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Old 09-14-2020, 01:45 PM   #1
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New Solar Install

Just getting a Jayco 22rb and wanting to pick up solar. Looking for confirmation that this will work. We rarely hook up to shore power sites and previously used generator for short runs of the microwave, coffee, etc. New trailer doesn't have generator. I've attached the basic idea of the components. I was going to keep the basic AGM 12v battery the trailer came with as backup and setting up the slide out and awnings, charged from the vehicle as I drove there. Plus the solar controller can charge different types of batteries connected to it. Like a house battery and vehicle battery. Once set up I would plug in the shore power cord to the inverter and defuse the battery charger in the load center, to not create a cycle of charging from the battery to the battery. Also switch to just the lithium battery and turn on the inverter when ever we needed to use the microwave, etc. Any ideas of why this wouldn't work? I am eliminating the need for an automated switch box for shore power this way. Both the solar charger and battery have bluetooth apps to monitor power usage and generation. I would never connect both batteries together.
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Old 09-14-2020, 05:46 PM   #2
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That should work, but it will be important to switch the solar charge control back and forth depending on which battery you are charging (AGM and Lithium)

I would think it will be more practical to just replace the AGM with another Litium.

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Old 09-14-2020, 09:46 PM   #3
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As Unplanned said you would have to switch the Solar Charge Controller between batteries and reprogram it for each. The best solution is to charge the Lithium Battery with the Solar Charge Controller and use a DC to DC Charger between the two batteries. Renogy makes a 20 amp DC to DC Charger that would work.
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Old 09-14-2020, 10:04 PM   #4
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Mixing chemistries and having ANY way that a loop can be created is just a bad idea.

The factory-provided AGM is likely just barely enough to keep the lights on and show what the appliances can do, it's not designed for actual dry camping "out of the box" because that would cost the manufacturer more and not everyone wants to use their rig in that way.

The dedicated solar charging is a great plan, the onboard charger is likely just a single or dual stage charger rather than a 4-stage quality unit (that the solar would be) so no loss in dropping that out of the picture entirely.
The lithium can power all the onboard 12V stuff (lights, water, awning, fridge) as it is, you don't need the AGM for that. A battery monitor like the Victron BMV-712 and the shunt it uses are going to be important so that you can see exactly how much power you have left at any given point, and how fast you are using it.

An inverter to power the microwave is a nice idea... BUT that's going to HAMMER that battery and the voltage drop will likely cut the inverter off anyway. Anything that is pulling more than 1000 watts is going to need close to a 150 amp surge (with losses) from the battery, and the batteries don't much appreciate that. A bigger array of batteries will spread that load, but an inverter generator like the Ryobi 2200 watt will likely be a much better value for the bigger loads.
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Old 09-14-2020, 10:04 PM   #5
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Quote:
Originally Posted by John Hilley View Post
As Unplanned said you would have to switch the Solar Charge Controller between batteries and reprogram it for each. The best solution is to charge the Lithium Battery with the Solar Charge Controller and use a DC to DC Charger between the two batteries. Renogy makes a 20 amp DC to DC Charger that would work.
Agree with this approach for now with the idea of adding a second Lion battery in the future.

I assume you know to add breakers/fuses on both sides of the solar controller and you know what wire gauges you need to be using for the distances and amps involved.
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Old 09-15-2020, 12:05 AM   #6
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Originally Posted by John Hilley View Post
As Unplanned said you would have to switch the Solar Charge Controller between batteries and reprogram it for each. The best solution is to charge the Lithium Battery with the Solar Charge Controller and use a DC to DC Charger between the two batteries. Renogy makes a 20 amp DC to DC Charger that would work.
The charge controller has the ability to charge two different banks. Bank 1 priority then bank 2. Thanks for the idea on the DC to DC charger.
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Old 09-15-2020, 12:13 AM   #7
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Mixing chemistries and having ANY way that a loop can be created is just a bad idea.

The factory-provided AGM is likely just barely enough to keep the lights on and show what the appliances can do, it's not designed for actual dry camping "out of the box" because that would cost the manufacturer more and not everyone wants to use their rig in that way.

