Inverter run from Leisure Battery(ies)

[Guest Tracker]

Would it be possible, and if possible would it be more (or less) efficient than a 12 volt inverter, to run a 24 volt input inverter - about 1000 watt for a microwave - off of the two leisure batteries wired in series?

 

There would, I guess, need to be some form of protection to prevent damage to the 12 volt system and engine electrics?

 

Any thoughts anyone?

 

 

[spospe]

The rule of thumb here is that the less the voltage needs to be changed the more efficient, so yes a 24-volt inverter would be better than a 12-volt version.

 

The downside would be the quite complicated battery wiring and changeover arrangements. Two 12 volt batteries in series would indeed give a 24 volt output, but given that your 'van has 12 volt electrics then these batteries would need to be charged in parallel, then switched to series working for the inverter.

 

All the other 'van electrical devices that run only on 12 volt, would need connecting to one battery only, meaning that the other battery would be used just for the inverter and would be unusable for other purposes ......... unless you designed a switchover arrangement that let the two batteries run in parallel until the inverter was switched on and then placed them in series (just for the inverter) and at the same time connected all the other 12 volt equipment to just one battery.

 

My advice is to forget it, it's too complicated and too accident-prone.

 

[Geoff Cole]

Hi Tracker,

certainly the current consumption would be less on 24v around 42amps compared with 84amps on 12v using a 1000w inverter, but the drain on even 2 batteries of 110aph would still be very high. I have come across these dual voltage sytems in boats where the lighting and light loads are 12v and heavy loads are 24v but here weight and space is not normally at a premium and the batteries are usually huge around 220aph each. There are normally 2 alternators fitted on the engine one at 12v and one at 24v and the wiring systems are completely separate.

The bottom line is that it is not a practical option to do this on a motorhome.

Regards Geoff

[Guest Tracker]

Thanks both for the replies - I too have come across dual 12/24 voltage system on a boat many years ago but I could not remember how it was done, which is why I asked.

 

I thought it would be impractical - so another bright idea bites the dust then!

[davenewellhome]

Hi Richard, basically its just not worth the effort. An 1800 Watt inverter will consume approximately 2000 Watts plus to give 1800 Watts at 240 Volts (probably a lot higher at startup of load and dependent on the efficiency of the inverter in question) regardless of the input voltage. Therefore there is no advantage to using 24Volts input over 12 Volts input. Especially if your charging system is 12 Volts.

 

D.