Not a Self-build, but a Tweaker

wildebus

Forum Member
Moved onto checking the power usage of the Water Heater today :geek:

The Cheyenne is fitted with the Truma Ultrastor Water Boiler. This is a 10L capacity system that can work on Gas (where you set the temp you want to heat to) or Electric through a 850W 240V AC Element (and water temp fixed at 70 Celcius).
I charged the batteries overnight and turned off the Fridge this morning so the Boiler would be the only load to monitor ....
Very similar to the pattern of my 10L 2kW Water Heater in the camper van, except of course that 2kW Heater will be faster to get to temp.
1600198832188.png

So initial heating up, then heater element cuts out once up to temperature, followed by a quick power burst as the stored hot water cools down a few degrees
I'll show the voltage/current graph to allow comparision to the Fridge data - you can see how the Voltage drops with the high current draw.
1600199620185.png


A much shorter duty cycle than the fridge, but over 4 times the power - so what does the SOC look like?
1600199108047.png

The main water heating took 8% of the batteries energy, and the later boost took 1.3%. Converting to a more typical 200Ah bank, that first 8% equates to be 24% of a bank that size for that initial heating session - so half the available energy of a Lead Acid bank.
Because the energy use is more focussed, using a battery bank is feasible if the timing is right (for example, you know you will be driving later or it is a sunny summers day.

The final multi-fuel device is the Truma UltraHeat Room Heater. I am not going to do a test for that as the likelyhood of running that of the battery is just about zero.
 

wildebus

Forum Member
I bought as an interim solution one of those extension blocks that plug into a 12V socket and give you 3 x 12V & 4 x USB Sockets. Handy little thing and seems to work well but of course all those connections are together and it makes me realize how much trailing leads around and not being able to use stuff where I want annoys me! When I built Clarence, I put 12V and USB sockets everywhere. And I mean literally everywhere! Got them in all 4 corners of the bed; by the end of the kitchen higher up; opposite side where we sit but lower down; and in the cab area.
Seemed like overkill in a way at the time, but now I know it was the right thing to do as when I want to plug something in, I just do it without thinking about it :) .
Something to put on the To Do list. (I doubt if there is any MH on the market which would be right for me in that specific way, but it should be such a simple change, no biggie to sort out ;) )
 

wildebus

Forum Member
I have now fitted a couple of Twin USB Sockets as a temp measure in the cupboard with the Sargent PDU- so that will be our "Charging Station" for a while (and out of the 4 USBs now available, 3 are already in use!)
I really knew I would not be able to manage with just the extension jobby even in the shortest term (although I am impressed with it for the money and will maybe use it in the cab area for travelling in the longer term)
 

wildebus

Forum Member
Looks like your new "flimsy" has enjoyed a cossetted, loved, life Dave, mind you I'm a bit worried about you going down the "flimsy" route as the next thing we will all be seeing are details about some kind of 'A' frame and a small car to tow behind :ROFLMAO:

Phil
Hey Phil,
It is very handy when you arrive at a Motorhomer Meet and you have your car with you to nip out to the shops or whatever ;)

1600453697439.png
 

wildebus

Forum Member
Well, I think I will be needing new batteries as opposed to just wanting then!

Been away for a little over a day and batteries are down to 11.6V! Setup the battery monitor up so been monitoring from a full charge and IF the batteries still had their full capacity, I would still have 72% of the capacity left (which is what the BMV is saying), but with that voltage level it is more like half that.
Not really surprised as although the batteries were good quaility when installed (confirmed with info from Alpha about the make and model (y)), that was many years ago so they are really at the end of their service life I think.
Just be a matter of using them I think and not worrying too much about dropping below 12V as that stage is pretty well gone :)
Going to try an equalization process a couple of times though as that might give them a wee boost in capacity. If they last another 8 weeks of intermittant use, that will be fine :D
 

wildebus

Forum Member
That’s what happened with mine Dave but much shorter life lol
I was watching TV via a Firestick and the electrics suddenly cut off around 10:30. Voltage went to 10.x V and the sargent system cuts out at that level.
Checking the log I got a total of 76Ah out the battery bank and the voltage did touch just below 9V, so pretty well drained down

