• Hi Guest!
    You can help ensure that British Car Forum (BCF) continues to provide a great place to engage in the British car hobby! If you find BCF a beneficial community, please consider supporting our efforts with a subscription.
    There are some perks with a member upgrade!
    **Upgrade Now**
    (PS: Subscribers don't see this gawd-aweful banner
Tips
Tips

Lucas strikes again

Share this page

Stewart

Stewart

Darth Vader
Country flag
Offline
Lucas has stuck at a bad time for me. Some where there is a drain in the system that is killing the battery over a period of about 2 to 3 weeks. I will not get a chance to work on the car till early August and I was thinking of either ordering up a trickle charger or a priority start (automatic battery cutoff switch at a predetermined voltage)to protect the battery till I can fix the problem.

Anyone have any recommendations on brand and pros and cons on either type of battery protection? Ease of installation is a must as my father will be installing it and he's not mechanically oriented.

I figure the first thing I get to do when I get back in august is a bosch conversion. The original alternator has done a pretty good job for the last 30 years.
 
I'm guessing that the priority start (any brand) will be a good thing... Also, taske the battery to Advancem or Auto Zone... They'll check it on the machine. Pick a store that has the battery anylizer out where you can see it, and watch it... It's not that hard to read, and in about 30-40 minutes, you'll be able to either tell the guy off, and walk away with a nicely charged battery, or may need to buy one.
 
[ QUOTE ]
till I can fix the problem.


[/ QUOTE ]

Why not just follow K.I.S.S. Rule?? /ubbthreads/images/graemlins/hammer.gif

Have him disconnect neg. cable and leave as is??? /ubbthreads/images/graemlins/confused.gif

/ubbthreads/images/graemlins/cheers.gif
Ed
 
Yep, see above. A charger with a trickle on it is only like 12 bucks.
 
[ QUOTE ]

Why not just follow K.I.S.S. Rule?? /ubbthreads/images/graemlins/hammer.gif

Have him disconnect neg. cable and leave as is??? /ubbthreads/images/graemlins/confused.gif

/ubbthreads/images/graemlins/cheers.gif
Ed

[/ QUOTE ]

That was my first thought as well -- just disconnect the battery....
 
[ QUOTE ]
[ QUOTE ]

Why not just follow K.I.S.S. Rule?? /ubbthreads/images/graemlins/hammer.gif

Have him disconnect neg. cable and leave as is??? /ubbthreads/images/graemlins/confused.gif

/ubbthreads/images/graemlins/cheers.gif
Ed

[/ QUOTE ]

That was my first thought as well -- just disconnect the battery....

[/ QUOTE ]

Agree; better yet - add a battery disconnect switch. I have one from Hella mounted on the heelboard, just ahead of the battery. Works great.

No offense meant, but why a Bosch alt? Seems like you've got a parasitic drain somewhere. A high output alt will charge it, but the real issue is drain.

switch.jpg
 
while a battery disconnect might work for some people it doesn't necesarily solve the problem. Instead, a battery disconnect solves the symptom. However, disconnecting the battery is a good interum measure to use until you do have the time to get in there and really search for the cause.

Sounds to me like it's time to pull out the wiring diagrams and start trying to figure out where the leak is.
 
[ QUOTE ]
while a battery disconnect might work for some people it doesn't necesarily solve the problem. Instead, a battery disconnect solves the symptom.

[/ QUOTE ]

It all depends on your definition of 'problem'. If you know the source of the drain (clock, stereo presets) a disconnect is a great idea. It is also a handy theft deterrent.

If you have no idea why the battery is discharging, then by all means trace the source of the leakage.
 
The source of the drain needs to be traced,fitting battery disconnects will certainly stop the battery discharging.But you'd still have the problem,wouldn't you?

Stuart. /ubbthreads/images/graemlins/cheers.gif
 
erm... station presets and internal clock in a stereo shouldn't draw enough power to drain a car battery to the point of not being able to start the car in 2, 3, or even 4 weeks time. Over winter storage... maybe, but I doubt it.

I don't think the stock analog clock would draw that much power either. However, we ARE talking Lucas electrics there. So, that MAY be possible, but I would not be willing to bet a MG stock Lucas analog clock would drain a car battery in a month's time, unless the clock was malfunctioning in some way.
 
[ QUOTE ]
erm... station presets and internal clock in a stereo shouldn't draw enough power to drain a car battery to the point of not being able to start the car in 2, 3, or even 4 weeks time. Over winter storage... maybe, but I doubt it.

I don't think the stock analog clock would draw that much power either.

[/ QUOTE ]

Huh? Figure 10-20mA for the stereo, another 10-20mA for the Smiths clock. I've also got a Smiths voltmeter to indicate charge rate. That's enough discharge to drain the batttery in a week or two.
 
Yup... My Toyota drained her battery in about 2 months before I removed it from the truck and set it on the front deck for 4 more months - but luckily, it came back to life on a 17-18 hour charge on a cheap 6 amp manual charger.
 
hmmmm... I've personally never had a radio drain a car battery that fast (a week or two). The radio in my B is wired directly to the battery, but the speakers/wiring to the speakers are shot so it never get turned on, but the battery easily lasted 2 weeks when I went on vacation over Christmas, and lasted the 3 weeks it was down due to the clutch. *shurg* I'd personally start looking for problem areas if the battery drains in under a month, or ways to reduce iggy switch off power consumption.

Two months, I'd definitely worry that the battery might be dead. Anything under a month though I'd find annoying. But that's just me...
 
Obscure suggestion: Does the '75 have a light in the boot, bonnet and/or the glovebox? If so, check to insure the switch(es) are actually breaking contact when the lids are closed. IIRC the later cars had these lights but they were wired thru the running light circuit... so they should only come on with the switch, but my last electron chasing session on one has been so far back I can't really remember.
 
Good suggestions all, but we must remember the original question: What can Stewart instruct his father to do to save the battery until August? I still think the simplest solution is to disconnect the battery....

It won't be until August rolls around and Stewart can work on the car that he can begin to troubleshoot.
 
Point taken. Disconnect indicated.
 
/ubbthreads/images/graemlins/thumbsup.gif Disconnect the battery and look for the drain in August. /ubbthreads/images/graemlins/savewave.gif

Stuart. /ubbthreads/images/graemlins/cheers.gif
 
To finally update this. After talking to my dad and asking what would work best for him it was decided that the priority start would be the best option for him.

For the source of the drain it sounds like it may be coming from the stereo. After charging the battery there was a static sound coming from the speakers with the keys out. The noise went away after starting the car but the radio while it turns on there is no sound so I'm hoping this is all over a grounded out speaker doing something weird.

The new alternator wont fix the problem but with discharge but it will look a lot nicer and charge the battery a little faster especially on the short trips its currently being used for and how often do you see a 31 year old Lucas alternator in MG's now days. Not to mention its the only thing in the engine bay that looks 31 years old.
 
Back
Top