Has anyone looked at car to car chargers for mhs (1 Viewer)

[xsparks]

Its not meant as a permanent fixture its a get out of jail card. It will get you going when no help is around. Much the same way the space saver spare wheels do . Besides who worries about other items they plug in such as 150w inverters and other charging devices or even tyre inflation pumps? You just need to get your head around the concept. I wonder how many people believed putting air in tyres would catch on?

 

[Motorhome Man]

Hi all, I am an electrical/mechanical engineer and there are two things to consider when talking about cable sizes, firstly, what is the current ( or load [Amps] ) to be drawn, the other is the length of the cable as this affects the voltage drop due to the resistance of the cable itself. In regards to vehicle charging from another vehicle or source it is actually the voltage that is the important factor and as long as the charging voltage is higher than the battery to be charged then the dead battery will charge. The amperage received from the donor source is very small and therefore only requires small cables. Charging from a designated charger is different as the cable has to be matched to the charger amperage output. Which in most motorhomes is a max 20 Amps. Take a look at the cables coming from your leisure battery to the PSU. Jump starting a vehicle is totally different, in some commercial vehicle applications the current draw when starting can be as high as 600 Amps which is why the cable from the battery to the starter motor is that big. I hope this has explained things a little clearer. Regards Luke

 

[Old Soldier]

Hi all, I am an electrical/mechanical engineer and there are two things to consider when talking about cable sizes, firstly, what is the current ( or load [Amps] ) to be drawn, the other is the length of the cable as this affects the voltage drop due to the resistance of the cable itself. In regards to vehicle charging from another vehicle or source it is actually the voltage that is the important factor and as long as the charging voltage is higher than the battery to be charged then the dead battery will charge. The amperage received from the donor source is very small and therefore only requires small cables. Charging from a designated charger is different as the cable has to be matched to the charger amperage output. Which in most motorhomes is a max 20 Amps. Take a look at the cables coming from your leisure battery to the PSU. Jump starting a vehicle is totally different, in some commercial vehicle applications the current draw when starting can be as high as 600 Amps which is why the cable from the battery to the starter motor is that big. I hope this has explained things a little clearer. Regards Luke

Thanks for this. One of the questions was could a charged leisure battery help to recharge the same vehicle battery using one of these devices? Are the "negatives" from both battery circuits linked in any way and if so could that compromise charging one from the other?

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[xsparks]

Thank you Luke for being so succinct perhaps this will put the subject to bed.

 

[Motorhome Man]

Hi Pete, the circuits for habitation and vehicle electrics are separate in that vehicle electrics have a negative return via earthing points on the chassis, whereas hab electrics are returned directly to the battery. Linking a cigar lighter outlet on the hab to the cigar lighter socket in the cab will charge the vehicle battery if on EHU or solar. This obviously is a temp connection and should be disconnected as soon as vehicle battery is charged. Luke

 

[Old Soldier]

Thank you Luke for being so succinct perhaps this will put the subject to bed.

Just shows what happens when someone doesn't read the question correctly or does not understand it!!, throws the thread right off track! Anyway, hopefully I will get an answer to my last post before the sheets are drawn up!!

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[Old Soldier]

Hi Pete, the circuits for habitation and vehicle electrics are separate in that vehicle electrics have a negative return via earthing points on the chassis, whereas hab electrics are returned directly to the battery. Linking a cigar lighter outlet on the hab to the cigar lighter socket in the cab will charge the vehicle battery if on EHU or solar. This obviously is a temp connection and should be disconnected as soon as vehicle battery is charged. Luke

Thanks for the clarification. Will try out my gizmo with a little more confidence now!!