I recently had a van wired up ready for towing a caravan.
Excuse my ignorance on this subject, but what voltage should the grey anderson plug be putting out?
The vehicle does have a smart alternator, like most modern vehicles, and it has not been bypassed.
My vehicle, and one other I checked put out 12v to 14.3v.
I thought it would be higher if it going to link to my dc.dc charger in the caravan?
I recently had a van wired up ready for towing a caravan. Excuse my ignorance on this subject, but what voltage should the grey anderson plug be putting out? The vehicle does have a smart alternator, like most modern vehicles, and it has not been bypassed. My vehicle, and one other I checked put out 12v to 14.3v. I thought it would be higher if it going to link to my dc.dc charger in the caravan?
Sounds correct'ish to me, although perhaps 12.0v is a bit low, which may indicate your crank battery is due for replacement, or that connections are not quite as good as they should be. With no load connected it should be showing the same voltage as the alternator. If the dc to dc charger thinks it needs higher it will increase the voltage.That's what dc to dc chargers do, & the reason for having the dc to dc charger in the van, to compensate for any voltage drop in the length of cabling between it & the crank battery. (However without any load connected there should be no voltage drop). You could test this by checking the voltage across the terminals on your crank battery & at the anderson plug at the same time - readings should be the same at each whether the motor is running or not. Higher if motor running of course. The dc to dc charger needs to be one suitable for a smart alternator - not all are.
12.7v is around the standard reading for a good fully charged battery, 12v at the plug would account for a voltage drop to the back of your vehicle, depending on who did the wiring and the price you were charged, the wires may be a tad small, 14.5V or around there would be with your engine running, which is what can be expected. My van has a voltage sensitive relay which is designed to operate at around 13.2v , this is when the alternator will start charging my batteries. If the voltage is measured from the vans plug when disconnected a negligible reading will be obtained.
12v at the plug would account for a voltage drop to the back of your vehicle
--------------------------------------------
Only if the reading is taken when the plug is connected to a load (ie. the dc to dc charger is working, or other things in the van are powered direclty from the anderson plug).
If that is the case then 12v is a big voltage drop over that distance & the wiring is far too skinny. - but check every connection first.
If the anderson plug is not connected to a load, then the cause is not voltage drop.
OP needs to clarify the details of the measurement taking
-- Edited by Cuppa on Sunday 19th of February 2023 01:45:01 PM
Confusion.
Ok, maybe people read the post wrong.
My VAN is my tow vehicle.
My CARAVAN is the big ugly brick that is being towed.
I get it though. So everything is tickety boo.
Thanks.
As already pointed out with no load the voltage should be the same at either end, maybe a few millivolts difference.
If the cables out the back of a SB50 Anderson plug (6awg maximum) are each not the diameter of your little finger I would be questioning the wiring. If trying to power a 3 way fridge off 12 volts while driving there will be at least 0.5 voltage drop with 6awg.
The DC-DC charger should be in the caravan. The point is to boost the voltage with say 24 metres of wiring ( + & - ) so you can charge the batteries & power the fridge.
__________________
Procrastination, mankind's greatest labour saving device!
50L custom fuel rack 6x20W 100/20mppt 4x26Ah gel 28L super insulated fridge TPMS 3 ARB compressors heatsink fan cooled 4L tank aftercooler Air/water OCD cleaning 4 stage car acoustic insulation.
A smart alternator will never fully charge your cranking battery. The scangauge on my vehicle often shows a charging voltage of 12v, after the initial post engine start charge cycle has been completed. I dont see anything untoward with what you are seeing with your vehicle.
A DC:DC charger in your van will compensate for the reduced voltage output from your smart alternator and improve the charging of a secondary (caravan) battery. You do have the option of disconnecting the shunt on your vehicle and increasing the charge and thus battery voltage, with no ill effects, should you decide to do so. As many people have already done.
Anderson plug colour usually indicates usage. Red is direct connected to source and usually fused at both ends, grey has voltage controlled device between source and the output plug to protect from draining source, so often only has fuse at battery/alternator end because there are smart circuit breakers built into the devices plugged in.
Electronic Stability Control (ESC) and Emergency Break-Away Brake controllers should use the Red 'Always On' plug while a 3 way fridge or house battery charger should be through a Grey plug to protect the starting battery.
More colour info here - https://thegreynomads.activeboard.com/t64231472/blue-anderson-plug/
bye.
__________________
Bruce & Judy pulling a 3T 23.5' Traveller Prodigy behind a Diesel Range Rover
