Quick alternator ampage question

I have an 88amh battery fitted to my 1984 '90'

The current alternator is only putting out 36amps at peak and consequently not charging the battery enough.

What amp alternator should I get for an 88amh battery?

Cheers, Daz

what are you trying to power from it?

The battery Ah and Alternator o/p are not necessarily linked.

Nothing special, I don't even have leccy windows. But I have to charge the battery with a charger every so often, otherwise it can let me down on cold mornings. As it did last Monday. RAC man condemned the battery and questioned the alternator. When I put main beam on, the battery is losing power, even at 2000 rpm.

didnt he check the alternator?
how old is the battery?

get it checked and then revise the options.

The battery is just out of warranty and it was the battery place that tested the alternator. The battery has alledgedly suffered from continual charging up and running low but, with a better alternator would still be ok. I used to have to charge the previous battery, which is why I bought this one just over 2 years ago.

If I buy another battery, I don't think the problem will go away until I improve on the current alternator. BUT, I don't want to buy one not up to the job, hence my question.

what alternator is it,what engine and is the battery cold start rating

See here: Charging System Basics

if my memory serves me correctly the early 90's had a 45amp alternator but these are no longer available. a 65amp alternator is the next one . i would be inclined to clean or even replace the cable from the alternator to the starter terminal with a larger diameter as there would be a voltage drop depending on the cable diameter. i was running a n/a in my 1986 90. this was replaced with a 200tdi but i upgraded to a 100amp alt from a 300 as i run a winch and have had problems with the smaller alternator not giving enough.

Thanks for the info guys.

It let me down again this morning

You wouldn't believe the chasing around I have done to try and get a replacement from any of my local motor factors. No-one seems to be able to confirm that a 65a alternator will be sufficient to keep my 88ah battery charged (well, the new 88ah battery when I get one next week)

Most of them keep trying to sell me the standard 45a alternator and those that can get a 65a one in can't confirm that it will be exactly the same fit. Surely it can't be this hard?

Maybe I'm complicating things somehow

SuperDaz said:

Thanks for the info guys.

It let me down again this morning

You wouldn't believe the chasing around I have done to try and get a replacement from any of my local motor factors. No-one seems to be able to confirm that a 65a alternator will be sufficient to keep my 88ah battery charged (well, the new 88ah battery when I get one next week)

Most of them keep trying to sell me the standard 45a alternator and those that can get a 65a one in can't confirm that it will be exactly the same fit. Surely it can't be this hard?

Maybe I'm complicating things somehow

Click to expand...

Ive used these myself and recommended em before on ere
WHY Take Risks??? Come to the Experts

I don't know if it will fit your engine but IIRC, the alternator from a 200/300 discovery is more powerful than the same from a defender and easy to get hold of too

Harry

nathan5346 said:

Ive used these myself and recommended em before on ere
WHY Take Risks??? Come to the Experts

Click to expand...

Thanks Nathan, I did call the number after my mate did a google for me while I was out and about pulling my hair out. But I think it was after 1:00pm I was hoping to get it sorted today but it's too late now. If I can't make any progress tomorrow (unlikely) I'll give them a call Monday.

Boris113 said:

I don't know if it will fit your engine but IIRC, the alternator from a 200/300 discovery is more powerful than the same from a defender and easy to get hold of too

Harry

Click to expand...

Cheers Harry, Ill try and find the part numbers and see if they will cross-reference.

Daz

SuperDaz said:

Thanks Nathan, I did call the number after my mate did a google for me while I was out and about pulling my hair out. But I think it was after 1:00pm I was hoping to get it sorted today but it's too late now. If I can't make any progress tomorrow (unlikely) I'll give them a call Monday.



Cheers Harry, Ill try and find the part numbers and see if they will cross-reference.

Daz

Click to expand...

£45 fer a recon 200tdi alt off them

nathan5346 said:

£45 fer a recon 200tdi alt off them

Click to expand...

That's my kind of price!

SuperDaz said:

That's my kind of price!

Click to expand...

i got 1 fer £35 last year but the price gone up a tenna

mad hat mans right a 45a alternater will keep even a 120ah battery charged but wont cope with lots of accesseries,you need to have both checked by someone who has no interest in trying to sell you either. not easy i know

try these peeps - sell thru E-Bay.... [email protected]

HOOK said:

mad hat mans right a 45a alternater will keep even a 120ah battery charged but wont cope with lots of accesseries,you need to have both checked by someone who has no interest in trying to sell you either. not easy i know

Click to expand...

I've found the RAC report out and it says

"Flat battery, boost start and check system. 13.3v@10amps - test battery battery U/S Suggest replace battery and re-test alternator output. Initial test results would indicate a possible alternator fault"


I then went to the battery supplier (battery just out of warranty) and he did some tests and concluded that battery was showing signs of age but still servicable. Alternator output was only 36amps@peak and only 7amps@tickover he recommended a higher output alternator (which he doesn't sell and didn't try to send me anywhere in particular)

I know this might be a daft question but does 36amps sound right for what I presume to be a 45amp alternator (I can't see any markings to tell me the amps)

And... even though there are 3 terminals on the alternator, I only have two wires connected to it

Daz

RAC man sounds about right. Voltage is a bit low and so is the output assuming a 45 Amp alternator. If you are doing a lot of short trips with a slightly faulty alternator then you are going to end up with a flat battery. It never gets a proper charge. Get a good battery on it and see what voltage it is charging at. It should be about 13.8. Get it looked at by someone who repairs alternators.
As everyone says, you shouldn't need a higher output alternator unless you are using a lot of accessories.
And don't worry about spare terminals. If something wasn't connected it wouldn't work at all.