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Old 22-08-2018, 23:28   #76
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Re: LITHIUM BATTERIES FOR DUMMIES!

Just a comment on my view/belief on AC versus DC generators. I prefer DC to charge because:


1) DC generators are easier to tune to the optimum efficiency point regarding fuel consumption.
2) Why create AC current to charge DC batteries. Lets eliminate a transformation point, innefficiencies of the transformation and more breakage points. Simpler is better most of the time.

3) I found DC gens lighter than AC gens in general. This is very important to me.
4) DC gens are usually smaller than AC gens for the same Watt output.


I installed a large alternator on my previous boat to charge my homemade Lithium bank (200 amp alternator with Balmar controller with 800 amp of batteries). I found that I got 50% output after 20 minutes at max due to heat buildup. The solution of adding a specific vent directed at the alternator was just too big a job in a cramped engine space. I also thought that running an 80hp engine to charge batteries was inefficient.


This is how I got to maybe getting a DC generator on my current boat.
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Old 22-08-2018, 23:37   #77
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Re: LITHIUM BATTERIES FOR DUMMIES!

Separate DC gens like Polar Power or FP (who does mostly AC but also offers some DC) just bypass the need for big AC to DC chargers (which may be inverter-chargers). But whether an AC or DC generator, it's still an extra engine with the associated weight, separate exhaust, etc.

Most boats already have a propulsion engine or engines that can be used for the power generation, instead of a separate generator.

That is, if the batteries can take enough current to sufficiently load up the engine/s enough to be fuel efficient. Li batteries certainly make this possible.

With Pb the acceptance is lower, especially during absorption, so the smaller engine of a separate generator (AC or DC) is more fuel efficient.
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Old 23-08-2018, 02:09   #78
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Re: LITHIUM BATTERIES FOR DUMMIES!

On larger boats I think there is still justification to carry a suitably sized Diesel AC generator.

To supplement solar for bulk charging at anchor I think the best is using Smart Chargers Invertors like Victron multiplus to manage and charge whatever technology of batteries you adjust to.

But you need AC power to do that!

Further, the safety and convienience trend is away from propane cooking to Induction stoves and Microwave Ovens.

Also my 2 Ozefridge compressors and isotherm drawer fridge will run on either 240v AC or 24v DC

My Hot Water tank is 240v as are my 3 Air con units and dive compressor.

The point I am making is that with all these AC appliances, when I run my 12Kw Northern Lights Generator for battery charging purposes at Anchor, I have no problem harmonizing other AC needs to keep Gen 75% loaded.

Underway, I find it more useful to motor sail and charge batteries via main engine Alternators if needed,

Consider the cable sizes needed if those heavy consumers were all DC.

So, my opinion is that sticking with AC domestic generator for mostly all domestic appliances, is by far more easier and versatile to manage.

I am quite happy to consume on average 5 liters of diesel a day. (We cary 2,500 liters) to comfortably stay out of marinas and have all of those AC consumers available for so little dino juice.

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Old 23-08-2018, 02:13   #79
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LITHIUM BATTERIES FOR DUMMIES!

Quote:
Originally Posted by Rimica View Post
Just a report on my experience with Lithium.


I bought a brand new catamaran last year and I had requested that the electrical system be 12 volt and Lithium. The builder put an all Mastervolt system in the boat (700 Amp batteries, switches, relays, fuses, charger and inverters). All of it is connected to an onboard computer for monitoring. This is the source of the numbers I am giving below.



I have been sailing for 15 months now full time. The system is superb. I have 700 amp of Mastervolt lithium batteries. Over 15 months they have accumulated 54 cycles out of an expected usefull life of 4000 or so. They should last another 90 years at that rate. I run everything off the batteries including my Air Cond but not the stove.



I am at the dock 2 days a week on average where any accumulated deficit gets topped off. I do not have a generator on board. I use solar panels (550 watt) and a Watt and Sea water generator. When the boat goes over 8 knots (easy on a Cat) it is self sufficient over a 24 hour period. This includes watermaking.


The downside of large capacity lithium is the charging if you do not have a DC generator. After several days at anchor I can be at 50% of capacity. I therefore have 350 amp to generate to go back to 100% charged state. The boat use 10amp an hour when anchored and 15 to 17 when sailing on autopilot. While sailing at 8 knots and with the water generator I produce 30 to 35amp, 15 go to the boat and 15 to 20 go to the batteries. I need to sail 15 to 17 hours in good conditions to fill the batteries back to 100%. Here in the Med the sails from point to point are shorter. I seldom succeed in getting back to 100%. Crossing the Atlantic will be no problem, I will run out of food before running out of electricity.



