How does Solar work ?

[Jim Bennett]

Originally Posted by Vermilye

You would need to add a switch between the panel & the controller to shut them off. That might not solve your problem since I suspect the EMF is created by the controller, not the panels. You might need to add a switch at the controller output to isolate it as well. Do not disconnect the controller from the batteries without also disconnecting the panel; that can damage the controller.

Does Escape now use breakers on either side of the controller for protection and a disconnect? I kinda thought that was standard in solar installs so I included them in my setup.

I am curious to as to how disconnecting the batteries from the controller, and not the controller from the panels, would cause harm to the controller. I imagine that it would see zero voltage and would attempt to charge at a higher voltage, but being disconnected there would be no current. Kinda like having a 120V to 12V charger plugged into the source, but not connected to a battery.

Yep, still learning stuff.

[LJY]

I'm using the battery disconnect switch now as way to minimize the EMF.. there's still a little bit of EMF, but hundreds of magnitude less than before. The controller just shows 0% charging to battery. Hopefully, I'm not harming any hardware...

[alanmalk]

Originally Posted by rbryan4

Alan, would an MPPT controller reduce the EMF?

MPPT is just a fancy term for DC to DC converter ( typical 24v to 12v). The amount of EMF produced is directly related to the quality and the design but the potential is there for significant EMF since it works with square waves feeding an inductor at 50 to 500 KHz. Messy, from an electrical noise point of view - but efficient. Filters and shielding can help a lot but add to the price.

[alanmalk]

Originally Posted by LJY

... Hopefully, I'm not harming any hardware...

Something to think about is that your Escape solar is hooked up 24 hours per day but making electricity only during daylight. Nothing is harmed if nothing is flowing into the controller. So use an On-Off switch between the solar and controller freely without worries.

[Sean Murry]

Originally Posted by LJY

Thanks for your help.
Not being argumentative.. but really questioning the use of a battery if I can only use 50% of it? I used it while towing to run the refrigerator. If this is a bad thing, how much should I expect to pay to replace the batteries and when?

As to why I'd like to shutoff the system temporarily.. I get headaches when near high EMFs.. and I was getting them and checked and found extremely high EMFs from the solar panel when it was sunny outside. So, there's no way to disconnect/disable thru the controller panel?

I am seriously looking at going with Lithium batteries. They are quite a bit more expensive but should last a lot longer than lead acid batteries, so in the long run the costs should be pretty close to equal. Big advantages for lithium in my opinion is that you can run them down to 10% or lower without shortening the life of the battery, they charge faster as you can do a full charge to 100% (lead acid batteries have to charge the last bit at a slow trickle charge rate), they keep their full voltage through the discharge cycle, you can charge up to whatever percentage you want without shortening the life of the battery (lead acids are supposed to be charged to 100%), Lithium's are 1/2 the weight, don't leak or vent, can be stored on their side or inside the trailer. They simply require little to no maintenance. So if you are willing to pay the upfront cost, I think it is a better way to go in my opinion. You can get a 200A lithium battery for about $1900, but that gives you 200A of usable power. A lead acid battery rated at 200A really only gives you 100A of usable power.

[Ron in BC]

Originally Posted by Sean Murry

I am seriously looking at going with Lithium batteries.

Well, yes, you can, I guess. But after living on 12 volt lead acid batteries in boats and trailers for 40 years I sometimes think that the theoretical and reality have a bit of a gap on this issue.

Yup, easy to say lead acid batteries have this or that negative but my reality is that my 100 watt solar panel keeps me in all the power I need. I have two 12 volt batteries separated by battery selector switch. On my recent 18,500 km. trip the battery selector staying on battery #1 the whole trip while I used my microwave on occasion, my wi-fi network, my TV etc. I checked the water at the halfway point and it didn't really need topping up.

Maybe, if you get a trailer, you'll see that lead acid batteries do a pretty good job.

Ron

[Dave Walter]

Originally Posted by Sean Murry

I am seriously looking at going with Lithium batteries. They are quite a bit more expensive but should last a lot longer than lead acid batteries, so in the long run the costs should be pretty close to equal. Big advantages for lithium in my opinion is that you can run them down to 10% or lower without shortening the life of the battery, they charge faster as you can do a full charge to 100% (lead acid batteries have to charge the last bit at a slow trickle charge rate), they keep their full voltage through the discharge cycle, you can charge up to whatever percentage you want without shortening the life of the battery (lead acids are supposed to be charged to 100%), Lithium's are 1/2 the weight, don't leak or vent, can be stored on their side or inside the trailer. They simply require little to no maintenance. So if you are willing to pay the upfront cost, I think it is a better way to go in my opinion. You can get a 200A lithium battery for about $1900, but that gives you 200A of usable power. A lead acid battery rated at 200A really only gives you 100A of usable power.

