300W of Solar should replace 100AH of usage daily?

[NJKris]

Originally Posted by Eric H.

Everyone talks about Lithium's having more usable capacity but the biggest advantage is how fast you can replenish them compared to lead acid. Lead acid can only slow charge at 15 amps max. 100 ah battery at 50% SOC = 3.5 hours to charge no matter what the charging source and that's only if you're getting the full 15 amps.

Lithium Iron you can pour on the coals at 100+ amps. The same 100 ah Lithium at 50% SOC can charge in under 30 minutes with a good charger.

It isn't that hard to isolate or heat your lithium batteries for winter use and many come with built in heaters now.

I was just discussing this with TitanMike. Just how do built in heaters work if you are not on shore power?

[Hclarkx]

Originally Posted by elob_tx

If you go to www.wunderground.com you can find solar radiation information in watts if you don't want to use the NREL site. It doesn't do all the math for you but it will give you that information from personal weather stations that have the solar radiation measurement hardware. Personally I just use the NREL datum since it is easier to access. Don't forget to take the information and massage the data by your panels efficiency and subtract ate losses.

The panel efficiency is taken into account in NREL's PVWatts. Wiring losses are also taken into account. Likewise, some amount of shade is assumed as well as outages due to equipment failures. For RV purposes, one should zero out about half of the 14% losses that PVWatts applies. Those can be considered separately in a more realistic manner though most simply do not apply. I've found reducing the losses to about 7% makes most sense for my RV application.

[Hclarkx]

Originally Posted by NJKris

I was just discussing this with TitanMike. Just how do built in heaters work if you are not on shore power?

I haven't surveyed a lot of self-heated LiFePO4 but I think with most you can turn off the heater during storage. For boondocking, I believe all use a thermostat. It doesn't take much wattage to keep the battery 10F above where it might otherwise sit. And it might take a few days for the battery to get down to 32F or below when one is camping in the 20's. The heat generated in an LiFePO4 by the load current or charge current is modest, but may be enough, especially if the day time temps are higher. For most users the built-in heater is just backup and won't get much use.

Personally, I would put some insulation over and around the battery if I thought the heater might be activated. This might avoid using the heater and would reduce heater usage if indeed the heater does come on.

[Mikec557]

Originally Posted by NJKris

I was just discussing this with TitanMike. Just how do built in heaters work if you are not on shore power?

My understanding, looking at Battleborn, is that the heater self consumes from the battery. Two leads from the heater go to the two battery posts. I don't know if there's an elegant way to control the on/off.

[Hclarkx]

Originally Posted by Captain Insaino

Another question. Panel to controller to battery.. 30 amp fuse in line on the negative cable between the panel and controller close to the controller. And some type of switch/disconnect on the negative between the controller and battery, correct?

Most solar controller makers suggest a switch of some kind between the solar controller and the panels as well as between the solar controller and the battery. They also tell you to close the switch in the line to the battery first, to boot up the solar controller before closing the switch on the panel side to apply voltage to the solar controller. In some cases this was because the solar controller is a 12/24 volt unit and needs to select the correct voltage upon boot-up. My own units can be set to 12V rather than auto. But, there may be other reasons to switch battery side then panel side so I do that.

Since you need switches on both sides of the solar controller, you can use circuit breakers and have double-duty, switch and short-circuit protection.

As for the panels needing fuses, series panels don't need fuses (or circuit breakers) because it's impossible to detect a short-circuit current but not the load current. In most panels the short-circuit is just an amp higher than the maximum load current. I.e., a 200W panel might max out at 10 amps load current but produce only 11 amps of short-circuit current. Fuses are not all that precise so having one pass 10 amps and blow on 11 amps is just not going to happen. So here the panel side circuit breakers is simply a switch. But, it's a convenient one.

With two parallel panels or parallel series strings, the problem is the same. 20 amps load and 22 amps short-circuit. Just no way to fuse this. With three or more parallel panels fuses on the roof do function (two panels feeding 20 amps into a third short-circuited panel). Here a 12 amp fuse could be useful.

I prefer to keep the ground/negative side of things clean, no switching and no fuses and no circuit breakers. I put the circuit breakers (switches) in the positive leads.

If the solar controller is any distance from the battery, and you run, say, #10 wire, you do have some exposure to short-circuit current that can be problematic. Here the problem would be a short-circuit in the solar controller or in the wire between the solar controller and the battery. And the problem short-circuit current source would be the battery (which can supply hundreds if not thousands of amps of short-circuit current). Because #10 wire (or #8 wire) will heat up quickly with such currents, you will ideally have the circuit breaker between the solar controller and the battery at the battery end of that wire.

