Help! Data overload!! 12volt Bank Upgrades

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Senior Member
Jan 12, 2014
Vessel Name
Miss Rita
Vessel Make
2004 Heritage East
Bought a newer boat, Plan A, 3 months to rig it for 6+ months in Caribbean, much on the hook.

  • 4 450watt solar = 1800watts possible.with MPPT controller.
  • 170 amp Idlepro Leece Neville Alternator with smart charger. One for now.
  • New 5 250ah LiFepo4 Batterys = 1250ah One bank for everything
  • Some remote guages to see whats going on.
  • New plottercharter and radra, No wait thats another post!!

Need some thoughts on systems, cost is a factor, but good system is too.

      • What size MPPT do I need for 1800 watts?
      • What smart charge would work for Alternator?
      • I have a 12KW Genset, how many Amps charger should I get for My Lithiums

Boat is 46' twin 220 Cummings, I go 7mph, Alternator will have small pully.
My head hurts because I am researching so many subjects, including nav systems, watermaker, the trip advice, etc.
Look forward to advice. Selling Gulfstar, no time to list now. Steve
Congratulations on the new boat!

As far as the MMPT it will depend on how your have your panels wired, series or parallel. I would suggest that you discuss your system with a knowledgeable vendor and get some guidance that way. As a rough guess, I'd look at something like the Victron SmartSolar MMPT 250/100 controller.

For the charger for your batteries, Lithium batteries are a relatively new tech and I would strongly recommend you have someone design the system for you that knows what they are doing. LiPo battery systems are not anything I'd want to roll my own at this point in the technology.

I just put together a very simple solar system for my boat. The system was small and the batteries are tried and true AGM. For what you are doing, and for the amount of money invested, get some professional help.
MPPT controllers are usually rated by the maximum current that can be delivered to the batteries, usually 12V ones. So with 1800 watts divided by a nominal 12 volts that gives 150 amps. I would split the panels in two and use two 90 amp controllers or maybe one for each panel at 50A each.

I can't begin to comment on LiPO4 charging. That is a very specialized topic which I have no knowledge of.

get with BOB at SALT inc in marathon fla. They design systems and sell everything you need.
A VERY, EXPERT, knowledgeable electrical type, known here as CMS and on Cruiser Forum as Mainsail, refuses to get involved with self done Lithium systems because too many of us screw it up, either by being foolishly cheap or thinking they understand the battery requirements when they don't.

The system success depends very much on the details and with the expense of them going in even more so.

Your question tells me you are headed for trouble unless YOU start NOW doing some serious research and learning about them. I looked into these things a couple years ago and stopped because too much of it was still in the bit fiddler stage meaning left up to the boat owner to sort out all the contrary information. I am an electrician so was reasonably familiar but realized it was not worth it to me.
To you maybe but you must do your research., seriously do your research.

Don't get me wrong. It can be done but not by asking on a forum like this, at least not yet. Get it wrong and it will be a very expensive failure.

Go to CMS's site and his writings about LiFePO4 :

Solar again as above however there are a few decisions YOU must make.
--how do you want them wired? All series, all parallel or series-parallel.
It makes a big difference to the controller. Untill some of those decisions are made you are going to have trouble setting the system up and making decisions about what to buy.

Solar is worthwhile but pay attention to what CMS has to say about solar and LiFePO4 batteries.

As D.Marchand and Dhays suggested a series-parallel setup would be good. That way shading of a part of the panels won't shut the whole system down.

As far as only one battery including for engine starting NO WAY would I recommend that. If anything happens to your one bank for any reason you are literally up the creek, Li battery or no. No bank is absolutely safe from problems.

You can tell me to go fly a kite but be carefull. Rushed into you could set yourself up for a lot of trouble and expense.
Your solar system output is impressive. Where are you getting a 450w panel? I would guess a 450 w panel would be at least 6’ by 6’?
I retired a few years ago from a commercial hybrid drive system. With a hundred engineers on the payroll we still had challenges with Li batteries. Lots of progress in the last two years but still an emerging technology. so I must agree with other posts that you really do need professional help. That said, I would love to move to Li myself.
The simplest way to keep the batts charged is to reduce the DC loads.

