Anchoring Amps/Day

[JC522]

I would like to encourage you to think and calculate amp-hours per day. Or even better, watt-hours or kW-hours per day. The whole amps/day thing drives me absolutely crazy with how wrong it is.

Could be the first time in a very long time that anyone but my mother thought they needed to encourage me to think. Thanks.

 

[Blue Crab]

Nigel Calder will take you further than any Chinese poet.

 

[Se7en]

With a fridge, but no freezer, 4 people and an hour of TV a day average, we consumed around 120 AH per day.
440 watts of solar - which was our bimini - put that back in quite comfortably. Solar and AGM go together very well, you get enough of a bulk charge during the day, then as the sun goes to a more oblique angle it gives you a couple of hours of float each day. We were power independant for the 6 months we lived onboard - water was our limit, giving us a week to 10 days.

And water is where the cutover for Lithium is in my mind. If you are happy to be a smelly water miser, AGM like we did works just fine. If you want to have long showers each day and have a watermaker, then you might as well have lithium.

If you want showers, you need a water maker. To have a watermaker, you really need to run a generator every few days to power it. If you are going to have a generator anyway, then you are able to give lithium the fast charge they want. And the charging regime will allow lithium to stay in the 40 - 80 % charged rate they prefer.

So, smelly cruisers have AGM, clean cruisers have lithium.

 

[mckenzie.keith]

I got to total amps/day by measuring the amperage draw from each device and multipying that by the amount of time I use each. For example one refrigerator uses 4.8amps with the compressor running. I figure the compressor runs 50% of the time. So, 2.4amps times 24 hours equals 57.6 amps in a day. The TV uses 1.5 amps and we might use it 4 hours. That's 6 amps/day. Add everything up and it comes to 140 amps/day. Not good enough?

4.8 amps * 12 hours per day = 57.6 amp-hours per day. Amps times hours = amp-hours (or Ah). Amps times hours per day = amp-hours per day (or Ah/day).

 

[JC522]

If you want showers, you need a water maker. To have a watermaker, you really need to run a generator every few days to power it. If you are going to have a generator anyway, then you are able to give lithium the fast charge they want. And the charging regime will allow lithium to stay in the 40 - 80 % charged rate they prefer.

So, smelly cruisers have AGM, clean cruisers have lithium.

Water is a whole nuther issue. I have 152 gallons onboard. At 12gal/hrs per day how long would that last?

 

[JC522]

4.8 amps * 12 hours per day = 57.6 amp-hours per day. Amps times hours = amp-hours (or Ah). Amps times hours per day = amp-hours per day (or Ah/day).

No, it doesn't if you read it literally. Anyhow, I think I was really really clear in my meaning. You don't ever get tired of this, do you????

 

[toddster]

I'm finding the power budget much bigger than I worked out on a spreadsheet. But on the old boat, I built everything from scratch, LEDs, efficient refrigeration, low power gadgets. Etc.

The new boat has a lot of old systems to go through and improve. There are several amps going down the drain when "everything is turned off." Tank level monitors and standby power for various gadgets, I suppose. Just having the charger/inverter on with the laptop and iThings & sundry battery chargers plugged in and Starlink going is 10 amps x 24 hours = 240 amp hours! Which was basically my entire power budget. So now I'm only flipping on the AC circuits when I want to use something, or we're plugged in.

In these short dark northern November days, the wind generator often out-does the solar panels. So far I have not really exercised any power budget discipline - lights blazing, TV playing, etc. Gotta run either the engine or a suitcase generator for an hour or two to make up the deficit most days.

 

[Jud - s/v Sputnik]

National Lampoon? For you I'd particularly recommend the April 1976 Sports issue.

Nigel Calder will take you further than any Chinese poet.

I suggest leavening with liberal quantities of Feynman. Calder is but an engineer. And the Chinese sages were, well, sages.

 

[Alaris]

Oh, no? A lot of my friends are engineers and every one of them is a PITA.