I am by no means a battery expert, but I had done a bit of research before buying lithium based batteries for an electric bike that I own. Sure lithium batteries can be discharged down to 10% or more, but my understanding is that those deep discharges are hard on the batteries and really decrease the number of charge-discharge cycles that a battery can handle in its lifespan. A good source for battery information is How to Prolong Lithium-based Batteries - Battery University

From the battery university website, they indicate that lipo4 batteries discharged to a depth of discharge of 40% would have a life span of about 3000 discharge cycles, but if the depth of discharge was increased to 80%, the life span would decrease to 900 cycles. Seems pretty significant.

100% DoD ~600 cycles
80% DoD ~900
60% DoD ~1,500
40% DoD ~3,000
20% DoD ~9,000
10% DoD ~15,000

[alanmalk]

Originally Posted by Sean Murry

I am seriously looking at going with Lithium batteries. ...

It took solar many years to get down to $1 per watt. When lithium gets down to $1 per AH then I'll be first in line.

[Brian B-P]

I think the use of batteries in electric vehicles provides some good insight into how those batteries can be effectively managed... although I do realize that the discharge rates are much higher in automotive propulsion than in typical RVs. The auto industry has moved from lead-acid (not useful for normal vehicles), to nickel metal hydride (NiMH, effective for hybrids), to various lithium chemistries (effective for plug-in hybrids and straight battery EVs).

One reason that the NiMH batteries in Toyota hybrids have been impressively reliable is that they are never either deeply discharged or fully charged, even though as consumers we expect to fully charge both NiCd and NiMH batteries whenever they are charged. The lithium batteries in battery EVs can be charged fully, but the auto manufacturers promote the idea of a partial charge (to 80%, for instance) before driving again. Ever since the Tesla Roadster, EV manufacturers have been almost paranoid about excessive discharge.

In an RV, I would probably be reluctant to cycle thousands of dollars worth of lithium batteries close to their limits in either direction. I would expect that most of the weight benefit of lithium would result from lower density (less mass for the same volume and nominal capacity), rather than a wider cycle range.

[rubicon327]

Besides the cost of the lithium batteries themselves you would also need to invest in a Battery Management System. AM Solar is nice enough to scare most of us back to reality (i.e. lead acid and AGM) by indicating that your into it for about $5k if you attempt a basic DIY lithium install. Costs go up from there.

Lithium Battery Banks

[Brian B-P]

Originally Posted by rubicon327

Besides the cost of the lithium batteries themselves you would also need to invest in a Battery Management System.

A BMS can be a big deal, especially in a larger system, so some suppliers package lithium cells into 12 volt (nominal) batteries complete with a simple BMS, so that the whole package can be treated essentially like a lead-acid battery that just wants different charging voltage settings, and no "equalization". The complication and cost are still there... just enclosed in the box!

[Ron in BC]

Originally Posted by Brian B-P

I think the use of batteries in electric vehicles provides some good insight into how those batteries can be effectively managed...

And other applications. A fellow member of our soaring assoc. has a very pricey glider with a front mounted folding prop and lithium batteries. They're not very old and now they're starting to "bulge". Replacement is going to be very pricey.

I agree with the comment that when we see a price drop similar to the one we've seen with solar panels then it might be time to re-visit the issue.

Ron

[ReagentGrade]

My thoughts, with some repeating of others.

IMO lithium benefits are:
- more usable energy
- less weight (as little as 1/3 that of lead)
- 5 to 10 times more cycles (very long life)
- fast recharge times (if you have a charger that can do it). This is really useful if you need to recharge your batteries with a generator!
- insensitive to partial recharging

Disadvantages are
- much higher cost
- the need for good chargers. Some Li batteries may do fine with chargers rated for AGM, but they will do better with those designed for lithium batteries. The converter in the Escapes isn't optimal for AGM, much less Lithium.
- if you have solar, you need a good charge controller. It should have at least an AGM charge profile; a lithium profile is better
- all lithium batterys require battery management systems (some have the BMS inside the battery case)
- lithium batteries have higher voltages than lead batteries. Some lithium installations call for a DC - DC converter to provide the RV with lower than battery voltage.

