Does a 10A 12v to 24v dc-dc charger draws 20A from my alternator?

[navyblue]

Hi. I plan on doing a 24v system for my Kei van but the alternator is only rated for 60A so I can only draw a maximum of 30A. This makes using a dc charger difficult because I don’t want to tax my alternator too much

The reason I need an alternator charger is because roof space is also limited and the biggest panel I can get is 485W

I was thinking about using a Victron orion-tr 12 to 24v 10A dc-dc charger but I’m not sure how much it will draw from the alternator and if I could use a 15A charger I would prefer that

Sorry if the question is too basic, but I couldn’t find any info and searching it is difficult since the keywords are too common

 

[justinm001]

They have the watts right on there. 12/24 10a is 240w so 20a on 12v.

They make a tr-smart 12/24 15 which you can program and limit the amperage. The smart is much better as it'll actually have a charging profile and can charge to 100%
Also a 12/24 5 (120w) so you can get the 10 and the 5 and get 15 amps 24v.

It's nice to have multiple as you can set the voltages a bit different. I have 4 of the largest and twist the voltage screw a bit more on some so as the battery gets fuller it doesn't charge off alternator as much.

 

[navyblue]

Thanks for clarifying. I didn’t know you could limit the amperage on the tr-smart. This makes things so much easier

 

[Aussieguy]

I would stay with 12v... just get a dc-dc that is sized to what your max amp is to be
20amp would work? it is designed that the 20 is the MAXIMUM output
then add the correct 12v wire size ...

it's such a small van the wire run from
starter battery to dc-dc then to house
won't be expensive

 

[0truck0]

if you are serious and this is more that a weekend toy then get a bigger alternator. That same alternator casing can be made to have more amps. Call a rebuilder if you cannot find an alt to fit your vehicle., Every big city has multiple remanufactures . Killing an alternator while on a trip will ruin the trip.

 

[navyblue]

if you are serious and this is more that a weekend toy then get a bigger alternator. That same alternator casing can be made to have more amps. Call a rebuilder if you cannot find an alt to fit your vehicle., Every big city has multiple remanufactures . Killing an alternator while on a trip will ruin the trip.

Thank you for your reply. The plan is to have a 20A dc-dc charger so it isn’t too taxing on the alternator and maybe upgrade the alternator from 60A to 95A later. But I want to get things working first before thinking about upgrades

 

[navyblue]

I would stay with 12v... just get a dc-dc that is sized to what your max amp is to be
20amp would work? it is designed that the 20 is the MAXIMUM output
then add the correct 12v wire size ...

it's such a small van the wire run from
starter battery to dc-dc then to house
won't be expensive

What is the downside of going 24v? If i go 12v it will cost more for the inverter and the mppt charger only than if I bought a 24v hybrid inverter, not to mention the size and the easier install. I can get everything in 24v or use a converter for the things I can’t find

 

[datdude]

Thank you for your reply. The plan is to have a 20A dc-dc charger so it isn’t too taxing on the alternator and maybe upgrade the alternator from 60A to 95A later. But I want to get things working first before thinking about upgrades

Watts are watts, regardless how to slice current and voltage.

 

[Aussieguy]

What is the downside of going 24v? If i go 12v it will cost more for the inverter and the mppt charger only than if I bought a 24v hybrid inverter, not to mention the size and the easier install. I can get everything in 24v or use a converter for the things I can’t find

small van with a small solar capacity

no reason to go 24 controller for under 1000w of panels
Inverter.. put it close to battery .. wire size is not that much more expensive and certainly doable

no need to worry about alternator voltage
or having to add a 24 -12v converter
van storage space is limited

what is benefit on a small van to go 24v

 

[navyblue]

small van with a small solar capacity

no reason to go 24 controller for under 1000w of panels
Inverter.. put it close to battery .. wire size is not that much more expensive and certainly doable

no need to worry about alternator voltage
or having to add a 24 -12v converter
van storage space is limited

what is benefit on a small van to go 24v

For me it would be the cost. I would save from 30 to 40% if I go for 24v.

I did some measurements and 24v would actually use less space. That’s why I’m asking if there a clear disadvantage other than it not being practical

 

[RV8R]

For me it would be the cost. I would save from 30 to 40% if I go for 24v.

I did some measurements and 24v would actually use less space. That’s why I’m asking if there a clear disadvantage other than it not being practical

Without reviewing all aspects of your 24v system I my recommendations would be somewhat assumptive.

Kisae makes IMO decent DC2DC chargers ,,, some are also dual ( alternator & solar ) all in one unit.

And the best part is they are setup by the user for such things as limiting the amps; 5, 10, 15, 20, 25 ,,, to 50 or even 100;

I have a Kisae 1250;

DMT1250 – Kisae Technology Inc

 

[Aussieguy]

First POST says it all

24v system for my Kei van

you might get 400w of panels on top of the van
no savings in wiring as even the cheapest PWM controller + 10g can handle that

Inverter + battery is not going to be HUGE either... so keep the cables short

Just where in a Kei Van are you going to put anything...
and what 120v are you trying to run?


Kei Vans are smaller than a old VW Kombi

 

[HRTKD]

For me it would be the cost. I would save from 30 to 40% if I go for 24v.

Where are you getting those savings numbers from?

 

[time2roll]

I stayed at 12v for 2000w inverter and 675w solar. Zero voltage complications.
Saved the expense of voltage conversion for 24v charging and saved the expense of voltage conversion to run 12v accessories.

 

[navyblue]

Where are you getting those savings numbers from?

Sorry, I forgot to point out that I live in Japan and prices here are kinda weird right now so 24v would save me a bunch

 

[0truck0]

your alt is super low capacity, even going 95 is pretty low, but would work. Can you go bigger? Look up "alternator starter rebuilders" in your area. They might can build you a custom one on the same alt case and make it higher amperage, over 100. It all depends on the case and how much they can fit into it, but generally builders can build an alt to have higher amps.

 

[Aussieguy]

Sorry, I forgot to point out that I live in Japan and prices here are kinda weird right now so 24v would save me a bunch

what devices you think will be able to save money on?

you physically can not carry enough solar to make 24v better option
often the same controller will be used ... 12/24 output
wiring of panels is no problem I got 740w and use 10g for about a 25 foot run

Inverter next to battery solves any wiring issues
you can't carry enough batteries or AC appliances to make a 3000w inverter worthwhile
so inverter + wiring will be small

then you have to factor in the alternator system needs changing to 24
and then you need a 24-12v step down to use any 12v pumps, lights etc