There was quite a lot of discussion recently on what the result would be of running 2 Ctek D250 chargers , as many people felt that one didn’t put enough charge into your batteries (they have a 20 A maximum) , and this input was further reduced if you had accessories like fridges running . In my case my charge would drop as low as 12 A if the fridges where running in turbo mode
So with a bit of help (and a loan unit) from Jacque at Bushpower if thought I would give it a try .
DISCLAIMER : Nothing here is based on any scientific fact , it is all my own work , and you might not get the same results with your setup .
I also did try a Ctek Smartpass first , but the alternator would only out put about 45 A for a short period (5 min) and then settle down to about 23 A . This though at least gave me the peace of mind to try the 2 charger set up , as the alternator obviously had enough capacity to do 40 A
First off I have 3 Optima Yellow Tops (225 AH in total), results might differ with other types of batteries . They are also very close to the chargers , with very short cables
I ran a 16 mm cable from the alternator that feeds the 2 chargers
I took a 150 A out of the batteries (67% discharge) and then tested the input into the batteries using the Link 10 battery monitor that is installed on the auxiliary battery bank
The draw on the alternator was measured using a cable clamp meter
As you can see there wasn’t much loss over the cable , and the alternator didn’t have an excessive draw , as was speculated previously
I put 75 A back into the batteries (33 % discharge) , and the chargers where at that point still adding about 25 A in. (Sorry didn’t think to take a pic) – so not too much of a drop off .
I then charged the batteries until they only had another 20 A to go to full (10 % discharge) and the chargers where still charging at 8 A
With the following draw on the alternator
I then switched both fridges on , on turbo mode , they drew 8.5 A
As can be seen below , the charge into the batteries remained the same
With a resultant increase in draw off the alternator
This might not be the cheapest setup , but IMHO I’m going to stick with it , as I will easily be able to maintain my batteries with just a few hours driving each day . YMMV