I like to have the two circuit breakers on the solar controllers close to the solar controllers for ease of access and to make it easy to switch on the battery side first. Ideally then, I would have a circuit breaker at each end of the wire between the solar controller and the battery. Though if this wire is short and well protected from mechanical damage, the risk of a short-circuit is low and one can cut some corners.

If one has LiFePO4 battery/batteries, the fusing and circuit breakers are less critical. Upon a short-circuit, the BMS is going to disconnect the battery/ies long before a fuse or circuit breaker can open. With your AGM, you don't have this advantage and short-circuit protection becomes important.

FWIW, if you were to put a fuse between the panels and the solar controller, it would need to be at the panel end of the wire run. The solar controller will not feed current into a short-circuit in that wire run while the panels will. So to see that current, the fuse would need to be at the panel end. Though as I noted above, fusing panels in most situations is just not useful.

Yes, probably 20 minutes away. Call me if I can ever help. 1. 9 1 6. 4 2 6. 6 8 0 2.

[Eric H.]

Originally Posted by Hclarkx

Most solar controller makers suggest a switch of some kind between the solar controller and the panels as well as between the solar controller and the battery. They also tell you to close the switch in the line to the battery first, to boot up the solar controller before closing the switch on the panel side to apply voltage to the solar controller. In some cases this was because the solar controller is a 12/24 volt unit and needs to select the correct voltage upon boot-up. My own units can be set to 12V rather than auto. But, there may be other reasons to switch battery side then panel side so I do that.

Since you need switches on both sides of the solar controller, you can use circuit breakers and have double-duty, switch and short-circuit protection.

As for the panels needing fuses, series panels don't need fuses (or circuit breakers) because it's impossible to detect a short-circuit current but not the load current. In most panels the short-circuit is just an amp higher than the maximum load current. I.e., a 200W panel might max out at 10 amps load current but produce only 11 amps of short-circuit current. Fuses are not all that precise so having one pass 10 amps and blow on 11 amps is just not going to happen. So here the panel side circuit breakers is simply a switch. But, it's a convenient one.

With two parallel panels or parallel series strings, the problem is the same. 20 amps load and 22 amps short-circuit. Just no way to fuse this. With three or more parallel panels fuses on the roof do function (two panels feeding 20 amps into a third short-circuited panel). Here a 12 amp fuse could be useful.

I prefer to keep the ground/negative side of things clean, no switching and no fuses and no circuit breakers. I put the circuit breakers (switches) in the positive leads.

If the solar controller is any distance from the battery, and you run, say, #10 wire, you do have some exposure to short-circuit current that can be problematic. Here the problem would be a short-circuit in the solar controller or in the wire between the solar controller and the battery. And the problem short-circuit current source would be the battery (which can supply hundreds if not thousands of amps of short-circuit current). Because #10 wire (or #8 wire) will heat up quickly with such currents, you will ideally have the circuit breaker between the solar controller and the battery at the battery end of that wire.

I like to have the two circuit breakers on the solar controllers close to the solar controllers for ease of access and to make it easy to switch on the battery side first. Ideally then, I would have a circuit breaker at each end of the wire between the solar controller and the battery. Though if this wire is short and well protected from mechanical damage, the risk of a short-circuit is low and one can cut some corners.

If one has LiFePO4 battery/batteries, the fusing and circuit breakers are less critical. Upon a short-circuit, the BMS is going to disconnect the battery/ies long before a fuse or circuit breaker can open. With your AGM, you don't have this advantage and short-circuit protection becomes important.

FWIW, if you were to put a fuse between the panels and the solar controller, it would need to be at the panel end of the wire run. The solar controller will not feed current into a short-circuit in that wire run while the panels will. So to see that current, the fuse would need to be at the panel end. Though as I noted above, fusing panels in most situations is just not useful.

Yes, probably 20 minutes away. Call me if I can ever help. 1. 9 1 6. 4 2 6. 6 8 0 2.

To add to your post, all the charge controllers I've seen say you can damage the controller by connecting the panels to the controller if the controller is not connected to batteries first. Opposite when disconnecting. Connect panels last. Disconnect panels first.

[NJKris]

Originally Posted by Eric H.

