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Shortly after getting our Winnebago EKKO, I plowed into a massive electrical upgrade.  We called it “The 20k Project” because it brought our total battery capacity up to 20,480 Watt-Hours.  As part of that project, I upgraded nearly everything electrical in the RV – but the second alternator and its charge controller remained stock EKKO items.  That changes with this video!


There really were two separate goals for this upgrade, as you’ll hear in the video.

Increased Alternator Capacity

This shouldn’t be a surprise.  The stock alternator (a 170 amp Balmar) is a good match for the Winnebago EKKO and its battery bank.  But our battery bank is now two and a half times larger than the largest factory EKKO!  So it stands to reason that we’d want more charging capacity to pair with that larger battery bank.  To get this capacity, I turned to Nations Starter and Alternator.

We had a Nations alternator in our last RV, Lance, as a second alternator charging our Lithium battery bank.  We were satisfied with the performance and reliability of the alternator (although, admittedly, not fans of the location for the second alternator in a ProMaster).  Adam told us he had a 300 Amp second alternator available for the Ford Transit, and that it fit directly into the factory spot.  That sounded pretty good, and we were off to Missouri.  And honestly, just the alternator itself would have been a pretty cool upgrade, but there was more…

CAN-Based Charge Control

I explain exactly what this is and why it’s a good thing in the video, and it takes me about a thousand words to do it.

The really really short version is that it’s just a lot smarter to charge based on what the batteries are telling you they want, versus measuring a bunch of parameters to infer what the batteries want.  The Wakespeed WS500 charge controller replaces our Balmar charge controller, and can be configured to read data from a CAN network.  In our case, the CAN network will be created between our 5 batteries and the Wakespeed charge controller (so, a 6 node network).  Our batteries already have the CAN network capability built in, so completing this upgrade was just a matter of physically connecting the devices.  There are a number of advantages to using CAN data for charging

  • Charging decisions are now made by the BMS, which remembers its state of charge from one engine-start to the next.  This means no more overcharging on startups.
  • Battery temperature sensors are eliminated, as the battery temperature becomes just a piece of data sent over the CAN.  Only one of our 5 batteries had a temperature sensor anyway, so I always wondered if I had picked the right battery to mount it to.
  • Current and voltage sensing is improved.  They become just other pieces of data – not something that has to be measured remotely.
  • Running other loads won’t affect the charge delivered – because the target voltage and current are just data delivered by the batteries.  (Tough to explain, but it means we can run the air conditioner while charging, and it won’t keep us in a bulk charge any longer that it needs to because running the air keeps the alternator field at XYZ%.  The batteries are calling the shots, and when they’re full, the delivered voltage will drop as it should.)

So How Did It Work?

In a word: Awesome.

First off – hats off to Adam and his team for the install.  If we hadn’t been interrupting them with filming, they probably would have gotten us in and out of there in half a morning.  Even with us in their way, we were out by mid-afternoon.  In the end, they figured out how to run exactly zero new wires.  They were able to reuse the wiring harness from the Balmar, and simply splice into it to get the connections they needed.  This saved them a TON of time.

Besides the awesome install, the performance from the alternator itself has been outstanding.  We get around 230-250 amps while driving along in bulk charge mode.  This charges our batteries quite a bit faster than before.

We haven’t done much testing at idle yet, because it’s kind of cooled off outside.  BUT, you can see some of the idle performance in the video!  You can see that with the air conditioner running, we’re still getting a net of about 100 watts to charge the batteries at idle – so we’ve exceeded the 100 Amp target.

And before you say, “yeah, but that wasn’t at hot idle”… yeah it kind of was.  We had been tinkering with the alternator for a while before we filmed that bit, and the battery and alternator temperatures are reported in that same data stream you see in the video.  I’ve put the picture of the data here below, and you can see that the batteries are at 28 degrees Celsius (82 degrees Fahrenheit), and the alternator is at 46 degrees celsius (115 degrees Fahrenheit).  Now granted, I can get it hotter than that, but it clearly wasn’t a cold alternator.


And it’s occurred to me that in the video, I only showed aggregate data for all 5 batteries.  Rest assured, each of the 5 batteries is indeed reporting in on the network.  To show that individual data, you have to enter a debug mode.  We did that, and here’s a snapshot of that data.  The individual batteries are IDs 70-74.  We can see each of the batteries is asking for a 14.4 volt charge of up to 300 Amps.


So I’m calling this upgrade a resounding success.  We’re getting faster charging, and that charging is better regulated to exactly what the batteries call for.

I’ll finish off with a couple links that may be useful to anyone contemplating this kind of an upgrade – or who just wants to have a really close look at the data file snippets above.

The first is the communication guide from Wakespeed that tells you how to read the files.  It’s the answer key basically:

Here’s a marketing chart from Wakespeed that compares their charge controller with others available on the market.  Despite being a marketing piece, I found the information accurate.

And that’ll about do it for now.  If you have any questions, leave them in the comments below and I’ll try my best to answer.