The dedicated solar charging is a great plan, the onboard charger is likely just a single or dual stage charger rather than a 4-stage quality unit (that the solar would be) so no loss in dropping that out of the picture entirely.
The lithium can power all the onboard 12V stuff (lights, water, awning, fridge) as it is, you don't need the AGM for that. A battery monitor like the Victron BMV-712 and the shunt it uses are going to be important so that you can see exactly how much power you have left at any given point, and how fast you are using it.

An inverter to power the microwave is a nice idea... BUT that's going to HAMMER that battery and the voltage drop will likely cut the inverter off anyway. Anything that is pulling more than 1000 watts is going to need close to a 150 amp surge (with losses) from the battery, and the batteries don't much appreciate that. A bigger array of batteries will spread that load, but an inverter generator like the Ryobi 2200 watt will likely be a much better value for the bigger loads.
Yeah, I already confirmed the factory charger in the load center doesn't have a lithium program.
I just found the ionic lithium battery that has bluetooth built in with an app to eliminate the shunt wiring but gives you the details of charging current and output of the battery.
The IONIC battery can export 100amps with a 3 second max of 350amps. You dont think that will run a microwave for a bit? Its probably a 900watt microwave.
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Old 09-15-2020, 07:54 AM   #8
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Yeah, I already confirmed the factory charger in the load center doesn't have a lithium program.
I just found the ionic lithium battery that has bluetooth built in with an app to eliminate the shunt wiring but gives you the details of charging current and output of the battery.
The IONIC battery can export 100amps with a 3 second max of 350amps. You dont think that will run a microwave for a bit? Its probably a 900watt microwave.
900 watts / 12 volts = 75 amps at 12 volts. Add efficiency loss and other things running at the same time. Results are you need at least 200 amp hours of AGM batteries. I don't know the discharge profile of the Lithium battery.

Charging using a 400 watt solar array will vary a lot. You will only get 20 amps on sunny summer days for a few hours. The company selling the solar may provide examples of how many amp-hours you might get in a day under different weather conditions. Estimate your amp-hour usage and compare to what the solar might produce.

Charging lead acid batteries goes fast for the first few hours if you have a high capacity charger. A 100 amp hour AGM may absorb 30 or 40 amps for 4 hours. The lead acid still needs a long slow 14 additional hours maybe once per week to maintain full capacity and long life. A 20 amp charge for 6 hours will probably cause the battery to struggle to supply what you need.

Lithium batteries do not need the periodic long slow finishing charge. They can take their rated full charge from beginning to end. 6 hours at 20 amps will probably still be limiting.

I would choose a pair of lithiums over the mixed battery type. An alternate would be a pair of 100 amp hour AGM's. Pairs working together will support a 900 watt microwave for 10 minutes.

One lead acid alone will struggle. The inverter may trip due to low voltage on the 12 volt side. This is especially true when using the battery at low state of charge. For example, after running the furnace all night, the battery may not supply enough to keep the inverter running to support a microwave.

One 100 amp hour lithium may also struggle. Check with battery manufacturer.

Just a thought: A 1000 watt portable generator is enough to run the on-board charger plus a few other 12 volt things. Run the micro on the inverter. Charge the battery using the generator for 2 hours in the morning. Let the solar provide the long slow finishing charge all day.

I wish you good luck and happy trails ahead!
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Old 09-15-2020, 02:14 PM   #9
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Continuing the thought process from Persistent's reply...

Lead acid batteries (ANY flavor) can reasonably only be used to a 50% state of discharge. So that battery capacity is instantly cut in half. Lithium can be just about fully utilized, so that 100 amp battery actually WOULD give you close to 100 usable amps before the circuitry tells it "lights out" on the output.

Solar... Manufacturers market based on the best laboratory results, not the real world. The real world has clouds and shade and high temperatures. IF you have any way to control how the solar is installed, get them raised above the roof by a couple inches to help the ventilation. My solar array is 3 panels that collectively can produce 1020 watts according to the ratings, and with how I have it wired up... I've seen as high as 1000 watts instantaneous capture and over 4kWh per day captured. The limiting factor in the capture has been my battery bank - you have to have someplace to put the power right away, or it is lost.