To add to your post, all the charge controllers I've seen say you can damage the controller by connecting the panels to the controller if the controller is not connected to batteries first. Opposite when disconnecting. Connect panels last. Disconnect panels first.

I think I read that too. Sounds good in theory, but what the heck are you supposed to do with something like a solar suitcase that has a controller built onto back side of it already connected??? The second you pull the suitcase out of the case and open it, it is 'on' and connected to controller before you can hook up cables to battery/solar on side inlet.

[Mikec557]

I too have read the "connect batteries first" admonition, usually with the warning that to do otherwise will damage the solar charge controller. But my Victron MPPT scc clearly says that connecting the solar panels first will not harm the scc. Maybe the admonition is from the "old days"...

[Eric H.]

OK I retract part of my statement. You can't charge Renogy 100ah lithiums over 50 amps and neither of my Victron SCC's say you can cause damage connecting the panels before the battery. My 250/100 and 100/20 SCC's say connect batteries first to sense voltage but no warning. My last Renogy Voyager 20a PWM says NEVER connect panels without batteries connected. It could be the difference between PWM and MPPT controllers.

As far as built in heaters with Renogy and Battleborn;

Battleborn uses it's own energy to heat when internal temp drops below 35 deg f. They claim the heat function draws only 1.8a uninsulated at 0 deg f and only runs 30% of the time. It's only needed when charging so you'll loose 1.8a of your charge current to the heater. It looks like the function can be turned on and off.

Renogy says theirs turns on at 43 deg f but only if charging current reaches more than 4a so it is automatic. They do not say what the heat function consumes.

I have Valence Lithiums and I just disconnect them when storing with the potential for freezing temps. We're in N. Cal close enough to the coast that we don't have too many freeze warnings. If we were camping in the winter, I'm sure my front compartment would never get down to freezing with the heater running all night besides the inverter running in the same compartment.

[NJKris]

Originally Posted by Eric H.

OK I retract part of my statement. You can't charge Renogy 100ah lithiums over 50 amps and neither of my Victron SCC's say you can cause damage connecting the panels before the battery. My 250/100 and 100/20 SCC's say connect batteries first to sense voltage but no warning. My last Renogy Voyager 20a PWM says NEVER connect panels without batteries connected. It could be the difference between PWM and MPPT controllers.

As far as built in heaters with Renogy and Battleborn;

Battleborn uses it's own energy to heat when internal temp drops below 35 deg f. They claim the heat function draws only 1.8a uninsulated at 0 deg f and only runs 30% of the time. It's only needed when charging so you'll loose 1.8a of your charge current to the heater. It looks like the function can be turned on and off.

Renogy says theirs turns on at 43 deg f but only if charging current reaches more than 4a so it is automatic. They do not say what the heat function consumes.

I have Valence Lithiums and I just disconnect them when storing with the potential for freezing temps. We're in N. Cal close enough to the coast that we don't have too many freeze warnings. If we were camping in the winter, I'm sure my front compartment would never get down to freezing with the heater running all night besides the inverter running in the same compartment.

I remember reading that too, I have same controller on my suitcase. Kind of impossible, since controller is wired to panels already! I've only deployed my suitcase twice so far, no problem when opening panel and then connecting to battery. So far!

[sdelam]

I have a Renogy 40a MPPT controller. I inadvertently disconnected the batteries without disconnecting the panels. The result was that all the 12v items (that were turned on) in the camper flashed on a 2 second interval, including the charge controller. My assumption was that the panels were not producing enough current to support the load. It did this for a minute or two tops before it dawned on me what was happening. Does not appear that there was any permanent damage.

[Eric H.]

Originally Posted by sdelam

I have a Renogy 40a MPPT controller. I inadvertently disconnected the batteries without disconnecting the panels. The result was that all the 12v items (that were turned on) in the camper flashed on a 2 second interval, including the charge controller. My assumption was that the panels were not producing enough current to support the load. It did this for a minute or two tops before it dawned on me what was happening. Does not appear that there was any permanent damage.

I thought maybe it was the difference between PWM & MPPT but I just looked at Renogy's 40a MPPT and it has the same warning. Their portable suitcase with built in Voyager charge controller does not have an available manual for the system and no warnings but does have a manual download for the charge controller that says NEVER connect panels before batteries. So how confusing is that? It is apparently an unnecessary warning. Either that or a warranty denial excuse.

[NJKris]

Originally Posted by Eric H.

