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Author Topic: Electric Van Conversion Shower Battery Question (for RV owners too)  (Read 743 times)

Gottohaveashower

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I'm curious about why there is no information on people doing Shower setups with electric heating?

I was looking at this Webasto water heater that ran off the diesel but it's super expensive so i was wondering if i could just get a nice tankless water heater and put that money into lithium batteries.  I figure if have my water tank inside the van, a 54 amp heater with 13k watts would change the temperature from 70 to 106.  I don't know the draw on like a 100 amp/hr battery would be. Is that half it's life in an hour?  Would a charge controller help or is that just for bringing power into the batteries?

https://www.grainger.com/product/RHEEM-208-240V-General-Purpose-Electric-53UJ85?cm_sp=Product_Details-_-Products_Based_on_Your_Search-_-IDPPLARECS&cm_vc=IDPPLARECS

Anyways, looking to weld a pan into the floor.  Trying to figure out shower curtain options.

https://www.youtube.com/watch?v=QqIWMNo0aJ4

this guy has it right.  the webasto is just so pricy and i was thinking i'd do the heater with a rooftop a/c

Gizmo100

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Re: Electric Van Conversion Shower Battery Question (for RV owners too)
« Reply #1 on: December 12, 2019, 01:49:57 PM »
Welcome to the RV Forum Gottohaveashower

 I'm pretty sure that the number of lithium batteries you will need to run the water heater will cost more than Webasto water heater.

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Arch Hoagland

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Re: Electric Van Conversion Shower Battery Question (for RV owners too)
« Reply #2 on: December 12, 2019, 03:26:44 PM »
Welcome to the RV Forum Gottohaveashower

 I'm pretty sure that the number of lithium batteries you will need to run the water heater will cost more than Webasto water heater.


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Gottohaveashower

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Re: Electric Van Conversion Shower Battery Question (for RV owners too)
« Reply #3 on: December 12, 2019, 03:52:32 PM »
i think the webasto is 3.5k.  i was told 100 amp batteries were 900 each and i read somewhere they can drain at 20-30 amps per who knows what.  i was already going to get a 400 amp hour setup to run tv and electronics, maybe even an induction cooktop.  i'm just worried i can't supply 13K watts. i mean maybe if that was peak but the 10k watt inverters i was looking at were around 1k but thats not for the pure sine.  i'm planning on having enough batteries, i'm just wondering what type of electronics i would need to get a 240 volt whatever working even if thats possible.

or am i a dummy and trying to get 12v all the way to 240? can you get 240 volt ac from 12 volt dc? haha, too much


thanks so much by the way. first post here, probably will be one of many

SLOweather

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Re: Electric Van Conversion Shower Battery Question (for RV owners too)
« Reply #4 on: December 12, 2019, 05:10:45 PM »
What Lou Schneider said.

A small undersink model Bosch US9 Tronic 3000 C Under Sink Electric Tankless Water Heater draws 9.6 kilowatts (9600 watts). At 240 volts, that's 40 amps. At 12 volts DC, that would be about 800 amps. So, you now need at least 8 or 9 100 AH lithium batteries (10 would be better). 10 BattleBorns would be $9,500.  Then you still need a 10kW inverter.

Y'know, if you're gonna do that, I'd wire the 10 batteries in series to make 120 volts DC and use a residential solar inverter. That would make the wiring much easier. However, I'd check with the battery mfrs about wiring that many in series.

Then, how are you going to charge all those batteries? Probably not with the engine alternator or solar on the roof. A 200 amp engine alternator would take at least 5 hours at full output to make the 1000 amp hours that bank would need.
2014 Itasca Sunstar 31KE
1988 Itasca Suncruiser 31RQ
1968 Travco 201

Lou Schneider

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Re: Electric Van Conversion Shower Battery Question (for RV owners too)
« Reply #5 on: December 12, 2019, 05:15:50 PM »
i think the webasto is 3.5k.  i was told 100 amp batteries were 900 each and i read somewhere they can drain at 20-30 amps per who knows what.  i was already going to get a 400 amp hour setup to run tv and electronics, maybe even an induction cooktop.  i'm just worried i can't supply 13K watts. i mean maybe if that was peak but the 10k watt inverters i was looking at were around 1k but thats not for the pure sine.  i'm planning on having enough batteries, i'm just wondering what type of electronics i would need to get a 240 volt whatever working even if thats possible.

or am i a dummy and trying to get 12v all the way to 240? can you get 240 volt ac from 12 volt dc? haha, too much

Sure you can, it just takes 20 times as much current at 12 volts than you'll get at 240 volts.

