How Many Amp Hours?

[ssullivan]

How many Amp Hours does your entire boat contain for house batteries, not including the starting battery?

[Strygaldwir]

4 6 volt 375 amp deep cycle batteries. If these go, I'll replace them with the equivalent Rolls batteries. They are warrentied for 7 years and rated for 1300 discharges.

I think just as good a question is how much charging capacity does each boat have. I am still working on that.

Keith

[Vasco]

A couple of 4D's which is a bit over 400 amps. Can usually go three days without charging.

Kiss wind generator
100 amp Zantrex charger
100 amp Balmar and
a Honda EU2000i (to be bought before the winter season)
Would like a couple of large solar panels but they're still a bit pricey. Maybe next season.

[Talbot]

330 amp/hrs

180w solar panel
850w generator
intentions - to have a duogen wind/water generator

[sv_makai]

Makai has

680 amp house bank with seperate starting
2 x 160 amp alt dedicated to house and 2x 55 for starting
4 kyrocea 120 watt panels
50 amp RV power MPPT controller
Kiss windGen
2kw honda portable generator

This will hold us for now

[Jon D]

Sirius has

840 amp hour main bank [Rolls 2 volt cells with hydrocaps]
Seperate starting bank [ 2 x grp 31 start]
270 amp main alternator w/ link 2000R
150 amp bank up alternator with smart regulator [normally charges start batteries only]
100 amp charger
4.2 KW Fisher Panda
KISS wind generator

Might be a tad overkill but we like it.

[CaptainK]

Hey Vasco,

I might be able to direct you to cheaper solar panels? Here's the weblink below:

http://hardydiesel.com

They sell all kinds of stuff. Wind generators. Solar collectors. Diesel generators. Marine diesel engines.

When I had plans to build a sailboat. (Right now I have that idea on hold.) I was going to use this website (Company) to outfit some of the equipment on my boat.

But, I hope that helps ya out?

Regards,

Kevin
CaptainK

[Rick]

ssulivan,

Your question "fits" into the mathmatical case of just how relevant is any statistic to a particular individual. It is not very relevant to YOU. You need to determine for YOUR case just how many Amp-hours needed for YOUR battery bank for YOUR cyclical and non-cyclical requirements. No amount of external data is beneficial to your in this regard.

I have to disagree with rick. As cruising is not an exact science, going with popular averages is a good indicater of what is comfortable. Granted, not very scientific, but if most people like a room at 72 degrees, it is a pretty good bet that you wil not be uncomfortable at 72 degrees.
As for my set up, for live aboard dock side, and weekend trips, 2 4D's, and 2 group 31 starting batteries seems to work just fine. I do not use the inverter much while we anchor on weekends. For extended cruising, I have built, and wired in a 3rd bank with 3 8D's. Straight to the inverter. I will add 2 75 watt panels. By my calculations, this should be more than sufficient.
When we had our house, we lived with 6 Trojan L16's, 2 48 watt panels, and one 75 watt panel. No Generater. This was fine, but most of our lighting was done with oil lamps, our fridge, and hot water, and stove were propane. TV, occasional light, stereo, toaster, and occasional power tools were 110v. The TV was on most of the time, as my wife stayed at home, and we had young kids at home. The jist of it is more is always more comfortable, but an average such as the 400-600 showing up is probably a good place to start.

[GordMay]

From ABYC Section E-11

11.10. LOAD CALCULATIONS

11.10.1. FOR DC SYSTEMS

11.10.1.1. The following method shall be used for calculating the total electrical load requirements for determining the minimum size of each panelboard, switchboard, and their main conductors. Additionally this information may be used to size the alternator, or other charging means, and the battery. (See E-11.7.1.1.1 and ABYC E-10, Storage Batteries.)

11.10.1.1.1. In column A of TABLE II, Electrical Load Requirements Worksheet, list the current rating (amps) of the loads that must be available for use on a continuous duty basis for normal operations;

11.10.1.1.2. In column B of TABLE II, list the current rating (amps) of the remaining loads that are intermittent, and total these loads. Take 10% of the total load in column B, or the current draw of the largest item, whichever is greater, and add this value to the total from column A to establish the total electrical load.

NOTE: Calculations are based on the actual operating amperage for each load, and not on the rating of the circuit breaker or fuse protecting that branch circuit.


TABLE II - ELECTRICAL LOAD REQUIREMENT WORKSHEET

Load ~ “A” Amperes ~ “B” Amperes

Navigation Lights
Cigarette Lighter
Bilge Blower(s)
Cabin Lighting
Bilge Pump(s)
Horn
Wiper(s)
Additional Electronic Equipment
Largest Radio (Transmit Mode)
Trim Tabs
Depth Sounder
Power Trim
Radar
Toilets
Searchlight
Anchor Windlass
Instrument(s)
Winches
Alarm System (standby mode)
Fresh Water Pump(s)
Refrigerator
Engine Electronics

Total Column A ~ Total Column B

10% Column B

Largest Item in Column B

Total Load Required
Total Column A _____
Total Column B _____ (The larger of 10% of Colum B or the largest item)
Total Load _____

11.10.2. FOR AC SYSTEMS

11.10.2.1. POWER SOURCE OPTIONS
The method shown in E-11.10.2.2 shall be used for calculating the total electrical load requirements for determining the size of panelboards and their feeder conductors along with generator, inverter, and shore power capacities. The total power required shall be supplied by one of the following means.

