Clueless requesting help with electrics

[JumpShip]

Ok so we currently have an agm battery that runs 4 led roof lights , a powered cool box , a tap and a telly .
The only way to recharge the battery is to plug our c-tek charger into the ehu.
We spend 90 days out each year in france/spain and feel the need to step things up in the power department.
Solar , lithium , maybe an inverter (to run our little nespresso coffee machine) .
We don't have a massive budget for all this and zero experience so gonna need plenty of help from you guys .

 

[Howzat]

For a quick and easy solution, get this. Built in controller, clip to battery when parked up, sorted.

For a more permanent installation, get this and one of these. For the inverter size you're gonna need to find out what that nespresso draws and what it surges at during startup.
I'd do all that before even considering a lithium.

 

[JumpShip]

Thank you for that , I had considered a flexi but I hear the slating they get and realise I may have to go for rigid if I want any sort of lifespan out of them .
Not poptop by the way so they'll be fixed flat to the van
Is a 40a right for my needs ? No clue
Do I need dc to do? Again no clue ...

 

[d8smt]

Thank you for that , I had considered a flexi but I hear the slating they get and realise I may have to go for rigid if I want any sort of lifespan out of them .
Not poptop by the way so they'll be fixed flat to the van
Is a 40a right for my needs ? No clue
Do I need dc to do? Again no clue ...

DC to DC will charge up your battery when you start the engine. Not sure what van you have but the alternator will feed current when the engine is running into the DC-DC and that in turn will charge the battery. My T6.1 charges my 100Ah battery in about 2 hours this way.
All good, but once the battery is flat then you need to recharge it again. So that either means running the engine for ages, reconnecting your ehu battery charger or... wait for it.... doing what @Howzat recommends and getting a solar panel and mppt, which will charge it in the background when the sun is shining. (This will keep the battery topped up when the engine isn't running, and also charge the battery when the van is moving (albeit more slowly) through the solar panel).
If you want to do the DC-DC charging, Renogy do a combined MPPT/DC-DC charging unit for not much more ££ then the Rover MPPT controller that @Howzat recommended. But you'll need to get it plumbed in by an electrician if you're not electrics-savvy.

 

[JumpShip]

Thank d8 , we have a t5.1 so no smart alt if that makes much difference .
Believe it or not I qualified as an electrical engineer when I was a youth but many years not using them skills means I don't remember much of it .

 

[d8smt]

me too on the ElecEng! But 12v electrics have their foibles, I'm not too well up on it myself.

Basically, the best thing you can do is to do a power plan(actually, current plan). I don't know how big an AGM battery you have, but you need to work out how much power/current you need over a 24 hour period - fridge, lights, don't forget USB phone charging, that can suck up Amps (about 5A per hour on a 12v adaptor). Then you'll have a better idea of what your hourly battery drain is, and therefore the battery size you need, and how to charge it. FYI a 100W solar will provide about 5A charge power per hour nto the battery in good sunlight. So a 40A MPPT controller will allow a calculated 800W solar (although in reality it won't because of peak currents, etc. but should be good for 4-500W of solar panel).
If you look at the other solar threads, there's talk of a 360W Victron rigid solar panel for about £175. Coupled with a decent 30/40A MPPT, and with it installed on the roof, that should help keep your battery topped up since it will provide about 15-18A per hour (I'm assuming it's a 100-200Ah battery) assuming decent weather conditions.

 

[JumpShip]

105 agm at the mo , will work out draw .
I'm guessing at 200ah lithium battery maybe and 200w + of solar??

 

[d8smt]

OK, so 100Ah AGM will give you 80Ah in reality of useable capacity, that's 3.3A per hour over the 24 hours. If you add a 200Ah lithium to the AGM, that will give you ~10Ah in total per hour over a 24 hour period. Not sure if your can mix lithium & AGM though, someone can comment. Night be a problem charging both batteries from the same controller.
Assuming you get 10 good hours of sunshine a day (better experts on here than me for this), this means you need to provide 30A per hour of solar for those good hours of sunshine to keep the 2 batteries topped up. That equates to about 600W of solar panel if you're going to survive on solar alone.
HOWEVER this assumes your are going to use all of that battery capacity, which I don't think you will need for a fridge, TV, tap, lights, phone charging. You need to check but I reckon that will only drain around 20A per hour , in which case you can get away with a smaller solar input. The fly in the ointment is your Nespresso machine.... it's gonna cost you an arm and a leg to get that coffee in the morning since you'll likely need a 3kW (?) inverter for that.

 

[JumpShip]

hmmm....maybe azera instant for off grid and nespresso for ehu ...I could live with that .
600w means I need to get a bigger roof .

 

[d8smt]

good call
In reality you won't likely use that much power. You just need to make it what you currently use and size it up from that. A 200 - 360W solar would suffice. Worth going bigger if you can IMHO for very little extra money.

 

[Anakin]

If you’re always going to be on EHU then you don’t need to change anything. It’s when you want independence that you need to start changing a lot.

Changing to 100Ah lifePo is £200 immediately, but it will give a massive increase in available capacity as your AGM battery should only be discharged to 50% or you risk damaging it. LifePO would need a new charger though

 

[JumpShip]

We have been without ehu on a very rare occasion in the past and realise the freedom it would give me when camping in europe to have this facility ( especially with solar )
Yes I am aware lithium will give me more usable power and with an upgrade to 200ah even bigger still .
Charger will need doing anyway so no biggie

 

[Velosaurus]

Just in process of upgrading my T5.1 AGM to 160ah lithium & an existing 150W solar panel. Think I will get 5-6 days without hook up and not using an inverter.

 

[JumpShip]

Now perusing the renogy website for an idea on costs , is there anywhere else I should look ?

 

[Anakin]

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[Anakin]

With a 100Ah LiFePO4 battery and a 150W solar panel, I can run the fridge continuously and not need EHU. I don’t use an inverter though, just use gas for boiling water and an Aeropress for coffee.