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Old 07-28-2019, 01:56 PM   #1
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Batteries

How many deep cycle batteries and what kind would I need to power 12 wall sockets? 2 of these sockets will power a refrigerator, microwave and an oven stove, the rest will be used for house hold appliances. Also how would I power a water pump

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Old 07-28-2019, 02:12 PM   #2
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How many deep cycle batteries and what kind would I need to power 12 wall sockets? 2 of these sockets will power a refrigerator, microwave and an oven stove, the rest will be used for house hold appliances. Also how would I power a water pump
Number of connectors is 100% irrelevant.

You need to measure the Ah per day average consumption for each, then add them up to get a total.

Also, batteries are just a time buffer, what are your actual energy sources recharging them while living away from shore power?

The more efficient the appliances, and ideally 12V native as much as possible, the less money you are wasting long term.
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Old 07-28-2019, 02:18 PM   #3
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cross fertilizing http://www.skoolie.net/forums/f49/so...elp-28046.html
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Old 07-28-2019, 02:46 PM   #4
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Number of connectors is 100% irrelevant.

You need to measure the Ah per day average consumption for each, then add them up to get a total.

Also, batteries are just a time buffer, what are your actual energy sources recharging them while living away from shore power?

The more efficient the appliances, and ideally 12V native as much as possible, the less money you are wasting long term.

Thank you, this will help a lot, I will be charging the batteries via the bus alternator, unless I can find a more efficient way that’s not so expensive
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Old 07-28-2019, 02:58 PM   #5
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I'm afraid doing it right requires investing up front, but lowers costs in the long run.

If you don't get the bank back to 100% Full at least a few times a week, it will need replacing more frequently.

Minimum charging time is 6-7 hours no matter how many amps are available. Idling your propulsion engine is not cheap over hundreds of hours. But on long road trips you'd want to capitalize on the "free" energy.

A small genset and / or solar is called for, more the merrier. But you do not need to buy it all at once
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Old 07-28-2019, 03:06 PM   #6
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I'm afraid doing it right requires investing up front, but lowers costs in the long run.

If you don't get the bank back to 100% Full at least a few times a week, it will need replacing more frequently.

Minimum charging time is 6-7 hours no matter how many amps are available. Idling your propulsion engine is not cheap over hundreds of hours. But on long road trips you'd want to capitalize on the "free" energy.

A small genset and / or solar is called for, more the merrier. But you do not need to buy it all at once
Thank you this has been very helpful, I will definitely be changing my way of charging the batteries to solar
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Old 07-28-2019, 03:08 PM   #7
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better to have more than just one source, solar might put out 1/10 the power compared to ICE sources, especially in the first Bulk stage
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Old 07-28-2019, 04:32 PM   #8
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better to have more than just one source, solar might put out 1/10 the power compared to ICE sources, especially in the first Bulk stage
+1 on the multiple sources.

Leverage everything you can. I will have charging from solar (1800watts), shore & generator power and a dedicated alternator.

The last one has been challenging. I have found tons of brackets for adding a second alternator on a 5.9 Cummins but have not found one for the 8.3. If anyone sees one please tell at me
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Old 07-28-2019, 04:52 PM   #9
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Just put the main alt output direct to House, maybe upgrade to higher output if you think worth it.

Keeping Starter topped up is so trivial does not warrant a dedicated alt.
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Old 07-28-2019, 05:06 PM   #10
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Wouldn't that also be dependent on operating loads while driving? Especially those blessed with A/C?
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Old 07-28-2019, 08:43 PM   #11
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Your aircon while driving does not touch House electrics, powered off the engine fanbelt system
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Old 07-28-2019, 08:45 PM   #12
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Alternator output should be much highr than usual load consumption.

Ideally an hour of runtime would cover 24 hours' average usage or more.
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Old 07-28-2019, 09:04 PM   #13
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My bad.
I didn't specify 110 A/C, and whether that'd be problematic for a standardly rated alternator to keep pace with w/o running too hot.
My apologies if that concern had been addresed elsewhere, and I missed it...Click image for larger version

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Old 07-28-2019, 11:35 PM   #14
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I didn't specify 110 A/C, and whether that'd be problematic for a standardly rated alternator to keep pace with w/o running too hot.
One of us is confused, no one brought up AC power recently?

And whether 240V, or 110/120V as here in the US, has nothing to do with alternators.

Finally, within the context of their DC output, although usually 12V, they commonly come in 24V, even 48V, but that Voltage "pressure differential" does not effect the waste heat they produce much.

Until the **power** Watts or current Amps demanded by the load starts to exceed the alt's capacity.

and/or it's just too hot, you need better ventilation in there.

