Alternator

[scottonthefen]

I changed my fan belt today and took the opportunity to clean up the alternator contacts and test the battery with a multimeter. I'm taking the 2A on the road for the first time this summer and want to run over to a couple of shows so I'm going over things with reliability in mind.

Voltage over my battery switched off and at a slow idle after just starting is about 12.4. If I prop the throttle down a bit to rev her up the voltage goes up to about 13.8 at best. Is that about right? (I don't have a lot on the 2A I can switch on at the moment to test it under more load, no wings so no lights etc.)

 

[kermit_rr]

Alternator or dynamo?
Either way 13.8v is weak for keeping a battery healthy

 

[scottonthefen]

Alternator. Not the right alternator either, I might add. It has a Ford sticker on it. I don't know the history. What kind of voltage should I get across the battery for a healthy alternator working as it should?

 

[kermit_rr]

Ok. The ideal voltage for a lead acid battery to reach gassing point is about 14.4v

 

[kermit_rr]

There's no right alternator, apart from what fits. It was a popular upgrade although i never did it! I found the dynamo to be sufficient for my needs

 

[Colthebrummie]

Try cleaning your battery terminals and measure again.

Col

 

[tottot]

If you are only using your truck now and then put the battery on a mains battery charger for a few hours once a month.

 

[Bobsticle]

Sounds a bit tired to me. I had similar when I got mine so upgraded the alternator. For sixty quid it’s given me trouble free starting for years.

 

[Blackburn]

Mine sits at 13.8V and occassionally makes 14V never above , personally I would finish your rebuild and try it will be winter time when you need more electrics on will show if not delivering sufficient power.

 

[scottonthefen]

Cheers all. I cleaned the terminals before testing. Looks like one for the keep an eye on it list based on your replies here.. 13.8 seems tired to some, but ok to others so I think I can risk a few road trips over the summer.

This Ford alternator doesn't fit right anyway. There's only two mount points on it which means the 'through-bolt' on the engine block is not being used at all, and the closest I can get the belt alignment is 3 or 4mm to one side of the fan pulley without shimming the lower bracket and then fouling the bottom drive pulley with the timing indicator . It's not slipping or overly tight, but it's not 100% true. £60 @Bobsticle? What model is that and does it fit well in terms of mounting and belt alignment? The Lucas ones I've seen are knocking on 100 which is not a problem in itself - just curious.

 

[kermit_rr]

13.8v will charge your battery, it will just take longer to reach full charge. This may or may not be an issue depending on the length of journey. It could also be an issue during the colder months when your charging system will have to work harder charging a cold battery, again not an issue if you don't use it in winter or regularly use a battery maintainer

 

[Bobsticle]

Cheers all. I cleaned the terminals before testing. Looks like one for the keep an eye on it list based on your replies here.. 13.8 seems tired to some, but ok to others so I think I can risk a few road trips over the summer.

This Ford alternator doesn't fit right anyway. There's only two mount points on it which means the 'through-bolt' on the engine block is not being used at all, and the closest I can get the belt alignment is 3 or 4mm to one side of the fan pulley without shimming the lower bracket and then fouling the bottom drive pulley with the timing indicator . It's not slipping or overly tight, but it's not 100% true. £60 @Bobsticle? What model is that and does it fit well in terms of mounting and belt alignment? The Lucas ones I've seen are knocking on 100 which is not a problem in itself - just curious.

Got mine off ebay. There are lots of them advertised as (LUCAS TYPE) for series Land Rovers at different amps. The more amps the more money. Like I said it was about three years ago or so. They may be more expensive now but I managed an 80amp for sixty quid back then.

 

[rob1miles]

I got something very similar off the local car electric guy, same sort of price. Works a treat.

 

[mystery]

has it the correct size pulley fitted the ford it came off might have revved higher

 

[scottonthefen]

Which pulley @mystery? The one on the alternator, or are you saying the one on the fan or behind the starter dog might have been changed? What do you mean by the ford might have revved higher?

 

[kermit_rr]

what he means is, the pulley on your crank is most likely a different size to the pulley on the ford engine crank. as such, the alternator could well be spinning slower than intended when running on your engine

 

[scottonthefen]

Got it. Thanks for that hadn't even thought of it. That would explain why the charging voltage seems a bit low even if the alternator is in good nick (assuming it is).

But I don't want to change my crank pulley to better suit a Ford alternator.. if i have charging issues I'll fit a more suitable alternator.

 

[kermit_rr]

you should be able to get a smaller pulley for the alternator

 

[marjon]

you should be able to get a smaller pulley for the alternator

Doesn’t the OP note he is already having alignment/tension problems. And incorrectly fitted alternator (mounting points missing)
Reliability wise probably best fit an alternator/brackets that fit correctly. Not big money in the reliability scheme of things.

J

 

[kermit_rr]

Doesn’t the OP note he is already having alignment/tension problems. And incorrectly fitted alternator (mounting points missing)
Reliability wise probably best fit an alternator/brackets that fit correctly. Not big money in the reliability scheme of things.

J

yes you're right, sorry, I got carried away with the low output aspect

what about spacers, bending the bracket etc? or making a new one?