I've been struggling since I bought my 07 Tundra back in March with its power system. I'm at my wits end and turning to you for help.
I've added 2 yellowtop optimas to a truckbox in the bed of my truck.
Cutting to the chase ... the 150A heavy duty alternator won't put out anything more than 13.8 volts, and most of the time it's more like 13.2. Charging additional batteries at 12.9-13.2 volts doesn't work unless I drive from here to Arizona every day. I really need 14.4 volts if I can get it.
1. I assume the Denso alternator has internal sensing. If the stock battery is low (12.2v without charging) or fully charged (12.7v) I still only see about 13.8 volts being output. Is this because it's tuned to only charge the stock battery?
2. I added an isolator from SurePower. This didn't work out since the alternator didn't sense the 1v drop and therefore the optimas never charged.
3. I removed the isolator and put in a battery separator from SurePower. It's a little better, but I still only have 13.2 - 13.6 volts to charge these optimas, and that's not enough for a high amperage charging.
4. I see a .2v - .3v drop from the front alternator to the back batteries, this is the 4 gauge wire. I am replace that with 0gauge wire tonight but that's still not going to get me more 14.4 volts.
Main Question: Why does the Denso alternator only like to output 13.2 - 13.8 ? Can I get 14.4? Can I remove the sense wire and give it voltage from the back batteries to help with it determining what to output? Can I put a resistor in the sense wire to drive up the voltage ?
The new 07 tundra is great, but I look stupid charging batteries in my driveway every day. Every other car on earth I've seen 14.4 volts coming from the alternator. If I remove my separator and put it back to factory, I still only see a max of 13.8 coming from the alternator. Is there anyone out there with an 07 tundra that can check the voltage for me ? Im wondering if the isolator fried my denso regulator somehow.
Please help : )