Lithium upgrade

[otdrmn]

hey all,
i’m looking at upgrading to 200Ah lithium in our 2019 Sunlight T68, along with solar upgrade.
i’ve drawing up this schematic to try and understand what i’m missing, would appreciate any information.

 

[Raul]

Trickle charger is in the wrong place, it should be between leisure to Starter.

 

[Bolti]

my mppt charges starter.

Trickle charger is in the wrong place, it should be between leisure to Starter.

 

[otdrmn]

Trickle charger is in the wrong place, it should be between leisure to Starter.

Im pretty sure the MPPT has the option to charge 2 batteries, hence why it can also connect to the starter

 

[Hoovie]

Im pretty sure the MPPT has the option to charge 2 batteries, hence why it can also connect to the starter

It depends on the Solar Controller. Some do, some don't. So both of you are right (possibly)

What controller are you looking at getting?

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[otdrmn]

It depends on the Solar Controller. Some do, some don't. So both of you are right (possibly)

What controller are you looking at getting?

MPP350 Votronic MPPT 350W Duo 12V 25.5A/1A

 

[Hoovie]

MPP350 Votronic MPPT 350W Duo 12V 25.5A/1A

Decent enough controller. And as you say as a trickle charge output (but only 1A, which can be limiting).

 

[rod_vw]

Speak to the chaps at Roamer, they will do a design service for you.

 

[Itsmcb]

I 'upgraded' to a dual solar controller. As mentioned above it only sends 1amp to the starter battery, however, in reality that's only when there is daylight AND the hab batteries are full so it actually sends a very minimal amount to the vehicle each day, especially in the winter when it's most needed. Not enough to replace the current taken by the alarm over 24 hours. In my opinion your better off with a single output solar controller and battery master type device.

 

[Raul]

Im pretty sure the MPPT has the option to charge 2 batteries, hence why it can also connect to the starter

Then, that’s not a trickle charger, it’s a solar duo charger. What we call a trickle charger, it’s a separate device by its own, commonly named: trickle charger, battery maintainer, battery master etc. Hence my reply. If it’s a duo, then that’s ok.

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[autorouter]

The wire from the Engine to EBL119 isn't right. The wire should go from the starter battery to the EBL119 instead. It's the wire with the 50A fuse next to the starter battery.

That's as the existing wire is now. However you should be thinking about a Battery-to-Battery (B2B) charger to charge the lithium battery from the alternator. If you decide to fit one, then if it's not too big, say 30A, then it can go in that wire from Starter battery to EBL. Note, a B2B is also called a DC-DC charger or Charge Booster. They are a nice upgrade for any motorhome, but regarded as essential for a lithium battery.

 

[GMLS]

Speak to the chaps at Roamer, they will do a design service for you.

And an offer on if you are quick

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[otdrmn]

thanks for all the feedback, below is where i’ve landed and install begins next week.
any orange is input, any green is output.
hoping that a 10a charger is sufficient to top up battery when on mains

 

[autorouter]

There's still a couple of points to consider. The inverter outputs power to the 240V Panel. It's not clear on the diagram, but I hope the 240V/12V Charger is not being powered by the inverter. This results in the charger charging the battery, which powers the Inverter, which powers the 240V Panel, which powers the 240V/12V Charger, and so on in a loop. The charger needs to be on a separate breaker that is not powered by the inverter.

Also the diagram shows 240V power going to the EBL119, which is not necessary if you have a separate charger.. The only thing that 240V does in the EBL is to power the internal 12V charger. So if there is a separate 12V charger then no 240V is required by the EBL. If you disconnect the 240V from it, it will still work fine on the 12V side, just as if there was no 240V supply to the motorhome.

 

[Lenny HB]

You don't appear to have a B2B to control the charging of the alternator to the Lithium.

If you want the starter battery charged from the mains when you are EHU you can leave the EBL connected to mains and pull the 20 amp fuse that controls leisure battery charging.

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[MisterB]

The Votronic range of MPPT's will feed your hab battery aswell as the leisure battery, The thread has suggested that in the winter the charge might not be enough to keep your vehicle battery healthy (not sure how that translates to NZ) but i would see if there is the option of just swapping the output that would normally go to your leisure battery to your vehicle battery. So the vehicle battery, which keeps the alarm etc working, gets more of a charge, of course if there is no solar then neither would get a charge anyway, so its irrelevant whether you use a DUO or a battery master type device.

i have the 250 Duo and the way i have mine set up is the two outputs from the MPPT go to a fuse holder directly below the MPPT, it would take 10 seconds to switch them over if i needed to,

As regards the technical stuff, there are few very knowledgeble funsters already helping you, who have probably fogotten more than i will ever know !!

I just need to tidy the wiring up (installed a 250 to replace my 165 this afternoon

 

[Petroleumblownapart]

I 'upgraded' to a dual solar controller. As mentioned above it only sends 1amp to the starter battery, however, in reality that's only when there is daylight AND the hab batteries are full so it actually sends a very minimal amount to the vehicle each day, especially in the winter when it's most needed. Not enough to replace the current taken by the alarm over 24 hours. In my opinion your better off with a single output solar controller and battery master type device.

Agreed... The battery master acts like a one way valve and if ever the hab batt has a higher voltage than the engine it tops up into the engine battery until they balance.
This will effectively lengthen the time you can run the alarm but because of the one way effect the hab battery will eventually run out of juice. This because as soon as the engine battery drops the battery master will try to top up from the hab. When balanced voltage it will again turn off the transfer until an imbalance occurs again, which gradually pulls everything from the hab, unless you have solar to keep pumping things back up again.