Disconnecting battery to prevent battery drain
Discussion
Hi Everyone,
I bought a new battery in the spring because obviously a big old V8 needs a decent battery. I haven't used my Chim that much in the year that I've had it, really because I wanted to get it running right and fix all the niggles before I start using it regularly, but with the winter weather now upon us, it's going to be a while before I venture out in it (but if we get a period of dry/warmish weather, I will). This means the car is sat there for weeks on end not used. I have to charge the battery with a charger every 3/4 weeks to keep it charged - I assume the immobiliser is the parasitic drain on the battery. I'm worried that disconnecting the battery for weeks at a time will cause the key fobs to stop working, as the immobiliser "forgets" the signal from the key fob - this has actually happened to my MK3 MR2. Is it the same for 90s TVRs?
I'm worried that charging the battery regularly with a charger isn't doing it any favours - my chim failed to start during the recent cold spell even though it was in a good state of charge - it started ok when the temperatures increased....
I bought a new battery in the spring because obviously a big old V8 needs a decent battery. I haven't used my Chim that much in the year that I've had it, really because I wanted to get it running right and fix all the niggles before I start using it regularly, but with the winter weather now upon us, it's going to be a while before I venture out in it (but if we get a period of dry/warmish weather, I will). This means the car is sat there for weeks on end not used. I have to charge the battery with a charger every 3/4 weeks to keep it charged - I assume the immobiliser is the parasitic drain on the battery. I'm worried that disconnecting the battery for weeks at a time will cause the key fobs to stop working, as the immobiliser "forgets" the signal from the key fob - this has actually happened to my MK3 MR2. Is it the same for 90s TVRs?
I'm worried that charging the battery regularly with a charger isn't doing it any favours - my chim failed to start during the recent cold spell even though it was in a good state of charge - it started ok when the temperatures increased....
Exactly that - a maintainer, not just a basic charger.
I use a relatively cheap one from Draper (the tools people), the popular choice seems to be a CTek, but they're more expensive.
I've also got a socket with a timer fitted to the outside of the house, so it turns on when our tariff is at a more favourable rate - ironically it's a rate we have as a result of owning an EV, but it's waaaaay cheaper electricity overnight.
If I'm using the car regularly I don't bother with the charge, but if it's going to sit for 2-3 weeks, or if it's very cold (like it's starting to be), I plug it in.
I also managed to find the drain on mine, and now the discharge rate is comparable to a modern car.
I use a relatively cheap one from Draper (the tools people), the popular choice seems to be a CTek, but they're more expensive.
I've also got a socket with a timer fitted to the outside of the house, so it turns on when our tariff is at a more favourable rate - ironically it's a rate we have as a result of owning an EV, but it's waaaaay cheaper electricity overnight.
If I'm using the car regularly I don't bother with the charge, but if it's going to sit for 2-3 weeks, or if it's very cold (like it's starting to be), I plug it in.
I also managed to find the drain on mine, and now the discharge rate is comparable to a modern car.
I have my Accumates timed for 12 hours on a Wednesday (8am- 8pm) , I prefer charging during the day in case of any problems (not bothered about peak rate 
) ,
When flat/need conditioning they draw 27 Watts ...once charged it drops to 5 Watts , so i know when it's done without having to go in the garage.
) ,When flat/need conditioning they draw 27 Watts ...once charged it drops to 5 Watts , so i know when it's done without having to go in the garage.
Edited by The Three D Mucketeer on Tuesday 26th November 10:12
Many thanks for the replies people. I'm a big fan of Draper tools - I've always found the value for money of their products superb - even their "budget" range is excellent.
Ok then I'll look into getting a draper battery conditioner, but what would happen if I were just to leave the battery disconnected for a few weeks at a time? Would the fob stop being recognised by the immobiliser, requiring it to be reprogrammed?
Ok then I'll look into getting a draper battery conditioner, but what would happen if I were just to leave the battery disconnected for a few weeks at a time? Would the fob stop being recognised by the immobiliser, requiring it to be reprogrammed?
I can’t answer on the alarm as I don’t know.
I think it’s different for different systems.
Mine is the original Foxguard, and I believe it doesn’t lose its coding to the fob, but I haven’t tested it.
If the battery is disconnected (or runs flat - ask me how I know), the system trigger the siren on a backup battery in the siren unit. The biggest wonder is how a 30 year old battery still has power.
Regarding the hours of charge, I like the overnight because of the cold winter hours thing too - batteries can freeze.
And the culprit on the drain was a poorly constructed and incorrectly wired hot start kit. To e relay was wired wrong, so it was constantly energised. It was warm even when the car had been sitting on the drive for a couple of days. A fairly unique situation I think.
The only other modification is the interior light delay relay has been removed and the relevant slots on the fuse board are bridged - this was done by the previous owner.
I think it’s different for different systems.
Mine is the original Foxguard, and I believe it doesn’t lose its coding to the fob, but I haven’t tested it.