Your reefer is probably the biggest consumer of power 24/7 , what have you done to reduce its hunger?
Not an expert, but I wish i had this problem. :) (I don't, I only have an Albin 25 with a 50A generator and 240Ah battery bank), but working with my parents on their recent upgrade to lithium in their boat (Bavaria sailboat, 39') and the decisions they made as well as being quite interested I thought i'd give a shot at a couple of answers from my perspective.

When it comes to lithium batteries there are LiFePo4 (cells) and LiFePo4 ("12v packs") to choose from that i know of.

The cell-kind of LiFePo4 is the cheaper one, you build your bank with separate 3.6V cells without any integrated control electronics, here you can easily screw up and cause rapid uncontrolled disassembly or combustion of stuff you don't want disassembled or combusted.
The control-electronics is mandatory, you need balancing circuitry for the cells that are in series (4 cells), you need charge-control circuitry so you won't overcharge them (stuff goes boom if you do), you also need undercharge protection circuitry although that is usually included in the overcharge circuitry or the cells will stop working. This means you can never connect anything directly to the batteries, everything has to go through said charge / discharge protection circuitry, no excuses!
I highly recommend consulting with a profesional who has done these kinds of installations to at least review the planned setup and schematics.

The other kind of LiFePo4 is stuff like this: (being swedish i refer to our neighbouring country norway): (13 800nok = roughly $1629 each)

These batteries are basically a drop-in replacement for ordinary 12V batteries, the LiFePo4 cells required are already connected in series inside the battery, they have the charge, discharge and balancing circuitry in the casing, you just plug it in and use it as a normal battery, although since the voltage doesn't change almost anything going from roughly fully charged to fully discharged you would need an amp-meter (victron or whatever you fancy) of some kind which everything related to charge/discharge goes through so you get a nice number on the dashboard saying "-130Ah".

Fuses is also important, not just with LifePo4.. I'd put a fuse on every battery separately so you won't end up with one battery malfunctioning and then getting 4 other batteries dumping all power into the malfunctioning one, things tend to get hot if you do that and this really applies to lead-acid as well...

When it comes to solar panels I personally prefer one MPPT controller per panel, If you use one controller for them all and plug them in series, the weakest link (like one panel being covered 30% by a mast) will cut production by 30% in total, while if you use separate controllers or at the very least plug them in in parallel you only loose 30% of 1/4 of the panels = 7.5% in the same scenario.

Separate MPPT regulators also brings a bit of redundancy as if one regulator dies you still have three more if you have four panels. These should be fused separately of course.

Charge-controllers have two maximums to keep in account, max volts and max amps. They also (the higher-end ones at least have it defined sometimes) have an efficiency-curve of where they are highly efficient. Connecting a 10kW mppt charge-controller could mean you're burning 250W of efficiency since it's not optimal for the use-case for example. To say anything more i'd need to know what kind of panels you're planning to use (to get max Voltage and max Amps from them) and then spend a few hours finding a good MPPT-regulator to fit. Not sure I have that time though but maybe you have. :)

When it comes to charging the LiFePo4 batteries like the ones i mentioned above, they take 1C continuously until fully charged, 1C = 1x capacity of the battery, so 250Ah battery should take around 250A continuously from empty to around 95% charged.
With this in mind, the 170A alternator will work at 100% output for around 6.5-7 hours going from empty to full batteries, so make sure it has cooling. (Although you probably don't have a small 0.7m³ box your engine is installed in where things get very warm, like I do)
The batteries should be able to absorb around 1250A in your mentioned scenario, multiply that by 14.4V charge-voltage and you realize you could dump 18 000W into them in over one hour, which is a lot of power..
Although, to charge them full within an hour assuming you have something like 5 meters of cables from charger to batteries (2.5m plus +2.5m minus) you need around 500mm² cables to only lose 562W into heat in the cables. (watercooled cables maybe?)

If I were to go this route myself i'd try to put all "mains"-power on a high efficiency inverter going from the battery-bank, then look for a charge-setup that i'd connect to the genset and/or mains which would max out the gensets capabilities, the genset would then run about fully loaded when it's running which should roughly maximize fuel-economy and it would basically only be running when charging the battery bank.