My view after 15 month of experience would be that:
1) Lithium was worth the expense given the weight saving and the capacity

2) Charging is not a problem if the sailing is over long distances.
3) No need to run engines to charge while at anchor for several days particularly if its sunny
4) If no long distance sailing is expected or if no water generator having a meaningfull output at the cruising speed of your boat is installed then one has to think about a DC generator for recharging unless you go back at the dock every few days.


I am thinking about adding a DC generator. Fisher-Panda has a 90kg 3,200 continuous watts. This would shove 200 to 230amp an hour in the batteries. That means that after 4 days at anchor, I run the machine for 1.5 to 2 hrs and I am back to 100%. Then I could have an electric stove and Nirvanna is reached.


Caveat:
I do not run my AC 24/7. When sailing, it is not on. When at anchor I will run only the one in the Master bedroom to cool it off before going to bed (30mins) on very hot days. I do not heat my hotwater tank at anchor. I do not use my wahsing machine unless at the dock.



Background:

I am an energy pig. I have an always on computer on board plus 2 other portable that needs recharging once a day in addition to "always on" WIFI and 4G receiver. I have a fridge and a freezer plus a Nespresso coffee maker.


Notes:
Charging the batteries with the engines is not realistic. My 2 engines at 2,000rpm will put out 145amp continuous in total. That is 2.5 hours at 2,000 rpm to get back the 350amp above. In an anchorage it is not doable. You need to leave and go for a 3 hour boat ride and come back. Not a solution in my view. In the Med, 5 boats will have taken your spot before you come back.


I have tried, for interest sake, to use the small Honda generator (2,000 Watt) to charge the batteries. It was connected to my charger which outputs 100amp. First the Honda is not powerfull enough to permit the charger to output 100amp. I need to set my charger to 80amp max for the generator to work. In fact I have to ramp up the charger starting at 25amp and bring it to 80 by stages otherwise the Honda chokes. At 80 amps, you need to run it for 4 to 5 hours to go back to 100% charge and it is noisy (65 to 70 dBs). Its is better than running the engines though.



Hope I contributed positivly to the discussion


Thx


Thanks for the report.
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Old 23-08-2018, 02:37   #80
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Re: LITHIUM BATTERIES FOR DUMMIES!

Quote:
Originally Posted by OceanPlanet View Post
Separate DC gens like Polar Power or FP (who does mostly AC but also offers some DC) just bypass the need for big AC to DC chargers (which may be inverter-chargers). But whether an AC or DC generator, it's still an extra engine with the associated weight, separate exhaust, etc.

Most boats already have a propulsion engine or engines that can be used for the power generation, instead of a separate generator.

That is, if the batteries can take enough current to sufficiently load up the engine/s enough to be fuel efficient. Li batteries certainly make this possible.

With Pb the acceptance is lower, especially during absorption, so the smaller engine of a separate generator (AC or DC) is more fuel efficient.
The problem with that is that the business end of our light duty diesels are connected to a gear and prop shaft. The other end is what drives our alternators and is not designed for heavy loads of very high output alternators. At least some manufacturers have limits on what can be safely driven and would deny warranty claims if it's exceeded.
A good solution to charge large banks: Fischer Panda DC AGTPM5000 https://fischerpanda.com/fischer-panda-dc-agtpm5000/
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Old 23-08-2018, 04:19   #81
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Re: LITHIUM BATTERIES FOR DUMMIES!

Quote:
Originally Posted by kmacdonald View Post
At full output of 210 amps at say 28.8V: 15.59HP
I used the data of 160 amps @ 24V with 9.9HP posted above to come up with that figure. It's really close to reality.

If the Balmar is only charging the start batteries it's not putting out 70 amps. The start battery stays at a very high SOC and wont accept much current.


140 amps @ 28.8V=10.4HP

Idle: 70 amps @ 28.8V would be 5.2HP
Thanks for that. Probably explains why I have lost 200rpm off of top end on bollard pull test
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Old 23-08-2018, 05:01   #82
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Re: LITHIUM BATTERIES FOR DUMMIES!

Quote:
Originally Posted by kmacdonald View Post
The problem with that is that the business end of our light duty diesels are connected to a gear and prop shaft. The other end is what drives our alternators and is not designed for heavy loads of very high output alternators. At least some manufacturers have limits on what can be safely driven and would deny warranty claims if it's exceeded.
A good solution to charge large banks: Fischer Panda DC AGTPM5000 https://fischerpanda.com/fischer-panda-dc-agtpm5000/
Yes, the loading may void the warranty on a new engine, but not always. The mfg reps give inconsistent info. Of course on older engines it doesn't matter and after having done this for many years still don't know of a single engine that has actually reported any issues on the front of the engine.

I had an Ample Power 130A x 24v set up on Ocean Planet's Yanmar 3GM 27hp for both RTW races. Never had an issue, although you couldn't motor the boat and charge at the same time. Which of course doesn't matter when racing as motoring not needed or allowed. For deliveries when motoring used a 1/2-power setting with the external regulator, or turned it off.
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Old 23-08-2018, 07:50   #83
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Re: LITHIUM BATTERIES FOR DUMMIES!

