Realistic non-bs comparison of lithium to lead

[a64pilot]

I understand, and agree on your comment on a towable generator, only ones I know of are on real fast, long distance race boats, at the speeds they make and the sail power they have, I’m sure it makes sense.
But most of us buy folding and or feathering props cause just a freewheeling prop slows us more than we want, start drawing power from that prop and your going to be slowed a lot more.
Only times I have excess sail power is when I’m at hull speed, for me that is 7.7 kts, and I can count on one hand how often that has occurred. Once that I can remember we hit 8.3 kts sustained for a few hours, but I’m pretty sure there was some current involved with that too, had to be.

As far as recharging from Solar, that is easy math, we know from too many observations that you can get roughly 1/3 of rated wattage in amp hours from a decent array, so for my 1000 watts of Solar assuming a bank that never gets cut back due to acceptance rate ( lfp) I can get 333 AH, if we assume 100% efficiency in the charge cycle, you can’t of course but for arguments sake forget inefficiencies of charging.
My problem is I go through about 250 in a 24 hour period for house loads.
But forget that, how far will 300 AH move a typical cruising boat at say 4 kts, keep the speed down to be realistic, this drive an EP boat at hull speed is just silly. That is how far I could go on an average day, if I give up pretty much all of my toys that make life nice, like refrigeration.

[GrowleyMonster]

Originally Posted by KTP

Growl, what do you use for grounding once you pulled your motor? Do you bond the negative battery lead to the prop shaft and use a galvanic isolator to shore power? I need to read up on this a bit more...

Most guys do NOT ground the propulsion system. Negative is floating. I followed the thundering herd and did not ground mine, either. Except OOPS... yeah I did. Via the DC/DC converter which of course grounds via the normal 12v house electrical system. 12v ground is bonded to several through hulls and the strut. Sigh. Sometimes you just can't win even with the best intentions.


My motor is not a brushed DC motor, btw. It is brushless, and more correctly is a PMAC, Permanent Magnet AC motor, three phase, commutated according to an array of three Hall Effect sensors which basically detect when the magnets pass by them. The controller pulses the phase leads and so energizes the coils in the correct polarity a buncha times per revolution to make them attract and repel, as needed, the magnets on the rotor disk. So no grounding through the motor and shaft.



No galvanic isolator onboard. No isolation transformer, either. My zincs do not dissolve any faster than other boats, and I have been under the boat dozens of times to clean the bottom, changing shafts, props, etc and never had so much as a tingle even with bare hands on the strut. So it seems to be an electrically clean system. But not everyone uses the propulsion bank for house loads. Some guys keep their house bank just the way it is, including the inverter. I have a 5kw inverter and a 500w inverter, both fed from the 48v bank. The big inverter is nice when you need to run a power tool for a minute or two and don't want to fire up the generator. or to make a nice cappuccino without all the noise. The DC/DC converter powers the very few 12v circuits I have, without a separate house bank, and there is a backup as well.

[GrowleyMonster]

Originally Posted by BigBeakie

Or you could design it and engineer it properly so you DO get kW's instead of watts. Or you could use a prop that gives you 140 watts. Your choice.

Sent from my iPad using Cruisers Sailing Forum

If I did that, then it would not be engineered properly for propulsion and it would STILL be inefficient. How efficient is YOUR electric boat in regen mode, anyway? Can you give us data from YOUR boat? Or are you referencing the glossy brochures designed to make people buy stuff? Brochures seem to be the most efficient thing going!

[KTP]

Ok good info. I like to spend money so will probably go for the 30 amp shorepower rated ProMariner ProSafe fail safe galvanic isolator (about $250). I am going to use a Magnum 4.8kW 48V inverter/charger (60A charger at 48V) as my motor battery bank charger and also the house inverter. A 48V to 12V DC-DC of about 60 amps to power other loads. The Magnum inverter has a neutral transfer switch built in and recommends using a galvanic isolator on the shore power ground line as it enters the boat.

Here is some light reading on the matter:

"In a boat / RV, the shore power connection is provided from AC Power Distribution System of the Marina / RV Park and hence, the Neutral of the shore power supply is bonded to the Earth Ground only at one point at the AC Power Distribution System of the Marina / RV Park. Hence, when the boat / RV is accepting power from shore supply, the Neutral of their distribution system should NOT be bonded to the local Boat Ground / RV Chassis Ground.