I thought maybe it was the difference between PWM & MPPT but I just looked at Renogy's 40a MPPT and it has the same warning. Their portable suitcase with built in Voyager charge controller does not have an available manual for the system and no warnings but does have a manual download for the charge controller that says NEVER connect panels before batteries. So how confusing is that? It is apparently an unnecessary warning. Either that or a warranty denial excuse.

Exactly what I was thinking.

[Eric H.]

Originally Posted by NJKris

Exactly what I was thinking.

I used to think Renogy was relatively high quality but I'm learning that spending the money on brands like Victron and Battleborn get you better specs/parameters/functions.

[Flybob]

Originally Posted by wls

I'm new to solar also, so what would happen if you upped to 2 batteries. The solar wattage would not be able to get the 2 batteries topped off or close? Thanks

Adding a second battery will buy you a little more margin for cloudy days, but with out additional panels you will not be able to replace the power used on a cloudy day. If you are weekend camping only (2 days) you should be OK. Think of it this way. You have a storage tank that holds 4 buckets of water and you have the ability to add two buckets of water a day on sunny days and 1 bucket on cloudy days. You can not get the last 2 buckets of water out of the tank. If you use 2 buckets of water from the tank per day on sunny days the tank will remain full. If you have a cloudy day you will only have 1 bucket for the second day. If you add a second tank that holds 4 buckets of water, you have a reserve, but if you still only replace 1 bucket on a cloudy day you only get an extra two days.

[Mikec557]

Originally Posted by Eric H.

I used to think Renogy was relatively high quality but I'm learning that spending the money on brands like Victron and Battleborn get you better specs/parameters/functions.

Don't sell Renogy short. I think they're good quality for what they are. You can't compare Renogy to Victron because that's like comparing a lower end Chevrolet to a Cadillac. There's a place in the world for both.

I once bought a Renogy PWM SCC that included a lithium profile. It came with a one year warranty. Toward the tail end of my warranty, Renogy increased their warranty on a ton of products to two years, including my model SCC. They sent an email saying they increased my warranty to two years. That was nice of them, they didn't need to do that.

But lucky me, either my SCC or the separate Bluetooth dongle went bad. I couldn't tell which. Emailed with tech support and they couldn't tell which one to replace, so they said send them both back in for warranty work. Shortly after they received them they sent me new units for both of them.

Now, my problem was that we were full-timing. I couldn't or didn't want to wait for warranty work. So I ordered Victron and was back in business. That's not Renogy's fault. That was my choice.

But I still benefitted from their warranty coverage. When I sold that 5th wheel I kept all my Victron equipment and installed the new Renogy equipment. It was a win-win deal.

If your budget and circumstance can take the hit, then I recommend Victron. But I think renogy is still a good product.

[Eric H.]

Originally Posted by Mikec557

Don't sell Renogy short. I think they're good quality for what they are. You can't compare Renogy to Victron because that's like comparing a lower end Chevrolet to a Cadillac. There's a place in the world for both.

I once bought a Renogy PWM SCC that included a lithium profile. It came with a one year warranty. Toward the tail end of my warranty, Renogy increased their warranty on a ton of products to two years, including my model SCC. They sent an email saying they increased my warranty to two years. That was nice of them, they didn't need to do that.

But lucky me, either my SCC or the separate Bluetooth dongle went bad. I couldn't tell which. Emailed with tech support and they couldn't tell which one to replace, so they said send them both back in for warranty work. Shortly after they received them they sent me new units for both of them.

Now, my problem was that we were full-timing. I couldn't or didn't want to wait for warranty work. So I ordered Victron and was back in business. That's not Renogy's fault. That was my choice.

But I still benefitted from their warranty coverage. When I sold that 5th wheel I kept all my Victron equipment and installed the new Renogy equipment. It was a win-win deal.

If your budget and circumstance can take the hit, then I recommend Victron. But I think renogy is still a good product.

You're right & I used the wrong wording. I should have said higher end vs. higher quality. My comment was based on features & functions vs. quality.

[Captain Insaino]

I very much appreciate all of the mentoring here. I’m starting to gain the confidence to make the purchases to fit my application. I was just blindly pulling the trigger before.

[spower]

What a great thread with lots of great info!! My question is......

What are you running/using that will consume 100ah in a night?

[NJKris]

Most high consumers are trying to power a residential fridge on an inverter, or have one of these new DC only fridges. Life is still a gas with me. Propane baby! Propane, propane! Time to play the game!