In the last chapter in this Online Book we looked at splitters and relays to combine battery banks for charging and concluded that while usable, both had a fundamental problem: engine battery overcharge.
Now let’s move on to a solution that fixes that, albeit at a price in both money and complexity.
There are two variants to think about:
- DC/DC chargers, like the one from Victron I just installed on our new-to-us J/109.
- Alternator-to-battery chargers from Sterling Power.
Have you looked the Battery Bank Manager Plus for Emily and Clarks Adventure? This seems like an interesting device for mixing lead and lithium batteries. Would be interested to here thoughts on this device.
Hi Foster,
Yes, I’m aware of that gadget, but not a fan. I have watched his videos. Bottom line, mixing lead acid and lithium in the same bank is both dangerous, and in my view, pointless. The whole point of lithium is higher energy density for a given weight and volume, so my thinking is either do it right, or stick with lead acid.
In my view this guy is a better YouTube presenter than he is battery engineer. In fact this show cases the danger of YouTube: a good presenter, which he is, can make a bad idea look like a good one. One of the danger signals of this kind of thing is the presenter who claims to have it all figured out and know better than the companies that build batteries. Also note that he has changed his tune since the first videos—at least he is learning.
We also only need to look at his boat to see he is much more interested in making YouTube videos than actually going anywhere, particularly offshore, where his ideas would be really tested.
If we want a fully integrated system from real engineers we need to turn to Victron, Mastervolt, or Lithionics or some others, all sell full systems that do what his will, and far more. And probably the best, or at least one of the best, places to buy it is from Ocean Planet Energy.
And if we want a lead acid backup, and I think we should, serial, not parallel, is, in my view, the right and safer way to do it: https://www.morganscloud.com/2022/07/03/building-a-seamanlike-lithium-battery-system/
Sorry to be so harsh, but that kind of thing gives me gas.
Not harsh at all to me (I have dog in the fight either way) Thanks for taking the time to answer and generally I agree with what you are saying. Say their device a while back and never heard it mentioned anywhere. Wanted to hear some experts advice/opinion. thx
Hi Foster,
Glad it was useful. One thing I will give them is that I do think their idea of a battery current measuring solar regulator is a good one. That said, I think Victron’s kit can do that when all connected together with their monitoring back bone, but I have not actualy dug into that.
Hi John,
Victron’s solar charge controllers can and do use current data from BMV monitors when networked over bluetooth (no monitoring device necessary). The tail current needs to be adjusted in battery settings in expert mode. Otherwise they default to 1A.
I wish Victron made an alternator regulator. They have all the pieces to make a competitor product for Wakespeed WS500 and probably with even better user experience.
Hi Alex,
That was my guess, but thanks for the confirmation, saves me a bunch of research. The good news on the Wakespeed is that Al tells me they have worked very closely with Victron on integration so I’m not sure if a Victron product would be any better. I’m also on the the Wakespeed Beta test list and I see a lot of updates coming through adding functionality to work ever more closely with Victron. That said, I do wish that Victron had bought Wakespeed, rather than Battle Born…or maybe not, since that might have resulted in Victron making the WS 500 more proprietary…hum, don’t know.
For an all lead acid system, with a modern sealed starter battery how big an issue is the overcharging of the start battery that you’ll get with a charging relay system? Is this actually likely to shorten the start battery life enough to justify the additional cost and complexity of a battery to battery charger? I guess that’s probably one of the many unanswerable “it depends” type questions.
Hi. John answered this pretty good in the relevant chapter, but as you say, it depends. On my boat, I set everything for the house bank, and just let the starter battery suffer. The voltages are not very different for the two batteries, and I don’t motor much, so I can’t imagine that it will have a huge impact, at least not until I am upgrading the whole system and implement a DC-DC charger.
Hi Bruce,
I covered that in the last chapter, but the short answer is if you have a charging relay and all is working fine, it’s probably not broken, that said, there are other factors, again covered in the last chapter.