Inverter Chargers are used in RV and marine applications for converting DC battery voltage to AC Power and for charging DC batteries when AC power is available from shore power. It consists of an Inverter, a Battery Charger and a Transfer Relay. As long as the external AC input power from shore power is available, it is passed through to the AC loads through the Transfer Relay Section. At the same time, the Battery Charger Section converts the external AC input power from the utility to DC power to charge the DC Battery Source. In case the utility fails, the load is transferred to the inverter. In case shore power / onboard AC power is not available, the Inverter can be used to provide AC power.

As per Code, the Transfer Relay is required to switch both the Line and Neutral conductors during the switching operation. The Hot and Neutral AC output terminals of the Inverter Charger will be switched either to the two current carrying conductors of the Inverter or to the two current carrying conductors of the shore power (Hot and Neutral). As required by NEC and UL specification 458, inverter / charger installations in the U.S. that are used in RV or Marine applications should be provided with a“Neutral to Ground Bond Switching Relay”to switch bonding of the Neutral Output Connector of the Inverter Charger as follows:

• When operating as an inverter, the current carrying conductor of the Inverter Section that is connected to the Neutral Out connector of the Inverter Charger should be bonded to the metal chassis of the inverter by the “Neutral to Ground Bond Switching Relay”. As the metal chassis of the inverter is bonded to the RV Ground (chassis of the RV) or to the Boat Ground (DC Negative Grounding Bus Bar and the Main AC Grounding Bus Bar are tied together in a boat and this is called the “Boat Ground”), this current carrying conductor of the Inverter Section will become the Grounded Conductor (GC) or the Neutral of the Inverter Section. This meets NEC requirements.

• When in the Pass Through Mode / Utility Mode, the Neutral of the shore power will be connected to the Neutral Out connector of the Inverter Charger. At the same time, the “Neutral to Ground Bond Switching Relay”will un-bond (disconnect) the Neutral Out connector of the Inverter Charger from the chassis of the Inverter Charger. This will ensure that the Grounded Conductor (GC) / Neutral of the shore power is bonded to the Earth Ground at one single point at the location of the AC Power Distribution System of the Marina / RV Park.

In some marine applications, Neutral-to-Ground switching is not required or acceptable. The potential for galvanic corrosion caused by small leakage currents between boats with dissimilar metals is present. The proper and safe ways to prevent this is by using galvanic isolators or include an isolation transformer for the AC input. Disconnecting the common ground between the AC and DC system could contribute to ahazardous and potentially fatal situation. "

[GrowleyMonster]

Originally Posted by a64pilot

I understand, and agree on your comment on a towable generator, only ones I know of are on real fast, long distance race boats, at the speeds they make and the sail power they have, I’m sure it makes sense.
But most of us buy folding and or feathering props cause just a freewheeling prop slows us more than we want, start drawing power from that prop and your going to be slowed a lot more.
Only times I have excess sail power is when I’m at hull speed, for me that is 7.7 kts, and I can count on one hand how often that has occurred. Once that I can remember we hit 8.3 kts sustained for a few hours, but I’m pretty sure there was some current involved with that too, had to be.

As far as recharging from Solar, that is easy math, we know from too many observations that you can get roughly 1/3 of rated wattage in amp hours from a decent array, so for my 1000 watts of Solar assuming a bank that never gets cut back due to acceptance rate ( lfp) I can get 333 AH, if we assume 100% efficiency in the charge cycle, you can’t of course but for arguments sake forget inefficiencies of charging.
My problem is I go through about 250 in a 24 hour period for house loads.
But forget that, how far will 300 AH move a typical cruising boat at say 4 kts, keep the speed down to be realistic, this drive an EP boat at hull speed is just silly. That is how far I could go on an average day, if I give up pretty much all of my toys that make life nice, like refrigeration.

Using those numbers, how can a 1kw solar array push your boat at a sustained 4kts? Simple answer is, it probably can't. You are talking less than one horsepower no matter how you look at it. I think I will need at least 2kw to push my little boat day and night, on sunny days, at even 3kts, but the solar isn't up yet so I am speculating. What 1kw of solar WOULD do for you is noticeably cut your fuel consumption on long motor passages, or build your bank up for occasional use or for docking or whatever. Remember, it is free energy, once you have already spent your kids' inheritance on panels and charge controllers. Takes a load off the propulsion diesel, in a parallel hybrid system. Or reduces the load on the generator, in series hybrid configuration. Either way it is as insignificant or as significant as you make it. Or... maybe enable you to limp home with a busted diesel.

[GrowleyMonster]

Originally Posted by KTP

Ok good info. I like to spend money so will probably go for the 30 amp shorepower rated ProMariner ProSafe fail safe galvanic isolator (about $250). I am going to use a Magnum 4.8kW 48V inverter/charger (60A charger at 48V) as my motor battery bank charger and also the house inverter. A 48V to 12V DC-DC of about 60 amps to power other loads. The Magnum inverter has a neutral transfer switch built in and recommends using a galvanic isolator on the shore power ground line as it enters the boat.