If the battery is disconnected (or runs flat - ask me how I know), the system trigger the siren on a backup battery in the siren unit. The biggest wonder is how a 30 year old battery still has power.
Regarding the hours of charge, I like the overnight because of the cold winter hours thing too - batteries can freeze.
And the culprit on the drain was a poorly constructed and incorrectly wired hot start kit. To e relay was wired wrong, so it was constantly energised. It was warm even when the car had been sitting on the drive for a couple of days. A fairly unique situation I think.
The only other modification is the interior light delay relay has been removed and the relevant slots on the fuse board are bridged - this was done by the previous owner.
The Three D Mucketeer said:
I have my Accumates timed for 12 hours on a Wednesday (8am- 8pm) , I prefer charging during the day in case of any problems (not bothered about peak rate ) ,
When flat/need conditioning they draw 27 amps ...once charged it drops to 5 amps , so i know when it's done without having to go in the garage.
Are you sure about that? More than 13A sustained would blow the supply fuse. ) ,When flat/need conditioning they draw 27 amps ...once charged it drops to 5 amps , so i know when it's done without having to go in the garage.
I use a Datatool one on on mine and it draws very small amount of power according to the smart meter. Due to transformer effects, it's cheap to maintain charge in a 12V battery, do you mean 27 Watts?
Ok I've just bought the draper conditioner/charger thing off Amazon - only 30 quid, hopefully it will suffice. In 30 years of motoring, I've never used one (as you can probably tell by my original post )
So basically I can leave the battery connected to the car as normal, put the clips from battery conditioner on the battery terminals, and just leave it running 24/7? Or would a 12 hour charging session once a week suffice? (as already mentioned in this thread). Perhaps slightly more in cold weather? Maybe constantly on during really low temperatures....
Mine doesn't have the hot start mod, but I need to do this ASAP because at the moment I have to wait about an hour after turning it off before I can start it again, and all the current to the starter solenoid is going through the ignition barrel - can't be that bad for it surely, being for the solenoid, not the starter itself...
) So basically I can leave the battery connected to the car as normal, put the clips from battery conditioner on the battery terminals, and just leave it running 24/7? Or would a 12 hour charging session once a week suffice? (as already mentioned in this thread). Perhaps slightly more in cold weather? Maybe constantly on during really low temperatures....
Mine doesn't have the hot start mod, but I need to do this ASAP because at the moment I have to wait about an hour after turning it off before I can start it again, and all the current to the starter solenoid is going through the ignition barrel - can't be that bad for it surely, being for the solenoid, not the starter itself...
I’m not familiar with the Draper device but the CTEKs are connected to the battery terminals in-situ and are just left on all the time.
They work out when the battery needs anything.
The amount of electricity involved is so small that its not worth over complicating things with timers.
I can’t answer about the hot start device. I’ve never had need for one.
They work out when the battery needs anything.
The amount of electricity involved is so small that its not worth over complicating things with timers.
I can’t answer about the hot start device. I’ve never had need for one.
I always used Accumate & plugged it into the cigar lighter for ease of access.
When the cigar lighter fell into the door (
) I discovered a handy lead somebody else had fitted that went direct to the battery & popped out over the passenger carpet. The battery can be a devil to get to otherwise.
It was just plug in & forget!
When the cigar lighter fell into the door (
) I discovered a handy lead somebody else had fitted that went direct to the battery & popped out over the passenger carpet. The battery can be a devil to get to otherwise. It was just plug in & forget!
THEDAVINATOR said:
Ok I've just bought the draper conditioner/charger thing off Amazon - only 30 quid, hopefully it will suffice. In 30 years of motoring, I've never used one (as you can probably tell by my original post )
So basically I can leave the battery connected to the car as normal, put the clips from battery conditioner on the battery terminals, and just leave it running 24/7? Or would a 12 hour charging session once a week suffice? (as already mentioned in this thread). Perhaps slightly more in cold weather? Maybe constantly on during really low temperatures....
Mine doesn't have the hot start mod, but I need to do this ASAP because at the moment I have to wait about an hour after turning it off before I can start it again, and all the current to the starter solenoid is going through the ignition barrel - can't be that bad for it surely, being for the solenoid, not the starter itself...
I was wondering how you paid half of what I did; you got the 4A version, mine is 10A, but it doesn’t matter for a maintainer. ) So basically I can leave the battery connected to the car as normal, put the clips from battery conditioner on the battery terminals, and just leave it running 24/7? Or would a 12 hour charging session once a week suffice? (as already mentioned in this thread). Perhaps slightly more in cold weather? Maybe constantly on during really low temperatures....
Mine doesn't have the hot start mod, but I need to do this ASAP because at the moment I have to wait about an hour after turning it off before I can start it again, and all the current to the starter solenoid is going through the ignition barrel - can't be that bad for it surely, being for the solenoid, not the starter itself...
Just leave it plugged in, and the unit does all the thinking for you. Mine came with ring terminal connectors, so they are permanently on the battery, and the cable has a plug that pokes through the finger hole of the battery cover.