As has been said – probably not a problem. I have run our boat this way (with a simple Cytrix charge relay to tie in the engine start batt when voltage is over 13V) for 10 years with zero issues, on the same batteries (all FLA), same alternator and no changes to the system over that period. Is there some reduction in reserve capacity of the starter battery? probably – it’s 10 years old! but it has not seemed to matter to me – and I (regrettably) have done a fair amount of motoring on our last 3 summers excursions to Newfoundland, Bermuda and Sable Island – probably in the region of 550-600 hours (I could find out exactly – but i’m not on the boat right now…).
Hi John,
I have a separate alternators for house bank and engine start batteries 24V. And for that matter generator alternator. For gen start battery 12v. The big main alternator with WS500 and all the bells and whistles. Do to recommend regulators for the start batteries and gen. I thought the internal regulator would take care of overcharge but not sure. Start batteries 2 Northstar AGM31’s and 1 12V for gen. By the By; 10 FireFly carbon Foam and so far no quality issues as of yet.
Hi James,
You should be fine with he standard alternators and internal regulators on the engine and generator start, as long as you are not using the same alternators for house charging.
They dedicated to the start batteries only.
Hi James,
I understand that, just making things clear to others.
When I purchased the boat it appeared to be a factory setup (Swan) which at the time I thought was brilliant. Also I used the existing Victron Skylla 24V 80amp charger for the engine start batteries only; Big Quattro inverter/charger for mains, probably complicated overkill. I would love to have you out for an audit on all the refit work done, mostly inspired by what you have written about.
Hi James,
Be careful what you wish for, I could cost you a fortune! 🙂
Hi John
I’m using the Victron DC/DC charger. Stock Yanmar alternator (80amp) Since the Victron charger max’s out at 30amp I should be well within your recommended 75% max of alternator’s output. I’ve been keeping the maximum charge time at 3 hours. Not sure if this is correct. I would like to be able to charge longer but I don’t want to toast my stock alternator. Overall, love the system and the adjustment available. Just need to do some finally tweaking.
Hi Mark,
I’m guessing that your usage is comparatively low in which case that will be fine, although my guess would be. that the alternator will still only go less than 500 hours at best, before needing replacement. The bottom line is that stock engine alternators are not designed for continues duty and so have short lives when asked to do that. More here: https://www.morganscloud.com/2013/11/06/10-tips-to-buy-and-install-a-liveaboards-alternator/
Hi John
Thanks for the great articles on battery systems.
I suggest to finish it off it requires one or two proper electrical drawings detailing all you have recommended? Cheers Ray
Hi Raymond,
I agree that at least block diagrams are required, although maybe not detailed schematics. I have already started that process on recent chapters and will do more once I have taken a break from electrical stuff.
Hi John
The Victron Orion can have higher output than 30 amps. It is rated at 360 watts (30 amps) at 40 C but 430 watts at 25 C. I know of at least one person who has installed a fan below it for cooling and achieves 35 amps continuous.
Hi Brian,
Sure, that’s true, but I would not stress the Orion in that way. Most all gear lasts way longer if used a bit under it’s rated capacity. And anyway, if we do as I believe best practice and connect all charging sources to the house bank, there is no need to push DC/DC chargers like that: https://www.morganscloud.com/2022/09/04/battery-bank-separation-and-cross-charging-best-practices/
Hi Mal,
No, I have not looked into them and probably won’t given that I believe the right way to set up a system is with all charging sources feeding the house bank, and therefore a DC/DC charger at 30 Amps is plenty to keep an engine start bank happy.
Also, I was always under the impression that transformers only work on AC current, not DC?
A planar transformer is just a transformer whose windings are made of thin copper sheets, or etched on a PCB, instead of being wire-wound. They’re a common component of DC-DC converters. (All DC-DC converters work by inverting DC to AC at high frequency, usually tens of kilohertz, changing its voltage with a transformer, and then rectifying that output back to DC.)
There’s no fundamental limit to how big you can make a DC-DC converter. The ones sold for boats are only a couple hundred watts because that’s all we ever need in our applications. But I can go buy a 4 kW one off the shelf today from Bel Power or Vicor, and semi-custom DC-DC converters rated at over 1 megawatt have existed since the early 1990s.
I don’t know which specific products you are referring to, but APS & Safiery both sell a variety of power electronics parts that are all based on standard switching-mode and DC-DC conversion topologies.
Hi Matt,
Thanks for the fill on that.
