Alternator upgrade

[Laird Scooby]

Just had a look on fleabay and found this - much cheaper than Hellfrauds :

https://www.ebay.co.uk/itm/HB096-Lea...v/192434766703

Almost certainly the same battery under the stickers!

[940volvoman]

Hi Dave,ive just found the paperwork and there are no numbers there either.So it would seem that if they agree I may need to get a new battery...

[quevatre]

How many types of alternator were fitted to these models? I have a problem where the alternator is charging but the (new) battery is being drained overnight. I'm looking to change the voltage regulator on the back of the alternator as I'm suspicious that one of the diodes might be leaking voltage backwards. There seem to be lots of different items available. Where is the best place to purchase from?

Cheers

André

Volvo 940 2.3LPT auto, DFR: 25 Apr 1997, Vin: YV1945816V1204001 Eng: 0370620V

[Laird Scooby]

Originally Posted by quevatre

How many types of alternator were fitted to these models? I have a problem where the alternator is charging but the (new) battery is being drained overnight. I'm looking to change the voltage regulator on the back of the alternator as I'm suspicious that one of the diodes might be leaking voltage backwards. There seem to be lots of different items available. Where is the best place to purchase from?

Cheers

André

Volvo 940 2.3LPT auto, DFR: 25 Apr 1997, Vin: YV1945816V1204001 Eng: 0370620V

In answer to your questions :

Two, Bosch and Nippon-Denso. The bosch alternators had various different outputs and confiurations, the Denso was only 100A.

Changing the voltage regulator WON'T alter a parasitic drain, even if it's the alternator causing it. The voltage regulator is not connected to the battery!

First, you need to check it's your alternator causing the drain.

DO NOT DISCONNECT THE BATTERY EARTH -ve TERMINAL AT THIS POINT!!!!

Being VERY careful, remove the nut holding the B+ lead on the back of the alternator, taking careful note where it comes from. Wrap insulation tape round the end of the B+ lead so if it sags overnight, it doesn't cause a fire.

Reconnect it again in the morning, again being very careful not to let the spanner touch any of the surrounding metal work - it HURTS!!!!!

Try starting the car - if the battery is flat again, you know it's not the alternator alone causing the parasitic drain.

If it starts without a problem, it's likely to be the rectifier.

To find out which one you need, there is a green label on the Bosch alternators giving the output spec 14V @ xxA and a number, tn digits long, start with "0 120" usually. Some later models start "0 123" - you need this 10 digit number to find which rectifier you have.

If you don't do it this way, you could be hunting forever and a day for a parasitic drain.

[940volvoman]

As fracas I understood it,Save the 940was limited to 100amp alternators.One we go to the 960 and/orV90 other outputs were available.No doubt the brackets were different,though.

[quevatre]

Cheers Dave,

In between posting my message and reading your reply, I have had a chance to take a photo (after work in the dark) of the alternator. I have also had a mechanic friend offer some help. Thanks for your advice. I hope to have a better look at things tomorrow lunch time. Interestingly I connected my digital multimeter between the negative terminal and the (now disconnected) earth lead expecting to measure some current. The display stayed at zero! My only explanation is that the current drain is more than 200ma which is the highest range on my multimeter. I have an idea that if the meter reads a current flow higher than this, it will just stay at zero. There must be some leakage happening in order for the battery to flatten so quickly.

The main reason for me suspecting the alternator is that this was what the guy who sold me the car (for £200). Of course he could well have been given duff advice.

At least I now know that I have a Denso alternator but I won't go rushing to buy a regulator without first checking as per your advice.

Great to have a community of like minded Volvo owners to call upon!

Cheers

André

[Laird Scooby]

Originally Posted by quevatre

Cheers Dave,

In between posting my message and reading your reply, I have had a chance to take a photo (after work in the dark) of the alternator. I have also had a mechanic friend offer some help. Thanks for your advice. I hope to have a better look at things tomorrow lunch time. Interestingly I connected my digital multimeter between the negative terminal and the (now disconnected) earth lead expecting to measure some current. The display stayed at zero! My only explanation is that the current drain is more than 200ma which is the highest range on my multimeter. I have an idea that if the meter reads a current flow higher than this, it will just stay at zero. There must be some leakage happening in order for the battery to flatten so quickly.

The main reason for me suspecting the alternator is that this was what the guy who sold me the car (for £200). Of course he could well have been given duff advice.

At least I now know that I have a Denso alternator but I won't go rushing to buy a regulator without first checking as per your advice.

Great to have a community of like minded Volvo owners to call upon!

Cheers

André

Why did you disconnect the earth lead?

[aardvarkash10]

To diagnose your problem properly you need to identify WHY the battery is going flat overnight, and then identify the exact cause of that fault. There are literally hundreds of variables, some likely, some less so.

Dave's advice is great - I fully endorse the approach he's taking and I understand what he is trying to acheive. But then, both of us have done this proferssionally for many years (too many I think Dave would say) and we speak the same language, understand the same nuances and make similar assumptions about prior knowledge.

Unfortunately, it looks like you are not following his instructions exactly. Thats understandable - its new to you and can be confusing.

Take your car to an auto electrical specialist and have it diagnosed. Its not hard, won't take long and is less likely to end in a ball of flames and damaged test gear.

[940volvoman]

Aardvarkash10, and Laird Scooby thank you for your comments.As someone else has entered the fray and hijacked my post ,so I'm not sure what is going on,now.

Never mind battery back on charge overnight.....

[Laird Scooby]

Originally Posted by 940volvoman

Aardvarkash10, and Laird Scooby thank you for your comments.As someone else has entered the fray and hijacked my post ,so I'm not sure what is going on,now.

Never mind battery back on charge overnight.....

As i understood things Shaun, you'd come to the conclusion you needed a new battery on the grounds that yours isn't holding charge, Halfrauds have discontinued the type of battery you have due to problems and you really lead a normal lead-acid battery, not a calcium based one.

As such i made a couple of suggestions including the Lucas battery on ebay further up this thread.