Should I install a 3rd Lith battery

[lgcotton]

Last year I installed 400w solar, 2 100w lithium batteries and a 3000w inverter. Everything worked well during the summer months when the solar got plenty of sun and I supplemented with a couple of hours on the generator in the morning. Over 4 separate weeks we would be up to 100% battery when the sun went down. We used the inverter to power the TV and Microwave and 12v for lights, a fan and propane heater (occasionally). The battery level would get down to 40-50% by morning.
Now with the shorter days and less sun I am thinking about adding a 3rd battery. We have a couple of trips planed (boon docking) and I want insure there is enough power.

 

[PhilFromMaine]

With the low price of lifepo4, go for it. Eventually, you will need it.

 

[nvs4602]

With 40% to 50% of battery left when you have more sun, doesn't sound like you have a storage problem, you have a charging problem. I would at minimum add another 200w of panels or go to 800watts.

Doing so may even negate the need to run the generator.

 

[GolfingDave]

I agree with posts #2 and #3 above.

See post #8 here.

https://www.forestriverforums.com/forums/f218/low-battery-voltage-shuts-down-gopower-controller-282990.html#post2996987

I only have a 1000W inverter and keep its usage to a minimum.

 

[tomkatb]

Ditto Dave.

You have what is sort of the two day weekend setup.

The solar will supply 100 ah of charging on its best day from mounted panels. In the Midwest less most of the time. However you use more than that likely per day.

The inverter should be off when not being used. Standby consumption on them is 1-2 ah per hour.

Two 200 ah batteries and a generator is what we use. No solar. A gas electric fridge. A non electric coffee pot. Kherig electric and go Joe when no shore power. We run the generator every 3-4 days. No solar.

More battery is the first step.

You know that you need to be sure the additional batteries are THE SAME as existing. Different brands and sizes can be problematic. This is harder than it sounds.

 

[Aussieguy]

X2 what NVS4602 said

you should have plenty of roof space to add more solar


I was able to put 2 x 370w residential panel side by side at the back of my trailer
plus a budget MPPT 50amp
was able to use the existing wiring from panel to controller as the voltage was increased
added 4 g from controller to battery

you can also KEEP the existing panels and controller giving you a total of 1000 - 1200 w
just set BOTH controllers to have the same OUTPUT VOLTS

battery will happily take 2 or more controllers

measure your roof and work out the BEST solar layout
too many people skimp on this ... "400w will do"
and then get frustrated that solar is not performing

Upgrade your existing 400w to maximize the controller you got + add another sttring

you only got 5 hours a day to harvest the solar... don't skimp on wiring, connections and panels.
got my 370w panels from Facebook NEW ... 9 bus $150 each

you can probably find a lot of suppliers over there... and don't be afraid to even look at used panels... as long as they are not showing brown spots or snail trails and are producing close to the sticker voltage I would look at them...

NOT hard to run a new wire for an extra controller
get your controllers next to the battery for best wiring and performance


3000w inverter?
what do you use it for...
since you don't have a big battery I am assuming you don't use it a real lot
if you only watching TV, running the fridge and and making coffee a smaller inverter with less overhead may make sense?

you can have both ... run whichever inverter best suits your load at a particular time
turn OFF the inverter when not actively using it!

if you do get another battery... I like to have about 3 days of capacity
get a 200ah battery so you have a total of 400ah
make sure all your battery parallel cables and lugs are the best quality and size.. OVER size them a bit won't break the bank!

only the parallel cables joining the batteries together ... not the whole system!
use BUSBAR for connections you don NOT want 3 or 4 lugs on a battery terminal
bus bars don't have to be BIG and only cost a few $

 

[5picker]

I guess I don't understand the suggestions to add more solar?

The OP says:

Over 4 separate weeks we would be up to 100% battery when the sun went down. We used the inverter to power the TV and Microwave and 12v for lights, a fan and propane heater (occasionally). The battery level would get down to 40-50% by morning.

Sounds like the solar is working fine if it is topping off the battery bank to 100% by sundown.

I'm not against adding more solar but I read they want more reserve capacity. If so, that's more battery.

Of course, with more battery capacity, comes the need for more solar but just adding solar, for a situation of needing more capacity, just doesn't make sense to me.

 

[Aussieguy]

OP said will get to 100% at sundown and uses generator to supplement

sure sounds like a charging issue to me?

Upgrade the solar
add another battery only if you want to allow more capacity for bad days
generator can supplement in case of continuous bad weather

 

[MrPukaShell]

I would use a smaller inverter for watching TV. I have a 12 volt refer and can run the TV/DVD player on the 1000 watt that came with the trailer. Will use around 60/80 amps over the night.