That's the problem with battery charging, especially lead. As was mentioned, it can only take full power for a certain time - usually this is described as an 80/20 relationship. 80% of the charge can be stuffed into the battery in 20% of the total time... But that last 20% takes 80% of the time! My solar is charging into an 880 amp array (8 GC2 batteries of ~220 amps each) and if you calculate the "total sun hours" as just 5 hours per day... That will tell you how much power you can reasonably expect in "real world" solar results. So for a 400 watt array, you can reasonably expect about 2kWh total per day. Into a 12v system, that's around 160 amps per day.

If you had TWO of those lithium batteries and they were totally flat, you would probably be able to finish them off to full each day... BUT that's with no other loads sharing the power at the same time. It's always better to have way more solar than you need, you can always just not capture, versus still needing more power when the sun goes down.
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Old 09-15-2020, 02:42 PM   #10
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Lead acid batteries (ANY flavor) can reasonably only be used to a 50% state of discharge. So that battery capacity is instantly cut in half.




.
Where are you getting this information ?

Any battery can be used to full capacity. Leaving 10% to 20% as a cushion, so not to discharge them below 10.5 volts is strongly recommended, but only discharging down to 50% to protect them is a myth.

Look at any depth or discharge chart and you will see that DOD ( depth of discharge ) coincides with cycle life. The deeper the discharge, the less cycles the battery will supply. This is true of all types of rechargeable batteries, including lithium.

The 50% recommendation, ( not rule ), is a compromise of cycles and length of service.

Are lithium batteries superior to lead acid batteries, yes, but thats because of many more cycles avalable. Drawing lithiums down to 10%, compared to 50%, will shorten their life the same as lead acid. There are only so many AHs in a battery.

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Old 09-15-2020, 04:45 PM   #11
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Trojan battery:

https://www.trojanbattery.com/tech-s...y-maintenance/

"Discharging batteries is entirely a function of your particular application.

However, below is list of helpful items:

Shallow discharges will result in a longer battery life.
50% (or less) discharges are recommended.
80% discharge is the maximum safe discharge.
Do not fully discharge flooded batteries (80% or more). This will damage (or kill) the battery.
Many experts recommend operating batteries only between the 50% to 85% of full charge range. A periodic equalization charge is a must when using this practice.
Do not leave batteries deeply discharged for any length of time.
Lead acid batteries do not develop a memory and do not need to be fully discharged before recharging.
Batteries should be charged after each period of use.
Batteries that charge up but cannot support a load are most likely bad and should be tested. Refer to the Testing section for proper procedure."
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Old 09-15-2020, 05:20 PM   #12
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Originally Posted by geordi View Post
Trojan battery:

https://www.trojanbattery.com/tech-s...y-maintenance/

"Discharging batteries is entirely a function of your particular application.

However, below is list of helpful items:

Shallow discharges will result in a longer battery life.
50% (or less) discharges are recommended.
80% discharge is the maximum safe discharge.
Do not fully discharge flooded batteries (80% or more). This will damage (or kill) the battery.
Many experts recommend operating batteries only between the 50% to 85% of full charge range. A periodic equalization charge is a must when using this practice.
Do not leave batteries deeply discharged for any length of time.
Lead acid batteries do not develop a memory and do not need to be fully discharged before recharging.
Batteries should be charged after each period of use.
Batteries that charge up but cannot support a load are most likely bad and should be tested. Refer to the Testing section for proper procedure."
Great, it says what I did. You can draw them down 80%, no harm.
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Old 09-15-2020, 05:46 PM   #13
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Great, it says what I did. You can draw them down 80%, no harm.
Great - it confirms what I said - less than 50% discharge is recommended.

You want to go deeper, knock yourself out. But it will be reducing the total lifespan of the battery.
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Old 09-16-2020, 08:15 AM   #14
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What really kills a lot of lead acid batteries is people don't use a battery state of charge monitor with a shunt. People discharge the batteries until stuff stops working. They also use Lead Acid batteries that aren't true deep cycle so they fail even sooner.

Victron Energy has recently released the SmartShunt that is a bit cheaper. The 500 amp version will soon be available for about $131.00 at some places. It has integrated bluetooth and no other display. You interact with it using a smart phone app or link it to something like the Cerbo GX.

https://invertersrus.com/product/victron-smartshunt/
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