1996 960 - Parasitic Currents

This might be of interest to some of you (or not!), or you might be able to add information to it. Some of you might have noticed from my more recent threads that my present area of interest is the battery condition of my 1996 960 and the charging circuitry. This is because, now I'm retired, my motor gets used for just the occasional longer run and sits in the garage for four or five days at a time, with us using my wife's little Ibiza as our day-to-day local runabout. Anyway, the Volvo has been used like this for two years now and I have only just recently discovered that the battery (genuine Volvo, 4 y.o., 70Ah, 600CCA) was pretty depleted. I've reconditioned it and it seems ok now but, in sorting it out, I've been doing a bit of fiddling around and have found the following: a) The alternator and charging circuit are generally 'not bad' - the voltage at the battery terminals at 2000rpm is 13.8v (no load) and 13.5v (full load - ie, all lights, fan, seat heaters, rear screen heater and wipers running). My Volvo main dealer assures me that this is just within spec and shouldn't be the cause of any battery discharge problems. b) The total 'parasitic' current with the car parked up is 40mA. Investigating this further and isolating different circuits, I found that the drain via the clock, radio and alarm/immobiliser is 27mA. The remaining 13mA is lost via the seat power adjustment system! Again, my local Volvo dealer tells me that, as far as they are aware, this is not unusual - apparently it is the power seat memory function that draws current from the battery (ie, disconnecting the battery wipes the power seat memory). So, a parasitic drain of 40mA adds up to about 1Ah drained from the battery every 24 hours. This means that every time I leave the car sat in the garage for five days, it loses about 5Ah from the battery and the hour or so I run the car when I do use it is apparently not sufficient to fully return the battery to full charge. It has taken two years of this regime for the battery to become seriously depleted, but it is something to watch out for. I have now invested in a 'smart' charger (which is allegedly safe to use with the battery still connected to the car) and I intend hooking it up to the battery whenever I think the car is going to stand idle for more than a day or two. Hope this is of interest and any comments or tales of other people's experiences will be welcome. Stan.

Thanks for the info, I was thinking of getting one of these, they look quite a handy bit of kit.

I actually clicked reply then thought about what i was gonna type. I was going to suggest getting a deep cycle battery which im sure would hold charge for a lot longer, but as ive just thought it through, this will just prolong the inevitable... Sorry for the useless post lol It is interesting to know though, that the seats and clocks are the suspect equipment which draw on your power. Maybe d/c the electric seat function for the time being as its draining. Only downside is that the memory will be wiped and ul have to plug it back in to even adjust the seat slightly. regards Justin

a little bit of a idea for u to use with the smart charger if u mount a caravan socket at the back with the wiring going to 12 volt suply then u can just plug the smart charger at the back on my old car i had plug and play jump lead sockts front and back so i could jum cars with out lifting the bonet