11.10.2.1.1. Single Shore Power Cable – A shore power cable, power inlet, wiring, and components with a minimum capacity to supply the total load as calculated, complying with E-11.7.2.1.1.

11.10.2.1.2. Multiple Shore Power Cables - Multiple shore power cables, power inlets, wiring, and components shall have a minimum total capacity to supply the total load as calculated complying with E-

11.7.2.1.1. All sources need not be of equal capacity, but each power inlet shall be clearly marked to indicate voltage, ampacity, phase (if a three phase system is incorporated), and the load or selector switch that it serves.

11.10.2.1.3. On Board AC Generator(s) or Inverter(s) - On board AC generator(s) or inverter(s) to supply the total load as calculated. Total minimum installed KVA for a single phase system is as follows:

KVA =
(Maximum Total Leg Amps. X System Voltage) / 1000

11.10.2.1.4. Combination of Shore Power Cable(s), On-board Generator(s) and Inverter(s) - A combination of power sources, used simultaneously if the boat circuitry is arranged such that the load connected to each source is isolated from the other in accordance with E-11.5.3.6. Shore power cable(s) plus on-board generator(s) and inverter(s) capacity shall be at least as large as the total electrical load requirements as calculated. Generator(s) and inverters(s) installation and switching shall be as required in E-11.7.3.

11.10.2.2. LOAD CALCULATIONS

11.10.2.2.1. The following is the method for load calculation to determine the minimum size of panelboards and their main feeder conductors as well as the size of the power source(s) supplying these devices. (See E-11.10.2.1.)

11.10.2.2.1.1. Lighting Fixtures and Receptacles - Length times width of living space (excludes spaces exclusively for machinery and open deck areas) times 20 watts per square meter (2 watts per square foot).

Formula:
Length (meters) x width (meters) x 20 = _________ lighting watts, or

Length (feet) x width (feet) x 2 = ________ lighting watts.

11.10.2.2.2. Small Appliances - Galley and Dinette Areas - Number of circuits times 1,500 watts for each 20 ampere appliance circuits.

Formula: Number of circuits x 1,500 = _________ small appliance watts.

11.10.2.2.3. Total

Formula:
Lighting watts plus small appliance watts = _________ total watts.

11.10.2.2.4. Load Factor

Formula: First 2,000 total watts at 100% = _________.
Remaining total watts x 35% = _________.

Total watts divided by system voltage = _________amperes.

11.10.2.2.5. If a shore power system is to operate on 240 volts, split and balance loads into Leg A and Leg B. If a shore power system is to operate on 120 volts, use Leg A only.

Leg A / Leg B

______/______ Total Amperes

11.10.2.2.6. Add nameplate amperes for motor and heater loads

______ /______exhaust and supply fans
______ / _____air conditioners *,**
______ / _____electric, gas, or oil heaters* ______ /
_____25% of largest motor in above items
______/_____Sub-Total

NOTE: *Omit smaller of these two, except include any motor common to both functions.

**If system consists of three or more independent units adjust the total by multiplying by 75% diversity factor.

11.10.2.2.7. Add nameplate amperes at indicated use factor percentage for fixed loads:

Leg A / Leg B

______ ______Disposal -10%
______ ______Water Heater - 100%
______ ______Wall Mounted Ovens – 75%
______ ______Cooking Units - 75%
______ ______Refrigerator -100%
______ ______Freezer – 100%
______ ______Ice Maker - 50%
______ ______Dishwasher - 25%
______ ______Washing Machine – 25%
______ ______Dryer - 25%
______ ______Trash Compactor – 10%
______ ______Air Compressor - 10%
______ ______Battery Chargers – 100%
______ ______Vacuum System - 10%
______ ______Other Fixed Appliances
______ ______Sub-Total

______ ______**Adjusted Sub-Total

NOTE: **If four or more appliances are installed on a leg, adjust the sub-total of that leg by multiplying by 60% diversity factor.

11.10.2.2.8. Determine Total Loads

Leg A / Leg B

______ ______lighting, receptacles, and small appliances (from E-11.10.2.2.5)
______ ______motors and heater loads (from E- 11.10.2.2.6)
______ ______fixed appliances (from E- 11.10.2.2.7)
______ ______ free standing range (See NOTE 1)

______ ______calculated total amperes (load)

NOTES: 1. Add amperes for free standing range as distinguished from separate oven and cooking units. Derive by dividing watts from TABLE III by the supply voltage, e.g., 120 volts or 240 volts.

2. If the total for Legs A and B are unequal, use the larger value to determine the total power required

[ssullivan]

I know, Rick.

I was curious what kind of power consumption and reserve others had. For instance, there are the folks out there that have a single 100 Amp Hour house and that's it. Then, there are people running water makers, TVs, etc... all the time.

