Burning out Convertors

[thatoneguy]

Ok so back story, Ive been boondocking for 3 months, not by choice but because im waiting on power company to hook power up to my lot..

I currently own a 2020 Cougar 32RLI TT, 50 amp. I have a Predator generator 8750 that im using to charge my batteries and for about an hour or 2 of tv at night..

I have now fried 2 converters on this. It seems if i let the batteries run too low, and then start the generator with the furnace on, it almost instantly fries the converter, however, it has no issues running every single appliance, both acs, 2 tvs etc on that generator and if the batteries are over 11v prior to starting the generator it has no issues. Ive been a full time rv'r for over 4 years and this seems like a ridiculous problem.

Any suggestions other than the obvious of turning furnace off until batteries recharge?

[bsmith0404]

What size converter are you running? Maybe try stepping up to a larger amp converter. I’d assume the OE would have been sufficient, but never know. I’ve never seen one blow almost instantly because of load, but I don’t have any other ideas of what could be causing it if it runs everything ok and only having problems when the batteries are too low.

[bobbecky]

If you are letting your batteries get that far below 12 volts, the batteries are the problem that is killing your converter. Your batteries can not survive long being discharged that far. Unless you are using lithium batteries, you should never let them go below 50% charge without doing serious damage to the batteries.
https://rvlifestyle.com/understandin...ate-of-charge/

[Steveo57]

What do you mean it fries the converter? Maybe it's just blowing a fuse?

[thatoneguy]

The batteries go from 12v to 10v extremely fast, 2 brand new interstate deep cycle. tbe come back to 12.8v pretty fast once on shore/generator power after a charge and only seems to have issues if also running the furnace.

note it will run the furnace just fine as low as 9.8v but as soon as i flip the generator on, the convertor hates it . Im guessing because the furnace is the largest system on 12v but if the furnace is on and working and batteries are low, turning off the furnace to recharge batteries seems like a design flaw.

[thatoneguy]

Originally Posted by Steveo57

What do you mean it fries the converter? Maybe it's just blowing a fuse?

Tell that to my rv filling with smoke lol, deffinetly the convertor

[thatoneguy]

Originally Posted by bobbecky

If you are letting your batteries get that far below 12 volts, the batteries are the problem that is killing your converter. Your batteries can not survive long being discharged that far. Unless you are using lithium batteries, you should never let them go below 50% charge without doing serious damage to the batteries.

https://rvlifestyle.com/understandin...ate-of-charge/

my batteries at max charge have never seen more than 12.8... you reduce their life expectancy sure but it shouldn't be whats killing the convertor/battery charger

[flybouy]

Originally Posted by thatoneguy

my batteries at max charge have never seen more than 12.8... you reduce their life expectancy sure but it shouldn't be whats killing the convertor/battery charger

What you're describing is exactly you're problem. Let's dive into this a little deeper.
What size, type, age batteries?
How are you deriving at the 12.8 volt charge? IE what are you testing it with any when? When it's charging? 10 min after charging, or an hour after charging?
Have you checked the water level in the batteries?
What size converter do you have?

I'm going to guess without the above information so here goes. My guess from what you've described is that you are first off depleting your batteries far below the recommended 50% level. Then attempting to charge the batteries while the appliance that draws the most 12v DC amperage is running. So when you start up the generator to charge the batteries the converter is going to immediately start off in "bulk charge" mode to charge the dead battery PLUS it's going to try to supply the furnace and all the other 12v DC loads at start up. This exceeds the converter's capacity and it fails.

The other possibility is that repeatedly discharging the batteries has damaged them to the point of causing an internal short. When that happens a battery may take a "top charge" or "surface charge" meaning the battery charges rapidly, the voltage reads fine, but will discharge rapidly. The charger sees this as fully charged then needing a bulk charge on and off that may become a rapid cycle. That continuous on/off state will overheat the charger and make it fail. A shorted cell if sever enough will destroy a charger quickly as it's basically a direct ground causing it to act as a welder.

i
In either situation the converter is performing as designed and is designed properly, just not being used properly.

[thatoneguy]

Originally Posted by flybouy

What you're describing is exactly you're problem. Let's dive into this a little deeper.

What size, type, age batteries?

How are you deriving at the 12.8 volt charge? IE what are you testing it with any when? When it's charging? 10 min after charging, or an hour after charging?

Have you checked the water level in the batteries?

What size converter do you have?



I'm going to guess without the above information so here goes. My guess from what you've described is that you are first off depleting your batteries far below the recommended 50% level. Then attempting to charge the batteries while the appliance that draws the most 12v DC amperage is running. So when you start up the generator to charge the batteries the converter is going to immediately start off in "bulk charge" mode to charge the dead battery PLUS it's going to try to supply the furnace and all the other 12v DC loads at start up. This exceeds the converter's capacity and it fails.



The other possibility is that repeatedly discharging the batteries has damaged them to the point of causing an internal short. When that happens a battery may take a "top charge" or "surface charge" meaning the battery charges rapidly, the voltage reads fine, but will discharge rapidly. The charger sees this as fully charged then needing a bulk charge on and off that may become a rapid cycle. That continuous on/off state will overheat the charger and make it fail. A shorted cell if sever enough will destroy a charger quickly as it's basically a direct ground causing it to act as a welder.



i

In either situation the converter is performing as designed and is designed properly, just not being used properly.

