RB340 checking possible over charge

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andrewh
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RB340 checking possible over charge

#1

Postby andrewh » Tue Nov 07, 2017 4:09 pm

I keep suffering from my battery spilling acid from the top filler lids and I want to check that my dynamo/regualtor is not overcharging. The battery charges very well indeed and the dynamo was overhauled professionally and then I fitted a new manufactured RB340 regulator. I do wonder whether the regulator is allowing too much charge but not sure how to check this in spite of the instructions in the book. Can anyone talk me through this? Is this the cut in voltage or drop off voltage or the current regulator? There is quite possibly nothing wrong with the set up, it may just a battery that leaks, but since its the second battery I have suffered this with, I feel I must at least check the battery is not being over charged. I have an AVO analogue meter on its way to me as I know digital meters are not good for this sort of work. I am interested to learn about this dark art.
1962 3.8 Series One FHC

http://etype860897.blogspot.com/

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Re: RB340 checking possible over charge

#2

Postby Heuer » Tue Nov 07, 2017 4:38 pm

Simplest test is to put a voltmeter across the battery with the engine running - when revved to 3,000rpm it should read 14.3 volts. Any higher and you have a problem.
David Jones
S1 OTS OSB; S1 FHC ODB

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Re: RB340 checking possible over charge

#3

Postby andrewh » Tue Nov 07, 2017 5:17 pm

ok, well that sounds simple enough! thanks David. However, what if its charging it at 14.3 Volts regardless of the underlying state of the battery. i.e overcharging it? I mean if you charge a 12v battery at 14.3 regardless of the drain surely that would still overcharge it?
1962 3.8 Series One FHC

http://etype860897.blogspot.com/

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malcolm
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Re: RB340 checking possible over charge

#4

Postby malcolm » Tue Nov 07, 2017 6:04 pm

No, doesn't mean it's Charging at 14.3 volts all the time, it's just reaching that. I believe a normal figure is 13.7 volts to 14.7 volts max, with engine running, and with everything on (wipers, headlights etc,) it should still be 12.6 volts or more
If it never exceeds 14.7, it can't be overcharging.
Malcolm
I only fit in a 2+2, so got one!

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Re: RB340 checking possible over charge

#5

Postby cactusman » Tue Nov 07, 2017 8:48 pm

Malcolm et al are spot on...look for around 14.2-14.5 volts at 3000rpm....any more and the unit is dud...and they are a pain to set up correctly once they malfunction....

Owning an mg with an RB340 as well as the E I now have several in my shed and most are duds. My experience with the new manufacture copy units has been universally rubbish. Some are not even electrically the same internally as the genuine Lucas unit either. I have had two start overcharging with the battery terminal voltage reaching 17.5 volts.....touch wood the genuine article in the e type works fine....the one in the mg I scrapped out the junk innards and fitted a electronic replacement....but that is another story :bigrin:
Julian the E-type man
1962 FHC
1966 MGB....fab little car too

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Re: RB340 checking possible over charge

#6

Postby andrewh » Tue Nov 07, 2017 9:32 pm

oooh Thats sounds bad. I will check the voltage across the terminals and report back . May be a while as I have the battery out currently and doing some other works. Lets see what it charges at and report back from there. thanks chaps, as always
Andrew
1962 3.8 Series One FHC

http://etype860897.blogspot.com/

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Series1 Stu
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Re: RB340 checking possible over charge

#7

Postby Series1 Stu » Tue Nov 07, 2017 9:52 pm

I had a MK2 Cortina on which the regulator packed up and the dynamo over-charged to the point that the battery acid was boiling and spewing out of the battery. It sounds like you have a similar problem.

I had the manual to adjust the regulator but it was hopeless. IIRC the contacts fused together on one of the coils which meant it wasn't making and breaking. No amount of dressing of the contacts would stop it happening.

Fortunately, in those days, you could visit a local scrap yard and find what you needed easily enough.

Regards
Stuart

If you can't make it work, make it complicated!

'62 FHC - Work In (slow) Progress
'69 Daimler 420 Sovereign
'94 X300 XJR basket case

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Re: RB340 checking possible over charge

#8

Postby abowie » Wed Nov 08, 2017 12:31 am

If it were me I'd just take the car to an auto electrician.
Andrew.
881824, 1E21538. 889457..oops
http://www.projectetype.com/index.php/the-blog.html
Adelaide, Australia

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Re: RB340 checking possible over charge

#9

Postby cactusman » Wed Nov 08, 2017 7:10 am

You can take it to an autoelectrician but really there is not a lot more they can tell you . The RB340 has three solenoid coils and three contacts. One is the low volts cut out that isolates the dynamical the battery at low dynamo output voltages....or when the engine is off. If it does not then the battery discharges back through the dynamo...bad. This section is also connected to the ign light. The other two are current and voltage sensitive. One will open its contacts if the current from the dynamo exceeds a set amount....usually around 22-30 amps depending on the dynamo it is calibrated for. The other will open if the battery voltage exceeds around 14.2 volts and protects the battery from overcharging.

