Should I keep the stock inverter?

Capt_Kirk

Hi

I was hoping for a few minutes of your time to help me plan a solar system for my 2012 Skyline Layton 19' travel trailer.

It is currently equipped with the stock converter. World Friendship Co LTD WF8955PEC 30 amp service. I think it was responsible for the death of one of my old 6 volt batteries.

I am using 2 GC2 220Ah 6 volt batteries and they will last for 3 days without using the generator. 

When we get home I take the batteries off the tongue and bring them inside to charge them with a 8 amp battery minder charger/maintainer. I know the arizona heat will kill a flooded battery so I keep them inside on the charger. I also use the water miser Caps.

I do not know my current daily amp draw but most of the time is an hour or 2 with the 12volt 24" LED TV . 3-4 hours with the stock jensen radio, a few minutes  with the bath room fan and range hood fan. We charge 2 cell phones at night on the 12v charger. Rarely when it is super cold I run the furnace for 30 min to knock off the chill before bed.  I let the water heater run 1 cycle for showers and then the water pump as needed. 

I understand to get a better idea of my useage / demand I need a battery monitor. but there are so many to choose from, the cheap chinese ones from ebay to the $150-$200 ones.  Right now all I use is the 3 lights on the stock monitor panel and most of the time it reads full or charging. When the last set of batteries died it read empty and the tongue jack would not budge. Suggestions? 

I understand installing solar panels, running the correct size wire, connecting a solar charge control that will take care of the batteries and not boil them off. and connecting a monitor to check on them. 

My question is what to do with the stock converter when I plug into shore power. It will just dump juice to the batteries and cause the solar charger to switch off. How do I keep this from happening?

Should I pull out the old stock converter? Wire in a new cool inverter so we can make a quick pot of coffee in the morning? Can I do that with my batteries?

If I do remove the stock converter do I install a separate panel for the 120v items and another for the 12v items.  Is there a converter that is stand alone? or do they make an inverter that also converts?

I read about a magnum inverter that is smart, meaning when shore power/generator is a bit short on amps it will take from the batteries to help with the demand. True?

In the summer I use a yamaha 2400 ESFI to run AC. I plug the 30 amp plug in to the generator. turn off the 120v breakers that are not needed and then turn on the AC. I had to install soft/easy start capacitor on the AC but it starts and runs on the generator. but when the AC cools off the camper and turns off the generator goes into overload and shuts down requiring a restart. 

My camper roof is limited by 1 AC, 1 vent. and plumbing vents. I might be able to get 4 up there but 2 will fit for sure. 

BB.

Capt_Kirk said:

It is currently equipped with the stock converter. World Friendship Co LTD WF8955PEC 30 amp service. I think it was responsible for the death of one of my old 6 volt batteries.

Do you have a hydrometer to check you batteries' state of charge? There are a lot of discussions about how good (or not) a stock RV converter is very good a charging deep cycle batteries or not... In general, it looks like your model may have the charging voltage set a little low (14.4 volts charging--Many times, flooded cell would be better at 14.75 volts for charging and ~15 volts for equalization). Using a hydrometer is a good start at figuring out if if it is keeping your batteries up or not.

I am using 2 GC2 220Ah 6 volt batteries and they will last for 3 days without using the generator.

For nominal operations, we suggest to avoid deep cycling the battery below ~50% state of charge very often, and never below 20% state of charge (damage/ruin battery bank). When you say that yoru batteries will run the RV for 3 days--Is that to "dead", or 50% state of charge (somewhere around 12.0 volts no load, ~11.5 volts under load)?

For RVs that are not used full time, you can take a battery bank deeper cycles (deeper than 50% state of charge) because RV batteries are not cycled that much (weekends, couple weeks a year)--And they will usually age out rather than cycle out.

When we get home I take the batteries off the tongue and bring them inside to charge them with a 8 amp battery minder charger/maintainer. I know the Arizona heat will kill a flooded battery so I keep them inside on the charger. I also use the water miser Caps.

Oh boy--That sounds like fun. But you are correct, for every 10C (over ~25C), increase in battery temperature, the battery will last 1/2 as long). An 8 amp battery minder is not great for charging a deep cycle battery (typically, you want 10% rate of charge or so, or for a 200 AH bank, 20 amp charger). However, for long term storage (float) the Battery Minder should be fine for job.