I have tried looking at the Victron demo app and the webpage, but these DC-DC chargers don’t seem to have a “storage” setting, only bulk, absorption and float. Is it correct that they will leave the starter battery on float voltage “permanently” then until you pull the fuse to give it a rest? That seems to me will fry the AGM starter battery eventually, unless you put the float voltage a fair bit lower?
Arne.
Hi Arne,
That’s true, but not a problem. The answer is simply to set the charger so it goes to sleep when the input voltage is lower than say 14.2 volts. That way it only wakes up when the engine is running or there is another charging source active and the house battery is still in acceptance. The rest of the time it won’t be charging the engine start bank at all.
I have been using an Enerdrive DC2DC+ for a few years now, Input is alternator and separate mppt solar, automatically switches between the 2. Output is up to 50 Amps. Charge parameters are adjustable.
Hi Paul,
Looks like an interesting alternative. However, as a general rule for an offshore boat I prefer separate devices for separate functions, also for a live aboard boat just 50 amps from the alternator would be rather limiting.
All that said, it looks like a nice easy to install option for less demanding usage profiles.
I am looking into using a 24v alternator to charge a large 24v house bank from the engine. I had looked into using a B2B 12 to 24v charger but the currents are quite low for a large bank. I see the new (available 1Q 2023) Sterling B2B chargers have been completely redesigned and one model can support 12 to 24v at 120 amp input amps:
https://sterling-power.com/collections/battery-to-battery-chargers
https://www.youtube.com/watch?v=gBiaiJRSqKc
This is much higher than a Victron 30 amp Orion (Orion more of a choke point unless you parallel a few of them). Do you see any downside to using such a higher capacity B2B device instead of my replacing the 12v stock alternator with a 24v one, or adding a second alternator that is 24v?
I don’t think your criticism of the Sterling unit is fair – because you are applying different standards when commenting on this compared to other bits of kit. And I think one your main criticisms is wrong as a point of fact.
The criticisms about the alternator requirements make no sense to me because *whatever* approach you take to achieve high charge rates will involve replacing the alternator. Anything over maybe 120ah and you will need to replace the pulley as well.
So this is not a disadvantage of the sterling kit – it is just an underlying fact that achieving a high charge rate will need a high output alternator. It is a ‘whole category’ issue that applies to every alternative approach.
Indeed your own recomended approach is “good big continuous-duty alternator, external regulator, and DC/DC charger.”
And I think using terms like ‘magic’ to refer to one bit of kit – but not your favoured approach – runs counter to your generally high standards of objectivity!
The sterling unit is no more ‘magic’ than all those blue boxes you recomend and *certainly* no more so than the highly sophisticated Wakespeed.
Finally, you say “ If the thing dies there is no way to use the engine to charge any of the batteries on the boat without replacing it.”
This is simply NOT TRUE – because it requires no modification of the alternator, if the sterling unit fails you can simply failsafe back to the (be it inneficient) factory default.
I am not arguing that your own recomendation is wrong, but that the dismissal of an alternative is using arguments that do not really stand up.
Sorry that seems harsh – maybe you have answers on these points!
Hi Richard,
You are certainly entitled to your opinion on this, and have argued it well, but on the other hand I’m comfortable with my position on the Sterling solution, so I’m not going to get into debate on this except to say that I don’t think falling back on the internal regulator is a viable backup solution, at least for an offshore live aboard cruising boat.
I guess the obvious question is what happens if your wakespeed fails?
My approach is two Sterling B2B chargers. If one fails I can switch to the other. If both fail at least the alternator is providing charge and I am not entirely stuck.
My most likely point of failure is if the alternator itself crashes out – and I very much have in mind a wise man who recomended carrying a spare alternator!
Hi Richard,
I think we are at the point on this where agreeing to disagree is the best way forward.
In addition to my comment about the Sterling Alternator to Battery Charger – I think there is another solution to the problems you describe that is – for *some* people at least – that better than either of the options you describe here!
That is, the Sterling Battery to Battery Charger. This offers a simpler than your recomended approach – and I think is more fail safe. It is not the same as their alternator to battery charger but has some similarities.
