R29CB Next Gen Cannot Power Both A/C units

L

Lori's Den

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Aug 13, 2020
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Fluid Motion Model
C-24 C
Vessel Name
Lori's Den
We just purchase a 2019 Ranger 29CB with 16 hours on it, so basically brand new. Maiden voyage was a great success. The main issue that I am finding is that the Next Gen 3.5kw generator seems to be too small for the 2 A/C units. The surveyor pointed this out and broker "poo-pooed" it saying the breaker tripped during inspection because surveyor was overloading generator with other accessories at the same time. Well, interesting at orientation, Broker's employee that trained us, also informed us that Generator cannot in anyway power both A/C units. I called Next Gen and they confirmed this "off the record". Hmm, why would Ranger make a boat with 2 A/C units that can only be powered by Shore Power? Not knowing this before our voyage, we lost our A/C 2 days into our first trip. Generator ran, but delivered no power .. could not get the breaker to reset until days later. On our journey we confirmed that yes, the Generator is not powerful enough to power both A/C units. Problem is that on our Ranger we discovered that the Forward A/C is the only unit that also powers the pump which draws in the cooling water ... But when underway, we don't need the forward A/C, as we are not typically hanging out in the forward berth in the middle of the day. So the Ranger 29CB does not allow you to run the Aft A/C unit from the generartor EVER, as you cannot run it without also running the pump that draws in the cooling water? I am quite dissapointed with this .. hoping one of you has some clarity for us.
 
Try this.... open the front panel of your NexGen generator and locate the red round fuse on the upper right side of the generator. If it is listed as a 30 AMP you could change this out for a 40 AMP. I had the same problem with our 2018 R29S and when I called NexGen this is what the guy I talked to advised. You can order the fuse from NexGen. Let us know what you find.

Jim F
 
We have an Onan 5 that powers everything. We do run both AC on our 31 from one shore power cord, about 22A. Gen might not be enough to start compressor.
 
Shame on that broker, but which ever ac you turn on the pump should engage. In all of our nearly 1000 hours of usage we have never needed both on. Purchase 3 camco fans to move your air around. They move a ton of air but use little amperage. Also be sure to source a spare capacitor for the generator. Easy fix. After a 10 day heat wave of 100 plus daily using the ac 12 hours a day it finally blew. Enjoy your boat.
 
Ethan, is the capacitor you mention different then the 40 amp fuse I mentioned? If not where is this located?

Jim F
 
Good morning Jim. Yes it is different. When taking the protective covers off the unit, right side, you will see a cannister about 3 inches long. That is the capacitor. Easy and cheap fix once sourced.
 
We have the NexGen generator and have never had a problem running both AC units simultaneously. I did swap the 30amp breaker for a 40amp when we first purchased the boat on the advice of this forum.

Gordon
 
I had the same problem until I finally burned out my water heater circuit breaker and wires. I had that fixed, but the mistake I made was the setting for the water heater. Never, ever have the water heater on except when at shore power or both a/c units are off. The forward 12000 BTU unit is just 8.5 amps. The salon 16000 BTU unit is 11 amps. The NextGen can theoretically handle 30 amps, but running at 25 or so is much safer. The rest of the boat runs off the 12v batteries and the only thing running of the 120V is the A/C and water heater. So nothing else you turn on affects the A/C load. After I turned off the water heater, I have had no problem running both A/C units since.
 
Does anyone have a Ranger 29 with the NexT Gen 3.5 where the AFT A/C does power the water pump that provides cooling for the A/C unit? As in my earlier post. My water pump only comes on when my FWD A/C unit is on .. which seems odd. I am just trying to figure out if my particular boat is wired wrong on something is defective. Thanks!
 
My boat is on the hard while our seawall is being rebuilt (boat is normally on lift behind our house). But my recollection is that the pump runs when either (or both) units are on. It sometimes takes a minute or two for water to begin flowing after turning the unit on.

I’ll confirm this for you after I get the boat back in the water.

Gordon
 
Thanks Gordon .. I appreciate it. LMK what you find when you are on your boat next time.
 
I often run one A/C unit at a time, so obviously, they both turn on the pump. There is a delay which is a safety step to protect the A/C unit from a short cycle.
 