 

[TitanMike]

With the low price of lifepo4, go for it. Eventually, you will need it.

When it coes to boondocking, there are only two kinds of battery storage.

First is called "Some" the other is called "More". There is no such thing as "Enough" when boondocking with a large Inverter.

Sometimes the same can be said for Solar but supplementing with a small, quiet inverter generator is usually a lot less expensive than building a monster solar farm on the RV's roof.

Solar for boondocking is most efficient during summer months and 400 watts is usually enough unless in shaded campsites. It becomes most inefficient during winter months unless you are in more Southern states and supplemental charging with a small generator is often needed, even with larger solar panel arrays.

Also worth mentioning, Solar Panels and Batteries add weight. If one's TT is already close to the weight limit as ready for a trip, adding panels and batteries can put the weight over the limit.

200w panels can weigh ~26# each and an average 100 ah LiFepo4 battery from 23#-33# each.

4 panels (800w) can add another 100# to trailer weight. Might not sound like much but if one get's carried away it can all add up.

That said, I just added 400W of solar panels to my trailer's roof and total extra weight was only 15# (2-200w Yuma CIGS flex panels) but the cost per panel wasn't cheap. My issue is weight which is close to the max spec'd for my trailer. The 400 watts has proven to be more than adequate to charge my 270 ah battery via a Victron MPPT solar controller.

 

[lgcotton]

Everyone seems to be on the same page. I've ordered another battery and have plans to install at least 200w more solar in the spring. Yes, the inverter may be a little over kill but I could not pass up a deal. Also, we keep the inverter on at night because my wife uses an oxygen concentrator. I like using the generator to bring the batteries up to about 80% and then let the solar top them off. Works well when there is plenty of sum but not so much in the winter months. We are in Northern California so mostly year round camping, especially along the coast.

 

[Bob K4TAX]

With 40% to 50% of battery left when you have more sun, doesn't sound like you have a storage problem, you have a charging problem. I would at minimum add another 200w of panels or go to 800watts.

Doing so may even negate the need to run the generator.

I agree.

Based on your usage and ending up with 40% battery left, I see you have a charging deficiency. You need more solar power to charge the existing batteries having shorter daylight hours. If you add a 3rd battery, what source will be used to charge it? A 3rd battery does give more capacity but does nothing toward the ability to recharge the system.

Bob

 

[5picker]

With 40% to 50% of battery left when you have more sun, doesn't sound like you have a storage problem, you have a charging problem. I would at minimum add another 200w of panels or go to 800watts.

Doing so may even negate the need to run the generator.

OP said will get to 100% at sundown and uses generator to supplement

sure sounds like a charging issue to me?

Upgrade the solar
add another battery only if you want to allow more capacity for bad days
generator can supplement in case of continuous bad weather

I agree.

Based on your usage and ending up with 40% battery left, I see you have a charging deficiency. You need more solar power to charge the existing batteries having shorter daylight hours. If you add a 3rd battery, what source will be used to charge it? A 3rd battery does give more capacity but does nothing toward the ability to recharge the system.

Bob

I still need someone to explain to me if the OP is able to charge what battery bank they have, to 100% by sundown, how is adding more solar (through the hours of darkness) without adding more capacity, going to give him more capacity overnight?

I did not read where they were not able to get to 100% by darkness as some of these posts are suggesting.

I could understand if they were only getting to 80% or 60% (or whatever) but starting darkness with 100% and adding only additional solar, isn't going to allow them to have 75 or 80% remaining when the sun comes up?

Someone enlighten me?

 

[reidfo]

I still need someone to explain to me if the OP is able to charge what battery bank they have, to 100% by sundown, how is adding more solar (through the hours of darkness) without adding more capacity, going to give him more capacity overnight?

I did not read where they were not able to get to 100% by darkness as some of these posts are suggesting.

I could understand if they were only getting to 80% or 60% (or whatever) but starting darkness with 100% and adding only additional solar, isn't going to allow them to have 75 or 80% remaining when the sun comes up?

Someone enlighten me?

The way I read it, is that if batteries are typically 100% by end of day then there may be some excess solar capacity not being used. A third batter could potentially take that charge. True, overall capacity would likely be less than 100%, but 100% of solar charge could be utiliized.

Adding more solar would potentially allow 100% charging of the upgraded battery ssytem.Then rinse and repeat for more solar or battery.

 

[Aussieguy]

I still need someone to explain to me if the OP is able to charge what battery bank they have, to 100% by sundown, how is adding more solar (through the hours of darkness) without adding more capacity, going to give him more capacity overnight?