Current is only half of the equation.  Power (watts) = Voltage x Current (amps).

13,000 watts (13Kw) requires 1,083 amps at 12 volts or 55 amps at 240 volts.   Use 1,083 amps for 1 hour and you have 1,083 amp-hours drawn out of a 12 volt battery.  Use 1,083 amps for 30 minutes and you'll only use 541.5 amp hours.   Get the comparison between amps and amp-hours?

In other words, you'll need lots and lots of batteries.

SLOweather

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Re: Electric Van Conversion Shower Battery Question (for RV owners too)
« Reply #6 on: December 12, 2019, 05:30:35 PM »
I was going to say to go full hog and build your system around a Tesla Powerwall, but that only peaks at 7kW output, and you will probably need more to drive a water heater.

The problem you are facing is not so much the bulk capacity of the system (with on-demand, you are looking at just a few minutes of current draw for a shower, say). It's the bulk current at whatever voltage to convert into heat.

But, if you were to do a 10 battery system, your whole truck can perhaps be 120VAC wired, and not mess with any 12vdc, except for some lighting when the inverter is off.
2014 Itasca Sunstar 31KE
1988 Itasca Suncruiser 31RQ
1968 Travco 201

Mark_K5LXP

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Re: Electric Van Conversion Shower Battery Question (for RV owners too)
« Reply #7 on: December 12, 2019, 05:33:05 PM »
From personal experience, you can heat water with an electric water heater element and DC current from a string of batteries.  If you can get past the cost of that many Ah, how to charge it and the stuff it takes to make that happen, don't forget that this string of batteries has to live somewhere.  Since the operative word here is "van" I don't picture the space that will fit a pack this size, irrespective of chemistry.

I wonder though if maybe using a conventional RV hot water heater that has a heat exchanger using engine coolant to heat the water might be an option?  Use the electric version to heat when connected to shore power, otherwise run the engine to heat the water.  Doesn't sound elegant or efficient but it's not like you take a shower 5 times a day and it's using equipment already contained in the vehicle.

Mark B.
Albuquerque, NM

Gottohaveashower

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Re: Electric Van Conversion Shower Battery Question (for RV owners too)
« Reply #8 on: December 13, 2019, 01:25:27 PM »
I wonder though if maybe using a conventional RV hot water heater that has a heat exchanger using engine coolant to heat the water might be an option?  Use the electric version to heat when connected to shore power, otherwise run the engine to heat the water.  Doesn't sound elegant or efficient but it's not like you take a shower 5 times a day and it's using equipment already contained in the vehicle.

I've thought I heard something about that somewhere.  That actually sounds like a really cool idea.  This was the closest i could get to anything concrete in 20 minutes of searching: https://sprinter-source.com/forum/showthread.php?t=1374.  The problem is I couldn't find anything that was tankless.  Furthermore the models i looked at were dual heating (electric and something else). On the first listed item (webasto/isotemp) they said the electric heating element heats to 160 alone.  Are there heaters that just have the electric element?  I'm not sold on storing hot water just yet and my storage would probably be in the back under the bed so that would be a lot of tubes running from the engine and back .  This might be asking to much but I have no idea how the engine heat exchange works.  I understand the need for a regular ac plug for running the heating element.  I also understand having to run the van to get hot showers, but that's not the alternator powering anything right? The Webasto I was looking at runs off diesel, i assume that includes a pump but it said it was meant to be installed outside so maybe it needs ventilation?

I'm glad this is being tackled so early.  Keeping straight what i want with whats possible is hard! Thanks for the advise and help.

Edit: Found this: https://www.youtube.com/watch?v=HFRurSf0inM,  this guy: https://www.youtube.com/watch?v=i02m30hZLS8

and this https://www.amazon.com/dp/B0047RAQZG/ref=as_li_ss_tl?SubscriptionId=AKIAJO7E5OLQ67NVPFZA&ascsubtag=495240288-2-1654916390.1576173913&tag=shopperz_origin1-20

Can anyone kinda give me any blessings on moving forward with something like this?  Why don't People try this more often?  This seems like a pretty good alternative to lugging around a gas tank
« Last Edit: December 13, 2019, 02:30:52 PM by Gottohaveashower »

SLOweather

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Re: Electric Van Conversion Shower Battery Question (for RV owners too)
« Reply #9 on: December 13, 2019, 02:20:39 PM »
Quote
I still haven't seen a tankless setup with an electric element that could plug into ac.