I’m glad this topic was brought up. I have a 2019 R29CB. We bought it with 25 hours on it last December and just broke through 200 hours this past week. It’s been fun learning the boat and this forum has been a lot of help. Regarding the ACs I’ve experienced some of the issues that are addressed in this thread. I ran into occasions where the AC pump will not pick up water causing the units to fault and shut down. I’ll prime the sea strainer and pick up water but for some reason the pump still doesn’t seem to pick up the water. The only fix for this has been to run the boat and try again until the pump eventually picks up. I can run either unit independently of the other and the pump will power up. What’s of real interest to me here is the ability to run both ACs simultaneously. It’s been a hot summer this year and we tried to run both units on multiple occasions. Sometimes it works OK but often I blow a the breaker on the Ranger panel and it shuts one of the units down. When this occurs I am not running anything from the generator other than the AC units. Is the option of putting the 40 amp fuse in the generator something that Next Generation actually endorses. My concern is by replacing the 30 amp fuse with a 40 amp fuse are we creating a fire hazard. Based on the previous post in this thread the combined amperage of both units is only 18.5 amps it doesn’t sound like we’re overloading the 30 amp generator. Is the 18.5 number what the units draw when running or when starting up? I would be interested to hear more opinions on this and specifically anything that Ranger or the generator manufacturer might have said about changing the fuse to a 40 amp.
 
The 18.5 amps are the running amps. There is a higher number for start up, but circuit breakers usually allow for this short term surge. If both units were to start at the same exact time, then there might be an issue easily solved by resetting the circuit breaker. Always turn on one unit at a time.
 
I would caution the swapping of breakers to a larger capacity. The 3.5 Kw generator has a capacity of 30 amps. The Fuse or breaker installed in this unit is to protect the unit from an overload.

This is direct from the 3.5KW owners manual
(The circuit breaker will trip if the unit is overloaded or short- circuited. The breaker may also trip if the Gen-set is working to capacity in a very hot environment. In any case with a breaker tripping, it is advisable to determine the cause before restarting.)


With the Maximum output of this unit being 30 amps and installing a 40 amp fuse to protect it doesn't seem like the correct thing to do. I read in a different thread that a NexGen representative instructed a owner to replace the 30 amp with a 40 amp fuse. The reason was the 30 amp kept blowing. My question is if a Generator with a 3.5KW capacity which is just under 30 amps is blowing a fuse or lifting a breaker that is rated at 30 amps how is the fix correct to install a 40 amp breaker? I can see how it makes it work the fuse is greater than the capacity of the generator so it will not blow. The designed protection of the unit is removed. Or is it? My guess as to why the units are blowing or lifting 30amp protection is they are operating at close capacity plus operating at higher than designed ambient compartment temperatures. Resistance goes up with every degree of temperature. A fuse rating is based on ambient temperature of 77 degrees F 100% of its rated capacity. At 100 F the fuse is still very close to its capacity 30 amp fuse would blow or breaker would lift above 28.5 amps which is very close to the capacity of the 3.5 KW generator. Now put the generator in a compartment of 140 F the fuse capacity is now rated at 85% of capacity or 25.5 amps. 2 air units and a battery charger will probably blow a fuse or lift a breaker. The NexGen representative that advised the use of a 40 amp fuse is calculating the compartment temperature to be 170F. At 170 F a 40 amp fuse will give the designed protection of 30 amps. If this is what the compartment temperature is your generator is protected at design.

I question this theory. If the compartment is that hot you may be able to operate the generator but the longevity of the unit is being compromised. Keep a few capacitors on hand because you will be needing them along with oil pressure sensors, relays, or any other electrical component that is not designed to operate at these elevated temperatures. The blowers installed with the units are to help keep the generator portion of the unit operating in a normal range. The engine portion can operate at temperatures above 200 F with the type of cooling system it has so there is a need for good air circulation. Monitoring and maintaining the compartment temperatures is essential for proper operation. With a properly sized fan pulling outside air into the box and exhausting it back to the outside area of the hull it should be able to maintain ambient air temperature that will function with a 30 amp fuse and operate the generator properly. If you find that the installed fan is not large enough install a larger capacity or the duct work is not installed properly with many bends or restrictions repair it. The replacement of the fuse works but it is a bandaid not a repair. A 30 amp fuse should work with a unit that produces 30 amps if the unit is installed correctly and has the proper ventilation.
 
Brian is probably correct however.....when I called NextGen 2 years ago they were the ones who advised to go up to the 40 amp and even shipped it to me. This was over 2 years ago and I’ve not had a problem since. To double check call 904-642-8555. I spoke with a Ken Thomas

Jim F
 
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