You have a normal configuration of vanilla high output alternator with factory controller – wired to charge the engine starter battery. So *no* changes to alternator wiring at all. If anything later in this system fails, engine starter charges as normal and the alternator is not left in suicidal open circuit.
Then, you simply wire a B2B between the starter battery and LifePo4 or LA cabin battery and select the chemistry on the B2B settings.
Thats it. You are done. You now have an optimised multi stage charge of your cabin – with your starter batter also getting charged.
So you have gone from two bits of magic (expensive alternator controler and DC – DC charger) to one, that does both of these tasks.
As I say, if the B2B fails, the normal alternator controller takes over so you have starter charge and thus options.
The only problem I have identified is that it is possible for the B2B to drive the alternator too hard and overheat it, but that is easy to configure out of the system.
I have a 120ah alternator and have a 60ah B2B so it drives the alternator at 50% reliably and without overheating.
And since I got this so cheap (far less than half of the cost of a wakespeed plus victron dc->dc) – I got two of them. Rather than having one in the locker as fallback, I have wired in both of them but one has an isolation swich which takes it out of service.
If my B2B fails, I can flip a switch and the fallback comes into play. I also have the option (tested, but not used in anger) to turn on both B2B at the same time, pushing the alternator to work at full capacity – though shortening its life.
I like this system on KISS principles – and I like it that it provides a robust seperation between the alternator and the LifePo4 bank, reducing chances of voltage spikes wrecking the BMS or battery.
Oh and in the event the BMS shuts down, the B2B shuts down as well – but (presumably by magic!) manages to settle the alternator voltage without frying anything. The alternator settles at the normal float voltage for the starter battery.
But there might be something I have missed and really am open to feedback!
>> it’s the only option for systems with, for example, 24-volt house and 12-volt start, as is becoming more common.<<
There is a sterling B2B that has that one covered as well
https://sterling-power.com/collections/battery-to-battery-chargers/products/12v-to-24v-120a-input-60a-output-battery-to-battery-charger-w-reverse-charging-feature
Hi Richard,
One can do that, and, as you say, it might be the best bet for some usage profiles. Still, as a general rule I think that connecting all charge sources to the house battery is a better and more elegant solution. I have made my reasons clear over some five chapters, so I’m not going to argue it again here.
As to damage to the alternator, that can be managed in better ways, in my view, as I have already covered.
Bottom line on all of this for me is that I believe it is best for live aboard cruising boats if the alternator charging solution can supply at least 150 amps at ~14 volts to the house battery and for many situations 200 amps at 14 volts is better, and that’s a driver of all of my recommendations—based on living aboard and ocean voyaging for 30 years.
https://www.morganscloud.com/2013/11/06/10-tips-to-buy-and-install-a-liveaboards-alternator/
Clearly you are happy with less than half that, so you will have a different view on all of this and that’s fine.
>>if the alternator charging solution can supply at least 150 amps at ~14 volts to the house battery and for many situations 200 amps at 14 volts<<
The approach I use would scale to this, but obviously I can’t get 150 amps out of my 120 amp alternator!
My approach can get 120amps out of a 120 amp alternator at the flick of a switch – but I choose to run it cool most of the time.
But the same approach could get ~ 200amps out of a 200 amp alternator.
That is just a question of scale – not the underlying technology choice.
I am using lithium house and flooded cell for start. Charging: 120 amp alternator with brush box and Balmar regulator charging the start battery and Victron Dc to DC 30 amp charging the house bank. Works great. I know I am not taking advantage of the alternator but my intentions are to add more DC to DC charging to make 90 amps output. Your thoughts?
Hi Dan,
My thoughts remain he same that it’s generally better to have all charging sources connected to the house batteries, so as to take full advantage of the alternator. To me even 90 amps is not enough for most offshore live-aboard boats.