Here is some light reading on the matter:
<Snip light reading>

Sounds good to me. What type batteries? If FLA, will your charger be able to equalize them properly? Also, one nod to safety that I did make with my 120VAC system (boat was not wired for shore power when I bought it, just a shore power cable receptacle and a single 15a house wall outlet) when I wired it was a stand alone GFCI shore power breaker in it's own enclosure between the shore power receptacle and the breaker box. Made for outdoor spa use, not marine use, but I figured it would be better than nothing at all. But my disclaimer: ask your electrician about that. And oh, I would install a second DC/DC converter for redundancy. Sure, in an emergency you can just tap the bank 12v up from the negative end, but that's a little too trailer park for me.


Backup charger? Generator?



Sounds like you are putting a lot of thought into it. Good luck with the project.

[KTP]

Originally Posted by GrowleyMonster

Using those numbers, how can a 1kw solar array push your boat at a sustained 4kts? Simple answer is, it probably can't. You are talking less than one horsepower no matter how you look at it. I think I will need at least 2kw to push my little boat day and night, on sunny days, at even 3kts, but the solar isn't up yet so I am speculating. What 1kw of solar WOULD do for you is noticeably cut your fuel consumption on long motor passages, or build your bank up for occasional use or for docking or whatever. Remember, it is free energy, once you have already spent your kids' inheritance on panels and charge controllers. Takes a load off the propulsion diesel, in a parallel hybrid system. Or reduces the load on the generator, in series hybrid configuration. Either way it is as insignificant or as significant as you make it. Or... maybe enable you to limp home with a busted diesel.

Well your Cal 2-27 has a LWL of 22 feet. The max hull speed is...calculating...6.3 kts and 60% of that (a efficient speed) is 3.8kts. So pushing your Cal 2-27 at 4 kts is going to take some power...don't you already know these numbers though? You have had your electric drive for quite awhile now right? I would have plotted watt-hr used in flat water for 0.5 to 6 kts, probably on several different outings by now.

Our PS34 has a slightly longer LWL of 26.25 feet and a max hull speed of 6.9 kts and 60% of that is about 4.1kts. We are far heavier at 13,500 but in flat water isn't it water resistance which is the show stopper? Being heavy is just more inertia but once you get moving, the water resistance (and to a lesser degree air resistance) is what the energy of your electric motor has to overcome.

I have been reading that a kilowatt is likely to move a boat our size at somewhere between 2.7 and 3.5 kts depending on prop efficiency and what the wind/water is like.

[KTP]

Originally Posted by GrowleyMonster

Sounds good to me. What type batteries? If FLA, will your charger be able to equalize them properly? Also, one nod to safety that I did make with my 120VAC system (boat was not wired for shore power when I bought it, just a shore power cable receptacle and a single 15a house wall outlet) when I wired it was a stand alone GFCI shore power breaker in it's own enclosure between the shore power receptacle and the breaker box. Made for outdoor spa use, not marine use, but I figured it would be better than nothing at all. But my disclaimer: ask your electrician about that. And oh, I would install a second DC/DC converter for redundancy. Sure, in an emergency you can just tap the bank 12v up from the negative end, but that's a little too trailer park for me.


Backup charger? Generator?



Sounds like you are putting a lot of thought into it. Good luck with the project.

Well the type of battery is what this thread was originally about until I derailed it but I am leaning toward eight to twelve of the Lifeline AGM in the 12V 125AH group 31 package for the above mentioned space and mounting reasons. I wish I could fit the 6V 400AH L16s in there but just not real sure I can find a space for eight of those.

Oh, backup charger don't really have. Will have a MidNite Kid solar charger and about 1200 to 1600 watts of solar. We will probably take the EU2000i 1600 watt Honda generator on longer trips, perhaps converted to run off propane since we carry 8 gallons of that for cooking.

[a64pilot]

Originally Posted by GrowleyMonster

Using those numbers, how can a 1kw solar array push your boat at a sustained 4kts? Simple answer is, it probably can't. You are talking less than one horsepower no matter how you look at it. I think I will need at least 2kw to push my little boat day and night, on sunny days, at even 3kts, but the solar isn't up yet so I am speculating. What 1kw of solar WOULD do for you is noticeably cut your fuel consumption on long motor passages, or build your bank up for occasional use or for docking or whatever. Remember, it is free energy, once you have already spent your kids' inheritance on panels and charge controllers. Takes a load off the propulsion diesel, in a parallel hybrid system. Or reduces the load on the generator, in series hybrid configuration. Either way it is as insignificant or as significant as you make it. Or... maybe enable you to limp home with a busted diesel.

