Time on batteries (1 Viewer)

[Texan52]

We are going away this weekend fri to mon no hook up. PVC two 100ah batteries and 200w solar. My concern is with a compressor fridge and probably needing the heating on 24hrs plus the fact we will get negligible solar, will we run out of power ?

 

[pappajohn]

Probably!

 

[berni109]

Maybe!
Hookup at home on Wednesday so batteries fully charged and fridge down to temperature. Gives u a fighting chance but depending how much insulation u have and how cold it is outside u may be going home on Sunday.

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[Tombola]

The fridge will be the issue, if its a truma heater on the new system you could cope.
use Natures fridge

 

[Bobby-gg]

Switch the fridge off overnight when it's not being opened?

 

[Tombola]

Plenty times I leave gear to keep cool in the garage/locker and not in the fridge.
Beer mostly

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[Spriddler]

We are going away this weekend fri to mon no hook up. PVC two 100ah batteries and 200w solar. My concern is with a compressor fridge and probably needing the heating on 24hrs plus the fact we will get negligible solar, will we run out of power ?

With this weather, for only 4 days you could keep the fridge stuff outside but depending upon where you're going be careful it doesn't freeze.

 

[Texan52]

Thanks for your comments. The van is a S&L motorhomes Apollo one year old so should be insulated well. we were away last weekend on hookup. We only needed the truma4 heating on number 14 to keep warm. I am planning to Hook up at home on wed and put the fridge and heating on hopefully this will give us a head start when we get to site

 

[JockandRita]

We are going away this weekend fri to mon no hook up. PVC two 100ah batteries and 200w solar. My concern is with a compressor fridge and probably needing the heating on 24hrs plus the fact we will get negligible solar, will we run out of power ?

Without a doubt.............unfortunately.

As suggested, chill the fridge down first on EHU at home then stick in a couple of big bottles of frozen water, or milk, and only open the door when necessary. You'll possibly get away with not needing to operate it at all once on site. Some folks use the same technique when on a 3-4 day ferry crossing, with acceptable results.

This will conserve your (useable) 100 Amps of battery power for the more important heating fan, (and TV if one in use).

Good luck, and have a safe and warm weekend away.

Jock.

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[Vipar]

As at home we always have the freezer and fridges full open doors as little as possible. Cheaper to run and always have a stock of food should an emergency occur. Remember Lenny in Germany? Check for gall stone before you leave

 

[Texan52]

I like that idea of the frozen water bottles. We probably won’t need the fried after sat night

 

[Richard n Ann]

Buy a passive coolbox and keep it outside. We've got a coleman xtreme and it's good, I chuck some ice cubes in it in summer and water drains out the bottom

Also you won't need the heating on when you've been cooking.

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[TheMachMan]

I assume no gas for heating?

 

[Texan52]

Yes got gas truma 4e combi boiler. Just an other thought. If I turned the fridge of on fri night would I last out ok. I think the gas only uses about 2amps so might survive on that regime. It will be on very low setting at night

 

[Lenny HB]

You will propably just survive if you are careful, I don't understand why you would want the heating on 24 hours.

The Truma will take around 5-6 amps on startup but once the van is up to temperature will drop to about 1 amp (a bit more if you have the classic controls rather than the CP plus).
Idealy you don't want to run your batteries below 50% (unless they are Gels). 24 hours with the heating on you will be below 50% and that is without anything else running.

You say the van is well insulated so you shouldn't need heating at night and if it's sunny you shouldn't hardly need it during the day.
By not running the heating at night & during the day the fridge won't have to work so hard.

200 watts of solar won't do much at this time of year, if you have a good quality MPPT regulator on a bright sunny day with clear blue skies you may get around 10a/h on the south coast, less the further north you go.

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[Insider]

You will propably just survive if you are careful, I don't understand why you would want the heating on 24 hours.

The Truma will take around 5-6 amps on startup but once the van is up to temperature will drop to about 1 amp (a bit more if you have the classic controls rather than the CP plus).
Idealy you don't want to run your batteries below 50% (unless they are Gels). 24 hours with the heating on you will be below 50% and that is without anything else running.

You say the van is well insulated so you shouldn't need heating at night and if it's sunny you shouldn't hardly need it during the day.
By not running the heating at night & during the day the fridge won't have to work so hard.

200 watts of solar won't do much at this time of year, if you have a good quality MPPT regulator on a bright sunny day with clear blue skies you may get around 10a/h on the south coast, less the further north you go.