So, what kind of load devices are you thinking about here?
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Old 07-28-2019, 11:37 PM   #15
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I suggest you follow the links mentioned here and the next few

http://www.skoolie.net/forums/showthread.php?p=340843

And read a while.

Took me a few months intensive study to get up to speed in the beginning, not too much has changed in thirty years except prices
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Old 07-29-2019, 06:02 AM   #16
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Actually, I did reference AC, tangentially to the thread tho it was, in reference to your statement about alternator upgrade.

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One of us is confused, no one brought up AC power recently?
...and/or it's just too hot, you need better ventilation in there...
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Just put the main alt output direct to House, maybe upgrade to higher output if you think worth it.

Keeping Starter topped up is so trivial does not warrant a dedicated alt.
I'm not trying to be difficult, hoping the third times a charm...
My bus does not have factory air of any flavor. Better ventilation here in Texas only means that I'm being convectionally cooked.
So... I was inquiring about alternator loading, and the possible need for an upgrade in order to maintain charging of the house bank while drawing off that bank, while running the rooftop A/C off of the transformed AC.
Clear as mud? [emoji16]
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Old 07-29-2019, 09:48 AM   #17
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I'm not trying to be difficult, hoping the third times a charm...
My bus does not have factory air of any flavor. Better ventilation here in Texas only means that I'm being convectionally cooked.
So... I was inquiring about alternator loading, and the possible need for an upgrade in order to maintain charging of the house bank while drawing off that bank, while running the rooftop A/C off of the transformed AC.
Let's go from vague to slightly less vague... (impossible to be specific without some actual equipment selections/specs)

Let's assume some sort of 120VAC powered, 13,500-15,000 btu air conditioning unit - such as a rooftop unit found on most RV's. The math is pretty simple on these. With some variation for the different size units, you will need something around 14 amps @ 120VAC to run it. There is also a startup "demand" that is beyond that. If can add a 'soft start' to that to minimize the inrush load. Without a specific unit in mind, let's generalize this to 1700 watts while the unit is running full blast (high fan, compressor working, etc.). Further, let's guess that the inrush is something around 3000 watts.

All that means (again, being fairly generic) that you will need a 3000 watt inverter (probably pure sine wave) to run this air conditioner. With a very round efficiency number of 85%, you will need approximately 2000 watts into the inverter to run our imaginary air conditioner.

You will need this inverter hooked to a battery bank. Preferably one that is properly sized and constructed for this kind of use. This will keep the inverter running and happy when the battery charging source fluctuates (idling at a stoplight or a cloud rolls by).

So, how to charge/provide power to this battery bank? Within the rules of charging a battery bank, it doesn't matter too much. A big solar array/charge controller or an alternator will both work.

Doing so with an alternator, we know that 2000 watts at generic alternator charging voltage of 13.5 volts is 150 amps. That is to satisfy only the demand of the inverter (ignoring chassis/engine demands).

I'm afraid I don't have any numbers or data on running a typical automotive style alternator at the high end of it's rating. Meaning, I don't know if this will shorten it's life, if a 180 amp alternator will really put out 180 amps (at cruise engine rpm), etc.

Probably a distraction but... I've toyed with doing this with my coach. I have two 24 volt alternators, one 270 amp (at 24VDC) and the other a 100 amp backup). Yeah, 270 amps @24VDC is something around 7500 watts (theoretically). That said, I have ran one 15,000 btu air conditioner from my lithium battery bank and solar array for quite a number of hours. Works just fine. In my case, if the array is producing around 1500 watts, there is no draw on the battery.

Edit: I assume you've seen Christopher's thread/comments regarding how much cooling capacity (BTU) a big metal box cruising down the highway requires?? If not, refer to that (I do not mean to suggest by the above example that 15k btu is enough to keep you cool - I have no idea).
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Old 07-29-2019, 11:11 AM   #18
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Did not read the above.

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My bus does not have factory air of any flavor
Then you need to get aftermarket **engine-powered** aircon added, which can cost lost more than a bus is worth.

Aircon for use while driving cannot reasonably be powered by electricity, unless maybe running multiple generators off gasoline to produce it as well as using the full output from multiple alternators, which seems silly.

Unless you seal off a small box of space with 4" foam and try to aircondition that.

Clear enough?

PS in case you were using the abbreviation AC to mean aircon, that's extremely confusing when the main topic of discussion is electricity, especially with beginners involved.

