24volt to 12volt system hqw to charge leisure battery

[Deadsfo]

I have been to have a look at the Merc508 ex nato ambulances ,they are 24 v start up system with a transformer unit to convert to 12v for lighting (not sure if that includes head/side lights etc), what problems would this create for charging the leisure batteries.

 

[ivecotrucker]

Maximum leisure battery charging rate would be limited to whatever was the V & A output of the "lighting" transformer. If the "starting system is 24V" I would imagine the main vehicle electrics are also 24V, including the road lights.

 

[Sparks]

Post Deleted

 

[FULL TIMER]

I have a 24v system for the vehicle and also a 24v bank for the leisure batteries and use 24v - 12v droppers to my fuse boxes, only reason I kept to 24 leisure bank is because the truck already had 24v eberspacher heaters and the 24v split charge system and battery bank fitted, I havn't bothered wiring the fridge to come on whilst travelling though.

If you wish to have a 12v system for habitation area Sterling Power do excellent 24v battery to 12v battery chargers and really easy to fit see here Sterling Power Products: Battery to Battery Chargers .

to have the fridge working as you drive it would be easy enough ,I would fit a voltage sensitive relay such as this Extreme 4x4 Ltd SPLIT CHARGERS on the 24v vehicle batteries and then a 24v - 12v dropper such as this 0-578-22, 24V To 12V Durite voltage converter, 22A wired to the fridge obviously by correct fusing etc,

ps there are cheaper versions of the above available I am just showing these as they are what I know and have used. If you don't mind manually switching on the fridge when driving it would also be very easy and cheap to have a switch on your dash that would operate a standard 24v 4 pin relay wired to the fridge as such; 24v to switch - 24v from switch to relay terminal 86, 85 to earth, 30 supply from 12v battery bank, 87 to fridge. This might not be best practice mixing voltages, but it would work and only cost a few pounds. if you used an ignition switched 24v supply to the on /off switch it would prevent you from discharging the leisure batteries if you forgot to switch it off manually..

 

[AndyC]

Like Full Timer we also have a 24v vehicle system, in our Merc Vario 814.

We bought it already converted and there was a Waeco 24v > 12v converter to charge the 12v leisure batteries. This was absolutely hopeless so I changed it for a Sterling B2B charger which works very well.

If I'd been doing the conversion myself I would have opted to keep all the batteries and charging systems at 24v, but there was already a very good mains > 12v charger and 160w of solar panels fitted.

I would then have fitted a suitable 24v > 12v converter to supply the leisure fuse board with a regulated voltage. This would mean I could have had a proper charging system without having to worry about the potential for over voltage damage to sensitive equipment such as the TV.

AndyC

 

[Deadsfo]

Like Full Timer we also have a 24v vehicle system, in our Merc Vario 814.

We bought it already converted and there was a Waeco 24v > 12v converter to charge the 12v leisure batteries. This was absolutely hopeless so I changed it for a Sterling B2B charger which works very well.

If I'd been doing the conversion myself I would have opted to keep all the batteries and charging systems at 24v, but there was already a very good mains > 12v charger and 160w of solar panels fitted.

I would then have fitted a suitable 24v > 12v converter to supply the leisure fuse board with a regulated voltage. This would mean I could have had a proper charging system without having to worry about the potential for over voltage damage to sensitive equipment such as the TV.

AndyC

So you would charge the 24volts of leisure batteries off the engine with a split relay to charge the leisure batteries whilst running after the relay is happy with the charge in the starter batteries just as if it was a 12 volt systems ,another point I presume the internal leisure charger for mains hook up would then be a 24v charger

 

[Deadsfo]

I have a 24v system for the vehicle and also a 24v bank for the leisure batteries and use 24v - 12v droppers to my fuse boxes, only reason I kept to 24 leisure bank is because the truck already had 24v eberspacher heaters and the 24v split charge system and battery bank fitted, I havn't bothered wiring the fridge to come on whilst travelling though.

If you wish to have a 12v system for habitation area Sterling Power do excellent 24v battery to 12v battery chargers and really easy to fit see here Sterling Power Products: Battery to Battery Chargers .

to have the fridge working as you drive it would be easy enough ,I would fit a voltage sensitive relay such as this Extreme 4x4 Ltd SPLIT CHARGERS on the 24v vehicle batteries and then a 24v - 12v dropper such as this 0-578-22, 24V To 12V Durite voltage converter, 22A wired to the fridge obviously by correct fusing etc,

ps there are cheaper versions of the above available I am just showing these as they are what I know and have used. If you don't mind manually switching on the fridge when driving it would also be very easy and cheap to have a switch on your dash that would operate a standard 24v 4 pin relay wired to the fridge as such; 24v to switch - 24v from switch to relay terminal 86, 85 to earth, 30 supply from 12v battery bank, 87 to fridge. This might not be best practice mixing voltages, but it would work and only cost a few pounds. if you used an ignition switched 24v supply to the on /off switch it would prevent you from discharging the leisure batteries if you forgot to switch it off manually..

The system you have sounds very much like the system on these 508's these have a webasto or ebaspacher in the back ,this allso has an outlet in the front
I was told that the drop down 24 to 12 v was for the internal electrics in the back .It will take a bit of getting my head round it but it all seems very feasable
thanks for the info,I am at present in negotiation for the 508, but that will be another story.

 

[AndyC]

So you would charge the 24volts of leisure batteries off the engine with a split relay to charge the leisure batteries whilst running after the relay is happy with the charge in the starter batteries just as if it was a 12 volt systems

Exactly so.

another point I presume the internal leisure charger for mains hook up would then be a 24v charger

Yes, these are readily available in the truck and marine markets. I would also use 24v solar panels (or 2 12v ones wired in series).

AndyC

 

[gypsy]

Battery Equaliser

On my Merc 814d I use a battery equaliser (by Vanner) across the 2 x 12V batteries that form the 24v vehicle system. It then allows me to tap off 12v from across one of the vehicle system batteries to charge up my 12v leisure battery system (an additional relays in the wiring so as to only allow this to happen when the engine runs or the mains hook up is charging the 24v main system) . I believe my equaliser allows me to draw upto 100A at 12v which is much greater than most 24v to 12v convertors.