Thread: Alternator output

Originally Posted by Tins

It should have come up in the link, but I'll try again. Might be a Mac thing I suppose.


https://store-fhnch.mybigcommerce.co...U%20Manual.pdf

Tested this link, it opens an online, downloadable, PDF.

Thank you for that Tins.

Sharmy, that is NOT and Alternator to Battery DC/DC device.

It is a standard Battery to Battery DC/DC device and as such, I have no idea about the reason for that wattage statement.

There is a contact e-mail address at the bottom of the instructions. Try sending them a message and see what they have to say.

BTW, they have a pretty good name, so should do what you want.

Originally Posted by drivesafe

Thank you for that Tins.

Sharmy, that is NOT and Alternator to Battery DC/DC device.

It is a standard Battery to Battery DC/DC device and as such, I have no idea about the reason for that wattage statement.

There is a contact e-mail address at the bottom of the instructions. Try sending them a message and see what they have to say.

BTW, they have a pretty good name, so should do what you want.

Thanks, I will contact them to see if they know what it's about. They are a good mob, I have dealt with them before. I will let you know the outcome.

Well the answers aren't much chop, I am starting to wonder if I am talking to real people or not, or maybe some Chinese person with a western name. I will go ahead and fit it and hope for the best.IMG_0129.jpgIMG_0130.jpg

That's a bit of a worry.

With older type DC/DC devices, as the INPUT VOLTAGE from a SMART alternator drops, the DC/DC device compensates for the lower voltage by increasing the INPUT CURRENT draw. As the INPUT voltage goes down the INPUT current goes up to maintain a constant OUTPUT current and voltage.

If the INPUT voltage from the alternator gets very low, the DC/DC device may draw VERY HIGH INPUT CURRENTS.

If your DC/DC device is this type, it could draw in 70+ amps to be able to charge your battery at 40 amps.

You do not have to be a rocket scientist to realise the danger this poses.

New DC/DC devices actually limit the MAXIMUM INPUT current to avoid this danger.

But this means that in a vehicle with a SMART alternator operating at around 12.5v, your 40 amp DC/DC device might only be supplying 15 amps the the lithium battery.

I was given the job of testing a new DC/DC device for a company a few years back, and while this specific DC/DC device had some spectacular features not found in any other DC/DC device, the Australian company decided not to sell the unit based on my test results, where the input currents were just not safe.

That device has been upgraded but it should never have been marketed in its original state in the first place.

I don't understand the ins and outs of how these things work, but could they be talking about the 750W maximum draw after the car has taken what it needs to run its self. I believe it is a new model charger. and requires an 80 amp ANL fuse between the starter battery and charger. I don't know what ANL stands for, but I have ordered one.

The link to the item

Renogy 40A 12V DC to DC Battery Charger Lithium AGM Gel Dual Battery Maintainer | eBay

Hi again Sharmy and that, in my opinion, is way too high an amperage for the INPUT current.

That device obviously does not have an automatic input current limiting function and, again in my opinion, is not suitable for use with any vehicle with a SMART alternator function.

Your vehicle has a SMART alternator operation and has a 140 amp alternator.

This means, that once your vehicles own electrical needs are covered, and that would be less than 40 amps, there is around 100 amps available to power that DC/DC device.

That is nearly double the maximum limit set by the DC/DC manufacturer.

As for the fuse, you could have got an 80 amp MIDI fuse and MIDI fuse holder from your local Jaycar store.