diy solar

diy solar

Victron Orion DC-DC charger not charging at full output?

I tested this today. The alternator is a "temperature compensating" type. Initially voltage was 13.9V and dropped to 13.4V once the engine was nice and warm. I'll have to check the spec but I think that is normal.
I have a Tundra and the "temperature compensating" was causing issues charging my AGM due to the constant low voltage. There are a lot of threads on the Tundra forums with people that have the same issue, some people were actually putting there truck on a charger every night to top the battery up. They ended up finding that Toyota use one of the fuses to detect the voltage that regulates the alternator output, they put a diode inline using an add-a-fuse holder to increase the voltage. I ended up buying a replacement fuse that had the diode in it to trick the alternator. A company in Australia makes a couple of models, two are a fixed voltage increase and the other has an adjustable voltage increase. I bought the adjustable one, but honestly I haven't changed it since I got it and the setting I ended up using I think is the same voltage increase as the non-adjustable ones. I was a little leary about ordering something from Australia, but it arrived almost 30 days later. Here is their website if your interested, https://www.hkbelect.com/products/toyota/?model=tundra&year=2012
 
I have a Tundra and the "temperature compensating" was causing issues charging my AGM due to the constant low voltage. There are a lot of threads on the Tundra forums with people that have the same issue, some people were actually putting there truck on a charger every night to top the battery up. They ended up finding that Toyota use one of the fuses to detect the voltage that regulates the alternator output, they put a diode inline using an add-a-fuse holder to increase the voltage. I ended up buying a replacement fuse that had the diode in it to trick the alternator. A company in Australia makes a couple of models, two are a fixed voltage increase and the other has an adjustable voltage increase. I bought the adjustable one, but honestly I haven't changed it since I got it and the setting I ended up using I think is the same voltage increase as the non-adjustable ones. I was a little leary about ordering something from Australia, but it arrived almost 30 days later. Here is their website if your interested, https://www.hkbelect.com/products/toyota/?model=tundra&year=2012

Thanks. I am familiar with the diode trick to boost the alternator output voltage. It will actually create a slight voltage drop in the battery voltage measurement circuit of the alternator, causing the alternator to think it is outputting a lower voltage than it really is, and causing it to boost its charging voltage. This is mainly for use with AGM batteries as the vehicles charging profile is designed for standard FLA. The AGM/SLA requires a higher charge voltage. Keep in mind all of the vehicles electronics will see the elevated voltage, not just the battery. I am using a standard FLA starting battery so do not need such a device, and using it may actually damage the battery.


My issue was too much of a voltage drop between the alternator and the DC-DC charger for the house battery because I was using 8awg wire, causing the charger to not produce full output. I did a test using 6awg and 4awg and the charger did produce full output. So the takeaway for me is to keep the voltage drop between the alternator and charger to under 3%.
 
My issue was too much of a voltage drop between the alternator and the DC-DC charger for the house battery because I was using 8awg wire, causing the charger to not produce full output. I did a test using 6awg and 4awg and the charger did produce full output. So the takeaway for me is to keep the voltage drop between the alternator and charger to under 3%.
Well that's aggravating. I thought one of the reasons to use a DC-DC charger was to compensate for voltage drop between the power source and the target battery.
 
Well that's aggravating. I thought one of the reasons to use a DC-DC charger was to compensate for voltage drop between the power source and the target battery.

The charger can and does compensate for a lower input voltage (being a buck-boost converter), but it expects that input voltage to remain fairly constant over its range of output, hence the <3% voltage drop.
 
The charger can and does compensate for a lower input voltage (being a buck-boost converter), but it expects that input voltage to remain fairly constant over its range of output, hence the <3% voltage drop.
Yes! Use #2 wire and connect directly to the starter battery, and the Orion will be happy. The starter battery acts like a big "spike-snubber", and its voltage will be relatively stable, so it's a good point to connect to IMHO (as opposed to wiring to the alternator). We use use an MRBF fuse right at the battery terminal.
 
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