Amp Hours used overnight at anchor

[jefndeb]

Hello,

When we are at anchor, which is a bunch, we usually run the genset an hour or so in the morning too top up the house bank some and maybe use coffee maker, toaster etc. and again later in the early evening when making dinner and some hot water for showers.

When we hit the sack the battery SOC is usually around 93 to 96% and in the am its usually down to around 85 to 90% SOC.

(We have a single LG 375 watt PV panel that is enough, on a fairly sunny day, to actually provide around a 5 to 7 DC charging amps even while running basic daytime things to include the fridge/freezer.)

Just wondering if 80 to 85 amp hours consumed overnight would be considered similar to most cruisers based on a House bank 440ah AGM bank (2 8D) and your nighttime loads, and all those dang parasite mini loads.

It looks to me that when everything is shut down for the night the only load showing is about 5 or 6 amps which is the fridge running and maybe a DC fan and anchor light.

This screenshot is a 30 day graph showing the AH usage (there are 2 days in the middle where we were at a marina and plugged in and did not use any AH)

Thanks for your comments...

Jeff

 

[O C Diver]

Think your math is off a little bit. If you start at 95% and end at 85%, that equals 10% of your backs total AH. If the bank is 440 AH, then your consumption is 44 AH.

Ted

 

[DDW]

The trouble with AGMs is that running between 85 and 95% for long periods of time routinely (say more than a week) will leave them in an early grave.

 

[slowgoesit]

Speaking only for ourselves as full time cruisers:
We have 1,200 ah of LiFePO4, with 2,180 watts of solar. By sundown, the battery bank is usually down to about 95% or so, and by morning, after making morning coffee, it is in the 70% range, so about 300ah of battery drain overnight. That's one Large refrigerator, one small freezer, one 12 cu ft chest freezer, one ice maker, misc lights, dvd and TV for a couple of hours in the evening, computers charging, running Starlink, and one CPAP and anchor light all night. On a sunny day in the PNW, we will be back up to 100% by 10:00 OR 11:00 in the morning. In the AM, after running the coffee pot, and once the SOC is say 90% or so, we turn the water heaters back on as well. All this in the PNW, using solar to keep everything up while at anchor. If the sun is out, we have no need to run a generator. Now that will probably change during the Winter, and definitely will change on overcast days in the Winter.

Not sure if this is "average" or not, as we don't have anything to judge it by, but that's what we use.

 

[socalrider]

We have a 660ah 12V bank & 700W flexible solar (3 years old now, realistically more like 350W.) Sounds like our loads are similar to the OP - medium sized Novacool fridge, misc. iPads, phones, laptops charging, LED lights, etc. Over the 6 months we cruised this summer we'd go to bed at around 95% SOC and wake up at around 85%, then be back up to 100% by 11am just like slowgoesit with their much bigger bank & PV.

We have a DC water heater element that functions as a dump load & had plenty of hot water. Spectra water maker would run all day every 3 days or so. Balmar 105A alternator dumps over 1kW into the pack when we're moving, so that helps catch us up if there's an overcast day. I don't think we dropped below 78% or so the whole summer. No generator, never started the engine specifically to charge, never plugged in to shore power.

Eventually I'd like to move from flex to rigid panels as the Renogy 175W units we have seem to be degrading pretty fast - if they've stabilized, we're probably still good to go.

 

[AKDoug]

Your estimate of draw down overnight is pretty much what I have, 440 ah of AGMs with a refrigerator (estimated 8.5 amps) and the electronics running in the background as well as the stereo, intermittent water pump use, and the salt water toilet. After 36 hours on the hook the 100 amp alternator has me back to 100% in under two hours.

 

[psneeld]

Fridge cycling in Alaska vs Georgia in the summer can be huge.

Measuring amps is really the only way to determine and then it is climate and user dependent.

Even battery storage in cooler bilge temps may change the equation...someone here probably will do the math.

 

[bowball]

Speaking only for ourselves as full time cruisers:
We have 1,200 ah of LiFePO4, with 2,180 watts of solar. By sundown, the battery bank is usually down to about 95% or so, and by morning, after making morning coffee, it is in the 70% range, so about 300ah of battery drain overnight. That's one Large refrigerator, one small freezer, one 12 cu ft chest freezer, one ice maker, misc lights, dvd and TV for a couple of hours in the evening, computers charging, running Starlink, and one CPAP and anchor light all night. On a sunny day in the PNW, we will be back up to 100% by 10:00 OR 11:00 in the morning. In the AM, after running the coffee pot, and once the SOC is say 90% or so, we turn the water heaters back on as well. All this in the PNW, using solar to keep everything up while at anchor. If the sun is out, we have no need to run a generator. Now that will probably change during the Winter, and definitely will change on overcast days in the Winter.

