Battery drain

[Fredanz]

My Freda has its original 80Ah Nippon Denchi battery (95D31L-equiv by the looks) and has gone flat a few times over the summer. It doesn't get used more than once every week or two but tends to be at least 10+km trips when it is. Alternator voltage is fine -- both lightly and heavily loaded is over 14v at fast idle.

I'm trying to figure out if I just have a too-old battery, or need to sort out something in the circuits.

I've put an ammeter across the terminal and found that current drain is 110mA with door closed bumping to 230mA with the door open. The bump is just the the ignition light I guess, 'cos I have all the interior lights off.

By pulling fuse 1 ("interior") I can get the door-closed drain down to 60mA, and pulling fuse 8 as well gets it to zero. (Yes, I have the ACC ignition bypass, so my cig/mirror/radio are powered even with ignition off - so that explains the 50mA on fuse 8 I guess, though I'm wondering why it should be even that high).

Question: am I unrealistic thinking that 110mA is too high, i.e. should I be able to track and further reduce the fuse-1 load somehow? If so, how do I proceed?

Second question: does it seem reasonable that a continual 110mA load should run it flat in just a week or two? Or am I simply in "lad, you need a new battery" denial?

P.S. The main reason I did the ACC bypass was so I could install a solar trickle charger via the cig socket. Clearly, that ain't working

[g8dhe]

110mA is a bit on the high side that means your draining 2.64 AmpHrs every 24Hours, that is 37AmpHrs every two weeks that is about half your battery capacity. If you have bypassed your ACC switch then that will be part of the problem, car radios aren't designed with minimising currents in mind

Unless your covering your roof /AFT completely with solar cells then yes your wasting your time! (OK if your using the latest cells with a proper regulation circuit then you will get some benefit - if not then to be honest IMHO the only benefit was to the shop and manufacturers).

[bigdaddycain]

Is the radio switched completely off fredanz? My head unit is easily switched onto standby, yet is a little trickier to switch off completely...Mine too has been ACC bypassed.

[Fredanz]

Is the radio switched completely off fredanz? My head unit is easily switched onto standby, yet is a little trickier to switch off completely...Mine too has been ACC bypassed.

I don't think it has a way to do more than leave it in standby. Disconnecting it to find out how much of that 60mA is radio will be a pain, but is probably the next logical step.

Yeah, losing half the capacity per fortnight seems a bit excessive, and probably explains our recent grief. Half per month -- which is likely what I had before the ACC bypass, worked better.

[Aethelric]

I switched my original bongo radio for a CD/MP3/radio from VR. A horrible thing which flashed like a disco whenever it was working. There was on lead which was advised to connevt to the ignition circuit. It needed 12V on it to have the radio working. But even with the radio powered down, this lead took 200mA. Although I am an electronics engineer, I have no idea why it takes so much other than crap design. I had to put in another switch so I could switch on the radio while stationary but not flatten the battery when left for a few days. Even with no power at all to the radio it maintained ita memory of stations and places on the CD.
If this is the problem with yours - then a switch in the ignition wire to the radio may fix it. I put a push-on/pushoff button down by the steering wheek

I have since replaced the radio with an ancient "civilized" Panasonic radio/cassette player. This takes 7mA on standby. Still a lot in my opinion, but probably on a par with the self discharge of a battery anyway.

Solar battery chargers do not provide a lot of power. The outputs are usualy specified in bright sunlight, in summer around mid day. Add clouds, a low sun and limited daylight (as in the UK in winter) and it will be down to a few percent of its rated output. It may cover my 7mA but not your 110mA.

Dave

[Fredanz]

Here's more information and a resolution:

The CD/radio was 40-50mA. And whatever else is on fuse 8 is taking a further static load of 40-50mA, but my grey cells couldn't tell me what it would be. Idle mirror and curtain motors and unused cig sockets shouldn't!

When I disconnected removed the ACC bypass, the static load dropped to 10-20mA, which is perfectly tolerable. So the bypass is history.

I had thought that maybe the cruise control I fitted was taking something from fuse 8, but I see I've carefully noted that I took its 12V off the rear wiper fuse instead, precisely so I could safely enliven fuse 8 without too much drain. Clever, but still leaves me puzzled where that extra 40-50mA was going.

Anyway... at least I don't need to replace the battery.

[dandywarhol]

A dodgy interior light can drain it....................

[Fredanz]

A dodgy interior light can drain it....................

If they are all switched off (i.e. not on, not door-activated)? How?

[dandywarhol]

From what I remember it's the capacitor thingy for the striplight which can cause the drain - could be totally off mark of course but some folks found this a few years back..........

[francophile1947]

From what I remember it's the capacitor thingy for the striplight which can cause the drain - could be totally off mark of course but some folks found this a few years back..........

That's exactly what happened with mine. Fluorescent tube was fairly dull (I didn't realise it at the time, as I had nothing to compare it with) - new tube fitted and no more flat battery

[bigdaddycain]

I'd forgotten all about the dodgey strip light drain thingy.... Well remembered!

Fredanz? Is your striplight working properly, nice and bright? Or is it yellow and dim? The latter is indicative of a tube on it's way out,this can cause a battery drain as dandy and franco mentioned.

[Fredanz]

Fredanz? Is your striplight working properly, nice and bright? Or is it yellow and dim? The latter is indicative of a tube on it's way out,this can cause a battery drain as dandy and franco mentioned.

Easy answer to that one - NONE of my interior lights can be the cause, because I have them all switched to OFF (not DOOR) all the time. And if I turn it on manually, the striplight is nice and white and bright.

So there's about 40mA on fuse 1 that I can't explain, and a similar non-radio amount on fuse 8 if I have ACC bypass in. Odd.

[dandywarhol]

I THINK there's still the possibility of a drain at the interior light unit with everything OFF - there's still power going to the unit Fredanz

[g8dhe]

So there's about 40mA on fuse 1 that I can't explain, and a similar non-radio amount on fuse 8 if I have ACC bypass in. Odd.

Fuse I has the radio connected to it as well that is the connection that maintains the memory settings for the radio. The Fuse 8 is the main Radio feed also the 12vsockets, but if you have any other devices fitted then its likely that they will have been fed from this as well.

[francophile1947]

I THINK there's still the possibility of a drain at the interior light unit with everything OFF - there's still power going to the unit Fredanz

Yep, mine was turned off when it was draining the battery - but it wasn't very bright.