So 5.8ah is 5.8 amps of current flow over an hours time. That would equal 139.2 amps in 24 hours. 140ah would be 140 amps of current flow over an hours time or 3360 amps in 24 hours. The textbooks need to be rewritten in plain english.

139.2 amp hours and 3360 amp hours, as multiple people have already told you.

 

[accnick]

139.2 amp hours and 3360 amp hours, as multiple people have already told you.

Now boyz.......

 

[JC522]

139.2 amp hours and 3360 amp hours, as multiple people have already told you.

Look up pedantic.

 

[Alaris]

Look up pedantic.

Look up willful ignorance.

 

[JC522]

I suggest leavening with liberal quantities of Feynman. Calder is but an engineer. And the Chinese sages were, well, sages.

and National Lampoon?

 

[Bryanjb]

With a fridge, but no freezer, 4 people and an hour of TV a day average, we consumed around 120 AH per day.
440 watts of solar - which was our bimini - put that back in quite comfortably. Solar and AGM go together very well, you get enough of a bulk charge during the day, then as the sun goes to a more oblique angle it gives you a couple of hours of float each day. We were power independant for the 6 months we lived onboard - water was our limit, giving us a week to 10 days.

And water is where the cutover for Lithium is in my mind. If you are happy to be a smelly water miser, AGM like we did works just fine. If you want to have long showers each day and have a watermaker, then you might as well have lithium.

If you want showers, you need a water maker. To have a watermaker, you really need to run a generator every few days to power it. If you are going to have a generator anyway, then you are able to give lithium the fast charge they want. And the charging regime will allow lithium to stay in the 40 - 80 % charged rate they prefer.

So, smelly cruisers have AGM, clean cruisers have lithium.

Actually, with a generator and solar you don't need lithium.

 

[JC522]

Look up willful ignorance.

Kinda overtly willful don'tcha think? Not that obvious? I'll work on that. You work on a sense of humor.

 

[Se7en]

Actually, with a generator and solar you don't need lithium.

I agree.
But with a generator and lithium you don't need all the solar. Lithium will do fine with a short sharp charge each day from a generator.

 

[Jud - s/v Sputnik]

and National Lampoon?

My dear man, if you are otherwise challenged then, yes, you may as well. You’ve brought that title up twice here already, so I’d say: follow your gut.

 

[JC522]

My dear man, if you are otherwise challenged then, yes, you may as well. You’ve brought that title up twice here already, so I’d say: follow your gut.

I am many ways challenged, but somehow I manage where my "betters" do not. And don't call me Dear unless you really mean it, baby.

 

[JC522]

We are in a similar situation but with a smaller boat, one fridge, and much smaller house bank. I also looked at lithium, but the total cost including batts, new battery charger, beefed up alternator and belts, etc. did not make sense. Like you the goal was not to be energy independent for weeks, but rather be able to spend 3-4 days at anchor without using the motor. The solution was to add solar. A single 110W flexible panel is enough to run the fridge during the day in sunlight and also have some left over power to charge the batts. In overcast conditions it is much less helpfull, but will still let us squeeze another day or so out of the batts. We have limited deck space and only need solar for cruising so the panel is stored under the aft berth most of the time. Total cost including wiring, panel and charge controller was under $500 for good quality name brand stuff.

I like that idea. Just enough charging to add a few days at anchor before I'd head to a marina anyway to stretch my legs and go to a good restaurant. And it's a simple, cheap solution. Thanks.

 

[Jud - s/v Sputnik]

I am many ways challenged, but somehow I manage where my "betters" do not. And don't call me Dear unless you really mean it, baby.

I mean “dear” in the sense that you came here apparently seeking advice, but then also paradoxically seem disposed to “know it all”, not really endearing yourself to those disposed to give knowledgeable advice. That kind of “dear”.

It’s all good.

I’m in the middle of a fiddly carpentry and plumbing project on board, and needed a humorous diversion. But I stand by my earlier book recos.