, just my opinion. I look at the spec sheets of the LFP to determine if the battery will do what I need it to. Lithionics doesn't refer to my Li3 battery as anything other than a 320ah LFP battery.

2) It's not uncommon for LFP installs to have 2 battery chargers. The Orion-TR's have a config for detecting engine charging. It is possible for the 20amp battery charger to look like engine charging and thus, I get 20amps from the engine battery charger to house via the Orion-TR, plus another 60 amps from the dedicated house battery charger. I like that as I can sometimes get almost 80 amps of charging. Or, using the Victron app, I can connect to the Orion-TR and disable house charging via the app.

I kept the factory installed 20 amp battery charger, disconnected it from the house, renamed it "Engine/Thruster charger". Then I installed a second dedicated 60 amp Kisae battery charger dedicated to the LFP house battery bank.

Ultimately, I'd like to run an ignition wire back to the cockpit and wire the Orion-TR's such that the ignition wire will turn them on and off with the engine. But with the Orion-TR's auto-sensing engine charging voltage, it's not really necessary.

An advantage of LFP is quick charging. The 320ah Li3 battery supports charging up to 200 amps. There's just no way I can come close to leveraging this feature even if I ran both battery chargers, got 400 watts of sunshine, and idled the engine at the dock with a high RPM. Theoretically, I can get to 120 amps for charging. Realistically, I can get to about 90amps.

3) I love this question. 🙂 Why did I not keep the ACR for the engine to thruster, and instead, installed a second Orion-TR DC to DC charger for the Thruster?
I like to cruise off-grid and I want redundancy if I can get it. If my Engine to House Orion-TR were to fail, with a flat head screwdriver I can move one 6awg wire from the Engine to House Orion-TR over to the Engine to Thruster Orion-TR. I left myself enough slack in the wire for this. That would eliminate engine charging of my thruster bank and would restore my engine to house charging. I can live without my thruster battery being charged. I really don't want to go without engine charging. The 15 amps of engine charging that I get may not seem like a lot to rate such importance. But consider our SE Alaska trip which had an enormous amount of off-grid cruising. We would run for 6-8 hours a day. That's about 90-120 amp-hours a day from engine charging and we usually consume about 120ah daily. That makes solar a bonus, which gets me enough left over for hot water.

However...

I can charge the thruster battery with the 20 amp battery charger off the inverter. I would disable charging via the Victron app for the Engine to House Orion-TR, and let the 20 amp battery charger charge my thruster bank off the LFP house bank. It's unlikely I ever would since the bow thruster is not mission critical, but Engine to House charging is. I really like the two battery charger setup as I it gives me flexibility.

These are all fantastic questions and a great discussion. I filmed a video tech-talk all about my LFP setup now that I've had it for 3 seasons. How's it working? Am I happy with it? How is my setup different from the factory setup? The video is uploaded to YouTube and scheduled to be published this coming Tuesday

 

[Submariner]

I’m contemplating a second AC battery charger for the starter/thruster (and would use the kisae inverter/charger for the lithium house).

By the way, I do have a design for an RT29 diesel inboard with a 320ah (or 630ah) Lithionics battery already drawn up. It requires upgrading the factory Inverter/Charger (that doesn't support LFP) to a Kisae BIC 122080 Inverter/Charger that does. Then adding a second 40 amp battery charger dedicated to engine and thruster battery banks, which is necessary to be able to charge those banks on shorepower.

For the DC to DC chargers, I drew out a couple options. A 50 amp Kisae DMT1250 or a pair of Orion-TR 30amp DC to DC chargers in parallel. The diesel inboards alternators are usually about 115amp. 50-60 amps via a DC to DC converter is about 1/2 of 115 amps to keep the alternator from overheating.

The design would also work with other brands of LFP, but the t-class fuse and such would need to be sized to the LFP battery bank.

I also have one other design I did for an RT29 inboard diesel where I replaced the inverter/charger with a dedicated inverter, and a dedicated battery charger. This design only requires a single battery charger and has no inverter/charger.

I haven't published these publicly.

 

[shontm]

The price difference on these batteries is pretty remarkable. The LiTime 280AH is $618. The Dakota 320AH is $2400. The Lithionics 320AH is $4500. As you note, the latter two come with heaters but extended below freezing in PNW is rare. I do go out in winter but have never done it during one of our extended freezes, and even if I did, between warmth from the ocean and engine, I'd wager the port lazarette would quickly get above freezing if it weren't there already. As for using as a backup to start, the Dakota gets you 2 seconds at 1000amps whereas both LiTime and Lithionics are 1 sec (the latter at 1200amps). So I think it really comes down to US-made vs. China-made and longer warranty and whether those are worth 3-7x the cost!

From what I can tell, the Orion engine detection is purely based on voltage and couldn't distinguish bulk/absorption voltages from the alternator but you could configure so it shuts down during float. I don't like the idea of a 50amp DC charger running when I have only a 25amp charger going into the engine battery so I think I would isolate the DC charger on the other side of the engine battery switch, which I keep off at shore power.

