Best alternator for 110 2.5D n/a

ibizalandy · Sep 2, 2024

Hi, I'm having problems with my battery going flat over time, because I only use it locally and it never really gets a long run. The battery is new and I've checked all the wiring. If I leave it on charge overnight it's fine for a week or so.
Can I fit a higher power alternator?
I've seen them rated from 45A up to 75A.
Would a 75A one help it charge more or would it just melt the wiring?
The one on there doesn't have a bolt on cable, it's an oversize spade connector. It looks like a series 3 one.
Any ideas?
Thanks

miktdish · Sep 2, 2024

I think first you need to understand what is happening (a) when the engine is running and (b) when everything is 'off' and the key is out.
To do this you need a voltmeter or better still a digital Multimeter (DMM).
The voltage on the battery (+ to -) shound be around the 12.3V mark and with the engine running around the 13.7 to 14.1V range.
This indicates that your battery is OK and is being charged when the alternator is spinning.

With the engine off you should see the votage around 12.3V, slightly less is OK but below 12V would indicate that the battery is either not holding charge is is being discharged by something on your car.
To test if it is something on your car, you can dissconnect the battery, measure the voltage and leave it off for a couple of days and see if it is the same voltage.
DMM's do have an 'amperage' function which can be used to measure if there is a drain no the bettery. To do this dissconnect the + lead, sent the DMM to read Amps and connect between the battery terminal and the lead you removed.

I would expect to see a reading of around 100mA as the clock is permanently 'on' however if it is higher 1 or 2 Amps for example then there is something else that needs looking for.

If possible can you post a picture of your battery ?
A higher rated alternator won't melt any wires and the battery and other circuits will only draw as much current as they need and all of your circuits (lights etc) will be protected by fuses.
The 45A alternator will charge the battery at the same rate as a 75A alternator

tottot · Sep 2, 2024

You have the correct one for year. Lucas or Lucas type. Plug to alt will have two large spades to deliver power and a small one that takes "exciter" 12v power to the alternator.
Putting a more powerful unit on will not help. Something is draining the battery. Disconnect for the time you are not using it. If battery still drains it has a fault. If remains charged there has to be a fault in the vehicle electrics most likely ones feeding ignition switch or lights. It is also possible the alternator itself is the issue.
Ah,@miktdish got here first.

ibizalandy · Sep 3, 2024

miktdish said:
I think first you need to understand what is happening (a) when the engine is running and (b) when everything is 'off' and the key is out.
To do this you need a voltmeter or better still a digital Multimeter (DMM).
The voltage on the battery (+ to -) shound be around the 12.3V mark and with the engine running around the 13.7 to 14.1V range.
This indicates that your battery is OK and is being charged when the alternator is spinning.

With the engine off you should see the votage around 12.3V, slightly less is OK but below 12V would indicate that the battery is either not holding charge is is being discharged by something on your car.
To test if it is something on your car, you can dissconnect the battery, measure the voltage and leave it off for a couple of days and see if it is the same voltage.
DMM's do have an 'amperage' function which can be used to measure if there is a drain no the bettery. To do this dissconnect the + lead, sent the DMM to read Amps and connect between the battery terminal and the lead you removed.

I would expect to see a reading of around 100mA as the clock is permanently 'on' however if it is higher 1 or 2 Amps for example then there is something else that needs looking for.

If possible can you post a picture of your battery ?
A higher rated alternator won't melt any wires and the battery and other circuits will only draw as much current as they need and all of your circuits (lights etc) will be protected by fuses.
The 45A alternator will charge the battery at the same rate as a 75A alternator

Thanks for the detailed answer, it's very helpful. I have installed a Voltmeter on the dash, so I know it's charging properly. There's only a clock pulling current when it's off and i fitted that years ago, so i don't think it's that. I think it must be that being an old 2.5 n/a, it takes a bit of getting going and a some days I'm only driving a mile or so to work and it just doesn't get a chance to recharge. I spent time yesterday going over the whole system remaking all the connections etc so I'll see how it goes.

lynall · Sep 3, 2024

Fit a battery isolator, and make sure it kills everything especially that clock and any radio that keeps codes, it is the small power drains that people ignore.

You can fit the higher amp alternator, but you may need to upgrade the fat wire that runs from the back of the alternator to the starter motor positive terminal.
If you use an A127 alt, then a tractor brush box/rectifier will get you higher volts from the alternator.

LUCAS A127 ALTERNATOR REGULATOR BATTERY TEMP SENSED TRACTOR NEW | eBay

LUCAS A127 ALTERNATOR REGULATOR BATTERY TEMP SENSED TRACTOR GENUINE LUCAS LUCAS PART NUMBER UCB153, 28006, 37735FITTED TO MODEL A127 BATTERY TEMPERATURE SENSED ALTERNATORS ON AGRICULTURAL VEHICLES NEW HOLLAND PART NUMBER 83981529, E7NN10316AA...

www.ebay.co.uk

Best alternator for 110 2.5D n/a

ibizalandy

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miktdish

Guns n Chainsaws

tottot

Well-Known Member

ibizalandy

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lynall

Well-Known Member

LUCAS A127 ALTERNATOR REGULATOR BATTERY TEMP SENSED TRACTOR NEW | eBay

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