Q Why is there excessive drain on the leisure battery?
I have a new Swift Voyager fitted with the Sargent PSI system (in Dec 23).
I first consulted Sargent regarding fitting a Fogstar 105Ah lithium battery. Then, checking with Fogstar, it looked like a retrofit for the supplied 80Ah lead acid battery would be fine. I had noted others doing the same.
My first trip out, after an overnight stop, I noticed the control panel was reading low. On checking the BMS, I had only 50% despite a 200-mile run.
On further checking, using the BMS, a discharge was noted of some 20A. I managed our trip using hook-ups and switching off the battery via BMS, noting every day the state of charge.
On return to the UK I refitted the supplied battery and was advised to fit a Victron shunt, which I did. This confirmed the discharge.
Sargent has referred me to a dealer, saying it has not come across this problem previously.
The system did work after a week in storage. I used it on two outings and checked the on-charge status, which was fine.
Then, I took it into the dealer working. The previous day, I had discharged it to 57%. On arrival (after a 50-mile drive) I recorded a charge to 81%. The dealer checked the charging on hook-up and no fault was found.
On arriving home, I noticed the PSU switch off. Turning this on and starting the engine, the leisure battery discharge had returned, so it’s back at the dealer.
I am quite willing to have a DC-toDC charger fitted, but will this fix my problem? The dealer does not have any desire to get into this, so I cannot have it carry this out.
Any help would be appreciated.
Kevin Lee
A There are a few possibilities for this that a competent electrical engineer should be able to diagnose with access to the vehicle.
A discharge of 20A could be that the base vehicle alternator/stop-start is not engaging and so the lithium battery is feeding the vehicle battery and vehicle systems.
It might also be that the fridge is being powered by the lithium battery. Both of these are quite common and so a DC-to-DC (B2B) device may be required to prevent the backflow and to encourage the alternator to engage by seeing the load of the habitation system.
Your first stop must be the supplying dealer. If this visit fails then I suggest you make a formal arrangement for Sargent Electrical to sort it for you. While the ’van is within its warranty, I would not stray further than the dealer or Sargent Electrical. It is a hands-on job with a mutimeter first.
Clive Mott