Next step for me is to spend some time on the boat to see how all of this stuff would fit and then make the call on whether it's worth the trouble or I should just go with a bigger solar panel and MPPT charger.

I'll keep an eye out for your new video -- and thanks again for all the advice.

 

[Submariner]

Next step for me is to spend some time on the boat to see how all of this stuff would fit and then make the call on whether it's worth the trouble or I should just go with a bigger solar panel and MPPT charger.

I'll keep an eye out for your new video -- and thanks again for all the advice.

You're welcome.

I don't recommend converting to LFP unless solar has already been upgraded to something in the 300-400watt range. With solar sized for your needs you'll run during the day off sunshine and your battery bank will get you through the night. It's easier and less expensive than a LFP conversion.

Solar Upgrades

Solar Panels | LetsGoChannelSurfing

www.letsgochannelsurfing.com

 

[shontm]

I made the lithium upgrade this weekend and am quite pleased so far. My current AGMs were shot (1/4 of their rated capacity) and so I faced the choice of replacing with new AGMs (4x$250 each for Universal or 4x$450 each for better quality Fullriver) or making the lithium plunge now. Everything fit neatly in my R-29, although crawling in that port hold to access the batteries is a PIA and reason enough to go with lithium so you don't have to do it ever 3-5 years! Here's what I did:

Battery: Upon advice of an off-grid electrician I know, I went with Epoch Batteries -- specifically their new 300ah Dual Purpose model, which has the cranking amps to start my engine in a pinch (using the existing parallel switch), built-in heater for cold weather, and built-in bluetooth that lets me directly monitor BMS from my phone (plus Victron compatible comms, although I'm not using that now): https://www.epochbatteries.com/prod...nking-deep-cycle-lithium-battery-dual-purpose. Price was $1500 less 10% with a Labor Day sale. It's considerably more expensive than LiTime equivalent ($659 at https://a.co/d/2tNjifU) but still much cheaper than some of the high-end options. Will Prowse does a tear down of similar models from both manufacturers and the Epoch internals look well built:

. I replaced the engine battery with a Full Throttle AGM: https://fullriverbattery.com/batteries/part-ft1100-31/

Alternator Charging: I went with the Victron Orion 50 amp dc charger, which is less than half the amps from my Volvo Penta D320: https://www.victronenergy.com/dc-dc-converters/orion-xs-12-12-50a-dc-dc-battery-charger. To avoid the problem discussed above of having its engine shutdown detection (which is based purely on voltage) tricked by shore power charging of the engine battery, I installed an AC relay to its remote switch terminals (normally closed and then opens when AC shore power detected). It works like a charm. (My idea of wiring it to the other side of the engine battery switch didn't work because there's no access to that.) I installed two fuse blocks in the same location as the prior ACR I removed (which let me reuse existing wiring) and mounted the Victron equipment to the left of the existing gear on a thin aluminum plate so it's not directly against plywood.

Solar Charging: Victron SmartSolar MPPT 100/30: SmartSolar MPPT 100/30 & 100/50 - Victron Energy, which I wired to new battery with 6 AWG to handle 30 amps. I bought a 400 watt panel from https://www.bougerv.com/products/400w-10bb-mono-bifaical-solar-panel but haven't installed yet as it's a beast and I'll need a second hand to get it up there.

Shore Charging: My existing Kisae inverter/charger supports lithium profiles and so I'm reusing that to charge the new lithium. I installed a Victron 15 amp AC charger IP65 for the engine/thruster batteries. I reused the existing thruster ACR but rewired to engine battery. I added a new breaker in the AC panel for the charger, wired so (like the water heater on my boat) it will not run off the inverter.

All the Victron equipment is accessible via Bluetooth as is the new Epoch battery, which provides lots of ways to monitor and configure.

I took the boat out on Sunday and everything seems to be working great. Testing with the microwave on the inverter (drawing over 100 amps), the battery reported it could go for over 2.5 hours at that rate!

 

[croakz]

Nice job, @shontm. How many batteries did you go with? Did you consider the bigger 460ah, or was starter battery capabilities a priority for you?

​

 

[shontm]

Nice job, @shontm. How many batteries did you go with? Did you consider the bigger 460ah, or was starter battery capabilities a priority for you?

​

I did just one 300ah battery, which increases my usable capacity from the 200ah with new AGMs to 270ah (wouldn't want to go below 10%). I have the NW edition (no AC, webasto diesel heat, and hot water from diesel inboard). I figured that, coupled with the new 400 watt panel, will give me plenty for a few nights on the hook at one place even in cloudy weather. The dual purpose was not essential as in practice, I imagine a weak starter battery paralleled to ordinary lithium would work to start the engine. But the design of the dual purpose is a little more robust and takes you from 4000 to 6000 cycles, and since I didn't need 460ah, and I like the idea I could start the engine even if the starter battery was completely shot, I went with that.