Your 12kW genset could charge the battery bank from empty to full in about 1.5h, not taking ridiculous cables into account..
at 12kW that would mean around 16.3hp used which multiplied with the rough average of 0.185L of diesel per horsepower per hour (it's diesel, right?) gives 3L of diesel per hour or 4.5L of diesel to recharge the bank fully, assuming no losses somewhere (cables, generator, batteries).

Just my few cents.
I am going to add this link which you may already be aware of:

I don't know how Mastervolt stands in the Li battery dept. but in general they have a good reputation, I believe. They have been at the Li systems supply for several years now. Check them out.
LiFePO3, not ready for prime time

C Lectric:: Thanks for the link to CMS site. I have read some of it before but not LiFePO3 info. It long and packed with info, Damn I and glad I have not ordered any yet!! I was looking at the affordable Alixxxx stuff, I think I am going to look at gel batterys now. Its a money/ time decision. Still have solar and alternator to work out. The CMS report said a few eye opening things about Gel and the industry.
There is so much in that report how companys don't know what they are doing or down right lie! Wish I could find more advice like that.
Read my last post, and read

cms info. Thanks
I would like to know the source of these 450 watt solar panels. The largest I have seen were 400 but even they were difficult to source. Can you provide a link?
This will get sorted out with some more time. THe trick is to not get caught in a rush or the blabbergab promotions.

THat happened to the Gels many years ago. Touted as a Miracle battery you can just drop in place and get rid of those wet cells. Well the truth was they were not a miracle battery but they are a darned good battery with the attention paid to their specific needs. Unfortunately they gained a bad rep. That wasn't the battery's fault but rather the promoters who themselves didn't understand what they were talking about.

Just to be clear GELS, real gels also have some specific recharging requirements but the equipment is out there to take proper care of them. Just be sure YOU understand. If you do some research they actually last longer, more cycles to 50% than AGM. They are slower to recharge than AGM but AGM seem to be less tolerant of incomplete recharges than the Gels.

So you understand I do use GELS and have done now for nearly 20 yrs and have had good success. One catch is though that I have kept my boat quite simple compared to most. My alternator controller is a Gel compatible unit but not AGM. Yes, I modded my alternator for control by an aftermarket controller.
My charger is an old style ferro charger but I DO NOT just let it run and run. It also has several settings, use of those setting and with some knowledge I made them last , the house set 12 yrs and the eng. set now is pushing 20 yr and still whizzes that engine over.

A caution though is to not confuse AGM and Gels. ALthough similar they are not the same and the recharging needs are different. The AGM are seem to be more tolerant of standard alternator controllers BUT both types really need proper alternator controllers AND shore power chargers for the very best life which I think you will want.

As for solar they will help a lot. I just installed , portable setup, a small set of panels and it has kept my batts. right up. CLoudy days will still be a problem but less for me than before. Sunny days have been great.

Enough for now. I was hoping I had not offended you with my blunt post, maybe too much so, but it appears not, thanks. CMS is an excellent source who I have read now for quite a few years. Buy some stuff from him also although not as much as I should have as I no longer make the trips to Az. so goods crossing the border is a pain at times.

GOod wishes on your new boat and your trip.
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If you go gel or open lead acid, there are sveral good choices for 3 stage regulators for your Leece Neville alternator. I've been using a Sterling regulator with temp sensors for the batteries and alternator. Have been very happy with it tied to my 220 amp Leece Neville alternator. Don't buy the helm display. It's unnecessary and disappointing.

C Lectric:: Thanks for the link to CMS site. I have read some of it before but not LiFePO3 info. It long and packed with info, Damn I and glad I have not ordered any yet!! I was looking at the affordable Alixxxx stuff, I think I am going to look at gel batterys now. Its a money/ time decision. Still have solar and alternator to work out. The CMS report said a few eye opening things about Gel and the industry.
There is so much in that report how companys don't know what they are doing or down right lie! Wish I could find more advice like that.