I also checked what the Ah usage was when the Voltage went to 12.05 (What I regard as 50% SOC generally) and that was around 45Ah and the voltage started dropping faster, so probably got a realistic 65Ah of "pullable" battery ignoring the rule of not going below 50% (as too late to extend the battery service life as they have already exceeded that).
Going to be hard to work within those limits for someone who likes their gadgets, but we will see :)
I suspect the Sargent charger has not really charged the batteries ultimately right with too low a voltage for a full charge, so I have put on a Victron Charger with a high voltage Recondition setting which might give a bit of an extension and boost to the available capacity :)
 

wildebus

Forum Member
OK ... I like a little graph so here we go ....
Upto 15:20, parked up and voltage rather low!
15:20 to 15:35 was the engine running and the 'split-charge' system kicking (limping?) in with 10Amps of charge.
16:40 onwards is the Victron IP22 20A Mains Charger in recondition mode - voltage is creeping up (currently at 13.0V) and a pretty constant 20Amps whilst in bulk mode.
1600534693377.png

I thought the Sargents split-charge system (think it is just a relay controlled by the D+ signal) would have been better than just 10A? But the connection does only have a 20A fuse, so would be very unlikely to be better than 15A anyway.
No Fear though, a better one is on the cards ;)
 

mistericeman

Forum Member
I bought as an interim solution one of those extension blocks that plug into a 12V socket and give you 3 x 12V & 4 x USB Sockets. Handy little thing and seems to work well but of course all those connections are together and it makes me realize how much trailing leads around and not being able to use stuff where I want annoys me! When I built Clarence, I put 12V and USB sockets everywhere. And I mean literally everywhere! Got them in all 4 corners of the bed; by the end of the kitchen higher up; opposite side where we sit but lower down; and in the cab area.
Seemed like overkill in a way at the time, but now I know it was the right thing to do as when I want to plug something in, I just do it without thinking about it :) .
Something to put on the To Do list. (I doubt if there is any MH on the market which would be right for me in that specific way, but it should be such a simple change, no biggie to sort out ;) )


Same here when we went from the home built transit to the Moho....
It was a shock.... Lots more space BUT storage wasn't right for us...
And not enough electric (battery wise) let alone charging wise...
Amount of charging points was laughable....

Getting there now though with more batteries/solar/ring rscdc30/and USB points etc as well as mobile T'interweb via teltonika router and EE data card/Raspberry pi4 running victron software.

Frankly it was like something out of the dark ages lol
 

wildebus

Forum Member
OK ... I like a little graph so here we go ....
Upto 15:20, parked up and voltage rather low!
15:20 to 15:35 was the engine running and the 'split-charge' system kicking (limping?) in with 10Amps of charge.
16:40 onwards is the Victron IP22 20A Mains Charger in recondition mode - voltage is creeping up (currently at 13.0V) and a pretty constant 20Amps whilst in bulk mode.
View attachment 2962
I thought the Sargents split-charge system (think it is just a relay controlled by the D+ signal) would have been better than just 10A? But the connection does only have a 20A fuse, so would be very unlikely to be better than 15A anyway.
No Fear though, a better one is on the cards ;)
Recharging with the Victron in Recon mode and since the batteries have flagged as being at 100% (charge put back + efficiency factor = charge out since last 100% reset), they have accepted an additional 26Ah and are still charging at 7A in at the moment, so I think I will be able to get a handy amount of charge capacity recovered (y)
 

wildebus

Forum Member
Back to doing some power tests to check on what I need for the Electrics update in terms of Inverters ....

Something I do want to have in the Motorhome is an Electronic Breadbin. "What is that?", I hear you ask" Why do you want an 'electronic breadbin'?"
Well... they seem to be a 'breadbin' for many folk when in their Motorhome, but they usually go by the alternative name of 'Microwave Oven' :)

Took out the 800W Microwave out the kitchen to check how it fits in the cupboard for space, and also how much power it uses when running. I know it is more than the stated power of course, but not actually checked before just how much more. I've posted a graph (of course ;) ) below to show how much power for this specific microwave, heating up a large bowl of water for abut 5 minutes ...

Microwave is 800W model. When in use it actually draws 1214W of AC Power (so around 5A at 240V AC)
1600607045266.png

When off-grid and on the Inverter (which is something I am wanting to be able to do), there is the overhead/conversion losses to be considered of course. So while the 800W Microwave is running, we are actually pulling 1420W out the batteries (equates to around 110A-120A current draw depending on battery bank voltage).
1600607158899.png


So if getting a Victron Inverter, probably need to be looking at the smallest at the 12/2000 model (which is a 1600W Inverter. the 12/1600 is too close to the edge at 1300W).
 

Nabsim

Forum Member
Hmmm, I thought they were supposed to pull more on initial start then drop to or below rated watts. No can they call that an 800W model?
 

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