I have a 200Ah lithium house battery and 80Ah lead acid starter battery. The starter battery hangs directly on my stock Yanmar alternator while the house battery gets charged via a Redarc BCDC1225D charger from the alternator or solar. House and starter circuits are isolated by the Redarc. Since my boat lives on a mooring and solar / alternator are my only charging sources, I needed to figure out a way to maintain my starter battery. I installed a Victron DC/DC charger that uses the house bank to charge the starter battery. I use a relay that switches off the charger whenever the starter battery isolator is closed, i.e. when the engine may be running and Redarc would be charging the lithium battery as this would “short-circuit” the Redarc and the Victron and drain the house bank rather than charge it. On the Victron I have set a minimum input voltage level to prevent excessive discharging of the lithium battery (its internal BMS serves as ultimate protection). I also have a Victron battery monitor which could control the DC/DC charger based on state of charger rather than voltage of the house battery but feel like this is not adding much value. This is system is simple, quite cheap and once installed pretty much fool proof.
HI JP,
If it’s working for you great. That said, from your comment I’m assuming you are not a full time offshore live aboard voyager. For that usage profile the system is pretty much always more efficient, simpler, and more elegant, if all charging sources are connected to the house battery and the engine battery kept charged with a single small DC/DC charger.
I explain why in this Online Book starting here: https://www.morganscloud.com/2022/09/04/battery-bank-separation-and-cross-charging-best-practices/
Hi John, that’s correct. I use my boat for day sails and the odd holiday cruises. The reason why I decided to leave my starter battery connected to the alternator is to protect the alternator where the lithium battery charger switches off because the lithium house bank is fully charged. The dc/dc charger from the house bank to the starter battery is merely used to maintain the starter battery when the boat is not used for a few weeks.
Hi JP,
That makes sense. That said, I’m not sure you need to “maintain the starter battery”. Even liquid filled lead-acid batteries self discharge a lot less that I used to think they did. The other simple option when the starter batteries dies is to just replace it with a lifeline AGM which hardly self discharges at all and will easily start an engine after being uncharged for a whole winter—first hand experience over years.
How about an Echo Charger, which is connected to the House Bank along with all charging sources, and takes from the house bank to charge the starting battery?
Hi Stephen,
Sure, that’s fine, although I have had better luck with Victron products than Xantrex.
Any opinions on the Renology DC-DC 50A charger? Dual inputs for alt and solar. Flooded start to two 200A Li house batteries.
Hi Gregg,
Like the Sterling, the Renology is primarily designed for a situation where the alternator is connected to the starter battery. Since that’s not my preferred solution I don’t recommend either: https://www.morganscloud.com/2022/09/04/battery-bank-separation-and-cross-charging-best-practices/
I’m also not generally a fan of boxes that combine functions, just too many eggs in one basket.
In summary, my thoughts on the Renology are much the same as my thoughts on the Sterling above.
Thanks Cap!
Hi Mal,
As far as I know, the only reason to use an isolated ground DC/DC charger is on an aluminium boat where we want to ground the electronics to the hull but keep the rest of the system floating. That said, I recommend grounding electronics on an aluminium boat with capacitors.
Other than that, I can’t think of any good reason, but there may be one I have not thought of.
The article states a DC-DC charger must be directly wired to batteries:
Is that a vender recommendation? Is there a reason a regular battery switch could not be used to interrupt the input or output wire instead? That would be way easier than pulling a fuse, if a little overkill for a low-amp charger
Or wiring it to a breaker on the DC panel which avoids the use of a separate fuse (on one end at least)? I’m planning an install between two battery banks and I want to have a way to turn off the charger, say, for storage to avoid one bank draining the other while self-discharging
Hi Justin,
Not withstanding my comment above, I do disconnect the DC/DC charger, and all other battery direct loads, when the boat is in storage. But that’s five minutes work twice a year to pull the fuses and put them back, so I have not bothered with a breaker, and would not.
Hi Justin,
Sorry, I missed this. Yes, that’s the recommendation, at least from Victron.
I have wondered about putting the DC-DC the other side of the battery switches but don’t know what the unintended consequences would be.
Anyway, with the Victron, at least, you can set a “lockout voltage” so the charger only comes on when the house batteries are being charged. The result is that the rest of the time the charger is in standby and using a tiny amount of current.
Thanks, John. Yeah, I’ve poured over the Victron docs, and they definitely seem to want you to use the little remote connections for a switch and wire them direct to each battery. I assume they have their reasons.
Setting a lockout voltage could also make me feel less anxious.
Hi Justin,
I have not bothered with a switch on those connections, but rather just jumpered them out. My experiments showed that the lock out performs the same function.
