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bigfatbloke



Member Since: 08 May 2018
Location: London
Posts: 40

United Kingdom 2007 Range Rover Supercharged 4.2 SC V8 Stornoway Grey
Is a Bosch or Denso Alternator better?

Afternoon gents,

I am in a position where it looks like the voltage regulator on my current alternator has failed. Had the charging voltage checked at the battery and it’s showing 15.6. As a result I think it’s fried my battery too.

So I am looking to purchase a new alternator for my 2007 4.2 supercharged. Does anyone have any thoughts on whether I should get a Bosch or a Denso replacement?

The Battery is not a problem as I got a lifetime warranty with it when it was purchased.

Post #717371 4th May 2025 1:03pm
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GraemeS



Member Since: 07 Mar 2015
Location: Wagga area
Posts: 2677

Australia 

If I had the option then I would choose Bosch over Denso because I have found that Denso fit avalanche diodes as the rectifiying diodes for over voltage protection rather than desiging a regulator that shuts-down when over-voltage. However I don't know if Bosch do the same but I do know that some alternator manufacturers don't use avalanche rectifier diodes. The reverse conducting threshold voltage of avalanche diodes reduces with usage causing them to eventually short-circuit to ground at normal voltages, flattening the battery very quickly. L405 D350 SE Carpathian Grey D5 19" rims

Post #717375 4th May 2025 1:32pm
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cass



Member Since: 12 Oct 2011
Location: northumberland
Posts: 767

United Kingdom 

I would get the cheapest/most convenient of those 2. I would expect either to outlast a nearly 20 year old car.
The same can’t be said of a no name 1/2 price EBay offering.

Post #717377 4th May 2025 2:21pm
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diesel Dave



Member Since: 14 Aug 2015
Location: Stockport
Posts: 488

England 2019 Range Rover Autobiography SDV8 Santorini Black

I used a lot of Denso ones over the past few years and never had one back so far.

Post #717383 4th May 2025 3:07pm
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Mikey



Member Since: 10 Jan 2008
Location: Dundee
Posts: 1824

Scotland 

Denso are the OE supplier to JLR, if it's lasted this long, I'd buy another Thumbs Up

Post #717384 4th May 2025 3:09pm
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bigfatbloke



Member Since: 08 May 2018
Location: London
Posts: 40

United Kingdom 2007 Range Rover Supercharged 4.2 SC V8 Stornoway Grey

Thanks for the replies gents.

I think I will go with Denso as they are the standard fit for LR. There’s only £50 difference in price as well, so not really a price decision. More a “whats best for the job” decision.

Post #717398 4th May 2025 7:39pm
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JonnyCJ



Member Since: 12 Mar 2024
Location: Wirral
Posts: 210

United Kingdom 2012 Range Rover Vogue SE 4.4 V8 Sumatra Black

Just bought a Dan1110 Denso from AUTODOC for my 2012 4.4 TDV8. The price fluctuates daily, so I popped it in my basket and watched the price for from £230 to £250 to £278 and then down to £218.

Snapped it up at £218 and then used code SAM7 to get another 7% off, so with buyer protection at £3.95 (allows me to return it free within 200 days) I think I was at £203 all in.

Post #717402 4th May 2025 8:49pm
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