I wanted to know what was common, mostly out of curiosity. I currently have 300 Amp Hours, a 70 Amp alternator, and a 50 Amp charger. It's not meeting my needs, as the Alder Barbour fridge kills the fridge battery (100 Amp Hours) in less than 24 hours.

Rick once whispered in the wind:
ssulivan,

Your question "fits" into the mathmatical case of just how relevant is any statistic to a particular individual. It is not very relevant to YOU. You need to determine for YOUR case just how many Amp-hours needed for YOUR battery bank for YOUR cyclical and non-cyclical requirements. No amount of external data is beneficial to your in this regard.

[By Invitation]

Recommendation - Jack Rabbit Marine will design your entire system or re-design your entire system for $400.00. Their fee can be applied to any items you purchase through them and they will provide consulting for as long as you own the boat. They really know what they are doing and will give you all the advice and support you need. It's well worth it.

[Rick]

First, I agree with the previous submission in that I have had professional dealings in years past with Jack Rabbitt marine and found Jack to be an honest forthright businessman. I had wondered if he would ever retire (I think that he is even older than I).

Next, your situation is quite descriptive of what I like to refer to as the "ripple effect" where a nasty low-efficiency load causes an unnecessary complication and expense to the electrical system in order to expand it to meet the demand. Very often I have calculated battery system "size" to be in the region of 400 Amp-hours ONLY if the customer would change the refer to a high-efficiency unit such as a cold holding plate. Typically evaporative refer units are terribly inefficient (yet not always). Sometimes spending $1000 more on a good holding plate than the el-cheapo units will save more than the cost of having to oversize the electrical system (i.e. larger charger, alternator, mounts, battery bank, wiring, photovoltaics, backup genset, etc.).

Having done this type of system design since 1980 I have come to recommend that one such as yourself make a cursory investigation into energy requirements such as the info provided by Gord in order to discover BEFORE spending money on upgrading the electrical system. Initial investigation reveals approximately where one should spend money on more efficient energy loads like lighting (low emi compact flourescents, cold holding plate refers, LED anchor lights, etc.). Once one understands what approximately the number of kW-hours might be consumed over a desired charge/discharge time period (24 hours?) AND one attempts to provide an alternator that will come close to returning that energy in 1 to 2 hours THEN one can add photovoltaic or other secondary sources to enhance the system.

Put it all together with a GOOD battery monitor (one that will measure kW-hours in addition to Amp-hours consumed and returned) with a minimal battery bank (borrowed if necessary). Operate as you might for that discharge time period and MEASURE just exactly how much energy is used. THAT will then dictate the size of the battery bank to buy and accommodate. Knowing the kW-hour number one can debate whether or not to go with flooded or AGM or Gel-cell batteries (Amp-hour numbers will not tell you that because the three types of batteries having all the same Amp-hour rating will NOT have the same kW-hour rating).

[ssullivan]

Wise words, Rick. I am a huge fan of efficiency, and I hadn't realized the old Alder Barbour fridges were so much more wasteful than their modern counterparts.

You wouldn't believe how poorly the refrigerator was set up when I purchased it. It's a standard Alder Barbour with the tiny little "dorm fridge" condenser hanging in an ice box that measures approx 4'x3'x2'. I was on 24/7 before I reduced the size of the box and insulated it.

So are most people able to get 24 hours (or more?) of refrigeration out of a fully charged 100 Amp-Hour battery?

Anyway, thanks for piping in here. Each time I read one of your posts, I'm happy you're a member of this group. Electrical concepts are simple, but the simplicity goes south when you start to add so many existing systems in, and costs of replacing each... such as with the fridge.

For science folks, I feel like I have 3 equations with 7 unknowns sometimes!

Thanks again, Rick for reminding me to methodically focus on efficiency and run the dollar figures along side the electrical figures.

[Rick]

A well insulated 6 cubic foot "box" with a holding plate can be operated in a reasonable warm tropical environment and consume around 15 Amp-hours in 24 hours.

Be aware, though, that "sizing" a battery bank does not merely consist of determining an Amp-hour specification. Other specifications of interest are; internal resistance at the end of the discharge cycle; charge acceptance at the end of the discharge cycle; terminal voltage under the influence of loads.

Determining the later specifications are not necessarily straightforward or understood by battery distributors themselves, who rarely get involved to such a detail (one exception would be with stationary battery power specialists).

For example, it takes a much higher rated Amp-hour specification for a Rolls battery to deliver the same terminal voltage under load as a Trojan L16 with the equivalent Amp-hour rating. The Trojan would also charge accept faster on a recharge cycle taknig less time to reach full. Terminal voltage without load is directly proprotional to the specific gravity of the battery and virtually all AGM and gel-cell batteries have higher specific gravities and terminal voltages than generally available deep-discharge wet cell batteries. This would mean that bilge pumps would turn off faster with "equivalent" AGM or gel-cell bateries than a flooded-cell battery for the same amount of water and head pressure pumped, for example. There is more to this than the WestMarine technical advisor gives their customers in the catalog to influence purchase decisions.