Sargent General Electrical System Support

Charge the leisure battery fully first, using the vehicle's own built-in charger - hook up to 230V mains, turn the charger on with the PSU's green push-button and leave it for 24 hours. If you've got an active tracking subscription, the leisure battery should stay connected, and charged, all the time. For caravans, leave the leisure battery connected but switch the PSU off to save power.

If you want to keep temperature readings and remote control working, you can leave the PSU on instead, but you'll need to keep an eye on the leisure battery's charge (a 40W-plus solar panel connected helps a lot here). For motorhomes parked outside with a solar panel fitted, leave the leisure battery connected, PSU on, but switch off the control panel above the door.

For motorhomes under cover, in a carport, under a solar-blocking storage cover, or without solar at all, switch the PSU off but leave the leisure battery connected, since it'll need to keep the tracking unit running over the storage period.

Split charging means charging the vehicle battery and leisure battery simultaneously from one source - on a motorhome or caravan, that source is the engine-driven alternator.

Sargent PSUs have split charging built in, which needs connecting to both batteries (vehicle and leisure) plus an engine run signal. When that signal is detected, the internal relay energises and connects both batteries together to share the alternator's charge; without it, there's assumed to be no charging source, so the relay keeps the batteries electrically separate - stopping one from draining into the other.

Keeping the vehicle battery isolated from the leisure battery matters both ways: you don't want the vehicle battery flattened so the engine can always start, and you don't want the leisure battery feeding the starter either, since leisure batteries aren't built for that kind of short, high-current burst and can be damaged by it.

An engine run signal reads +12V only while the engine's actually running, dropping to 0V once it stops. A switched ignition signal, on the other hand, reads +12V as soon as the ignition's turned on - engine running or not - and only drops to 0V once the ignition itself is off. Using a switched ignition signal by mistake is a real problem: the split-charge relay would engage during cranking and link both batteries together - and that can damage the leisure battery.

You can substitute a switched ignition signal instead, but you'll need to add a voltage sensing relay (VSR) into the setup.

An engine run signal sits at +12V purely while the engine's going, and drops to 0V the moment it stops. A switched ignition signal instead goes to +12V as soon as you turn the key, whether or not the engine's actually started, only returning to 0V once the ignition's switched off. This distinction matters a lot for split charging - relying on a switched ignition signal by mistake means the relay engages during cranking and briefly ties both batteries together, risking damage to the leisure battery.

A quick flash or short flurry of flashes right as the charger switches on or off is completely normal - it's just the charger's own components settling as power connects or disconnects. No action needed.

On most Sargent systems, the reverse polarity light is only wired into the circuit while the charger's switched on - done deliberately, since it would otherwise interfere with readings taken during a routine electrical inspection. Since the charger also needs switching off for those tests anyway, its switch conveniently disconnects both at once.

Yes - many countries outside the UK (most of Europe included) don't earth the Neutral the way the UK does, so both conductors there are treated as 'Live' rather than polarity-specific, and they rely on MCBs that break both conductors together. Every one of our systems already uses MCBs that break both Live and Neutral for exactly this reason, so standard van equipment is safe to use on the continent as-is.

If you're ever unsure about a specific piece of equipment you're taking abroad, though, check with its own supplier or manufacturer.

That's expected, not a fault. To meet EMC directive 89/336/EEC and for safety, every Sargent system shuts the habitation 12V supply down as soon as the engine starts. In a caravan that's a complete shutdown, since nobody should be inside while it's moving; in a motorhome, a 12V and/or USB socket next to a seat with a seatbelt may stay live.

Don't try to disable this - it's a safety feature, and bypassing it will also break other functions like the fridge and split charging.

Yes, worth having if you've got a smart alternator, regenerative braking, or lithium batteries. Smart alternators throttle back their voltage once the vehicle battery's nearly full, which can leave a leisure battery under-charged if it's only getting a traditional split-charge relay. Regenerative braking can push the alternator's output as high as 15V+, enough to overcharge some leisure batteries (Gel especially).

And lithium batteries' own BMS can accept charge currents up to 70A, which can blow fuses sized for ordinary lead-acid setups. A DC-DC charger addresses all of this: it gives a fuller, faster charge on the move, compensates for voltage lost in cabling and connectors, applies the right multi-stage profile for whatever battery type you've got (AGM, Gel, Lithium...), and caps the current to avoid both overcharging and blown fuses.

Call the tracking monitoring station straight away on 0345 6027302 - they're staffed 24/7. Have your caravan or motorhome's serial number ready first: for a caravan, use the CRIS number's final 10 digits (e.g. SWH0123456); for a motorhome, use the build number, which begins MH, ME or AP (e.g. MH01234).

Vehicle manufacturers have to monitor the indicators and warn if one fails. Traditional road lights used a 21W bulb, drawing about 1.75A - modern LEDs typically draw only 2-3W (roughly 0.25A). If the tow vehicle's monitoring is calibrated for the old higher load (some down to just 1A), it won't register the LED's lower draw and will falsely flag a bulb failure.

Different manufacturers set different thresholds, which is why some vehicles complain and others don't.

The VLM4 unit was an older electronic control unit produced in 7 different versions depending on the vehicle manufacturer, but these are now obsolete and no longer manufactured. They have been replaced by the VLM6 unit, which is a single 'one size fits all' universal version designed to be compatible with most towing vehicles.