THE TEN-AMP BOTTLENECK

Why the next upgrade to Vanilla might not be another battery, another solar panel or another Jackery. It might simply be a bigger blue box.

There is a dangerous stage in every campervan build.

Not electrically dangerous.

Financially dangerous.

It is the moment when everything works perfectly… and the data starts suggesting how it could work even better.

Vanilla has reached that point.

The Fogstar is working. The 200W solar is working. The SmartShunt is watching every electron walk through the door. The Orion can throw 30A at the battery when the engine is running. The Jackery fleet gives me ridiculous amounts of portable 230V energy.

And then there is my Victron Blue Smart.

A lovely little charger.

Ten amps.

Suddenly, ten amps feels rather… polite.

Over 9 and 10 October I gave Vanilla a proper workout.

Not a theoretical spreadsheet test. Not “I left a light on for twenty minutes”.

Actual campervan life.

By 15:00 on 9 October the Fogstar was sitting at 98.4%.

Through the evening and overnight I proceeded to pull roughly 56.5Ah net from it.

By 07:00 the following morning:

45.8% SOC.

More than half a battery used.

And the Fogstar barely raised an eyebrow. Smart.csv

Then something even more interesting happened.

I charged it back up.

But I didn’t use the alternator.

The Orion contributed:

ZERO.

The only energy coming into Vanilla was:

the 200W roof solar and my 10A Blue Smart charger.

By the evening the SmartShunt was reporting around 90% again. Smart.csv

Brilliant.

Except it exposed something.

The battery wasn’t struggling.

The charger was.

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Ten amps is gentle.

Ten amps is easy on cabling.

Ten amps will happily leave a campervan plugged in for hours and quietly put energy back.

And when I had the old leisure battery, that made complete sense.

But Vanilla now has a 105Ah LiFePO₄ Fogstar.

That’s a different animal.

Fogstar’s own guidance says a sensible LiFePO₄ charge current is typically around 20 to 30% of battery capacity. For a 100Ah-class battery, that’s roughly 20 to 30 amps.

Thirty amps into my 105Ah battery works out at:

28.6% of capacity.

Not ridiculous.

Not aggressive.

Almost exactly the top of Fogstar’s recommended charging window.

In fact, Fogstar sells its own 30A charger specifically for batteries including the 105Ah Drift.

That rather kills the argument that 30A is somehow excessive.

It isn’t.

It is what the battery was built to deal with.

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Let’s return to that 45.8% morning.

A 105Ah battery at 45.8% has roughly:

48Ah remaining

and therefore needs about:

57Ah to get back to 100%.

With my current 10A Blue Smart, the basic bulk-charge maths says:

57Ah ÷ 10A = 5.7 hours.

And that’s before real-world loads and the finishing stage.

Five or six hours.

That’s not terrible.

But it is half a day.

Now substitute a 30A charger.

57Ah ÷ 30A = 1.9 hours.

Suddenly the same problem has changed character completely.

I don’t have:

“a flat-ish leisure battery that needs most of the day on mains.”

I have:

“a battery that needs a couple of hours while I have breakfast.”

That is a very different campervan.

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The Victron Blue Smart IP22 12/30 delivers up to 30A at 12V and has Bluetooth monitoring through VictronConnect.

Victron officially offers the IP22 range in 15A, 20A and 30A versions. The lithium charging profile uses 14.2V absorption, exactly in the territory required for the Fogstar. Maximum efficiency is around 93%.

So at full power:

Allow for charger losses and it needs roughly:

460W from the mains.

At 230V that’s only around:

2 amps AC.

That is almost comical.

A charger throwing 30A into the Fogstar barely tickles a normal UK mains supply.

And it is absolutely trivial for Forge.

⸻

This might actually be the bit that convinces me most.

I already have another enormous energy reservoir sitting in Vanilla.

The Jackery.

At the moment I can do:

Jackery → 230V → Blue Smart → Fogstar

But with the 10A Blue Smart, transferring serious energy takes ages.

The hose is too small.

Install a 30A Blue Smart and suddenly Forge can pump roughly 426W DC into the Fogstar.

So imagine I’ve been parked for a couple of filthy winter days.

Solar has been rubbish.

Fogstar is down around 30 or 40%.

I don’t need to start the engine.

I don’t need campsite EHU.

I don’t need to panic.

I turn Forge on.

Plug the Blue Smart in.

And effectively open a 30A energy bridge between my big portable energy bank and Vanilla’s 12V battery.

There are conversion losses, obviously. Jackery DC becomes AC, then Blue Smart converts it back to DC.

Thermodynamically elegant it is not.

Operationally?

Bloody useful.

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There is another nice distinction here.

I’ve been investigating feeding the whole van’s EHU inlet from the Jackery, which raises the interesting floating-neutral/RCD question.

This doesn’t.

Here the Jackery is simply powering a mains battery charger in the normal way:

Jackery socket → Blue Smart → Fogstar.

That is much simpler electrically.

The charger provides the DC output architecture.

No pretending Forge is a campsite pedestal.

No trying to energise Vanilla’s complete 230V installation.

Just a charger doing charger things.

That appeals to me enormously.

⸻

Quite the opposite.

The roof has just proved how useful it is.

On 9 October:

120Wh

On 10 October:

240Wh

Total:

360Wh from the sky. SolarHistory(20261011-014828).csv

And the 10th is particularly revealing.

