CHARGING HOUSE BATTERIES

[part time nomad]

ianc,

I am not very keen on the idea of taking away from the standard mercedes setup as it can create problems, however it seems that your system works well, it`s all down to getting the extra pulleys 100% in line and in the right plane, so it does not start scrubbing the edges of the belt. I have seen this happen many times on extra pulleys! leaving vehicles stranded as it also then effects the water pump/cooling

 

[part time nomad]

I think I will have another try at Mercedes at getting an extra pulley for the crank!

 

[ianc]

Its worth clarifying that it isn't actually a second pulley on the crank - its a different type of pulley with space for 2 belts. Keep in mind that you will also need a tension pulley for the additional belt

 

[canals1164]

We use 4 batteries on 24v system smart split charge relay with solar mains charger along with truck charging them, we then have a battery to battery charger to 1 12v house battery. We don't have a large drain on 12v but the charger from the 24v works well and even with low amps going into 24v from solar in winter it keeps on top of 12v needs. I think the least modification to the mechanical side the better. We have a generator but it has not been used since solar (3 x 250 w) was fitted. Most of the equipment is 24v but some either arnt available at a reasonable price so we did need 12v. One thing we have changed is a 24v to USB point which then charges most phone, sat nav and small toys.

 

[IdaSHO]

Keep in mind that you will also need a tension pulley for the additional belt

No need, so long as the second alternator mount pivots.

 

[part time nomad]

Ianc, I dont suppose you have the part number for it by any chance?

 

[ianc]

Ianc, I dont suppose you have the part number for it by any chance?

Sorry - I don't. But if you can get access to the EPC (my version is dead) then you can look it up

 

[part time nomad]

Thanks Ian, but I dont have the EPC for the Vario, I will try to get someone more helpful at Mercedes.

 

[part time nomad]

Thanks to everyone for all the replies and advice.

But I now have another question?

I have a Webasto Fridge freezer, that can run on 12 or 24 volt

If I run directly from the batteries at either voltage, once they drop below the fridge`s cut out voltage it will stop working!

To reduce this effect I can run it through a voltage converter, but is it best to step down from 24v to 12v or up from 12v to 24v

I feel that the former would be best, but is this worth doing anyway taking into account, the approx 10% consumption of the converter ???

 

[IdaSHO]

If you have 24v already, use it.

It will run a bit more efficiently at 24v

And you dont see the losses associated with a voltage converter.

 

[part time nomad]

4 different ways to make the power supply ?

I think at the moment I may be swaying towards the third option!

any thoughts? or other options. The fridge can run on 12 or 24 volt, and the solar can charge 12 or 24 volt.

 

[loonwheeler]

I find it easiest to stay at 24V for the entire system (truck + house) based on the OEM batteries and alternator. Obvious advantages are lower amps required at higher voltages resulting in smaller more flexible cabling for much of the system. I only step down to 12V for the small things that require small loads such as LED lights and other accessories.

Just my own personal opinion but I would vote for #4 option with an ACR between the house and truck battery system. Get a smart voltage regulator and good battery monitor that can watch both banks and you have a pretty decent system.

Just my 2C.

 

[surfer4life]

stay at 24v for leisures, then as suggested use a dropper for 12v stuff. I have 4 110AH batts being charged by a sterling 24v to 24v b2b, and 200w solar going through a soltronic mppt. Also have a sterling 240v to 24v (that ive never used) for when on a camp site. My sterling fridge is 24v/12v so to reduce voltage drop over distance, best to use 24v. My propex 2800W is also 24v. What i did was buy a control switch panel with 6 switches on each side, each side has its own feed. one side is fed with 24v then the other goes through a 24v to 12v dropper (alfatronix) to give me 6 24v feeds and 6 12v feeds, so i can run the 12v stuff, LED's, toilet flush, cooker etc...

This is the sort of switch panel i used http://www.ebay.co.uk/itm/12-Way-Rocker-Switch-Panel-with-Fuse-Protection-Marine-Boat-Narrowboat-/152017866442?hash=item2364f88eca:g:07oAAOSwRLZT82Er

 

[part time nomad]

Surfer4life thanks for that (and loonwheeler) I have one of those switches, but didnt think of separating the voltage, I will only be running the fridge at 24 v but I could use one switch to isolate the dropper. my heating is Alde 12v (see "another vario project")
thats a lot battery amps you have but a low solar watt, where are you in the world? I am UK and have 420 watts but thinking of increasing!

 

[surfer4life]

Im in the UK also, my 24v 200W panel going through a (decent) MPPT at its best in height of summer gives around 8 AH charge for maybe 6 hours (48AH) then lower amounts when the sun is rising and setting, but id say at least 60AH a day . Its enough to run the fridge (which uses around 24 A/H a day) the water pump, lights (led so use hardly anything) HD TV and ps4 for a couple of hours of a night, propex heater, charge laptops phones etc... and all other appliances.

In winter in the UK is where you'd struggle if full timing. But solar may not be the answer in dec/jan, back up genny maybe?