Ok first off I would like to say great online book it is very well presented and your reasons for YOUR application make a lot of sense. BUT I have a different option. My boat is small 29ft. I have 400watts of solar (2 200watt panels) (in Florida and the tropics) this keeps my 200ah battery bank topped off in just a few hours and meets all my power demands during the day. All my lighting is led. And my electronics are a depth , wind direction and iPad with navigation software and VHF with AIS receiver and GPS with a NMEA 2000 Wi-Fi server to get the depth, AIS and GPS data shared to pad app. I have a the largest load is a 2000Watt inverter and small refrigerator. I have no high load windlass or electric winches. My primary power is solar that charges my house bank my yanmar 2GM20 has a 100amp alternator and is connected to a the start battery with a dc/dc charger so some power will go to the house bank when motoring. BUT I spend 90% of my time with the engine OFF
the solar meets the power demands all day and at night the only load is the bilge pump monitoring the Engel Fridge from 0.5 – 2.7Amps (12v DC) and the propane solenoid. And maybe a few led lights until I go to sleep.
I motor when I need too and sail as soon as there is wind. So the alternator is not running much at all. But when I do run it I wanted the power from the alternator to run things while motoring. When is hag a AGM house bank I simply used a 1/2/both switch. But whe I replaced the house bank with one 200Amp LiFePo I installed a DCtoDC charger and installed it as the manufacture user Manuel with alternator connected to start battery and then DC/DC output to house bank, this seems to work great as the start battery discharge is practically nothing as apart from starting the engine it does nothing and the house bank gets its primary charge from the solar. When motoring the small amount of power for navigation lights and other electrical use for navigation instruments is more the. Handled by the DC/DC output to the house bank so while motoring I get plenty of power to the house bank.
my only concern is IF i needed to run the engine for a long time due to a lot of power use (like when others are on board and the inverter is used to power house hold electric (like my wife’s electric kettle and single induction cooktop);and low solar output. I have gone to 20percent battery capacity a few times and that’s why I decided to go lithium as the AGM could not handle the induction cooking and kettle.wonder could I OVER charge the start battery while trying to get power to the house bank through the DC/dc charger?
I didn’t want the expense of a voltage regulator to connect the alternator to the lithium (as I don’t want the risk of the BMS shutting down to house bank and blowing the alternator) but reading your articles I’m starting to think I might be heading that way to get all charging sources going to the house bank and then charge the AGM start battery with dctodc charger.
(oh and I also replaced the 1,2,both switch with two separate battery cutoff switches and the one on the starter/alternator also has a alternator field shut off.)
Hi Michael,
Thanks for the kind words on the book.
Sure, all this stuff is user profile specific. I say that over and over again. That said, this online book is about electrical systems for live aboard offshore voyaging boats. So, for example, if you were to sail your boat to the UK, where it can be cloudy for weeks at a time, you would probably regret that you and forgone one of the greatest benefits of lithium batteries: the ability to accept very high currents right up to fully charged, which in turn allows a cruising boat with a big alternator, properly regulated, and connected directly to the lithium house bank, to cover a lot, maybe even all, of daily usage while motoring in and out of port.
The point being that your system works well for you because you are in Florida with a huge amount of sun.
But even then, there’s another way to look at this. 400 watts of solar is a lot of clutter on a 29 ft boat. So I’m betting if you upped the alternator efficiency so you got a bunch of Ah when motoring in and out of anchorages, you might be able to get rid of say half that solar. Would that be worth it to you? Maybe not, but to me it would since I hate clutter and drag, as well as anything that gets between me and sailing the boat, even a little.
See what I mean, it’s all user and usage specific.
And, as you say, with your setup you are likely chronically overcharging the start battery. That said, I good lead acid can take a lot of that abuse, so probably not a problem with your set up.