Peak solar power was only 72W.

But because the Fogstar was hungry, the MPPT spent 670 minutes in Bulk.

Eleven hours and ten minutes.

It never even reached absorption or float that day. SolarHistory(20261011-014828).csv

That tells me exactly how the system wants to operate.

Solar does the marathon.

The Blue Smart does the sprint.

SUN IN. FREE ENERGY ALL DAY.

Then, when I actually need a rapid refill:

30 AMPS. NOW.

That is a far better division of labour than expecting a 200W October roof to rescue a heavily discharged battery by itself.

⸻

There is also something beautifully balanced about the proposed setup.

My Fogstar would effectively have three very different ways of finding energy:

Orion: 30A while driving. Blue Smart: 30A when 230V is available. SmartSolar: up to 15A whenever the sky cooperates.

I could arrive somewhere low.

Drive and recover quickly.

Stop somewhere with mains and recover quickly.

Or sit completely off-grid and let solar slowly refill the tank.

The battery doesn’t care where the electrons came from.

It just counts them.

And so does the SmartShunt.

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This video is particularly relevant because it is exactly the sort of installation I’m talking about: a lithium-compatible Victron IP22 30A charger going into a campervan, replacing a lower-output charger.

Then there is this more recent van conversion installation and review of the Blue Smart IP22 12/30 itself.

And because half the reason I like the Victron ecosystem is being able to interrogate it afterwards like an electrical crime scene, this is Victron’s own guide to the Blue Smart history and settings inside VictronConnect.

That’s the bit that makes this feel less like bolting in another charger and more like expanding the existing Vanilla power system.

Same app.

Same data ecosystem.

Same obsessive graphs.

Perfect.

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This is where I have to try to talk myself out of it.

The 30A Blue Smart is IP22.

My current Blue Smart IP65 is far more rugged.

IP22 means the new charger needs a proper dry, protected and ventilated installation position. It isn’t something I’d want getting splashed or stuffed inside a sealed cupboard.

And 30A means the DC installation matters.

Victron’s own installation guidance recommends 10mm² cable for the 12/30 at runs up to 3m, rising to 16mm² for 3 to 4.5m, with longer runs discouraged. The 12/30 specification uses a 40A output fuse rating.

So this absolutely isn’t:

remove 10A charger → connect 30A charger to the same skinny wires → celebrate.

The cables, fuse, terminations, ventilation and mounting all need doing properly.

Good.

They should.

This isn’t a USB charger.

It is a 400-plus-watt piece of battery infrastructure.

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Do I actually need it?

Strictly?

No.

The experiment proved the opposite.

My existing 10A Blue Smart plus solar successfully recovered Vanilla from the mid-40s back towards 90%.

Nothing failed.

Nothing ran out.

Nothing required rescuing.

So if the aim is merely:

“Can Vanilla work with the equipment she already has?”

The answer is emphatically yes.

But that’s not quite the question anymore.

The question is:

“Does the 30A charger remove a real limitation from the system?”

And now I have the data.

Yes.

It removes time.

And time is one of the most valuable commodities in an off-grid electrical system.

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THE DIFFERENCE IS NOT CAPACITY. IT IS RECOVERY.

I’ve spent months thinking about how much energy Vanilla can store.

Fogstar.

Jackery.

Solar.

Amp-hours.

Watt-hours.

Five kilowatt-hours of total energy available across the whole system.

But storage is only one half of the story.

A good off-grid system doesn’t merely ask:

HOW MUCH CAN I CARRY?

It asks:

HOW QUICKLY CAN I GET IT BACK?

That is what the 30A charger changes.

It doesn’t give Vanilla one extra watt-hour of battery capacity.

It makes the capacity I already own dramatically easier to reuse.

That’s arguably a more intelligent upgrade than simply adding another battery.

⸻

Here’s the question I keep coming back to.

Imagine it’s January.

Cold.

Grey.

Webasto has been working.

Fridge has been running.

I’ve spent the evening somewhere off-grid.

Fogstar wakes up at 45%.

With the 10A charger I look at that and think:

“Six hours.”

With a 30A charger:

“Coffee. Breakfast. Couple of hours.”

Or:

Forge on.

30A flowing.

Fogstar recovering.

Done.

That feels much more like the system I’ve been trying to build.

Not a giant battery bank designed around anxiety.

A small, clever, resilient microgrid designed around recovery.

⸻

SO… AM I CONVINCED?

Annoyingly, yes.

Because this isn’t an upgrade invented by a brochure.

Vanilla herself produced the evidence.

The Fogstar comfortably handled a real discharge to 45.8%.

The solar contributed 360Wh across two October days.

The Blue Smart successfully put the battery back together.

And the only part of that process that felt slow was the 10A ceiling.

Thirty amps is right in Fogstar’s recommended charging-rate territory. Fogstar itself sells a 30A charger for this battery class. Victron makes the exact 30A charger that fits the ecosystem already in Vanilla.

So I’m no longer thinking:

DO I NEED MORE BATTERY?

I’m thinking:

I NEED A BIGGER TAP.

105Ah Fogstar.

200W roof.

30A Orion.

30A mains charger.

Jackery reserve.

Every amp measured.

Every charging route independent.

Every failure leaving another way home.

USE. HARVEST. RECOVER. REPEAT.

That’s not battery anxiety.

That’s Vanilla Power 2.0.

TEN AMPS PROVED THE IDEA.