More flat-battery investigations.. Alarm?

[aaronjb]

Righto.. In a vain (so far) efford to figure out why exactly my battery goes flat in less than two weeks (an almost brand new battery remember folks, which was fully charged and had been given a good long run just before I went away), I've been outside with the multimeter again..

I don't think it's the static drain - I'm seeing ~0.04A once the alarm has settled down after reconnecting the battery (well, putting the multimeter in series, obviously). Now, with a 40mA drain, I'm guessing the 40Ah battery should last somewhere in the region of 1000 hours, which is 41 days..

Which is considerably longer than it lasted, obviously  s:) s:)

I even checked again with the main fuse taken out (in the fuse box beside the battery), as well as with various other fuses removed (radio, doors, interior lights, accessories, cigarette lighter etc) and always found the same 40mA static drain, give or take 10mA.

I did, however, notice that when the alarm is going off, the drain is around 1A (while the siren is going off, I didn't wait to see what it was when just the indicators were flashing), which is a fairly hefty drain. Obviously, the battery would only stand ~40hours with that kind of drain (probably less, given that at 0Ah capacity the battery would be utterly dead, and would probably have ceased supplying enough power to drive the cars systems some time before that).

Now I know my alarm does go off occasionally - it did it once when I was simply walking past the car.. so I'm wondering - does anyone know where the 'interior' sensor is? And/or, is there any way to read the alarm cause out of the system without going to Toyota? (I know my Clifford in the Nissan will flash a set code to tell you which sensor caused the last alarm etc).

I'm just wondering if maybe there's something in the car (loose change, say) that's setting the microwave sensor off, or if perhaps it's the action of wind blowing through the soft top/people passing by if the sensor is set with the sensitivity too high (although, ironically, you can practically climb into the car before it goes off..)

Thoughts, anyone? I don't really want to shell out another £55 on a new battery only to find that goes flat the next time I go away (unless I disconnect it of course, but around here, that could be risky - every time I've done it in the past, the cars have been broken into)..

[Tem]

That 1A drain probably isn't long enough to make a difference. Even if it lasted for a minute, it would only equal about 25 mins of 40mA drain.

[aaronjb]

That 1A drain probably isn't long enough to make a difference. Even if it lasted for a minute, it would only equal about 25 mins of 40mA drain.

Hmm.. then I guess I just have magic batteries with holes in the bottom, so all the charge is falling out  s;) s;)

Something has to be draining the battery.. if it's not the alarm, and it's not the static drain... what?  s:( s:(

It's maddening, especially at a time when my authorised overdraft is a distant memory, I can't afford to be replacing batteries every time I go away for more than a week  s:( s:(

Perhaps the car just wants to be owned by someone else.

[heathstimpson]

I have recently left mine for five weeks and it started up straight away. There must be something draining away at that battery of yours. I used to get the same problems on a 4X4 I owned and never got to the bottom of it; even though I'm a electrical engineer   s:oops: :oops: s:oops:   s:? :? s:?

[Tem]

Something has to be draining the battery.. if it's not the alarm, and it's not the static drain... what?  s:( s:(

I think you have 5 options:

1) The battery never gets fully charged

2) The battery is faulty

3) Something drains the battery very fast

4) Your electrical connections are faulty

5) Your starter system is faulty


1) When the battery is charged, what's the voltage? What's the voltage after a day, two, more? What's the voltage with lights on?
(engine not running)

2) Check as above and if possible, see if it's any different in outdoor temps and indoor temps.

3) If you're seeing 40mA, I suppose we have to believe that. Is the battery clean, so it won't drain itself between the pods? Does it drain itself, if you take it out of the car?

4) Are the battery cables properly connected? You could try battery spray/grease to get rid of possible issues and scrape the pods/connectors clean before that.

5) Very unlikely at these miles, I'd ignore this for now.

[aaronjb]

1) The battery never gets fully charged

Fairly sure I've ruled that one out - at least, the alternator seems to be putting out a good voltage at idle and off idle (neither too high nor too low), and after a 300 mile round trip, you'd think it'd have been charged before I went away..

2) The battery is faulty

This is the second battery don't forget.. The first one, maybe - it was two years old.. This one is brand new from Toyota as of October last year, and shows the same fault..

3) Something drains the battery very fast

But if it is, I can't find it.. Like I said - 40mA static drain, 1A drain with the alarm siren and indicators going off.

4) Your electrical connections are faulty

Would that cause the battery to go flat, though? I mean - everything is clean and grease free (aside from the terminals and connectors themselves, which are still covered in gloopy electrical grease stuff from manufacture), and the battery itself showed a very unhealthy voltage, including off the car..

1) When the battery is charged, what's the voltage? What's the voltage after a day, two, more? What's the voltage with lights on?
(engine not running)

Well it's hard to say now, since this battery is certainly dead - the plates will be warped beyond repair given it was absolutely, utterly, flat. But prior to that it showed a healthy voltage. At the moment (it was charged for about 6 hours on trickle yesterday, and then given a 50 mile drive, then left overnight) it's showing 12.3v with no load.