The key to this is in one of my posts up above.  Since I wrote that, I found a smaller Bosch under sink tankless water heater that supplies a half a gallon per minute at 45 degree F temperature rise. So, if you're camping and your water tank is at 50 degrees, it will heat the water to 95 degrees, which is still a cool shower and not much flow.

It draws 3,400 watts at 120 volts, or 28 amps. That would take ALL of a 30 amp RV connection to heat the water, with nothing else running. A standard wall 120 VAC outlet is 15 amps, or 20 with a bigger breaker and heavier wire and a different outlet.

Technically, it's possible, but not very feasible.
2014 Itasca Sunstar 31KE
1988 Itasca Suncruiser 31RQ
1968 Travco 201

Gottohaveashower

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Re: Electric Van Conversion Shower Battery Question (for RV owners too)
« Reply #10 on: December 13, 2019, 02:46:36 PM »
ok, gimme a sec on a couple points here:

The key to this is in one of my posts up above.  Since I wrote that, I found a smaller Bosch under sink tankless water heater that supplies a half a gallon per minute at 45 degree F temperature rise. So, if you're camping and your water tank is at 50 degrees, it will heat the water to 95 degrees, which is still a cool shower and not much flow.

My tank is inside the van so id hope the avg van temp would be around 70 degrees which would make for an ok shower at 110 degrees+.  Also i was thinking about doing a recirculating setup so i wouldn't mind if i had to recirculate the water to get it hot i just wouldn't want fresh water for rinsing to be freezing.

A standard wall 120 VAC outlet is 15 amps, or 20 with a bigger breaker and heavier wire and a different outlet.
I wonder though if maybe using a conventional RV hot water heater that has a heat exchanger using engine coolant to heat the water might be an option?  Use the electric version to heat when connected to shore power, otherwise run the engine to heat the water.

ok so atleast with that model it may not be possible to do what Mark was saying and use a regular rv connection at a park?  I was having a laugh for a second thinking that i could possibly do a 500 ah setup, 5 batteries, that would draw the necessary 120 volts.  The only problem is that i'd probably want a pure sine for running electronics and anything over 3000 watts probably puts me back at buying a Webasto. 

I dunno, maybe it is possible. https://theinverterstore.com/product/6000-watt-pure-sine-inverter-charger-24vdc-to-120-240vac-output-50-60hz-listed-to-ul-458-csa/?utm_source=Custom%20Feed&utm_campaign=Exclusive_InverterStore_Feed&utm_medium=cpc&utm_term=10662&gclid=CjwKCAiAis3vBRBdEiwAHXB29Ge0efKh5SktdrkXXgmMSsMj0mr05kIx0lPQ-QmeDgoCk5rywy1-PBoC_9cQAvD_BwE

plus my van water is probably going to stay similar to the avg temp of the van (70 ish). I'm probably going to insulate the floors and put the tank on top of that inside the van
« Last Edit: December 13, 2019, 02:50:53 PM by Gottohaveashower »

Mark_K5LXP

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Re: Electric Van Conversion Shower Battery Question (for RV owners too)
« Reply #11 on: December 13, 2019, 03:00:13 PM »
I have one of the "Motor Aid" water heaters in my class A, which isn't something I would've opted for but it came with it (used).  I haven't done a study of how long it takes to heat a tankful from a cold engine start, when boondocking I use propane and that keeps things heated as needed.  But it's "free", any day I've run the engine there's hot water ready to go.  Exchangers are simply a radiator in reverse - they take heated coolant from the engine and transfer the heat into the cold water in the tank.  Eventually the cold water in the tank will be at the same temperature as the engine coolant.  In my class A they simply used the dash heat outlet on the engine water pump to feed the dash heat and the lines going to the back of the RV for the rear heat and water heater.  Very simple from a plumbing point of view though it does need to be made to withstand radiator pressure (~15PSI).

Seems you're forging into uncharted territory a bit.  Most solutions for heating volumes of water aren't going to be compact or require just a little bit of energy.   Tankless optimizes your water storage but even if you could find a system that would work in a vehicle would require it's own volume and installation constraints that might make a storage tank easier and likely cheaper (tankless run on propane or natural gas anyway).  Another approach might be to use a diesel powered coolant heater and have that serve double duty as both water and cabin heat.  If you had some idea of your actual water demand and recovery time, electric could be an option using a small genset and appropriately sized element.  Water gets heated with a 1kW element just as well a 5kW, just takes longer.  I even saw a 12VDC model on the west marine site. 

