trying to understand the camper battery system

[Doff]

Hi All

We have a 2021 Hawk FWC that we bought new....we've had it about a year. I am hoping someone can explain to me the basic ins/ outs of the battery and solar system. I have tried to research, but electrical stuff really confuses me. When we bought the camper the folks at FWC told us to make sure the digital battery gage never dropped below 12.0. However recently during a phone call with FWC they told me it shouldn't drop below 12.8. What does all that mean? Fully charged, the cage seems to max out around 13.2. So what should we aim to keep the battery at?

We don't use a ton of electrical stuff in the camper (in my opinion). The fridge is always running, And once set up in camp, we often have our two ceiling fans running and in the evening maybe a few lights. We periodically turn on the water pump and often charge our phones through the USB outlets. having done this, I have had a few times in the morning where the battery gage is reading below 9.0. I am assuming that isn't good. Are we using too much power? Have I ruined our batteries? If so, and we need to replace the batteries, would lithium be a better choice?

Any insight into the battery system and what all the numbers mean would be really helpful for me.

Thanks!

 

[longhorn1]

More info is needed. What type batteries and how many batteries. What is the solar panel watt?

When you say 9, do you mean the reading of 9 was off your solar controller?

12.3 is the magic number to not drop below. You don't want to drop below 50%. If you dropped to 9 you may have damaged the batteries.

 

[pvstoy]

Remember that around 12.3 volts is at a resting state. Don't look at the gauge when you are running the water pump as the amp draw will show the battery voltage very low.

 

[heinphoto]

The person you spoke with at FWC was confused. With lead-acid battery chemistry, 100% charge is around 12.8V and 50% around 12.2-12.3V (so if you don't go below 12.8V, you won't actually be using the battery) . You don't want to discharge battery regularly below ~50%. Those voltage guidelines are for a resting battery with no loads applied. If you do have a load applied, the voltage may temporarily drop lower. However, if you were really at 9.0V, that's very low and you likely did damage the battery to some extent. Whenever you do a deep discharge, you should try and do a full charge cycle again before significant discharge.

The solar charge controller will try to take the battery through a charge cycle every day: Bulk > Absorption > Float. The actual voltages will depend on what is programmed into the controller, but during bulk mode the voltage will increase until it reaches the absorption voltage (typically 14.4-14.8V), where it will be held until fully charged. It will then drop to float voltage (typically 13.2-13.8V). It will stay in float as long as the charge controller has enough solar energy to maintain it. After the charge controller shuts off at the end of the day, the voltage will drop down to ~12.8V and then start discharging as you use it.

Keep an eye on the charge controller voltages and status - you may have a bad solar panel (common with the Overland Solar panels sold by FWC) and you aren't recharging.

 

[Vic Harder]

Gosh, where to start? This is why I wish FWC would stop using volt meters/idiot lights and use a proper Shunt based State of Charge (SOC) meter. That would take all the guesswork out of this.

My recommendation is to get a Victron Smart shunt installed and use that to see what your typical usage is like.

Your batteries have likely “suffered” because they were fully discharged a few times. No big deal. They can take a few hundred of those, as long as they do not get frozen (which they can do when discharged. The liquid in them resembles water a lot more than acid when discharged).

So, don’t panic, but do get a that shunt installed.

 

[PaulT]

Doff,

Don’t worry too much about running your battery down one time. I’ll assume you have AGM batteries. When our Hawk was new & on our first multi day camping trip, I didn’t understand a whole bunch about power needs & battery management. It was sunny but our campsite was surrounded by 100 ft plus Doug firs so there were shadows on the solar panel as the wind blew. Couldn’t get any charging from the truck because of the battery isolator. Plus, the fridge kept running too much & sucking about 5amps.

At any rate, we got good solar charging on the return home & I plugged into shore power and left it for a couple of days. My AGM’s lasted for more than 5 yrs after that and charged up to 12.7v until I switched to LiFePO4 batteries. I made sure those batteries went to full charge at least monthly.

I still use those AGM’s for ham radio.

Paul

 

[ckent323]

I second what Vic wrote, also what Paul T wrote.

1) get a smart shunt - Victron BVM-712 or equivalent
2) Run a power consumption check using the smart shunt to understand your actual daily use
3) Your AGM batteries may still have plenty of life remaining
4) Don't discharge routinely below 50% (I try not to routinely discharge below 60% - 70% my AGMs are already 8 years old and doing fine)
5) Always fully recharge each day before discharging again (this will probably drive the size of your solar system if you have one - or require you to use shore power or run your truck alternator)
6) Consider using one large residential solar panel (eg. 360 or more watts) vs multiple smaller panels. Total weight and cost will likely be less. Of course use the appropriate size solar controller (Victron or equivalent).
8) If your truck has a smart alternator use a dc-dc charge controller between the truck battery and the camper battery bank. If is not a smart alternator use a Blue Sea ACR relay or equivalent.
9) Use at least 6 ga good quality stranded wire (eg. Anchor) between the truck charger and the house battery bank
10) make sure you have an appropriately sized fuse (80 to 120 A or so) on each end of the wires between your truck battery and your camper house bank

I hope this is helpful

Craig

 

[Stan@FourWheel]

It would be a really good idea to plug your camper into 120V electricity (shore power) for a day or so, and charge up those campers batteries ASAP.

Plug the camper into your garage, make sure all circuit breaker are turned on inside the camper, and make sure the 12V "Master Switch" is pulled out (ON).

Like others have said about, 12.2V is kind of the low point ideally on where you wan to be.

This video might not help, but it will give you some of the basics.

 

[kmcintyre]

All I can say is that we can run our 3 way refrigerator (on propane), refrig. fan on full time when stopped, charge phones, run ceiling fans, lights, etc. like you do and we can go multiple days w/o an issue. The big caveat is that we have a 120ah LifePO4 battery.