Thanks is for the reply. True but really I have 2 panels (initially only I had two 100watt panels but technology upgrade same size panels now are 200 watt panels the two 100 watt panels were damaged in a hurricane struck by flying debris. The panels that replaced them have no more windage or take up any more space then the 100watt panels and are the same windage as a a Bimini top so not only do they give me power but are shade when at the helm, and believe me I sail a lot just always return back to my home on the ICW every year. This setup has weathered a direct hit by a hurricane windage wise (but as Ron white said it wasn’t “ that the wind was blowing”that damaged my initial panels but “what was blowing IN the wind” that damaged them) I agree a high output alternator would be beneficial and I am thinking about that but the expance at the time to both upgrade my alternator and install a high quality regulator so I don’t blow my alternator should the lithium BMS shut down initially put me off from connecting my alternator to the lithium bank. And also I hadn’t read your book yet and I followed the instructions from the manufacturer on how to install the doctor dc charger they showed the install with alternator to start bank so that’s what I did and it made sense to isolate the house bank and to protect the diodes in my alternator from a lithium shutdown. But I agree your system is superior especially with a larger boat with more power needs and a greater need to get the most from a high output alternator.
( I won’t make the mistake of leaving the panels on the arch again even through it is strong enough to handle the wind they are too exposed to damage by things being blown into them.)
PS also one of the drawbacks of a smaller boat (and benefit) is lack of tankage and provision space for long passages without anywhere to resupply so I tend to limit my passages I can do one or two overnights distances at a time . ( that way should something cause a slower passage I have Lee way and still be comfortable should it take a bit longer)
as I my fresh water and perishable food storage is limited. So a direct Atlantic crossing is out of the question on my boat unless I wanted to resort to carrying Jerry cans of water and reliving my army days of MRE rations for food. Sure I could probably provision my boat for a solo passage like that but why would I want too. It’s suppose to be fun and I don’t like pushing the limits of my boat better to stay comfortably within it’s and my limitations. If that is in a future plans probably would sell and upgrade to a boat better suited for that trip. I don’t have a reliable self steering system ether ( for me wind vane is preferable over electronic autopilots) but it’s funny prices of a good windvane haven’t changed much but electronics get cheaper and cheaper (relatively) all the time. But that would be another power drain and again increasing the need for a bigger electrical system like your recommendation
Hi Michael,
I hear you on that, we have the same issues with the J/109. No way I would sail her Tran-Atlantic either, even though people have. Still, there’s a lot of fun to be had in smaller lighter boats.
Just a quick question, I am hearing more and more marine electricians using mppt charge controlers in place of DC to DC chargers. I think the thought is they produce a proper charging profile over a wide range of input voltage. But I am unclear of the reasons for choosing them over a DC to DC charger. I am mostly seeing this in the expected location of house to start bank for maintenance. I wonder if it because mppt charge controllers are everywhere, familiar, and may be fit for this use?
Hi Carl,
A MPPT is a special DC/DC converter that optimizes the output of solar panels, it’s not a DC/DC charger or a substitute for one, at least that I know of.
Here’s a good explanation of MPPC controllers: https://www.solar-electric.com/learning-center/mppt-solar-charge-controllers.html/
And at Victron, for example, you can fine MPPC controllers and DC/DC chargers, but as you can see they are different products optimized for different functions. That said, I think it is true to say that they are both DC/DC converters.
Now that Victron has come out with the Orion XS that produces 50A from a much smaller and more efficient unit, what is your opinion of using two of them in parallel to charge a lithium bank from an AGM start bank with the system wired to charge the AGM directly from the alternator?
In my previous LFP installation (boo, drop in, but wired as best I could to be safe), I charged the LFP bank direct from the alternator using the now dated Balmar MC-614, programmed appropriately. It worked well and I monitored it closely. My new boat also has a 614 but I have decided to install LFP for coastal cruising in a more conservative way and not have the expense of a new Zeus or WS – thus the alternator (Balmar) wired to the AGM bank. The Orion XS seemed like a pretty nice option in which I could start with a single unit and, if I thought it necessary, I could parallel a second to double the charge.
Hi Jesse,
Sure you could do that. In fact we have that set up as one of the options we discuss in our buyer’s guide: https://www.morganscloud.com/2024/06/17/lithium-buyers-guide-budget-economy-options/
That said, 100A is not that much charging capacity and there are other benefits to having all charging sources connected to the house bank including coordinating them through Victron Cerbo DVCC with a WS500. So if I were doing a lithium system I would go with that more efficient and easily expandable architecture.