2019 TAB 400 Battery Charging

rh5555

It does run.  Seems to be controlled by current draw, as it comes on right away at high amp charging.

Tundra57

@rh5555

I emailed wfco in USA. Their senior tech thinks we shouldn't have to do this. I explained your reasoning which seems very reasonable to me. He said he will tell me his thinking on Monday when I call him. Should be interesting.

Tundra57

So I have a scheduled phone call with WFCO charger manufacturer Monday to see if they have any thoughts. However I just tested my tab by running fridge straight off batteries, no shore power,  the battery voltage is 12.59. At the distribution panel the voltage is 12v. So 25A for the fridge drops 0.59V. so at max charge current of 55Amps I would expect a drop over 1.2v so that is lot either for running off the battery or trying to charge it. I am looking into beefing up the distribution panel to battery wiring. This will help in both directions.

rh5555

I finally completed my WF-9855 converter substitution on my 2020 TAB400.  Other years will require some adaptation of this procedure.  Steps are pretty easy:

1. Disconnect and remove the converter from the WF-8955 power center. You can also remove the negative lead between the ground bus bar and the NEG- terminal on the fuse board as it is not needed.
   
2. Locate the new WF-9855 converter under the bed between the A/C unit and the inverter.  Connect it to the distribution lugs with 4 Gauge battery leads like these (you will have to cut off one of the connectors on each wire and strip them back).  WF-9855 plugs into the spare outlet which feeds power to the A/C unit.
   
   Use 4 screws to fasten the converter to the floor.
3. That's it!
    
   

Performance is really good, particularly compared to the old converter.  This is the recovery of a battery discharged to 46% of its full capacity.  In one hour it recovers to 70%, in two it recovers to 85%. 

The converter uses bulk charging for the first 4 hours, and then drops to absorption charging.  The area under the bed gets a little warm, but nothing excessive.

This is a really useful mod for anyone who wants to top up their batteries with a generator and doesn't want to run said generator for longer than absolutely necessary.

TNOutback

@rh5555 thank you for your analysis and sharing your results.  I would hope you would make NuCamp aware of your work as it seems they really need to rethink their electrical design for those units whose power centers are a long way away from the batteries.  

JeffroNC

Great info. Since I have a 2019 and my power center is closer to the battery, would the 9855 fit into the original space? Could I just swap them out?

rh5555

@JeffroNC, if your power center is already close to your batteries, you may not have an issue. We need someone with a 2019 TAB400 and an ability to measure charge current to determine how fast/slow the battery recovery is when batteries are 50% discharged. If charge rate is slow, then beefing up wiring between converter and battery may be all that is needed. Beyond that, you might look at Progressive Dynamics offering.  This can be forced into bulk charge mode to speed up re-charging using a generator.

JeffroNC

I'll test the battery over the next few days. The most current I have seen is 30 amps when I first apply 110 either by shore power or my generator.

rh5555

@JeffroNC, remember that you will need to discharge batteries by at least 30% to see the full recharge current of 55 Amps.