anyone know much about these Nissan GU Patrol Alternator Voltage Booster

[my third 256]

just saw these on eBay and was wondering if any good
or are they a gimmick
http://www.ebay.com.au/itm/Nissan-GU-Patrol-Alternator-Voltage-Booster-/221108819563?pt=AU_Car_Parts_Accessories&hash=item337b1cd66b

[Bagheera]

eBay link doesn't work for me. I'll assume you mean something like this: http://www.sidewinder.com.au/page159aa.html

They work by modifying the Alternator Sense signal so the alternator puts out a slightly higher voltage. Diodes produce a voltage drop, so the sense circuit sees a voltage ~0.5V lower than the actual voltage, and then compensates by adjusting the alternator output to be 0.5V higher. Seems to be a common fix for Prados that run dual batteries. The ECU reduces the charging voltage from 13.8V to 13.2V when the main battery reaches 80% charge state to reduce alternator load and improve fuel economy. This diode forces the voltage back up to the higher end of the range to allow for a battery isolator to charge the second battery.

Just make sure that any unit you buy still has fuse capabilities.

[Jock]

These devices are for heavily compensated altenators. Check your altenator output if above 14.1v you don't need one of these devices. You may end up cooking your battery/s . I have already made enquiries to a vendor about these devices. I have a 2010 GU with dual batteries and a cold altenator output of 14.4v. He advised me not to install one of these.

Cheers

Jock

[Yendor]

I wouldn't use it in a Patrol, as Jock pointed out you run the risk of over charging your main starting battery and possibly your second battery as well, depending on type of battery.

On the GU if the alternator, wiring and battery is in good condition (the GU is the only Patrol that has a fused battery sense circuit) then there should be no need.

If you are concerned about your second battery not being fully charged then you will need to look at your dual battery isolator or possibly install a DC-DC charger.