Please start a separate thread if you want to continue discussing aircon, let's keep this one on track for the OP.
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Old 07-29-2019, 11:48 AM   #19
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Let's go from vague to slightly less vague... (impossible to be specific without some actual equipment selections/specs)

Let's assume some sort of 120VAC powered, 13,500-15,000 btu air conditioning unit - such as a rooftop unit found on most RV's. The math is pretty simple on these. With some variation for the different size units, you will need something around 14 amps @ 120VAC to run it. There is also a startup "demand" that is beyond that. If can add a 'soft start' to that to minimize the inrush load. Without a specific unit in mind, let's generalize this to 1700 watts while the unit is running full blast (high fan, compressor working, etc.). Further, let's guess that the inrush is something around 3000 watts.

All that means (again, being fairly generic) that you will need a 3000 watt inverter (probably pure sine wave) to run this air conditioner. With a very round efficiency number of 85%, you will need approximately 2000 watts into the inverter to run our imaginary air conditioner.

You will need this inverter hooked to a battery bank. Preferably one that is properly sized and constructed for this kind of use. This will keep the inverter running and happy when the battery charging source fluctuates (idling at a stoplight or a cloud rolls by).

So, how to charge/provide power to this battery bank? Within the rules of charging a battery bank, it doesn't matter too much. A big solar array/charge controller or an alternator will both work.

Doing so with an alternator, we know that 2000 watts at generic alternator charging voltage of 13.5 volts is 150 amps. That is to satisfy only the demand of the inverter (ignoring chassis/engine demands).

I'm afraid I don't have any numbers or data on running a typical automotive style alternator at the high end of it's rating. Meaning, I don't know if this will shorten it's life, if a 180 amp alternator will really put out 180 amps (at cruise engine rpm), etc.

Probably a distraction but... I've toyed with doing this with my coach. I have two 24 volt alternators, one 270 amp (at 24VDC) and the other a 100 amp backup). Yeah, 270 amps @24VDC is something around 7500 watts (theoretically). That said, I have ran one 15,000 btu air conditioner from my lithium battery bank and solar array for quite a number of hours. Works just fine. In my case, if the array is producing around 1500 watts, there is no draw on the battery.

Edit: I assume you've seen Christopher's thread/comments regarding how much cooling capacity (BTU) a big metal box cruising down the highway requires?? If not, refer to that (I do not mean to suggest by the above example that 15k btu is enough to keep you cool - I have no idea).
Your less vague #s are pretty much spot-on for what I've got, & what's on my shopping list! [emoji106]
Solar's on that list, but low, so it would be a matter of the alternator keeping the house bank happy while running A/C from it.
May be in error, and that surely wouldn't be a first for me, my understanding is an alternator's output rating is it's top end capacity, much more than's required to charge the starts and run the standard bus accessories. Pretty sure that if forced to continuously run flat out will burn it out sonner'n later...
Oh yeah- when it comes to things A/C, CK is da man! Subscribed to the thread, & check each new posting.
Many thanx for taking the time answering an admittedly generic query!

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Did not read the above.


Then you need to get aftermarket **engine-powered** aircon added, which can cost lost more than a bus is worth.

Aircon for use while driving cannot reasonably be powered by electricity, unless maybe running multiple generators off gasoline to produce it as well as using the full output from multiple alternators, which seems silly.

Unless you seal off a small box of space with 4" foam and try to aircondition that.

Clear enough?

PS in case you were using the abbreviation AC to mean aircon, that's extremely confusing when the main topic of discussion is electricity, especially with beginners involved.

Please start a separate thread if you want to continue discussing aircon, let's keep this one on track for the OP.
Thank you for re-reading and re-replying!
The cost of upgrading to an engine-driven A/C ain't in the cards. Or my bank account... Just looking to see if I mayn't use what resources I have/will have.
Crystalline clear! [emoji106]
Nope: I know the nomenclature for alternating current is AC, & A/C is the abbreviation for air conditioning. Can't view my earlier post ATM, however if I inadvertently mis-spoke with a mis-type, my bad for fumble fingering my fon's minescule keyboard.
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Old 07-29-2019, 12:02 PM   #20
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Your less vague #s are pretty much spot-on for what I've got, & what's on my shopping list!
In keeping with the common warning, I would carefully consider the A/C needs of rig when "moving" before spending a lot of money on this approach and being unhappy.

I've had two motorhomes (34' Fleetwood Pace Arrow and 40' Newmar Dutch Star) and they both cooled acceptably while driving from the roof mounted A/C units (and running the generator). That said, I didn't attempt to keep either of them at icebox temps, I spent most of my time in the west (including hot southwest) - avoiding humidity, and don't recall doing a lot of driving when it was smoking hot (preferring to drive in the cool of the night instead). Yes, motorhomes are different and some supplement roof A/C with engine/dash A/C so this is not an apples to apples comparison. Just hate to see someone spend a lot of time and $$$ just to end up unhappy.
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