Quote:
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Thanks for that. Probably explains why I have lost 200rpm off of top end on bollard pull test
Your fuel burn will increase also. For a diesel figure about 1 gallon per hour for every 20 HP.
As you know, your boat is much larger than the average cruising boat we generally talk about here. An AC generator is most appropriate for your needs considering your boat and other AC needs. If reliability and money matters to you, stay away from lithium. There are really good LA batteries that could outlast most of us for a lot less money and much greater reliability. With the size of your boat, the extra weight won't matter.
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Old 23-08-2018, 07:55   #84
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Re: LITHIUM BATTERIES FOR DUMMIES!

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Sure it is BUT the torque curves are different. A diesel produces more torque at lower RPM's than a gas engine. The gas engine won't have the torque or HP at lower RPM's to get the generator up to speed without resorting to a higher HP engine. They both will put out the same HP to run the generator once started but a gas engine of that HP won't be able to get it up to speed, the diesel will.


Your kidding aren’t you? Cause there is no load until after the generator has been stabilized in RPM for one minute.
Do you realize that torque and horsepower are the same things, expressed differently?
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Old 23-08-2018, 08:02   #85
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LITHIUM BATTERIES FOR DUMMIES!

On engines it’s the side load that is relevant, not the power extracted. Guys it’s just the other end of the crankshaft is all.
A good serpentine belt system doesn’t require nearly as much side load, you could even go to a toothed drive belt, or if you were really worried a jackshaft.
Ideally I’d like to see one mounted to a PTO, by those are unusual, may as well wish for a million dollars.
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Old 23-08-2018, 08:09   #86
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LITHIUM BATTERIES FOR DUMMIES!

So far as tuning a DC generator to most efficient operating speed, is incorrect as you speed up an alternator to increase output so it doesn’t overheat. It’s actually the steady RPM AC generator that you could tune if you will so that most efficient RPM was the selected output frequency, but in truth is really doesn’t matter much, very little to be gained as the BSFC does change, but so long as your not at either end of the RPM range, it’s not much.
As far as the Honda’s I believe they are alternators, and may not have diodes, not sure, but if your inverting to 60 Hz AC, do you need to have dodoes to change AC to pulsed DC?
Either way, it’s the 21st Century and AC or DC is getting pretty blurred, it’s so easy and efficient to convert either way, that we aren’t married to one or the other like we used to be.
The alternator is a perfect example of that, an alternator is an AC device, if we had to have our DC, we would be stuck with heavy, low output DC generators
The big alternator for battery charging just makes too much sense to me, although I want it ideally defeated whether automatic or manual cause I’d suspect that under normal cruise the engine would be overloaded with the big alternator pulling a lot of power, engine size dependent of course. A 100 HP engine may be fine without having to derate the alternator, but less than 40 HP engine likely would need it.
Number just pulled from the air, they could be 150 and 75, I don’t know.
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Old 23-08-2018, 08:14   #87
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Re: LITHIUM BATTERIES FOR DUMMIES!

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On engines it’s the side load that is relevant, not the power extracted. Guys it’s just the other end of the crankshaft is all.
A good serpentine belt system doesn’t require nearly as much side load, you could even go to a toothed drive belt, or if you were really worried and jackshaft.
Ideally I’d like to see on mouthed to a PTO, by those are unusual, may as well wish for a million dollars.
Yes, it's the side load that matters most. The bearings aren't usually the same at both ends of the crankshaft.
The side load consists of the belt tension AND from the torque required to drive the alternator-----------the belt tension being so small in comparison to the torque component it's almost negligible.
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Old 23-08-2018, 08:16   #88
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Re: LITHIUM BATTERIES FOR DUMMIES!

Idler pulleys to help direct the load as needed. We do that often (with our custom pulley ace Mark Grasser).
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Old 23-08-2018, 08:16   #89
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Re: LITHIUM BATTERIES FOR DUMMIES!

I don't know who to quote here so in the clear.
An alternator belt properly tensioned is Set to approx 12ft lbs. So not much of a side load
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Old 23-08-2018, 08:18   #90
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LITHIUM BATTERIES FOR DUMMIES!

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Yes, it's the side load that matters most. The bearings aren't usually the same at both ends of the crankshaft.

The side load consists of the belt tension AND from the torque required to drive the alternator-----------the belt tension being so small in comparison to the torque component it's almost negligible.


Yeah, your probably right, it’s going to have a lot of side load even with a loose toothed drive belt.
I guess if your concerned, then a jackshaft driven off of the front of the crank is about the only way?
Or two alts, on opposite sides, 180 out?
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