T6: Battery Charging Via Inverter And 230v

[will-h]

I have a 2018 T6 with the usual CBE DS300 split charging setup, which I suspect doesn't work that well.

I was considering installing a DC-DC charger (£250+), but this got me thinking:
I already have a Victron 500VA inverter ready to be installed, and the van already has a CBE 16A mains charger for the leisure battery.

Has anyone considered doing the necessary work to power the inverter from the engine battery (while the engine is running, obviously) and charge the leisure battery via the 230V that produces?

There would be some efficiency loss, and it'd need some custom control work, but nothing too difficult. It would save on weight, cost and perhaps complexity.

Any thoughts?

 

[Phil_G]

Thats exactly what a B2B is, though at a lower intermediate voltage and higher frequency
50hz equipment has larger transformers than the higher-frequency torroids typiclal of a B2B, and bigger smoothing capacitors, but the principle is exactly the same. You would lose the auto-on when the engine is running but you could arrange something to cover that with your existing split-charge relay. Remember you'd be drawing more source current than you're supplying to the leisure battery, so the inverter will need a substantial feed. You'd need to organise the mains-carrying cables safely where they cant be trodden on or caught in a door or sliding seat.

 

[Dellmassive]

That could be done, but its MASSIVELY inefficient...... so its not done.

a low AGM battery may take 20 or more hours to charge up, if your driving that long? . . . . so assuming you are not going to be driving long enough, it would mean that the van would need to be running almost continuously, depending on the loads that are draining the AUX battery you are trying to charge. (65Ah AGM AUX battery drained with fridge,lights, inverter)

You will pay for diesel $$ to run the engine, to power the inverter %loss via a large relay $$, that will power the charger %loss to attempt to charge a leisure battery %loss. . . . to run your loads %loss

so you may end up with only 20% efficiency and need to have the van running way-to-long to effectively charge any leisure battery @ 16A.


just swap out the CBE DS300 split charging setup for a DC-DC charger,

that will cover the AUX batt charging when driving.

the 16A charger will cover AUX batt charging when on EHU.

run the inverter from the AUX battery.

look into adding some solar (fixed/mobile) to help free charge the AUX.

leave the engine to power the starter battery . . . . (but note the van lights will drain down the starter battery if camping etc for an extended period - just add some solar or run the van for a while in the daytime to replenish)



Dc-dc Charger (for Leisure Battery) -- How I Done It --

Battery Monitoring -- How I Done It --

Battery Chargers - How I Did It -

What Solar Panel & Controller ?

Stop/start...regen...smart Alternator... Dc-dc Charger For Leisure Battery Or Not?

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Dellmassive`s -- "how I Done It" -- Thread

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[will-h]

That could be done, but its MASSIVELY inefficient...... so its not done.

a low AGM battery may take 20 or more hours to charge up, if your driving that long? . . . . so assuming you are not going to be driving long enough, it would mean that the van would need to be running almost continuously, depending on the loads that are draining the AUX battery you are trying to charge. (65Ah AGM AUX battery drained with fridge,lights, inverter)

You will pay for diesel $$ to run the engine, to power the inverter %loss via a large relay $$, that will power the charger %loss to attempt to charge a leisure battery %loss. . . . to run your loads %loss

so you may end up with only 20% efficiency and need to have the van running way-to-long to effectively charge any leisure battery @ 16A.
.

Hi Dellmassive, thanks for your reply, and for the links - I have been lurking some time and realised I'd read most of this useful information already

I wasn't thinking about sitting there with the engine idling to charge batteries, but more about a setup for when we're driving wherever we need to go.

My initial thoughts were similar to yours; but I did realise I was looking at, say, a CTEK DC-DC charger with 20A output vs the existing CBE mains charger I have with 16A output. So in terms of charging time, I don't think there would be a great deal of difference. Obviously i can spend quite a lot more $$ for a 40A Redarc or similar, but I'd rather spend that money on better solar!

Efficiency. Well this is interesting. There aren't many efficiency figures quoted for these products. the Victron Orion DC-DC chargers are quoting 87-89% efficiency (at what load level?) and for the Victron 500VA inverter I have, 90% (also: at what load level?). the CBE CB516 charger is quoting 86% efficiency. So if I believed all that, my inverter/16A charger combo would be 0.90*0.86 = 77% efficient. This is probably something I can live with. (is loss such a huge concern when I have 110KW engine with a 180A alternator up the front?)

Someone's pointed out this is something I could test on the bench. I'll give it a try.

 

[travelvolts]

Your biggest problem with this method is the CBE 16 amp charger. It just isn't as clever as it would need to be to do this job properly. Yes, it would work but not very well.
Something like a Victron BlueSmart 12/30 charger would do a much better job.