No, I wasn’t talking feeding it direct, but if that 1KW of Solar put 300 usable AH into a 12V bank or 75 AH into a 48V bank, how far could you go using those 75 AH out of a 48V bank.
Know that number and you can infer how many KW of Solar you need to go X number of miles disregarding wind and current.
I think the number is only a couple of miles, let’s say for argument 5 miles.
Next place I want to go is 50 miles away, so assuming the bank is large enough, I have to sit at anchor and refuel if you will for ten days, then I can go that 50 miles.
It would I’m pretty sure require an LFP bank to keep weight within reason to have significant as in a 50 mile range on an average 40’ cruising boat? Keeping speed down, speed requires way more power.

I guess you could work it backward so to speak, cause it takes I believe me about 8 gls of Diesel to go that distance, but I’m wasting a whole lot of diesel heating water etc., a whole lot. So no, I don’t think you can do it that way.

I assume you know your consumption figures in either AH or KWH?

[CaptainJohn49]

I guess I got lost along the way. I'd like to say I installed a 8D Trojan AGM back in 2014 and have had 0 problems with it. It weighs 161 lbs.. and simplified connections quite a bit. The current price on the internet is about $550 although I paid quite a bit more back in 2014. I've included a link to their Technology page. Advanced Technology | Trojan Battery Company.


I have shore power, generator, engine power (alternator) and solar. My main reason for purchase was I wanted to reduce the number of connections and reduce maintenance. I had 4 golf cart batteries connected in series to get to 12v and parallel for more power. These were in a very confined space that required removal of the batteries for service. needless to say they only got serviced once! My fault I know, but the routine took over an hour. Now with the 8D AGM there is no service and only 2 connections to look after.

On my 8D AGM the connection to the battery and the power system is through a 250 amp fork lift quick connect. I had a forklift company in my area make a special cable. To remove the battery you don't remove the terminals, you just unsnap the connector and lift the battery straight out. It's completely shielded and relatively waterproof. Cost for the special cable and the heavy duty connectors about $100. Keep it well greased and you'll have no corrosion.


There are no 24v 8Ds but 4 of these in series would produce 48v, would only be 640 lbs. and cost about $4 per pound. I leave mine out in the open in a storage area and protect only the terminals. I had my welding shop make a custom hold-down for the 8D to keep in in position. Cost for the custom hold-down was about $30.


All I know is it works for me at this price point. I'm not saying this is applicable for your application, but if I were to do electric propulsion this is where I'd start. There are much better batteries just around the corner. Go now, Go cheap, Replace later.



Hope this helps


CaptainJohn49

[KTP]

Originally Posted by a64pilot

I think the number is only a couple of miles, let’s say for argument 5 miles.
Next place I want to go is 50 miles away, so assuming the bank is large enough, I have to sit at anchor and refuel if you will for ten days, then I can go that 50 miles.
It would I’m pretty sure require an LFP bank to keep weight within reason to have significant as in a 50 mile range on an average 40’ cruising boat? Keeping speed down, speed requires way more power.

In your example with a 40 foot boat that has a LWL of at least 30 feet or so (so no 10 foot bowsprit boats here lol), I would guess based on several reports of range from boat conversions I have been reading that you could motor on a windless day (otherwise you would be sailing those 50 miles, yes?) at about 3 kts with just 15 amps @ 48V. Thus it would take 50/3 = 17 hrs and use up 50% of a 500AH bank. A 48V 500AH bank made of lead acid would weigh 1200 pounds, which is really nothing in a 40 foot sailboat that displaces what? 22,000 pounds? Also if you have removed the engine, diesel fuel and associated equipment, you have probably lightened the boat by 900 pounds or more so the batteries and electric motor would be adding maybe 350 pounds.

And boy, when you are on the hook, you would have a honkin house battery!

[BigBeakie]

Originally Posted by GrowleyMonster

If I did that, then it would not be engineered properly for propulsion and it would STILL be inefficient. How efficient is YOUR electric boat in regen mode, anyway? Can you give us data from YOUR boat? Or are you referencing the glossy brochures designed to make people buy stuff? Brochures seem to be the most efficient thing going!

Growley,

OK, I'll give you the numbers from our boat. But first, you seem to be taking the position that since you have put an EP system together, (and full marks to you for doing that), we need to take that as state of the art. It sure doesn't seem that way to me, in fact, your regen number of getting 140 watts indicates fairly low expectation.