I do not know my current daily amp draw but most of the time is an hour or 2 with the 12volt 24" LED TV . 3-4 hours with the stock jensen radio, a few minutes  with the bath room fan and range hood fan. We charge 2 cell phones at night on the 12v charger. Rarely when it is super cold I run the furnace for 30 min to knock off the chill before bed.  I let the water heater run 1 cycle for showers and then the water pump as needed.

For "proper" understanding/managing of your battery bank, you really do need to know your loads. True battery monitors are expensive and each has its own idiosyncrasies. The Trimetric is probably the cheapest true stand alone battery monitor that our host sells. Difficult to program (much harder than the old VCR clocks). And, any current based battery monitor can "drift" over time if your battery bank is not fully charged once in a while (fully charging resets the monitor back to 100% full).

And there are voltage monitors (like the Midnite)--Probably less accurate, but less money and some other nice features (warns you if you have not fully charged the battery bank in the last week or so).

You can also go with a "precision shunt resistor" and remote meter--That would at least give you current readings so you can better estimate your power usage.

http://www.solar-electric.com/batteries-meters-accessories/metersmonitors.html

You can also get a "cheap" DC current clamp DMM (like this one from Sears, "good enough" for our needs) to measure the current of your major appliances. Also very handy for debugging your DC electrical systems (RV, Car, etc.).

I understand to get a better idea of my usage / demand I need a battery monitor. but there are so many to choose from, the cheap chinese ones from ebay to the $150-$200 ones.  Right now all I use is the 3 lights on the stock monitor panel and most of the time it reads full or charging. When the last set of batteries died it read empty and the tongue jack would not budge. Suggestions?

See above... I do not use off grid power/battery systems--So I cannot give you an exact list of what is "best" for your needs. The "cheap" import stuff--Sometimes you do find good equipment that works well, and many times, it is a waste of money. It is a bit of a gamble.

A good volt meter (with at least 1 or 2 decimal points... (i.e., 12.4 ro 12.41 volt display) can help you better manage your bank. But lead acid batteries are not easy to estimate capacity from voltage. Loads, charging, state of charge, temperature, age, etc. all affect voltage readings. If nothing else, a voltage meter or voltage based battery monitor will be better than what you have now. You can read a quick FAQ about batteries here:

http://www.solar-electric.com/deep-cycle-battery-faq.html

I understand installing solar panels, running the correct size wire, connecting a solar charge control that will take care of the batteries and not boil them off. and connecting a monitor to check on them. 

My question is what to do with the stock converter when I plug into shore power. It will just dump juice to the batteries and cause the solar charger to switch off. How do I keep this from happening?

Should I pull out the old stock converter? Wire in a new cool inverter so we can make a quick pot of coffee in the morning? Can I do that with my batteries?

It is OK to put several charging sources in parallel to charge a battery bank. The charge controller with the highest voltage set point will "win". There can be an issue with too much battery charging current causing batteries to overheat and, worst case, have thermal runaway. More or less, over 13% rate of charge (200 AH battery bank or 26 amps) is a rough max charging current. Your Battery Converter seems to have lower charging current and should not over current the battery bank when sharing charging with a solar charger.

There are solar charge controllers with Remote Battery Temperature Sensors which help with properly charging a Lead Acid battery bank. And you could install a simple remote thermometer (sensor in Styrofoam glued/taped to side of battery--sensor against battery, insulation to keep ambient temperatures from giving the wrong temperature). The fact that you R&R batteries after a trip does make temperature sensor(s) a bit problematic--Snagging/Broken wires).

If I do remove the stock converter do I install a separate panel for the 120v items and another for the 12v items.  Is there a converter that is stand alone? or do they make an inverter that also converts?

I am not quite sure what you mean by separating 120 and 12 volt items via panel... You do have to be "careful" that you do not wire the system up so that your AC inverter (battery powered) powers up the RV Converter (i.e., use the batteries to "recharge" the batteries). There are several ways of avoiding that (AC power only to converter input. Use an AC Transfer Switch to control AC power flow for Shore Power vs AC inverter power).

There are some very nice AC inverter-Charger units... But they tend to be for larger installations. For a small battery bank like yours (2-4x golf cart batteries), I would suggest only using a relatively small AC inverter--The 300 Watt MorningStar TSW 12 volt inverter is nice for this job--But no charger included.

I read about a magnum inverter that is smart, meaning when shore power/generator is a bit short on amps it will take from the batteries to help with the demand. True?