Not sure if this is "average" or not, as we don't have anything to judge it by, but that's what we use.

I'm like this, with only one large fridge, no computers charging, and wake up maybe 10% higher, but starting with a larger battery bank.

Do you use an electric cook top in the morning before starting up?

What would an inductive cook top breakfast due to usage?

I'm thinking of adding solar and lithium iron batteries, and I will start using Humphree at rest electric fins at night, though i have not yet.

 

[Retriever]

Your electrical use seems pretty miserly to me. I leave the inverter on 24/7, have some networking gear going all the time, and the usual household items. I’m not wasteful and use propane for cooking, but I also treat the boat like I would a home and I don’t hesitate to plug something in if it will improve life.

I typically used around 150-200 amp hours (12v) per night on my 37-footer.

On my current N50, it’s more like 300-400 amp hours (12v) per night. The sub zeros and huge chest freezer account for most of the power increase over the 37 and they’re worth it!

On the 77 footer I run, it’s at least double the N50, but we usually run AC and a genset all night. Otherwise it would be 400-500 amp hours at 24v.

 

[O C Diver]

Your electrical use seems pretty miserly to me. I leave the inverter on 24/7, have some networking gear going all the time, and the usual household items. I also treat the boat like I would a home and I don’t hesitate to plug something in if it will improve life.

Stopping around 5pm and starting around 7am usually has me consuming 100+/- amps, add 40 more if the Engel freezer is plugged in. Using the microwave for dinner and the electric blanket when it's cold out, can get me closer to 180 amps.

I will also admit to having a modest amount of stuff plugged in like a laptop, navigation computer and monitor, tablet, phone charger, and then there's the NEMA 2000 network and AIS that stay on 24/7.

I'm happy if I stay above the 50% (180 amps) I consider useable.

Ted

 

[ksanders]

My boat is a power hog. Two referigerators, ice maker, freezer, communications systems, etc... it all adds up.

Going to bed at 10:00 and up at 07:00 draws down about 35% on my 830 AH bank or about 250 amp hours.

I can recharge in the time it takes me to use the watermaker, make breakfast, etc... and then the solar panels run up to 100%

 

[slowgoesit]

I'm like this, with only one large fridge, no computers charging, and wake up maybe 10% higher, but starting with a larger battery bank.

Do you use an electric cook top in the morning before starting up?

What would an inductive cook top breakfast due to usage?

I'm thinking of adding solar and lithium iron batteries, and I will start using Humphree at rest electric fins at night, though i have not yet.

We use propane for cooking unless using the microwave/convection over, or the Instapot.

We also turn off the electric water heaters about 6:00 pm, take our showers, and don't turn on the water heaters until say 10:00 the next morning.

Hot water for cleaning, laundry, dishes etc, but don't use electric water heater unless we have sun for solar.

Optionally, we have hydraunic heat for hot water and heat in boat.

 

[Tator]

Hello,

When we are at anchor, which is a bunch, we usually run the genset an hour or so in the morning too top up the house bank some and maybe use coffee maker, toaster etc. and again later in the early evening when making dinner and some hot water for showers.

When we hit the sack the battery SOC is usually around 93 to 96% and in the am its usually down to around 85 to 90% SOC.

(We have a single LG 375 watt PV panel that is enough, on a fairly sunny day, to actually provide around a 5 to 7 DC charging amps even while running basic daytime things to include the fridge/freezer.)

Just wondering if 80 to 85 amp hours consumed overnight would be considered similar to most cruisers based on a House bank 440ah AGM bank (2 8D) and your nighttime loads, and all those dang parasite mini loads.

It looks to me that when everything is shut down for the night the only load showing is about 5 or 6 amps which is the fridge running and maybe a DC fan and anchor light.

This screenshot is a 30 day graph showing the AH usage (there are 2 days in the middle where we were at a marina and plugged in and did not use any AH)

Thanks for your comments...

JeffView attachment 131862

What program are you using to get the graph readout?

Tator

 

[bowball]

Looking at one boat with 1,000 amp/hr Li-Ion house bank, and they claim night time standby DC load of 35 amps (lighting, fridge and electronics).

Combined with slightly over 1,400 watts (49 amps) of solar, theoretical.

They also estimate the day time standby DC load to be 50-60 amps.