 

[ski3pin]

Welcome to the learning curve on living with and using a camper battery system. The three members below have given you solid advise and direction. Best of luck! We've all been on the same learning curve.

The best information is on State of Charge - only a Stunt monitoring system gives you an accurate state of charge. Reading a battery's voltage directly can be (and usually is) far from accurate in regards to state of charge as most have stated above.

Gosh, where to start? This is why I wish FWC would stop using volt meters/idiot lights and use a proper Shunt based State of Charge (SOC) meter. That would take all the guesswork out of this.

My recommendation is to get a Victron Smart shunt installed and use that to see what your typical usage is like.

Your batteries have likely “suffered” because they were fully discharged a few times. No big deal. They can take a few hundred of those, as long as they do not get frozen (which they can do when discharged. The liquid in them resembles water a lot more than acid when discharged).

So, don’t panic, but do get a that shunt installed.

Doff,

Don’t worry too much about running your battery down one time. I’ll assume you have AGM batteries. When our Hawk was new & on our first multi day camping trip, I didn’t understand a whole bunch about power needs & battery management. It was sunny but our campsite was surrounded by 100 ft plus Doug firs so there were shadows on the solar panel as the wind blew. Couldn’t get any charging from the truck because of the battery isolator. Plus, the fridge kept running too much & sucking about 5amps.
At any rate, we got good solar charging on the return home & I plugged into shore power and left it for a couple of days. My AGM’s lasted for more than 5 yrs after that and charged up to 12.7v until I switched to LiFePO4 batteries. I made sure those batteries went to full charge at least monthly.

I still use those AGM’s for ham radio.
Paul

I second what Vic wrote, also what Paul T wrote.

1) get a smart shunt - Victron BVM-712 or equivalent
2) Run a power consumption check using the smart shunt to understand your actual daily use
3) Your AGM batteries may still have plenty of life remaining
4) Don't discharge routinely below 50% (I try not to routinely discharge below 60% - 70% my AGMs are already 8 years old and doing fine)
5) Always fully recharge each day before discharging again (this will probably drive the size of your solar system if you have one - or require you to use shore power or run your truck alternator)
6) Consider using one large residential solar panel (eg. 360 or more watts) vs multiple smaller panels. Total weight and cost will likely be less. Of course use the appropriate size solar controller (Victron or equivalent).
8) If your truck has a smart alternator use a dc-dc charge controller between the truck battery and the camper battery bank. If is not a smart alternator use a Blue Sea ACR relay or equivalent.
9) Use at least 6 ga good quality stranded wire (eg. Anchor) between the truck charger and the house battery bank
10) make sure you have an appropriately sized fuse (80 to 120 A or so) on each end of the wires between your truck battery and your camper house bank

I hope this is helpful

Craig

 

[ckent323]

We can run our 3 way Norcold 300 refrigerator (on propane), refrig. fan on full time when stopped, charge phones, run ceiling fans, lights, etc. and we can go multiple days w/o an issue. I have converted most of the camper lights to LED.

We tend to consume less than 35 Ah to 40 Ah a day from the battery bank.

Our battery bank comprises two Lifeline AGM 6V 220 Ah batteries providing ~110 Ah usable power. Our solar system comprises a 360 W LG NeON Solar panel outputting around 35 v and 10 A (peak) into a Victron MPPT 100/50 Solar controller. In Summer we get around 5 - 6 peak solar producing hours and considering all available solar producing hours I have calculated that it typically provides between 50 - 60 AH a day at 12.8 V. Our battery bank is generally fully recharged by late afternoon every sunny day. I don't often see the battery bank go below 70% since I put this big panel on.

We only have one powered roof vent fan, the other is passive.

Two ceiling fans if run on high will consume upwards of 3 - 3.5 amps per hour.

The refrigerator fan should not be consuming much power. Use the BVM-712 and turn things on and off one at a time to see what they consume.

The water pump draws a lot of power but it typically isn't run very long (and should be shut off - no good reason to keep the system pressurized).

If you have incandescent lights - minimize their use. They are power hogs. Indeed, get led replacements. Fluorescent are a bit better but LED are better yet.

Here is a reference:

https://www.wanderthewest.com/forum/topic/9301-measured-fwc-power-use/

 

[RC Pilot Jim]

Doff,
I'm envious of the new electrical systems that the new campers have.
Four Wheels video on their "Truck Electrical Camper System is very good.

My 2 cents has always been to know what each of your electrical devices are drawing. Your electrical panel should
allow you to turn on each device an see the amp draw.

My old Trimetric TM2030-RV displayed amps in from each charge source: alternator, solar, shore power and out. and percentage of charge. My system was very simple. Everything ran off 12 volts (12.8 full) except in the winter. Either a Mr Buddy propane heater or if shore power was available a small 120 volt space heater.

We had one 80 watt AGM battery and one 150 watt panel. At 70% full on June 22nd (longest day of the year) panel put out 9 amps. On December 22nd (shortest day of the year) it put out 5.5.

Largest amp draw was our compressor fridge, 2.5 amps per hour cycling four times an hour in 85* temperature and the fan drawing 1,2,3 amps per hour depending on the fan speed setting. Unless you run your fans or lights all night your two batteries should run your fridge all night and only drop to 85% in the winter time (12-14 hours darkness). Ours never dropped below 90% full overnight after a full solar charge.

In my last 4 years of camping most of the time I was sitting in one spot at the Death Valley hot springs parked in one place for 7-9 days twice a year just running off solar.

Bliss - when you know what your hourly amp draw is and you know your solar panel can keep up with the draw with enough left over to daily charge your batteries.