Yes, many folks have used Magnum inverters and been happy with them. There are a few folks that have complained that the 120 VAC regulation is less than perfect (other loads can cause the 120 VAC voltage to fluctuate). I generally do not use inverters, so I will leave it to others to tell you their recommendations.

But, in your case, your battery bank is pretty small, so trying to install/use larger inverters is not going to be very useful (200 AH battery bank at 10% discharge rate is ~20 amps, 20 amps * 12 volts = 240 Watts of maximum "average" DC power recommended).

The inverter chargers can work with AC gensets very nicely and do some amazing things (Generator Support--AC inverter-charger can "help" the genset start/run heavy loads, then back into AC battery charging once the heavy loads "go away").

But, again, your battery bank is really too small to be of much use in this function.

See part 2 of answer...

BB.

In the summer I use a Yamaha 2400 ESFI to run AC. I plug the 30 amp plug in to the generator. turn off the 120v breakers that are not needed and then turn on the AC. I had to install soft/easy start capacitor on the AC but it starts and runs on the generator. but when the AC cools off the camper and turns off the generator goes into overload and shuts down requiring a restart.

Air Conditioning and small Solar Power systems just really do not go together. It is possible to run an efficient AC unit on 4x golf cart batteries and 1,000-1,500 Watts of solar panels--But for an RV, that many panels may not be enough for you.

There are mini-split A/C system (and heat pump) that have "inverter" internally--They still run from 240 VAC (some run from 120 VAC), but have no surge draw and when run at lower power modes, would run nicely with your Yamaha.

My camper roof is limited by 1 AC, 1 vent. and plumbing vents. I might be able to get 4 up there but 2 will fit for sure.

Any shading on solar electric panels "kills" the system output (typically by 50% or more). Moving/rerouting vent pipes, mounting panels above AC, tilt panels, "awning mounted panels", portable ground mount panels, etc. can help.

If you want to run A/C from solar--Figure out how many watts of solar panels you can fit (and how many individual panels). Perhaps you can run some AC from solar. And some other folks here can recommend "solar friendly" A/C

-Bill

Capt_Kirk

Bill, thank you so much for answering ALL of my questions. Since this post I have learned so much about putting solar on my TT.

Yes I have a hydrometer but i have not used it with the stock converter. Just tonight I checked what my BatteryMinder 12248 did and all was good. 12.87 V 1305 specific gravity after resting for more than 12 hours.

Good to know but that what may have killed the Sams Club Batteries

I have ordered the TriMetric 2030, shunt, and wires. 

It is OK to put several charging sources in parallel to charge a battery bank. The charge controller with the highest voltage set point will "win".

That is something i just learned. IF I buy the TriMetric SC2030 solar controller and set it to the battery manufacture recommended specs then the stock converter wont be a bother. and I may never need AC power again unless I need to use the air conditioner.

I will not be trying to use the a/c on the batteries nor the microwave. actually i will be removing the microwave to gain cabinet space.

I would love to wake up turn on an inverter and make a pot of coffee and turn off the inverter. I have a cheap 700 watt inverter but the coffee maker is 900 watts. so I need a smaller coffee maker or bigger inverter.  OR a DC coffee maker. 

I have DC power to Charge Cell phones. The Jensen dvd player/stereo is 12v. and my TV is 12V so ... a 12v coffee pot may be my answer. 

Once I get the Trimetric installed and go camping I will report my Amp Draw and determine  the correct size solar panel. I have no trouble plucking the jack rabbit TV antenna off the roof to install a better antenna further back. 

and I may leave the batteries on the TT during the summer so trimetric can keep track of them. I have a bedroom window right next to the TT where it waits for me so I can devise a window vent tube to keep the batteries cool in the summer. It would be easier to hook up a cooling hose than drag 100lbs of batteries back and forth.

Bill, 
Thanks again for taking the time to help me out. I hope others learn from my questions also.

Chuck

BB.

You are very welcome Chuck.

Regarding battery storage--Is the trailer (or at least the battery bank box) under shade? That can help keep the battery temperature from spiking during the middle of the day.

If you put cool air from your home into the battery box--Make sure the vent tube is insulated well (and shaded would help too). Even a temporary storage cover for the battery box (the "bubble wrap" silvered stuff cut and taped together to go over the box) should help--especially if the box is not insulated.

-Bill