 

[ksanders]

Looking at one boat with 1,000 amp/hr Li-Ion house bank, and they claim night time standby DC load of 35 amps (lighting, fridge and electronics).

Combined with slightly over 1,400 watts (49 amps) of solar, theoretical.

They also estimate the day time standby DC load to be 50-60 amps.

That is not unreasonable with a larger boat, especially if they have not changed over to LED lighting yet.

 

[jefndeb]

Its the Victron VRM. all your data from your various systems are collected and made viewable ....

 

[Nepidae]

Amp hrs used

First, I'll presume that everyone's mention of Ah availability is the 1/2 life of the battery bank. In example a 1200W battery bank would have generally 600W of usable power, AGM batteries, a little more.

Second, I'll presume that the use of the available Ah is a personal thing, that is, some will run a TV and charge toys others won't.

Third, we installed 3-220W Flex PV in '20. Mounting of PV is very important and ANY shading that may obscure the panels will have an effect on capability of that panel. The panels we have are Xantrex Max Flex and the MPPT is a Victron 150/60 model.

A house battery bank is not only Ah it is also the lead in a battery which provides the ability to store the power. The more lead the longer your Ah are available. We carry 6-6V L16 AGM batteries each weighing about 125#.

I was looking at some pictures from '20 of our Victron gauge output and saw that for the month of Oct '20 we had 45kWh of power generated.

We don't have a TV. We have a single 8cu.ft vitrifrigo and an apartment upright freezer. LED bulbs have replaced all of our lights, both DC & AC. We charge 2 laptops, 2 phones and 2 tablets plus a set of 2 marriage savers overnight. In the AM we make coffee and then will usually get underway. While underway we have Balmar equipment that includes 2-125A alternators, 2-614 regulators, duo chargers and a centerfielder which is supplying enough power to cook any breakfast that we want and bring our house bank back to float.

Now, all of that said and not having the daily usage and generation available I can say that as a test, after the PV was installed, we went for an anchorage and for 5 days lived off of the PV.

I don't believe that at any time in the AM we were below 70 SOC and during the day the PV generated enough to stay above 80-90 SOC. Overall generation was around 1.4kWh/day for the days at anchor.

I'd say that 80-85 SOC consumption (leaving 15 SOC in the morning) is not what we would consider normal. BUT, that being said it would depend on how much can be generated to recapture what was used. We do not have a genset on our boat so we would rely on our solar, which we did during our test period.

Each of us uses our power to meet our needs and ours are probably less than most.

Have fun & stay safe out there.

 

[Simi 60]

About 180ah @ 24v 5pm to 5am for us.

 

[Sleepy]

DDW - Can you elaborate on the problem with running AGM batteries between 85-95% ?

 

[Bacchus]

DDW - Can you elaborate on the problem with running AGM batteries between 85-95% ?

I have read repeatedly that AGMs need to be charged to full capacity frequently or they lose capacity. Frequently has been cited as once / week roughly. So not a good idea to rely on gennie charging if at anchor for extended periods and only short runs of gennie.

 

[av8r]

Mid-summer in the PNW our overnight consumption is approx. 60 ah for refrigeration, anchor light, toilet flush and fresh-water pump, and charging our i-devices from 12v chargers. Shoulder season we go pretty quickly to 125ah when we start running our diesel heater and have lights on longer.

 

[slowgoesit]

First, I'll presume that everyone's mention of Ah availability is the 1/2 life of the battery bank. In example a 1200W battery bank would have generally 600W of usable power, AGM batteries, a little more.

Charles, in our case (post # 4) since we have LiFePO, our available AH for the 1200 ah bank is more in range of 85% of the rated battery ah capacity, or about 1020 ah's available.

For FLA, or AGM, the 50% figure is accurate, but generally speaking, when people give the AH capacity of their battery bank, they are NOT speaking "available ah", but rather "rated, or total ah capacity".

LiFePO4 battery manufactures generally state that you can safely, and repeatedly draw their batteries down to somewhere between 5% and 20% of rated capacity depending on the specific manufacturer. We use 15%, per the manufacturers recommendations for our batteries.

So in order to actually know how many ah's they have available, you need to know the type of battery bank (FLA, AGM, LiFePO4, etc), as well as the age, since available ah's tends to go down the older the battery bank is . . . . . At least that's my take on it.

 

[SteveK]

For FLA, or AGM, the 50% figure is accurate, but generally speaking, when people give the AH capacity of their battery bank, they are NOT speaking "available ah", but rather "rated, or total ah capacity".

