Electric on-demand water heater?

ChasingOurTrunks

Well-known member
Hi folks,

I'm revisiting my electrical system as my Deep Cycle has given up the ghost. I need to buy a new battery anyway for my rig (my Deep Cycle AGM won't hold a charge anymore) but before I pull the trigger on a potential $1k battery (Yes, I'm drooling on Lithium!), I'm considering my other systems and want to decide if going all electric is worth the expense. I'm considering ditching my trusty Coleman for an induction cooker, and am currently deciding on my hot water system. Right now I use Propane but I'm thinking all electric for hot water hot water solution too, and I came across these things on Amazon:


I'm familiar with on-demand electric hot water heaters for homes, which is what I've linked to above. They are small and compact and light, but I am wondering if anyone has used one in an Overlanding context? By my napkin math, this on demand heater would require a 4000w inverter which is no joke, but if I had that then even an hour-long shower would only draw me down about 30 Amp Hours (and showers are more like 10 minutes tops so the AH draw will in reality be a lot less). Am I on the right track? Does anyone know of 12V water heater options similar to what I've linked? And can anyone comment on the practicality of this, assuming I could swing the inverter?
 

Victorian

Approved Vendor : Total Composites
Generally speaking you can use household electrical boilers. But the challenge is to have enough battery capacity to power the 4000watt inverter. You probably need 600a/hours lithium to do so. That is $6000 in batteries plus solar, plus inverter etc. Just to have true on demand hot water?
you probably better off with the propane system if on demand is super important to you.
if not, check out our 6 litre 12volt boiler. It produces enough hot water ( mixed with cold) for two people having a shower. It only takes roughly 35 minutes to heat up if you need more than 6 litres. .https://expeditionupfitter.com/collections/water-solutions/products/12-volt-water-boiler-for-camper
 

ChasingOurTrunks

Well-known member
Thanks @Victorian -- that's a lot more amp hours than I thought, and I reckon I did my math wrong when calculating it -- not sure how the use of an inverter changes the math.

But, the product you mentioned is great - that's exactly the kind of thing I was looking for, and fairly light too. I will look into that one and decide, thank you!
 

ChasingOurTrunks

Well-known member
Two level bubbles in the cab.
From the position of the bubbles I can tell how many wood blocks and which corner(s).
Shovel for extremes.
Simple, quick , cheap.
Conversion efficiency of inverters vary based on its design and at what percentage of its capacity the inverter is operated at.
Anyway on average its claimed about 10% energy is ’lost’ within an inverter.
Assuming your inverter is 12V input. Your ten minute 30Ah shower would actually consume about 33Ah.
Btw,
You might double check heating capacity of that linked water heater.
You need to know how many liters per minute it can flow and how much temperature rise to expect per liter.
Those heaters are really intended for a handwashing sink.
You might have to circulate a ration of water through it to accumulate enough heated volume for taking a shower.

Good advice, and thank you for correcting the math for me! I can see this getting expensive fast in terms of batteries so I'll think I'll "hold" if I don't go with the option Victorian posted - maybe in a van build someday I'll go electric. Good tips on the flow rates too!
 

ChasingOurTrunks

Well-known member
Just to chime back in so folks know what I landed on:

I decided to go with a cheap deep cycle battery with 100 AH, so not nearly enough for On-demand hot water, but more than enough for my needs (fridge, basic lights, charging).

For hot water, my current solution is an Eccotemp L5 mounted in a knock-off Pelican case, but my main gripes with it are it's size and weight; every cubic foot of volume and pound of weight is precious for me. Previously I had a Zodi Hot Tap, which was small and light and really worked great, but was stolen from me a few years ago when my Jeep got broken into. I've tried to find a replacement, including contacting Zodi, but they might be out of business -- no responses at all, and nobody seems to stock them to order from anywhere else.

I looked at the Mr. Heater and Coleman products that do hot water on demand, but they all represent pretty poor value for money when you consider the size, weight, bulk, and complexity of the, as well as the number of people who have reported that one element fails -- like the pump or the switch -- rendering the whole $$$ unit useless. As far as I can tell, they also are really limited in terms of water pressure; I don't need high volume, but water pressure to properly rinse off is handy.

So, I did the natural thing and took a look at my kitchen box (Remember how I started this journey talking about my electrical system?!?). We used to use a Coleman 425 stove and love it for it's rugged simplicity and if-it-burns-you-can-use-it-for-fuel versatility, but we are now the proud owners of a Jetboil Genesis Basecamp system. This replaces our stove, our pots and pans, and our water heater all in one package, and gets us closer to single fuel source for all of our needs. I just tested it in the backyard -- it takes a maximum of about 20 minutes to heat enough water for the whole family to shower, as we found that 10 litres of boiling water in an ice-cold 25 litre bucket is enough to make the water too hot to use so this 20 minute is a solid estimate. This timing is using the fancy pot that comes with the Genesis; it'll bring water from 5 Celsius to a rolling boil in about 9 minutes.

It was expensive (gift cards made a difference), but it replaces quite a bit of weight and volume in both our sanitation setup and our cooking setup, so we'll try it in July for our month-long trip and if this system works reasonably well we'll stick with it. If I were to get a second large pot (which I can't see myself ever needing but perhaps a Dutch Oven or similar), I could cut this time down to 10-ish minutes I think. All told I got to save quite a few cubic feet of storage in the back area, and I managed to get rid of about 50 lbs (I originally had written much less but that Eccotemp-in-a-case was heavy!).

That's not nothing - a Prinsu rack weighs about 50 lbs, so this weight savings can be applied to a better way to carry some things.
 
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