I haven't read it all yet, but from the first few pages I get this:
That dude is quite the alarmist, saying "bad **** happens!" a lot over LiFePo4, and it seems he's only referring to those cheap chinese LiFePo4 batteries sold on alibaba / ali express and similar.

If those super-cheap chinese ones were what you were aiming for it's good that you started looking elsewhere. Those can be used, if you really know what you're doing and what to look for, just like you need to know what you're doing when buying a "project"-boat..

When looking at LiFePo4 you should look at reputable companies where the products are used by professionals in marine installations.

If you're still looking at 1250Ah of battery-capacity, but lead-acid batteries instead of of LiFePo4 batteries, bear in mind that the lead-acid batteries will effectively be able to provide up to 1250/2 = 625Ah.

If you instead got 625Ah of lithium you'd have the same effective capacity.

Most stuff he writes about is related to a lack of BMS, BMS that's not doing what it should or a BMS "suddenly cutting out without warning". The fact that you've used for example 190Ah of a 200Ah bank should tell you that it's about to happen, a good battery-monitoring system counting amp-hours would tell you that, as long as you fully-charge once every few cycles to recalibrate the "+/-0" reference-point.
Same logic can be applied to Lead-acid systems with a low-voltage cut-off relay. For example a discharge-cutoff which cuts of the batteries when voltage reaches 11.8V, this is not too uncommon to protect the batteries from complete failure when leaving the refrigerator running, but I don't see him screaming about that being super dangerous, most likely those who could end up with this problem are sailors.

The one thing i'd be somewhat worried about is the frequently occurring load-dump when the batteries are about fully charged, a somewhat intelligent BMS would slowly stop charging (slowly being over maybe 2 seconds).
Load-dump is the behaviour he mentions where the cheap chinese battery suddenly disconnects, the alternator can't just make it's magnetic field implode instantly so it's still providing as much power as the moment before the load suddenly disappeared, when nothing is consuming amps it goes into a voltage-spike instead.
Load cut-off could be stuff like disconnecting a battery or you stop using the bow-thruster, if the alternator is working as intended and trying to keep up with the load, a disconnect can easily cause 100v in a 12v system for a few hundred milliseconds, although the batteries usually eat up quite a bit of that load.
Load can also be stuff like Xeon headlights in a car, so every time you switch them on / off you get load-dump behaviour in your car, a voltage spike in the system.

Load-dump should be taken into consideration for all designs for all electronics in an off-grid system, Electronics can't be certified for use in cars if they can't handle sudden large spikes in voltage, I'm pretty sure that the same should apply to marine-electronics for 12v systems, if not we'd see reports of nav-equipment and similar get toasted all over the place when people use their manual battery-bank selection switch to switch from charging battery-A to battery-B, something relatively common in smaller pleasure boats.

Here's an article about ISO specification for load-dump characteristics if anyone is interested in reading more:

In summary, I believe that LiFePo4 is an excellent choice if your demands of the system are high. if you can afford to buy the products from mastervolt, victron or some similar company which can provide guarantees, guidelines for a complete system installation and similar i'd definitely aim for LiFePo4. If such a system is way to expensive you shouldn't take the risk with cheaper Lithium batteries..

Back to my parents on their sailboat. With 300Ah lithium capacity and a normal consumption of 60-100Ah per day they can go days without any significant sunlight or other methods of recharging, no need to worry about the battery-bank sitting in a half-charged state and slowly deteriorating. Whenever they fire up the engine (everytime entering / leaving some kind of harbour) the alternator pushes pretty much it's rated maximum of 150A continuously, on an average day they pretty much fully charge their bank just by the 2*15minutes of running their engine. Their solar panel (with MPPT controller) keeps up really well when the sun is out.
They went with Victron's bms (700 series) and, Victrons MPPT charge controller for the solar panel and got great support for calibrating this to work together from both the battery manufacturer (makspower) and Victron.

Bow-thruster, windlass and starter is still on lead-acid batteries as they can crank out hundreds of amp's without much problem.
The 3x100Ah batteries they have are rated for a max of 100A each, this wouldn't be enough for the bow-thruster but the three combined would work with the windlass, although if one battery would be disconnected for some reason the remaining two would be overloaded so they put all heavy consumers on a separate lead-acid system.
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