Both the current and voltage reg contacts will open and close rapidly at times and are prone to contact wear that alters the current/voltage regulated level, and also to contacts welding together leading to either overloading the dynamo or overcharging the battery. The contacts can be cleaned using wet and dry paper and soldering 100 nanofarad capacitors across the contacts does reduce sparking and wear....and improves radio reception....but 're calibration of an RB340 requires patience and some test gear (a meter good for 30 amps D.C.) that most don't have. Easier to replace with a new one (usually crap) or Known good NOS one.
Julian the E-type man
1962 FHC
1966 MGB....fab little car too

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Re: RB340 checking possible over charge

#10

Postby phil.dobson@mac.com » Wed Nov 08, 2017 8:00 am

it was for the above issues with c...p replacements etc that i switched to a lightweight Alternator. Fit and forget.

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Re: RB340 checking possible over charge

#11

Postby andrewh » Wed Nov 08, 2017 8:52 am

Thanks Julian, very helpful. I have suffered with these on all sort of vehicles over the years. My first experience was on my Willys Jeep, not a Lucas unit, but the same sort of thing. Its definitely a dark art. I had a chap in Kent who was a wizard with these things, but he is ill and not working. Finding any other Auto Electrician that even knows what they are in this day and age is a task in itself. I have read about electronic conversions and have fitted a few in old motorbikes, but was hoping that as these are newly manufactured they may work. Perhaps I am being too hopeful. Anyway, I will have to suspend the rest of the story until I get the car started again. Just fitting an adjustable reaction plate and new Tbars , will move onto the charging after that. thanks chaps.
1962 3.8 Series One FHC

http://etype860897.blogspot.com/

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Re: RB340 checking possible over charge

#12

Postby Philk » Wed Nov 08, 2017 12:22 pm

I had been considering retro-fitting a dynamo as part of the final re-commissioning of my 3.8 but have decided to go the +ve earth Dynator route with the RB340 acting as a dummy unit. The control unit and relay are built into the Dynator. This keeps looks original but improves the charging at low speed and takes reliability issues (hopefully) off the table. Are you totally wedded to the Dynamo/RB340 for originality?
Phil
1964 S1 3.8 OTS

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Re: RB340 checking possible over charge

#13

Postby andrewh » Wed Nov 08, 2017 12:46 pm

Ah Phil. I had forgotten that as an idea. I saw these Dynators at one of the shows and the dummy RB340 and made a mental note....and promptly failed to recall it until your jog. I will look into that, if I can establish that the dynamo is overcharging the batter. Maybe a better long term solution. thanks for reminding me.
1962 3.8 Series One FHC

http://etype860897.blogspot.com/

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Re: RB340 checking possible over charge

#14

Postby cactusman » Wed Nov 08, 2017 7:48 pm

Dynators are an option but in defence of the good old dynamo providing you can get a genuine Lucas RB340 that works the system is ok. My e type has an old (original?) Genuine Lucas RB340 and it has worked perfectly for the five years I have had the car.....all I have done is refurbished the dynamo with new brushes and a good oil and cleaned the RB340 contacts with switch cleaner...
Julian the E-type man
1962 FHC
1966 MGB....fab little car too

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Re: RB340 checking possible over charge

#15

Postby rfs1957 » Tue Nov 14, 2017 1:42 pm

I've been in dinosaur land too with an RB340, dynamo, +ve earth since I bought the car etc about 15 years ago and apart from'checking and adjusting the RB340 about 4 years ago have never touched anything, maybe because the regulator was NOS.

I wrote an article on my experiences on the Forum in 2013 including a simplified version of the adjustment instructions, can't see on this tablet how to copy the link (PC currently at the breakers) but if you search for RB340 AND rfs1957 it comes up.

All the images and diagrams have been fritzed by the swine at PhotoBucket, but if - from reading the words - it sounds helpful, then upon request I'll dig out the images and stick them up again.
Rory
3.8 OTS Cream 877393 Built May 28th 1962
1978 Mini Van
(plus bevel and belt single-cylinder Ducatis)

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Re: RB340 checking possible over charge

#16

Postby andrewh » Tue Nov 14, 2017 1:48 pm

Thank you Rory. I will do just that and have search. I bought myself an AVOMETER to do all this testing with, but now diverted trying to get that to work!! will report back in due course. :bigrin:
1962 3.8 Series One FHC

http://etype860897.blogspot.com/

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Re: RB340 checking possible over charge

#17

Postby cactusman » Tue Nov 14, 2017 4:29 pm

I hope it was a proper vintage avometer. :bigrin: :bigrin: I love em The model 8 mk4 is a fabulous instrument with a superb damped meter movement. The ideal instrument for setting up the voltage cut out....
Julian the E-type man
1962 FHC
1966 MGB....fab little car too

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Re: RB340 checking possible over charge

#18

Postby andrewh » Tue Nov 14, 2017 5:40 pm

Its a model 8 MK5. I just got it working, well on voltage. Seems pretty accurate. Now need to teach myself how to use it. I have always despaired of digital meters for some tasks, as they are just not static and bounce around all over the place. I am hoping this is going to work on resistance and current as well, but as I am not an electrical engineer its testing my schoolboy physics. The good news with the meter I have bought is it has all its original leads, some probes, clip on and crocodiles. They tend to be hard to come by. Are you an expert, if so we may take this off line and explore some basic lessons for me?
Image
1962 3.8 Series One FHC

http://etype860897.blogspot.com/

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