To add to the quoted, the top 15% of FLA can take another 24 hours to charge, if the charger were still on. so really only running on 35% of the posted Ah. The lithium can be fully charged and now some rapid charged.

I will be getting additional house batteries over winter, so doing a lot of research.
But, still having issue parting with the extra coin when FLA banks can be increased to accommodate needs and still be less $ upfront and last 5 years.

 

[mvweebles]

Charles, in our case (post # 4) since we have LiFePO, our available AH for the 1200 ah bank is more in range of 85% of the rated battery ah capacity, or about 1020 ah's available.

For FLA, or AGM, the 50% figure is accurate, but generally speaking, when people give the AH capacity of their battery bank, they are NOT speaking "available ah", but rather "rated, or total ah capacity".

LiFePO4 battery manufactures generally state that you can safely, and repeatedly draw their batteries down to somewhere between 5% and 20% of rated capacity depending on the specific manufacturer. We use 15%, per the manufacturers recommendations for our batteries.

So in order to actually know how many ah's they have available, you need to know the type of battery bank (FLA, AGM, LiFePO4, etc), as well as the age, since available ah's tends to go down the older the battery bank is . . . . . At least that's my take on it.

How would you replenish 1000 AH of battery capacity?

 

[slowgoesit]

Charles, in our case (post # 4) since we have LiFePO, our available AH for the 1200 ah bank is more in range of 85% of the rated battery ah capacity, or about 1020 ah's available.

For FLA, or AGM, the 50% figure is accurate, but generally speaking, when people give the AH capacity of their battery bank, they are NOT speaking "available ah", but rather "rated, or total ah capacity".

LiFePO4 battery manufactures generally state that you can safely, and repeatedly draw their batteries down to somewhere between 5% and 20% of rated capacity depending on the specific manufacturer. We use 15%, per the manufacturers recommendations for our batteries.

So in order to actually know how many ah's they have available, you need to know the type of battery bank (FLA, AGM, LiFePO4, etc), as well as the age, since available ah's tends to go down the older the battery bank is . . . . . At least that's my take on it.

How would you replenish 1000 AH of battery capacity?

The lowest we've drawn down the LiFePO4 battery bank is about 64%. In sunny Wx in Alaska this summer, using the 2,180 watts (max rated) of solar only, to 100% usually took until about noon. That includes running the electric coffee pot in the am, microwave usage for breakfast, etc. If running the main engine, and the 12kw electric generator running off the pto driven hydraulic pump powering the Victron 12/5000 Inverter Charger, took about 2.5 hours. Either way, this battery bank charges faster than any battery bank I've previously had any experience with!

 

[sunchaser]

To add to the quoted, the top 15% of FLA can take another 24 hours to charge, if the charger were still on. so really only running on 35% of the posted Ah.:

We have no problem getting to 100% after a 200 amp over night draw down followed by normal day's cycle of 6-8 hours cruising and about 1 1/2 hours of genset time.

 

[Bacchus]

Charles, in our case (post # 4) since we have LiFePO, our available AH for the 1200 ah bank is more in range of 85% of the rated battery ah capacity, or about 1020 ah's available.

For FLA, or AGM, the 50% figure is accurate, but generally speaking, when people give the AH capacity of their battery bank, they are NOT speaking "available ah", but rather "rated, or total ah capacity".

LiFePO4 battery manufactures generally state that you can safely, and repeatedly draw their batteries down to somewhere between 5% and 20% of rated capacity depending on the specific manufacturer. We use 15%, per the manufacturers recommendations for our batteries.

So in order to actually know how many ah's they have available, you need to know the type of battery bank (FLA, AGM, LiFePO4, etc), as well as the age, since available ah's tends to go down the older the battery bank is . . . . . At least that's my take on it.

Even Trojan states 80% is usable w/o damage.
50% is useful as a design target but it is not a "limit" nor a point below which damage occurs... you simply use up the available AHs in fewer deep cycles vs more shallow cycles.

 

[Mac2]

To add to the quoted, the top 15% of FLA can take another 24 hours to charge, if the charger were still on. so really only running on 35% of the posted Ah. The lithium can be fully charged and now some rapid charged.

I will be getting additional house batteries over winter, so doing a lot of research.
But, still having issue parting with the extra coin when FLA banks can be increased to accommodate needs and still be less $ upfront and last 5 years.

I too had a hard time rationalizing the cost of LifePo4 as well. It helped with looking at how many cycles you get with LifePo4 batteries. 7k cycles (15 year design life) for the EG-4 I bought. My decision was validated this weekend after removing 4 8d batteries(agm). I left the other 14 in for ballast.