3) If you're seeing 40mA, I suppose we have to believe that.

Well I'd like to think I have enough brains to work a multimeter  s;) s;)

Is the battery clean, so it won't drain itself between the pods? Does it drain itself, if you take it out of the car?

It's clean, sat securely in the plastic battery tray etc (and not directly on anything metal). As far as I know it doesn't drain itself out of the car - or to be more exact, didn't drain itself out of the car. It arrived from Toyota fully charged (and would have, presumably, gone flat in their posession otherwise). I think it does drain itself now, but remember it was drained completely when I got back off holiday - I didn't check the voltage, but my guess would be down to about 8v.. i.e. it's toast now, but it wasn't before I went away.

4) Are the battery cables properly connected? You could try battery spray/grease to get rid of possible issues and scrape the pods/connectors clean before that.

Securely and tightly, and there's already a good amount of battery grease on there, and I've made sure the posts themselves are clean before fitting and not utterly oxidised.

Which doesn't really leave many options. Sadly it seems like I'll just have to buy another battery, then investigate while I watch that one go flat and die as well.. This car is damned expensive to own in batteries alone!

Perhaps there is some fault with the alternator circuit somewhere, but I can't find that either if there is one - and if there was, I'd have imagined it would go flat gradually regardless of use, whereas if I use the car regularly (every few days at least) then the battery stays just fine.. Heck, when I used to go to work every day, the battery was just fine despite only ever doing 20 miles per day..

[Slacey]

Why not in the interim get one of those battery conditioner / chargers that I bought?

They can be left connected indefinately, and will at least keep the battery in good shape while you sort the cause of the problem. The one I got was a Draper unit from Halfords, £19.99.

[aaronjb]

I thought about that - but my car sits at the side of the road (well, outside the front of the house).. I'd need to put in an external socket, make sure nobody tripped over the power lead and sued me, etc..

I might get one of the solar trickle chargers though - leave it on the back 'parcel shelf' - it should be flat enough that the roof will still go down with it there too, then just push the wires through any available grommet, and leave it hooked up to the battery full-time. At a trickle of just 1W (or 1.8W for the bigger one), it ought not overcharge the battery, and everything would be concealed inside the car (and therefore not a thief-magnet like a wire trailing to the engine bay would be..)

[Tem]

Fairly sure I've ruled that one out - at least, the alternator seems to be putting out a good voltage at idle and off idle (neither too high nor too low), and after a 300 mile round trip, you'd think it'd have been charged before I went away.

Should be ok then  s8) s8)

This is the second battery don't forget.. The first one, maybe - it was two years old.. This one is brand new from Toyota as of October last year, and shows the same fault.

Batteries can be faulty from the factory  s:? :? s:?  Though kinda unlikey...

But if it is, I can't find it.. Like I said - 40mA static drain, 1A drain with the alarm siren and indicators going off.

Makes me wonder if this is the reason then...40mA for 2 weeks should drain about 15Ah. If you have extra drain on top of that, even more. A battery with 20Ah left might not be enough to start the car, depends a lot from the battery  s:? :? s:?

4) Your electrical connections are faulty

Would that cause the battery to go flat, though?

No, but it might seem so...unless you measured the voltage, which you did, so probably not that either  s8) s8)

Which doesn't really leave many options. Sadly it seems like I'll just have to buy another battery, then investigate while I watch that one go flat and die as well.

When you get the new one, if you get a chance to leave the car alone for a week or two. Measure the voltage daily and see how it goes. And feel free to charge it when it gets down to 10V or so, so you don't have to get yet another one  s;) s;)

Perhaps there is some fault with the alternator circuit somewhere, but I can't find that either if there is one - and if there was, I'd have imagined it would go flat gradually regardless of use, whereas if I use the car regularly (every few days at least) then the battery stays just fine..

If the voltage controller is faulty, it's possible that the battery gets cooked by overvoltage, which kills it. Slowly, so the first symptoms might be dying after a long standstill  s:? :? s:?  But if you've measured the voltage during drive and haven't seen this, I guess that can be ruled out too.

[roger]

Aaron, how about going back and claiming a new battery under its warranty? Presumably 12 months maybe more.

You can make your own mind up if you want to tell them the whole history. If they want to check it out, presumably they will lend you another, so you could then try again. If that goes in a very short time it has to be the car.

At least this won't cost.....until they decide you need a new alternator, or whatever   s:cry: :cry: s:cry:  

Roger

[Anonymous]

Aaron,

I seem to have the same problem as you, with the same readings. Left the car for 5 1/2 weeks in my garage with the alarm activated and when I came to start it, as dead as a dodo.

I disconnected the battery earth lead as they tell you to do in the owners manual and used one of these fancy battery conditioner chargers to charge the battery. The battery after being left on for 24 hours only charged to 12.5 volts, where a fully charged battery should be I believe be approximately 13.5 volts.