And sorry, but the old chestnut that other claims of performance are hogwash because they are better than your numbers, just means either the claims are wrong, or that your results are sub-optimal. It's one or the other.

I encourage you you have a look at the OV Servoprop numbers, because they are from A) tank testing B) lab testing, and C) actual systems on boats that have been tested and certified by qualified engineers. My understanding is that there are 10 to 15 Servoprop systems on boats currently. The data is consistent across the three methods. This data by the way is gathered both with persons on board and also sent via Victron CCGX data capture and monitoring.

Here is the results plotted on graph as per their website.

https://oceanvolt.com/solutions/syst...op-sail-drive/

At 8 knots boatspeed about 1.7kW is generated by each motor. At another 2 knots of boatspeed, 10 knots, it climbs to about 3 kW per motor.

Do you actually think they are just making this up, pulling numbers out of a hat? Really? Do you think the judges that awarded the Servoprop the DAME award at METS for best solution in the propulsion and mechanical division are technical dummies and totally gullible?

I have validated OV's projections from several actual users, and in each case the OV numbers were if anything, conservative on projected performance compared to what was achieved.

Here are the relevant figures from our cat. Total seawater hull resistance at 8.3 knots boatspeed is 11.1 kW. Similarly,
7.7 kts = 8.3 kW resistance
7.1 kts = 6.1 kW resistance
6.5 kts = 4.5 kW resistance

Therefore if at 8 knots the Servoprop gives 1.7kW of regen, that means that 1.7kW of energy is taken from the 11.1kW of sail power it is taking to push the boat on the velocity vector at 8 knots. Make sense?

So subtract the 1.7kW of regen from the 11.1kW of sailpower and get 9.4kW of net sail power left. Make sense? So how fast would the boat goes at 9.4kW of sail power?
Well, we know it will go at 7.7 kts with 8.3 kW of sail power, and notice that that is only about half a knot difference! ( 8.3 kts minus 7.7 kts =0.6 kts)

So if we subtract 1.7kW of regen power from the sailpower, it would be the difference in speed between 11.1 kW resistance and 9.4 kW resistance, which is not very much at all! Get it now?

You subtract the amount of regen kW from the hull resistance (which is the velocity vector of the sailpower) at any given boatspeed, and then see what speed differential that corresponds to.

So Growley, in this case at 8 knots it would slow the boat less than half a knot, and give about 1.7 kW power, which is an order of magnitude more than your 140 watts.

Technology has moved along a bit.

[ranger58sb]

Originally Posted by KTP

I have been thinking about the 6CT 6V Lifeline but have a few questions/issues.

Are the 6V batteries built any better than the 12V for Lifeline? They don't mention any difference in cycle life in the literature.

Is there a big advantage in having one series string of eight 6V batteries to get to 48V vs two series strings of four 12V batteries (each fused) which is then paralleled?

I would get 50 extra amp hours at 48V with eight of the 300ah 6CT vs eight of the 12V 125ah 31XT. An extra 2400Wh.

The 6CT are 90 pounds vs 74 pounds for the 31XT. 20Wh per pound for the 6V and 20.27Wh per pound for the 12V (that is interesting...)

What do you think?

Can't really speak to most of your questions, but... it's not uncommon for 12V "deep cycle" batteries to more realistically be "dual-purpose" versus 6V deep cycle unit. Don't know if Lifeline is one of the brands that routinely does that, but it'd be worth a question direct to their customer service people. I've found them to be very helpful... especially on the phone...

And then they'd likely be able to speak to comparisons between series-only, parallel-only, and series/parallel installations.

-Chris

[Pete7]

Originally Posted by BigBeakie

Technology has moved along a bit.

Really? for a yacht to average 8 knots its going to be 50ft plus. He is sailing a Cal 27, that probably has an average speed of 4 knots. Is the electrical generation from a in water turbine linear?

The graph you refer to suggests that actually at 4 knots he is about right with 140w.

How much is one of those things? and would you be better off with some extra solar and a decent MPPT instead? Might be better bang for the buck.

Pete

[BigBeakie]

That's a very fair point. The effectiveness does need some boatspeed to start to be useful, and at 4 knots average, it may not be that useful.

Solar could well be a more productive approach, depending on the boat and cruising conditions.

But for a boat that does something between 6 and 10, as many cruising cats do, it's a lot of power when sailing. The point I was trying to address was this idea that it slows the boat significantly. The Servoprop does not, but that is not necessarily true for all hydrogenerators, it must be said.