New battery keeps going flat

[surfergirl]

IMG_20171127_143622.jpg (488.87 KiB) Viewed 3215 times

Hi folks greetings from soggy Cornwall! Usual winter problems with the moggy van, nice new battery , new dyno from Bullmotif, control box is a few years old.
So battery won't run the wipers they get slower and slower then stop, checked the surf out (pants) ! Had a coffee in the pub! Jump back in the van about hour latter, just managed to turn the engine over, drove back 6 miles without wipers, no fun.
Back home put a multimeter on battery it says 11.5 so tried to test with engine running but she won't turn over, battery flat. Mmmm The red light goes out like it should, so need to test the charging system any help please with what to test and which setting to put the meter on. Thanks, two pic of multi meter, no idea why!

[firedrake1942]

What sort of battery ? I find that those recommended by Halfords etc are too small for my 1957 with dynamo - esp in this sort of weather. If it looks pathetically tiny in the huge space provided then it is probably too small for the job (see my pic below) . Do you have additional electrics such as strop , heated screen, chargers etc. Otherwise, if the dynamo is doing its job, which it sounds like it is, then there is a problem somewhere. If it were the regulator, it is unlikely the ignition light would be going out. The battery itself, altho new, may be faulty.

There are loads of posts on battery size

viewtopic.php?f=11&t=67094&p=609135&hil ... ze#p609135

viewtopic.php?f=11&t=66264&p=600921&hil ... ze#p600921

viewtopic.php?f=11&t=66094&p=599707&hil ... ze#p599707

Get the electrics checked out properly.

[kennatt]

multimeter to dc volts set to 20. connect to battery and see if you get 12 volts, see here https://www.youtube.com/watch?v=2_sFE_M16ps will need to get it started then look to get 14 volts at least when running if not 12 volts AFTER charging,suspect battery,if no14 v at least when running dynamo or alternator if fitted no charging,check fan belt tightness as first port of call good luck.

[surfergirl]

Thanks for the reply, it does look small in the battery compartment, but is a 45 AH last one was a 38AH. I turned all lights off and heater, wipers on way home. Is there a test with the multimeter to see if the dyno is putting juice into the battery?

[philthehill]

Did you polarize the dynamo when you fitted the dynamo?
If your battery is fitted the correct way round and the dynamo was polarised negative when manufactured (a dynamo can be either pole) you will be taking current out of the battery instead of putting current in.
To polarise - Make sure battery is connected the right way round i.e. negative to negative and positive (earth) to positive - remove field (small) connection from dynamo, turn on the ignition and make contact with the field wiring several times, it will produce small sparks which is normal. Turn off ignition and refit field connection. The dynamo will then be polarised to suit your battery.
Here is hoping that is all it is.
All dynamos should be polarised before use.

[surfergirl]

Thanks, no didn't do anything to the new dyno. Just fitted it. The battery is neg. Earth so assumed the new dyno would be ready to go!

[philthehill]

The Minor is normally positive earth therefore I think that the polarising is the problem.
Leave everything as it is - take off the field winding connection, turn on the ignition flick the field winding against the dynamo connection several times and then refit the field connection.
That should sort out the charging and the charging current will flow the right way.

[surfergirl]

Hi thanks for the replies, I've spoken to Bullmotif and they say all their dynos are now negative polarity, and the van has been negative earth for a long time. Its possible I could have the one new one that's positive but its unlikely. I guess the red light wouldn't go out if the dyno was set up wrong?
Had the battery charging for a few hours and its pretty flat by the look of things, its a wonder we got home.

[philthehill]

The red light will still go out as the dynamo is still charging but the current flow is in the wrong direction.

As these dynamos are supposed to be negative earth it is even more important to ensure that the charging polarity is correct.

It will do no harm to make sure the polarity of the dynamo you have fitted is correct by undertaking the process described above.

Looking on the BullMotif spares web site there appears to be no mention of the change of polarity to the dynamo.

http://www.morrisminorspares.net/shop_item.php?ID=4971

[les]

It's not impossible to have a duff battery.

[surfergirl]

Hoping to work through the charging system tomorrow if its not snowing! Got no garage and live not far from LandsEnd, so there's nothing between us and America, wind goes right through, makes fiddling with wires a pain.

[JOWETTJAVELIN]

You say the control box is a few years old? I once had a brand new control box fitted - never again! The charging rate may be wrong, which as other members suggest, check with the engine running fast and the multimeter on the battery. I am not sure if modern control box/voltage regulators can be adjusted though. But, first of all I would check dynamo output running open circuit. Good luck.

[myoldjalopy]

OK,check the dynamo is polarised correctly, as per Phil's suggestion, to eliminate this possibility. You can check the charge at the battery with your multimeter - it should rise to 13.7 - 14.5v at fast idle, if charging OK. But if the battery and (correctly polarised) dynamo are both new, I would suspect the control box. 'Modern ones' are certainly not infallible See my recent post here: https://www.mmoc.org.uk/Messageboard/vi ... 11&t=67579
It is possible for the control box to undercharge yet still put the ignition light out! I know, cos it happened to me!

[surfergirl]

I've read up on the links on YouTube and also the dyno tests in the Haynes manual, so will see what the morrow brings! Thanks for all the advice, I'll let you know how it goes.

[Trickydicky]

Here is a link to the Lucas Fault Diagnosis Manual, it details how to test and diagnose the whole electrical system. http://www.gomog.com/allmorgan/LucasFault.pdf

[ManyMinors]

Les is right that you shouldn't assume your new battery is OK. I have just given up with the 6month old Yuasa battery on my car because it wouldn't hold a charge........
I'm not saying it IS the battery. Make the other checks too. Simplest test is simply to run the engine at tickover, switch the headlamps on when you can see their output/reflection, then rev the engine up to see if they brighten with the engine speed. If they do then you have some charging. Not very scientific but it's a start.

[myoldjalopy]

Similarly 'unscientific' is to gently rev the engine when the heater motor is running - it should speed up. I also find my wipers go faster when revving the motor. All these tests - lights, heater motor or wipers - indicate the dynamo is generating electricity.....

[surfergirl]

Thanks, I remember the wipers getting faster and the lights getting brighter few years back, but after fitting halogens that doesn't seem to happen and have a feeling the wipers are on the way out as the screen has to be wet to work!

[myoldjalopy]

Well, hopefully, you've got the heater motor to check out as a third 'test' option!
Have a look at the regulator contact (the left hand one as you face the car). If there is a powdering of black dust around the contact it could be the culprit.

[surfergirl]

Tested the battery and dyno. With the charged battery a multimeter connected and the engine off gave a reading of 12.33
Engine at tick over was 12.06
Increased engine speed the best reading was 13.
So checked the dyno next which gave 14 at a fast tick over.
Checked the D & F wires disconnected from the control box separately, each showed an increase with engine speed from 13 to 14.
Connected a test bulb to the D and F wire one at a time at the control box and the bulb got brighter with revs.
So figure must be the control box not supplying the battery enough juice?
See what you think.