Which Inverter? (1 Viewer)

[A S R]

I want to be able to charge my emtb battery while I’m driving in my CAR. I want a Victron pure sine wave inverter and will be powering it with a dedicated heavy duty wire directly from the cars battery ( via a fuse obviously ) but not sure how powerful an inverter I need. This is the bikes battery charger ( battery and charger both Bosch ) and the battery is a 500w one.
So, which inverter do I need?

Is this too big? https://www.sunstore.co.uk/product/12v-victron-phoenix-inverter/

Or this one? https://www.sunstore.co.uk/product/12v-800w-victron-phoenix-inverter/

 

[DBK]

In round numbers I think your charger will draw about 250W so that is the minimum rating you need for the inverter. Victron models (if they make a 250W one) may be able to run at full power continuously but I would allow a margin and go for 500W or 1000W. The main reason is also because the input rating suggests it will draw around 500W but I can't believe it is only 50% efficient so a rating based on the output of 6A at 36V seems more likely.

 

[Raul]

350w would be the smallest I would go for that specific charger. The 36v can go up to 42v x6A, victron rating is apparent power in VA so 350w will cover some inefficiency.

 

[RogerIvy]

2.15A at 230v is around 500w, which is what your charger will consume.

That will be an inductive load so when sizing an inverter you need to apply the power factor, which will be around 0.85

So minimum 500w / 0.85 = 588va

Take into account some conversion efficiency and a bit of margin and you’re over 600va (notice we’ve changed from talking in w to va).

So probably need to go for the 800va Victron

 

[A S R]

Well I ordered the 800w one yesterday. It just arrived. Blooming heavy for a “ small “ inverter! Hey ho, now got to find a hole in the bulkhead of my car to pass the big wires through! Wish me luck! Think I’m gonna need it!

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[A S R]

Ok, next question is what size fuse do I put in at the battery end? Also, a maxi or midi one?

 

[Raul]

Fuse size is dictated by the size of the cable, and fuse type is dictated by what battery you got. If lithium go mega fuse.

 

[treblid]

Well I ordered the 800w one yesterday

That one is 800VA and is rated at 650W (1500W peak).

 

[A S R]

Fuse size is dictated by the size of the cable, and fuse type is dictated by what battery you got. If lithium go mega fuse.

It’s getting powered off my cars battery only while I’m driving.

 

[Raul]

It’s getting powered off my cars battery only while I’m driving.

What's the size of the cable, and what length?

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[A S R]

Just over 1 metre long, 2 absolute maximum. Hang on….. I’ll go get some pics of the wire.

 

[Raul]

On a 25mm2 cable up to 2m long, and a max surge of 1.5kva a 100A fuse will work fine. Even a midi fuse will do as you use lead battery.

 

[A S R]

Excellent thanks.

 

[A S R]

Well it works!
All wired up with a 100 amp in line mega fuse. Put the battery charger on and away it went. I put a couple of small battens underneath to raise it off the carpet too so it shouldn’t overheat. Perfects.
Thanks to all for your help.

 

[autorouter]

That fat wire in the first pic looks a bit vulnerable on the left of the fuse, as it passes the black wire connection. I would put a bit of something, maybe some plastic conduit or at least a bit of plastic, between them. After a few months of vibration the insulation could easily wear through and short. And maybe fix the fuse holder to something as well, though that looks a bit difficult.

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