Same readings as you when I measured the current drain, starts of at about 0.3 amp (the alarm was armed) and then quickly goes down to around 0.03 amp. Reconnected the battery and managed to start the car with the alternator charging at 14.4 volts. Stopped the engine and measured the voltage drop on the battery. Over one hour period the voltage dropped from 12.5 volts to just over 12 volts, without the alarm on. I have now disconnected the earth lead and have put it back on the charger.

Seeing as the car is only 6 months old and only done 2000 miles, my take on the situation is that the battery has gone, probably a dodgy cell. At any rate I have booked mine into the Toyota dealer where I bought it to be looked at next Tuesday, so I will be interested to hear what they say.

Not very good, as I left my Audi outside in the drive for the same period of time, and despite being covered in snow it started up first crank of the starter. Even my 1957 MGA starts first time after being left sometimes for 2 months or more.
 
Rod

[Tem]

The battery after being left on for 24 hours only charged to 12.5 volts, where a fully charged battery should be I believe be approximately 13.5 volts.

I'd say ~12.5V is a fully charged battery and anything above that means it's currently being charged.

[GSB]

The battery after being left on for 24 hours only charged to 12.5 volts, where a fully charged battery should be I believe be approximately 13.5 volts.

I'd say ~12.5V is a fully charged battery and anything above that means it's currently being charged.

Read this:

 m http://www.homepower.com/files/battvoltandsoc.pdf m

[Tem]

Must depend from the battery then? I was just looking at the Odyssey manual, which says 12.85V is fully charged  s:? :? s:?

Also, I've never seen my battery stay above ~12.5V after turning the engine off.

[GSB]

It probabley wont, but the point is that you cant accuratley determine the state of charge by simply measuring the no-load voltage. Its better to see how the voltage holds up when theres a load on the battery, or by measuring current vs. volts when charging.

[Tem]

the point is that you cant accuratley determine the state of charge by simply measuring the no-load voltage

That's true.

[Anonymous]

I've got the same problem as you I'm afraid but mine goes flat within a couple of days!  Only bought the car in January and she's gone in to see the crazy fool today.  I ain't gettin on no plane - I, apparently, am not getting in no roadster!  Not happy!  I will let you know what they say (if helpful of course).  Grrr.   s:x :x s:x

[Chris]

I must admit that when mine was sitting on the drive for months on end, then the battery would go flat after about 2 weeks, which I put down to the alarm - so I decided to just disconnect the battery and remove some fuses (the ones to do with the ecu, smt and fuel pumps)..

[Anonymous]

Just to add a different point of view, mine was left over xmas for just over two weeks on the driveway, fully alarmed with sensors. It started up first time with no problems when I needed to use it. No help whatsoever, but I would have thought two weeks with no use should be fine.

[heathstimpson]

Just to add a different point of view, mine was left over xmas for just over two weeks on the driveway, fully alarmed with sensors. It started up first time with no problems when I needed to use it. No help whatsoever, but I would have thought two weeks with no use should be fine.

Over these winter months mine was left for five weeks fully alarmed etc and started up first time  s:wink: :wink: s:wink:

[Tem]

Makes me wonder who installs and configures your alarms? Importer or the dealer? Cause apparently there are several batteries that die within few weeks over here and I don't recall hearing about this issue on SC.

IIRC, mine has once been unused for 3 months over winter and it started up just fine. Even had the alarm on all the time. After that one time I've always disconnected the battery for winter and it's been just fine for up to 5 months.

[Anonymous]

Sorry to resurect this thread, but I am having battery drain problems.

I had Mr T battery in when got car a few months ago, took it out and put an optima yellow top in it.

After about 4 days of inactivity the car is very sluggish to start but it usually fires ok. Thinking that the battery was goosed I put the Toyota battery back in. It has been out of the car uncharged for about 2 months.

It does not fire the car up at all. I went a run a few times over the weekend but it failed to start the car the following morning. I wil lget a charger tonight and see what I can do.

I have upgraded by car audio system thinking that might be draining the car whilst sitting, but I removed the fuse at the battery terminal over the weekend, thus no possibility of battery drain here and the car still failed to start.

Interestingly though, I am convinced my multimeter should show 14.4v when the engine is running, but the max I can get cross the terminals is 14.2v

[Anonymous]

Just switched my lights on in the car without the ignition on and I watched the voltage of the battery drop to 8.2 in seconds.

[kanujunkie]

Interestingly though, I am convinced my multimeter should show 14.4v when the engine is running, but the max I can get cross the terminals is 14.2v

just checked the manual i have from Mr.T and it states voltage should be 13.2 - 14V so its not that

[kanujunkie]

just as a point the first thing the manual says is to check the wear on the accessory belt then is it charging properly? the output at 2000rpm should be 10A or less nominal and 30A or more under load with the High beams and heater on , i can e-mail you a zip file for fault finding this system if you want Stew, just pm me and i'll send you the lot