Td5 alternator

Hello everyone I have a td5 disco. and have found that with every thing on lights heated screens, heater blower e.c.t. that my alternator was not charging 12.7 volts with engine running and everything on (checked at battery). national luna split charge fitted also. it charges if i dont have the heated front screen on or if i have the heated screen off and everything else on. or heated on everything else off. sorry hope this is confusing. So i replace the alternator today and its still the same. Is this normal? poss battery fault? bad earth? Thanks Dan

there if a fuse in the engine compartment fuse box its the biggest one in there 100amp i think

At what RPM was the engine at when you checked it ?

You need to be at a fast "idle" 1500 rpm + then check what the charge voltage is with the loads on.

How did we ever manage with 35A alternators!

If you have absolutely everything turned on, and the engine running at lkess than at least 1500rpm as UP says above, then you'll not keep up with the loading, especially if the battery is a bit down to start with.

The Disco 2 alternators are Bosch 135A up to the facelift models, then a Lucas machine after that.

The other thing to remember is that they were never designed to carry everything you could switch on, they work on average usage values, so a windscreen demister would be classed as 15 minutes use then turned off, same for rear screen and so on.

Try again, but get the battery fully charged first, and make sure that your revs are up to 1500-2000 at least, more is better. Also note that the voltage will not change quickly, up or down, the battery will stop sudden swings either way.

Peter

You have a Luna monitor/controller in the cab then? Is this what you were taking the reading from?
Coincidence maybe, but my Luna reading since yesterday since the cold has hit hard has been all over the show-apparently Im over charging both batteries by 1.5 volts-the readout was flashing & beeping like a mentalist! I tested the output with a Bosch tester at work & all was fine-poss an issue with Luna monitors???

I was checking a idle. so have proberly just waisted my money on a new alternator. oh joy! Yea i do have national luna dual battery controller. was checking charge with a BT multimeter though.

My monitor to day goes back to normal charge when i have the heater on....i think best left til the cold snap is over-'leccy gremlins me thinks

mine went mental this morning flashing and beepeing i guess over charge. put the heater on and it stoped most odd.

distd5co said:

mine went mental this morning flashing and beepeing i guess over charge. put the heater on and it stoped most odd.

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i think i might mail Luna & see what they say..

Yea if you do let me know what the outcome is. Dan

they shut til new year