Dynamo and battery probs

Post by **sjstyles** » Thu Aug 19, 2004 10:56 am

Hi all,

Ive been reading through all the related threads and picked up a few bits and pieces but heres my problem anyway:

I recently had the dynamo burn out which was bad because it was only a few months old. I managed to get back on battery power and get a replacement dynamo. I also bought a battery charger so I could charge the battery up again.
The battery was started charging on monday morning and on the box it stated that it could take about 15 hours to fully charge. Besides there are LEDs on the charger which should flash when its all done.
It got to 3/4 charged (according to the LEDs on the charger) on monday evening. I left it charging and it was still at 3/4 the next morning. I took it off charge tuesday evening because it still wasn't reading fully charged.
Anyway, I put the dynamo on, polorised it etc, put the battery on and got the multimeter ready to check the control box. Pulled the starter and I only got half a whir of the starter: the battery was flat.

So, which ever way things happen I think I need a new battery now. I don't know if the previous dynamo failed because the battery was on the way out or the dynamo just failed and I broke the battery because the charger might be faulty or its a stupid charger which doesnt read full and I over charged the battery.
Whatever happened, I smelled burning (almost like burning brakes) and squealy noises before the dynamo failed and the charging light went out. But then the battery was fine to start the car and get back to Derby from past Cromford, which makes me think I broke the battery by charging it for too long. I was only going by the charger instructions.

If anyone has any ideas that would be helpful.

Also, I read the haynes manual about checking the control box cut out and regulator with a multimeter. Does anyone have anything to add to whats said in the book?

Many thanks

Post by **rayofleamington** » Thu Aug 19, 2004 11:45 am

Hi
Squealing noised from the dynamo? If the rear plain bearing ran dry it can squeal and the bearing would soon be damaged but it would normally take a while before it stopped working altogether. Could it have been a bent brush-holder or something like that?

If the battery was duff, that shouldn't have damaged anything else. At the time the battery must have been working anyway as you could still drive (unless the dynamo still had a small output)

Was the battery topped up before you charged it? If it's one of the 'maintenance free batteries' try and prise the caps off anyway to see if the acid is low in one (or all) of the chambers - if so, topping it up and recharging should help but it's not likely to last long.

You're very unlikely to damamge a battery from charging it for a couple of days. The battery charger should give out approx 14 to 14.5 volts when not connected to the battery (if it gives out 15 and above it might be faulty) - when you connect it up the current causes a voltage drop in the leads so it can read anything from 11 volts to 14 volts depending on how much current is going into the battery.
If you have a multimeter there's no harm in checking the battery charger anyway but they are usually very reliable.

One last thing to check for the slow starting - it might be cause as you have disturbed the battery leads or the earth lead etc.. That can appear to be a flat battery.
To tell the difference If the battery voltage drops from 13 volts to below 11 volts during cranking then it's not the leads!
A flat battery will drop a lot during cranking, or a good battery can drop a lot if the starter motor is drawing high current - if you supsect the battery as a cause of poor cranking the most sensible way to check is to swap batteries with another car where you know it is ok. The last time I had this was on my Honda and it turned out to be the starter even though at the start I was 99% sure it was the battery.

As for checking the voltage regulator... I've never had to do anything to one probably best if someone else advises.

Post by **Kevin** » Thu Aug 19, 2004 12:37 pm

You should also not rely on the charger for the condition of a battery a Hydrometer is much more accurate and can pinpoint if a cell is going home when the rest of the battery is ok.

Post by **sjstyles** » Thu Aug 19, 2004 12:43 pm

Hi Ray,

Im not sure if it was a bent brush holder or anything. I hadn't oiled it for a while so it could have been that making the noise. I would have attempted to find out what was wrong but the screws on the back plate were so tight I had no chance of getting in to it, so I phoned around for a new unit.

I've never topped up the battery. It does say 'maintenance free' but Ive always checked the fluid level and its always seemed fine - just above the top of the flat vertical plates in the cells. Is this right?

When you say the voltage might drop from 13 down to below 11, where would I put the meter to test for this, just over the battery terminals? I don't want to mess anything else up. This is turning in to a bit of a chain reaction*
The problem is, I don't have a spare battery or another car to use on off. Plus I can't take the car anwhere because its pretty inanimate at the moment!

*when the dynamo failed I pulled over to check it out. Pulled the bonnet release which just came out in my hand (the pin had obviously come out). Tried opening the bonnet with a screw driver, slipped and put a hole in the radiator. Managed to get it open, drain rad. and fixed it with super steel stuff. Couldnt really do much with the dynamo other than check the leads etc so drove back, now all this

its all fun really (I keep telling myself!)

Post by **sjstyles** » Thu Aug 19, 2004 12:44 pm

Hi Kevin. I had a hydrometer once (I brewed some beer) but it got broke in a house move. A trip to Wilkinsons I think!
Cheers

Post by **rayofleamington** » Thu Aug 19, 2004 1:16 pm

sjstyles,
Sorry to hear abouut your chain reaction (damaged rad etc..). It's a terrible feeling to break down and not be able to open the bonnet!

For the dynamo it just needs a little oil at the rear bearing every service - it's normally not done unless the owner is very thorough and I must admit that I often forget to do that too.

Yes - should have Mentioned that you measure across the battery terminal if you want to see battery voltage during cranking. If the voltage doesn't drop down a lot then check all the battery leads and the earth connection (between gearbox and gearbox xmember)

If the battery has enough juice to half turn the engine you might get away with the starting handle (if the engine starts v easily) or a trusty push and bump start off a friend.

As all the levels in the battery are above the plates and it won't turn the car over - I would recommend trying a new battery. You could always be cheeky and ask Halfords if you can 'try' a new battery to make sure that is what is at fault.
You might get away with it if you find a friendly member of staff. If it's not the battery, then make sure you have someone to bump start the car again!

Post by **sjstyles** » Thu Aug 19, 2004 6:00 pm

Thanks for all the advice Ray and Kevin.

It certainly is a unique feeling when the bonnet doesn't open!

I'll give things a go this weekend. Any tips on oiling the dynamo when its in place?! Its a bit of a farse when you've taken it on and off so much.

Post by **rayofleamington** » Thu Aug 19, 2004 6:12 pm

if you have one of those nice old fashioned oil cans wih a long thin spout and a thumb pump - these are very usefull to put a bit of oil on the rear dynamo brush.
If the oil can has engine oil in it it is alo ideal for topping up the dashpot

Post by **Alec** » Fri Aug 20, 2004 8:07 am

Hello SJS,
what can kill a battery is a dead short as the heavy current buckles the plates and internally shorts the battery; having a dynamo burn out could well cause such damage. What it could do to the regulator, I can't guess.

Alec

Post by **rayofleamington** » Fri Aug 20, 2004 9:24 am

a dead short shopuld have stopped the car from driving tho.. I kind of ruled that out based on his description, and that the car would still restart until after it the car was worked on.

Post by **Alec** » Fri Aug 20, 2004 2:39 pm

Hello Ray,
yes, that point makes sense, but I would be surprised if there was no damage to the battery at all.

Alec

Post by **sjstyles** » Thu Sep 02, 2004 7:13 pm

Got a new battery in the end and it works fine now. Fingers crossed. I checked the regulator as best as I could.
I must recommend the place I got the battery from though. Midland Car Parts, Parcel Terrace, Derby. I phoned at lunchtime and they delivered in the afternoon all for £17!
I think they only do local delivery though.
Thanks all.
Sam