Both batteries are brand new, 100aH "i think" lead acid interstate deep cycle batteries... im using the in-Command to determine voltages....they are car battery sized....i forget which group...

[thatoneguy]

I assure you, something isn't operating as it should with 2 batteries barely 2 months old and ZERO issues with converter if furnace is off...it makes it litterally almost impossible to boondock in the winter....though i considered a bigger converter

[thatoneguy]

sorry missed a question, its a 50a converter

[thatoneguy]

Do i just junk both interstate and buy s single battleborn to help stop whatever surge from the furnace or get a smart converter? or both

[ChuckS]

Looking thru the posts ... if you are only running that gen for a couple of hours and you were running that furnace for five or six hours.. plus other DC items the batteries are not getting charged

Even with a 8 to 10 amp DC surge with furnace blower motor that WFCO 50 amp OEM charger should not smoke...

Have you also checked all DC wire connections that go to Bus bar inside RV in power panel for tightness , etc...

[chuckster57]

I’ve seen brand new battery’s be bad. Get a hydrometer and test each cell. That will rule out the batteries. Then I would get a DC amp meter and watch the draw with furnace running, and then draw when it’s running and you plug into the gen. I would also test amp draw at the batteries with furnace running and then furnace running and plugged into gen.

Might seem like a lot of testing but you need to rule things out.

[bsmith0404]

I think a 60 amp converter would help. You’re putting a lot of draw on a 50 amp

[thatoneguy]

Originally Posted by ChuckS

Looking thru the posts ... if you are only running that gen for a couple of hours and you were running that furnace for five or six hours.. plus other DC items the batteries are not getting charged

Even with a 8 to 10 amp DC surge with furnace blower motor that WFCO 50 amp OEM charger should not smoke...

Have you also checked all DC wire connections that go to Bus bar inside RV in power panel for tightness , etc...

I had the dealership warranty the first one, when i checked them it seemed like wires on bus bar etc were good. Ive just recently started using the furnace and it dosen't stay on constantly as i set the temp very low so to conserve propane with my generator running and both AC's my voltage on my system reads about 13.5 or so, without a draw "no ac no furnace" 13.8 or 13.9 ish , 2 or 3 hours on generator usually seems to bring my voltages on batteries mid to high 12v's as stated.

im thinking i need upgrades if this is going to be able to boondock. Perhaps this and a Battleborn bank?

[thatoneguy]

Originally Posted by chuckster57

I’ve seen brand new battery’s be bad. Get a hydrometer and test each cell. That will rule out the batteries. Then I would get a DC amp meter and watch the draw with furnace running, and then draw when it’s running and you plug into the gen. I would also test amp draw at the batteries with furnace running and then furnace running and plugged into gen.



Might seem like a lot of testing but you need to rule things out.

i considered that i perhaps have bad new batteries... uggh

[thatoneguy]

Originally Posted by ChuckS

Even with a 8 to 10 amp DC surge with furnace blower motor that WFCO 50 amp OEM charger should not smoke...
.

My parts/service guys agree with this statement

[flybouy]

Originally Posted by thatoneguy

Both batteries are brand new, 100aH "i think" lead acid interstate deep cycle batteries... im using the in-Command to determine voltages....they are car battery sized....i forget which group...

Originally Posted by thatoneguy

I assure you, something isn't operating as it should with 2 batteries barely 2 months old and ZERO issues with converter if furnace is off...it makes it litterally almost impossible to boondock in the winter....though i considered a bigger converter

f the batteries are "car battery sized" that could be several sizes. If it's a group 24 (10 1/4" X 6 13/16" X 8 7/8" then it's not a 1oo Ah deep cycle. If it has a CCC (cold cranking amps) label it's not a deep cycle. If that's the size you have then it may be a "dual purpose marine battery". They call them deep cycle but they aren't. They are designed to start a boat motor and keep an anchor light on at night.

Is your converter 50 amps or the service to the trailer 50 amps? Don't know how accurate the in command is as a battery meter. Someone else could chime in that has more more knowledge.

Your furnace could be drawing excessive amperage or you could have killed the batteries. It can easily be done when repeatedly draining the batteries to an excessively low state, especially if they are the small marine dual purpose style.

When connecting the generator, do you start it, let it stabilize, then turn on the main breaker? The generator you list is a "contractor grade" generator and not an inverter generator. They are not very sophisticated generators and can have issues with electronics so it's very important how you start and stop the generator, specifically not loading the generator until it stabilizes at start up and not shutting it down without first Unloading (disconnecting the trailer by turning off the main breaker).

I would pull the batteries and have them load tested. If they are OK then I would follow the procedures and STOP discharging the batteries soo deep. Here's a chart of battery voltage and state of charge. You should never discharge a lead acid battery below a 50% state of charge.

[thatoneguy]

They may infact be dual purpose marine batteries. I know they don't last near as long as 2 batteries should. I was questioning their choice in batteries at the dealership but figured I'd go with what they had. My previous batteries i used was Optima Yellow Tops deep cycle. The interstate are what the dealer installed upon delivery.

thoughts on that 60a converter and a singke lithium battleborn?