Thread: Battery draining

no.
I've done this with a couple of my chargers(accidentally), never seen it.

batteries do self discharge tho, and the condition of the battery will determine how much/how quickly.

Hi Jim and carrying from Arthurs post, all battery chargers are designed to be left connected to batteries and not cause any drainage when the charger is not operating.


Can you post up vehicle details and how much driving and the type of driving, you have been doing over the last few months?

The vehicle is a Mercedes Sprinter camper conversion,
. Before purchase five months ago it was fitted with a new starter battery and two house batteries connected off the main battery by an automatic isolation unit. A solar panel is connected permanently to the house batteries via a controller. Twice lately the starter battery has gone low and had to be charged. There is a multi stage charger fitted to top up the house batteries when van connected to the mains.There is a 12v fridge left permanently running but I disconnected this after the first flat battery. A while back I heard the battery isolation unit clicking which I thought strange. The motor was not running at the time. Hope this helps

Originally Posted by jx2mad

..... A while back I heard the battery isolation unit clicking which I thought strange. The motor was not running at the time. Hope this helps

A bit more specifics can help.

eg. what isolator unit is installed. What battery used for starter and house
Is van parked out in the sun? Are solar panels charging(house batteries) via the isolator? .. or another controller?

eg.
Redarc (VSR) dual battery isolator unit can charge the starter battery if you connect the input power to the aux battery(s). It does seem to be a slightly flaky way to go about this, and it ends up being better to charge the aux, via the main instead.
What can happen if you charge the aux battery(for arguments sake in your case the 'house batteries') instead of the main battery .. is that the VSR relay goes into a hysteresis operation where it turns on and off at the pre set voltage levels it's set to work at.

As the charger charges the aux battery the Redarc then senses that volts are at (whatever value) volts, turns on relay, main battery starts absorbing a bit, pulling some power out of the aux, so aux drops a bit relay turns off charging the aux again a bit higher, so relay turns on again charging the start battery a bit again, which drains aux a bit so turns relay off again .. and so on.
So I found out that it's always better to charge the start battery which then keeps the relay on full time and charges the aux battery .. without the on-off hysterics of the Redarc relay in the background.

Not strictly strange to hear a pre set voltage relay to click randomly in the middle of the night.
I usually get home at say 5 or 6pm, batteries both charged from the drive home, so Redarc relay is always on until the starter drops to whatever the volt setting is(IIRC, maybe 12.7v). So at some random point during the night, or possibly next morning(this depends on ambient temp) the relay will sound it's click(off). This is normal.

While it's not normal for a battery to go belly up in 5 months, it's probably not the first one to do so either.
My Century dies at 10 months, maybe slightly prior .. I took it in for the warranty at 10 months, I use my D1 as my daily so it was harder to feel it dying slowly.
It dropped one cell, and this was found out only after I hadn't used the D1 for a day. This time off allowed the battery to fully settle, and car cranked very slow. Started tho, and then I noticed it a few weeks later first thing in the morning .. usually at 12.5v or so, sometimes(warm night) may had held 12.7v so Redarc isolator would always stay on.
But with the newly discovered dropped cell, I noted below 12v many times on the volt gauge. Remember that the 'issue' here is that with most isolators they keep the starter battery connected to the aux(or house) battery for a given time until the start battery reaches a certain voltage. This masks a dead battery to a certain degree. Then at some point it really dies and in doing so partially takes out the aux battery a little too.

As for the fridge, you would assume that it would be connected to the house batteries, and thus once the house batteries have reached a certain voltage will 'isolate' from the starter battery.. so I doubt the fridge will have had an effect on the start battery.
But we don't know how the van has been wired up.

Hi Jim, how much driving are you doing?

When you drive the sprinter, on average, how long is each trip?

Need to know the type of isolator because it should NOT be clicking on and off while motor is not running.

What year Sprinter? My guess is the isolator or wiring of it as my 2007 Sprinter can sit for 8 weeks and start no dramas when needed - but not sure if the later model (VS30’s) are the same though.

Originally Posted by drivesafe

....

Need to know the type of isolator because it should NOT be clicking on and off while motor is not running.

I have to question this.. if that's OK.

I'm wondering why it wouldn't?

If motor is off, for example just after a drive .. battery(s) has/have been charging. After some time(hours or whatever) start battery begins it's slow drain from it's highish initial rest voltage(say 12.7v) and slowly drops as the hours pass.
At some point(on my D1 about 12.62v) the isolator then clicks(off) to signal that the start battery is now isolated from the aux(house) batteries.

If the OP uses a Traxide system, I do understand that switch off voltage is at 11.9v(if that's correct) so yep... isolator shouldn't switch at all.

But as we yet don't know what DBS the OP got in the van, I reckon it's safe to assume that it may be a 'generally available' unit (as in from most camping/4WD retailers) of which most switch 12.7v or thereabouts.
If that's the case, then it's normal for the isolator to click at any time .. depending on the condition of the main battery.

Hi Arthur, it is actually commonplace for ordinary VSR isolators to click on and off when the motor is running, and this is usually caused because the isolator has been mounted too far from the CRANKING battery.

While the motor is running, it will at sometime, run at at least 13.2v, the TURN-ON voltage for most VSR isolators, but when the motor is turned off, the batteries will quickly settle below the TURN-ON voltage, and will eventually settle below the TURN-OFF voltage level of 12.7v.

Once the voltage drops below 12.7v and the isolator has turned off, the only way ordinary VSR isolators could turn back on again, is if there was a solar panel or battery charger connected.