It would seem your first step would be to come up with a more or less hard requirement of what you actually need.  A system that has to provide 3 gallons of water once a day vs 5 gallons once an hour, or unlimited/continuous are vastly different.  My take on it is the marine products are more closely suited to your constraints than motorhome solutions so that's what I'd be reading up on to start.

Mark B.
Albuquerque, NM

Gottohaveashower

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Re: Electric Van Conversion Shower Battery Question (for RV owners too)
« Reply #12 on: December 13, 2019, 04:49:23 PM »
Thanks Mark.  Yeah, I realize I have a lot of research ahead of me.  I think once I actually buy the van this spring I'll have better grounding on space.  I'm really gunning for the 144" but with a dog, cat, and girlfriend with a lot of clothes, I may have to go bigger which would open up space for thinking about things like using a storage tank.  In the spirit of having my van look like a work truck, as well as just going green, I'm not sold on the gas boxes that have to be installed on the outside.  I realize my solar panels might be a little obvious and gas cooking is so much nicer than induction but I'll be looking into exterior sidewall stuff, and I may end up taking this out of the country where i may not have easy access to propane exchange (i imagine).

I've done a little more research and there are 120v 15 amp tankless electric water heaters that increase the water at 2gpm about 10 degrees.  If i had a recirculating setup i could theoretically make it work then just use a heat exchange as a backup.  I'm still mentally invested in getting a shower out of my large battery/electronics investment.  Lemme get this straight slowweather: the powerwall is 14 kilowatts so at 12v thats 1000 amp hours (like ten batteries) and because its 5kw continuous that means theres an inverter built in.  i dunno, if i just ran everything off electric i guess a 6 thousand dollar powerhouse miiiiight be feasable. hah, didn't even know it existed.  honestly i'll probably work around it like the Webasto but it's a cool place to start!

edit: just got off the phone with my friend that owns a solar company.  Apparently the limiting fact is watts for a water heater. even though there's a 15 amp limit on shore power, i can draw more out of the batteries.  Plus, apparently I don't need ten batteries 12 volts dc doesn't have to add up to 120 v ac.  I can draw, depending on the battery, up to 100 amps at a time it'll just drain the battery really quickly.  I found out the limiting factor is the inverter; 6000 watt inverters are like 100 lbs and app aren't meant for mobile solutions.  i think i may go with something like this: https://www.grainger.com/product/STIEBEL-ELTRON-120V-Undersink-Electric-Tankless-49X671.  It might be nice to have hot water without having to run the van first. also, i asked about the powerwall, apparently you need a separate inverter and he said their meant for home use but is gonna see if they can standalone. funny, the battery has a 30 amp limit so there you go.
« Last Edit: December 13, 2019, 05:43:02 PM by Gottohaveashower »

SLOweather

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Re: Electric Van Conversion Shower Battery Question (for RV owners too)
« Reply #13 on: December 15, 2019, 12:48:54 PM »
Quote
If i had a recirculating setup i could theoretically make it work then just use a heat exchange as a backup.

What kind of recirculating setup are you thinking about?
2014 Itasca Sunstar 31KE
1988 Itasca Suncruiser 31RQ
1968 Travco 201

Gottohaveashower

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Re: Electric Van Conversion Shower Battery Question (for RV owners too)
« Reply #14 on: December 16, 2019, 06:58:00 PM »
I found this video and thought I'd model my shower off their UV setup. https://www.youtube.com/watch?v=U5_AZj1wrJ4

I'll probably have to ask around at a home improvement store or two.  Actually, I have an interesting update, I found out my Dad has been eyeballing the new electric mercedes.  They only have a 100 mile range at 55kwh but i put the idea up to him that we could build it ourselves.  i've been looking up tesla batteries all afternoon. found this guy too that put tesla batteries in an rv https://www.youtube.com/watch?v=Q3TLuiBq8qw

anyways, thats where i'm at.  the only problem is with this electric setup i would be completely reliant on electric water heating unless i did gas which i feel kinda defeats the purpose of going electric.

What kind of setup do you have?

edit: oh hey, sunstar, cool
« Last Edit: December 17, 2019, 10:00:46 AM by Gottohaveashower »