Apologies for hijacking the thread.......

Lenny - I have just bought the CP Plus control unit to replace the classic control of my Truma 4E and given that the CP unit only requires something like 30 to 60mA(from memory) I'm assuming that you're implying the Truma boiler is more efficient when controlled by the CP unit. Genuinely interested as to why - is it down to the CP having a microcontroller and thus better able to control the temp?

There should be a button to create a new thread for nerd questions like this - sorry to the OP again!!!

 

[Lenny HB]

Apologies for hijacking the thread.......

Lenny - I have just bought the CP Plus control unit to replace the classic control of my Truma 4E and given that the CP unit only requires something like 30 to 60mA(from memory) I'm assuming that you're implying the Truma boiler is more efficient when controlled by the CP unit. Genuinely interested as to why - is it down to the CP having a microcontroller and thus better able to control the temp?

There should be a button to create a new thread for nerd questions like this - sorry to the OP again!!!

The CP Plus does a far better job of control the fan and the boiler temperature. Being able to select the temperature you want in the van is far better than approx temp on the old dial and if you make use of the offset you can get it quite accurate.
Biggest difference I notice is that once the van is up to temperature the fan speed drops to a lower speed than with the classic controller. In my van once the speed has dropped I can't hear the fan and the outlet from the vents is a very gentle airflow & maintains the temperature in the van perfectly.
In this mode the current draw is 0.8 - 0.9 amps compared to around 1.25amps when using the classic controller.

 

[Dave_E]

Have you considered a b2b charger.Have a great few days away.

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[Deneb]

Also having a compressor fridge, and 200W of solar panels, which are pretty useless at this time of year, we managed 5 nights a couple of years ago in freezing conditions in the Dales, by being very economical with electrical consumption, including no TV use and reading via Kindle self-illumination after dark. We packed the freezer compartment with freeze blocks during the day and distributed them within the main fridge compartment before turning it off overnight.

I have since fitted a B2B charger, and found that with an hour or more driving each day we can pretty much carry on indefinitely without having to worry about an odd hour or two of TV or internal lighting, but of course if you are static on a pitch for several days with no intention to move, that is not going to help!

These are the conditions where a calibrated battery monitor such as the Victron BMV or Nasa BM comes into its own, as you have a pretty good idea of the state of your batteries at any time, and know how much further you can safely discharge them without dropping below 50% SOC or whatever limit you might choose to impose.

 

[Texan52]

Thanks for all your ideas. Think will use the frozen bottle idea and the cooler box outside for beers. After all only away three nights. Interested in the BVM. Any chance of a bit more info.

 

[Deneb]

Thanks for all your ideas. Think will use the frozen bottle idea and the cooler box outside for beers. After all only away three nights. Interested in the BVM. Any chance of a bit more info.

You could start with this thread:

Victron Smartshunt Battery Monitor

Is anyone using the Victron Smartshunt Battery Monitor? Any thoughts, recommendations, issues or otherwise? I’m thinking about adding one to monitor my batteries and compliment my Smartsolar controller. https://www.victronenergy.com/battery-monitors/smart-battery-shunt

www.motorhomefun.co.uk

Search the forum for "BMV" and I'm sure that plenty more will come up.

Victron now make a "SmartShunt" which is the same battery monitor without a physical gauge, needs to be read via an app on your phone. The "traditional" BMV is available as a physical gauge only or a bluetooth enabled gauge that can be physically read or interrogated via the phone app as per the SmartShunt.

Battery monitors - Victron Energy

The Victron Energy battery monitors monitor the charge status of your battery and ensure a uniform charge status.

www.victronenergy.com

Nasa battery monitors perform the same function, but have bigger displays - perfect for people with poor eyesight, but iut does mean you need more real estate to fit them . They also have a bluetooth device similar to the Victron SamrtShunt.

Battery Monitors - Nasa Marine Instruments

When you need a battery monitor but don’t have space for the display or routing the cables would be a nightmare, there is now a solution.

www.nasamarine.com

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[WillH]

The solar panel is a conundrum. I have a 100w panel on the van, today the sun will only rise to 12 deg above the horizon at midday and it rises at 8.30 setting shortly before 4.00 pm. I'll be lucky to get anything from the panel even if the sun does shine (it's 100% overcast at present). It certainly does not produce enough power to keep both batteries charged, I calculated I should need 400w of panel to do that and the roof ain't big enough.

 

[Fontie]

How did it go in the end, did your batteries hold up ?