Since my car is outside, I got an extension cable that passes through the roof flap (I used a lawn mower cable connector for a slim unit), and added some tennis racquet towel grip tape to protect the paint from the draped cable.
For the hot start kit, read this thread, it’s key to understanding the hot start issue. Which is a problem in the alarm/immobiliser unit, but also an issue with old starter motor cables and earthing.
https://www.pistonheads.com/gassing/topic.asp?h=0&...
THEDAVINATOR said:
Ok I've just bought the draper conditioner/charger thing off Amazon - only 30 quid, hopefully it will suffice. In 30 years of motoring, I've never used one (as you can probably tell by my original post )
So basically I can leave the battery connected to the car as normal, put the clips from battery conditioner on the battery terminals, and just leave it running 24/7? Or would a 12 hour charging session once a week suffice? (as already mentioned in this thread). Perhaps slightly more in cold weather? Maybe constantly on during really low temperatures....
Mine doesn't have the hot start mod, but I need to do this ASAP because at the moment I have to wait about an hour after turning it off before I can start it again, and all the current to the starter solenoid is going through the ignition barrel - can't be that bad for it surely, being for the solenoid, not the starter itself...
I found it was the immobiliser causing the hot start problem and usually requiring at least 30 mins before it would start again. Bi passed immobiliser and it never failed to start. I also had a new beefier starter cable fitted. ) So basically I can leave the battery connected to the car as normal, put the clips from battery conditioner on the battery terminals, and just leave it running 24/7? Or would a 12 hour charging session once a week suffice? (as already mentioned in this thread). Perhaps slightly more in cold weather? Maybe constantly on during really low temperatures....
Mine doesn't have the hot start mod, but I need to do this ASAP because at the moment I have to wait about an hour after turning it off before I can start it again, and all the current to the starter solenoid is going through the ignition barrel - can't be that bad for it surely, being for the solenoid, not the starter itself...
If you disconnect the battery it won’t do an harm at all but will require you to run the car fully up to temp and wait for fans coming on a couple of times. This enables Ecu to re learn its basic parameters and then it’s good to go.
Many thanks for the replies and PabloGee for the link in your post which I will read with interest. I have bypassed the the immobiliser relay (because it had failed) so now just rely on the fuel pump circuit for security. I suspect my hot start problem is the very old, very long, (probably) very internally corroded starter motor cable, which wasn't really up to the job when new according to what I've read in here.
Here's a link to the draper conditioner which I got tonight...
https://www.amazon.co.uk/Draper-53489-Charger-Batt...
Here's a link to the draper conditioner which I got tonight...
https://www.amazon.co.uk/Draper-53489-Charger-Batt...
THEDAVINATOR said:
Many thanks for the replies and PabloGee for the link in your post which I will read with interest. I have bypassed the the immobiliser relay (because it had failed) so now just rely on the fuel pump circuit for security. I suspect my hot start problem is the very old, very long, (probably) very internally corroded starter motor cable, which wasn't really up to the job when new according to what I've read in here.
Here's a link to the draper conditioner which I got tonight...
https://www.amazon.co.uk/Draper-53489-Charger-Batt...
I’m sure that’s just the ticket. Have you looked at your battery to make sure you can get to the terminals? I’m sure you’ll be able to by now. A couple of mine had a weird box over the top which was rivited from below! Here's a link to the draper conditioner which I got tonight...
https://www.amazon.co.uk/Draper-53489-Charger-Batt...
Doesn’t look like the Draper has the cigar lighter adapter, that makes the whole job such a breeze. (As long as nobody has messed with the “always live” configuration)
I had a trackday car with a battery drain. Previous owner had spent many many hours trying to source the drain without success. In the end he installed a battery cutout switch - big red button on the dash. Just hit the switch each time I got in and out of the car, worked well and meant the battery maintained the charge over long periods, several weeks. However, it was a b
h if I forgot when leaving the car. Fortunately it never left me stranded, but I did have a ctek battery charger in the garage for the odd time I did forget.
The car did have a Viper immobiliser which was unaffected by the cut out switch.
h if I forgot when leaving the car. Fortunately it never left me stranded, but I did have a ctek battery charger in the garage for the odd time I did forget. The car did have a Viper immobiliser which was unaffected by the cut out switch.
Ahhh ok, thanks very much for this - mine is a late 96 car with the META alarm too. Ok now I know this I can just disconnect the battery when I'm not going to use it for a while. I bought my car without the battery box - the car came with the battery just sat in the passenger footwell, I managed to get a box from a popular auction site, but it came without the lid (so I'll have to fabricate a lid somehow - think I'll avoid metal as a material to make it from . ) - this of course makes disconnecting the battery much easier for now.
Definitely worth having a battery conditioner for convenience though, with hindsight I should have got one that simply plugs into the cigarette lighter - D'oh!
. ) - this of course makes disconnecting the battery much easier for now.Definitely worth having a battery conditioner for convenience though, with hindsight I should have got one that simply plugs into the cigarette lighter - D'oh!
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