Post # 11 using generator to charge to 80%
I did not read where they were not able to get to 100% by darkness as some of these posts are suggesting.



I could understand if they were only getting to 80% or 60% (or whatever) but starting darkness with 100% and adding only additional solar, isn't going to allow them to have 75 or 80% remaining when the sun comes up?

Someone enlighten me?

doing some math might help
battery in morning is 50% (post #1)
100ah used @12v = 1200w

400w solar ... lets say hey gets 50% = 200w
5 hours charging = 1000w he can pump back into battery
Maybe/Almost..... could get a full charge

more solar will work well as he has a 5th wheel and is in sunny cali



Kinda backwards to run generator first
I would run it around 4 PM after you got the most from solar

Battery capacity is a bit low as I like to have 3 days available
just in case it rains... gives me time to bug out of the wet

 

[Giboneys]

Last year I installed 400w solar, 2 100w lithium batteries and a 3000w inverter. Everything worked well during the summer months when the solar got plenty of sun and I supplemented with a couple of hours on the generator in the morning. Over 4 separate weeks we would be up to 100% battery when the sun went down. We used the inverter to power the TV and Microwave and 12v for lights, a fan and propane heater (occasionally). The battery level would get down to 40-50% by morning.
Now with the shorter days and less sun I am thinking about adding a 3rd battery. We have a couple of trips planed (boon docking) and I want insure there is enough power.

Make sure you're not running your inverter for 120V unless you need it. Adding a third battery will give you more storage. Adding an addition solar panel will give you faster and more
charging. During the winter the sun is lower in the horizon, if your panels are on the roof they are not putting out much plus the shorter days

You may want to think about a portable panel and hook it to the solar port on the outside if you have on. Make sure the portable one has a built in charge controller because the charging port on the outside goes directly to the battery not through the built in charger.

I have 400 AH of batteries, 800 watts of solar on the roof and 400 watts of portable panels and the portable ones out performed the ones on the roof this time of the year. You can lean the portable and move around to get the most solar and if you get an extension cord and parked under trees you can move them out from under the shade from the trees.

 

[GolfingDave]

I still need someone to explain to me if the OP is able to charge what battery bank they have, to 100% by sundown, how is adding more solar (through the hours of darkness) without adding more capacity, going to give him more capacity overnight?

Does he have to come up to 100%? Or just keep it maintained so they draw down gradually during the length of the trip?

With my setup and location right now I can most likely go four days without running any generator. See the post I linked to. I opted to run my generator to give me a bit more of a boost on a rainy day since I knew I was going to be boondocking a few more days. The only time I was at 100% was when I set up camp coming from a site with shore power.

Adding another battery and solar panel will/may keep the batteries at the point they are at in the morning. He does not mention the length of time he is camping though. Long weekend no problem, as he can plug in at home and the solar will top them off for the next trip.

Even an extended stay he can run a generator if he needs to, long enough for the solar to top it off or just long enough to give him a few extra AH's. Adding both will give a little more leeway in having to run a generator.

That was my rational for going with 600 watts and 3 100 AH's. My two 75 AH AGM would not get me through a couple of nights and only one if I did not get good sun the next day. Added the extra panel along with the batteries and gave the AGM to my nephew for his step son's boat. Win win.

 

[reidfo]

You may want to think about a portable panel and hook it to the solar port on the outside if you have on. Make sure the portable one has a built in charge controller because the charging port on the outside goes directly to the battery not through the built in charger.

This is good advice, but I would add not assume any outside solar connector is actually connected to anything. Mine isn't. I'll have to fix that if I plan to ever use it. Also, Forest River often uses proprietary connectors from Renogy to make sure you buy their expensive portable panels. You don't have to buy those if you also get an adapter or replace the receptacle with a standard one.

 

[Aussieguy]

Also, we keep the inverter on at night because my wife uses an oxygen concentrator.

some systems can run off 12v
check if yours can

if so you can better use your battery by installing a 12v outlet


otherwise you are
charging up house battery
connecting to inverter ... and making 120 (losing some power from the conversion)

then the concentrator if it has one of those square brick (power supply) is changing it back to DC power... again loosing some power in the conversion



If YOU GOT A BRICK ..... what voltage and amps does it output!
if your model can connect to car battery ... connect it instead to the house battery

you can easily install outlets throughout the trailer rooms and even outside

 

[timfromma]

Exercise caution when adding a new battery to an existing bank. Make sure they are all at the same charge level before connecting them together.