I plan to go with lithium with a total cost of about $2,500:
- two 100Ah lithium batteries ($1,000 each, 29 lbs each). Each has an internal BMS
- a PD9160AL converter - $220 (I'll bypass the converter in the WFCO)
- a Victron MMPT 100/50 - $320. This is overkill, but I'll have an oversized solar system. (This doesn't really count because I'd also get this if I had AGMs)
- I'm holding off on a DC-DC converter. I'll install it if I decide I need it (bringing me up to the $2,500)

I'm doing this to get as many days of battery capacity as possible during inclement conditions. And for the weight savings - I want to use my inverter, but don't want to haul around a bunch of lead.

I understand it will take 10-15 years, OR MORE, to break even over the cost of AGMs. Even if I never break even, I'll still get the other lithium benefits.

As always, YMMV!

Rich

[Brian B-P]

Originally Posted by ReagentGrade

- a PD9160AL converter - $220 (I'll bypass the converter in the WFCO)

The WFCO converter could be just left off (with the PD converter/charger on a separate and addition breaker). Selection of converter/charger could be done by powering one or the other at the breakers, or by a SPDT switch ("three-way light switch") on the AC power, or a similar DC-rated switch on the output (a battery selector switch), or both AC and DC switching. This would keep the WFCO as a backup... if you're going to keep carrying it around anyway.

Originally Posted by ReagentGrade

- I'm holding off on a DC-DC converter. I'll install it if I decide I need it (bringing me up to the $2,500)

I've considered a 12V regulator (DC-DC converter), just to smooth out power for the furnace etc. despite the charger's cycling. I would want to have switches to bypass it, or just select direct from battery or regulated power, in case of regulator failure or low battery voltage.

[ReagentGrade]

Originally Posted by Brian B-P

This would keep the WFCO as a backup... if you're going to keep carrying it around anyway.

Great idea, Brian!

If I had AGMs, I'd get the Prog Dyn converter designed to fit in the same space as the WFCO converter. But the lithium converter is stand alone. Why not make it a backup?

Originally Posted by Brian B-P

I've considered a 12V regulator (DC-DC converter), just to smooth out power for the furnace etc. despite the charger's cycling. I would want to have switches to bypass it, or just select direct from battery or regulated power, in case of regulator failure or low battery voltage.

If I end up installing a 12V regulator, I'll probably put it where the WFCO converter is. That would kill the backup plan. Oh well. I'll cross that bridge if/when I get there.

[LJY]

Originally Posted by alanmalk

Something to think about is that your Escape solar is hooked up 24 hours per day but making electricity only during daylight. Nothing is harmed if nothing is flowing into the controller. So use an On-Off switch between the solar and controller freely without worries.

Thanks!

[rjbny]

Originally Posted by ReagentGrade

My thoughts, with some repeating of others.

IMO lithium benefits are:
- more usable energy
- less weight (as little as 1/3 that of lead)
- 5 to 10 times more cycles (very long life)
- fast recharge times (if you have a charger that can do it). This is really useful if you need to recharge your batteries with a generator!
- insensitive to partial recharging

Disadvantages are
- much higher cost

Rich

I've been looking into switching over to AGM in order to eliminate the maintenance considerations of the standard flooded batteries. In the process, I thought it would be interesting to know more about the cost of lithium so I did a rudimentary analysis in an attempt to roughly quantify the premium for going with lithium over AGM.

Here is a chart (note: extra equipment required for lithium not included):

In this model, the premium for lithium over AGM is $582, or 32% more, to deliver 320,000 AH over time. However, the upfront cost of lithium is obviously "much higher".

So, a key question to consider is how many years it would take to consume the 320,000 AH? Or, put another way, how long would it take before we'd need to purchase the second set of AGM's?

[BCnomad]

going from memory and using big round numbers for easy math, so proceed with caution:

Jon V has previously reported using a range of Ah per day that included 32Ah. Using that ultra convenient number as a baseline, would mean 10,000 days of camping. Or somewhere in the vicinity of 27 years full timing on battery power.



YMM/WV (significantly).

[rjbny]

Originally Posted by BCnomad

going from memory and using big round numbers for easy math, so proceed with caution:

Jon V has previously reported using a range of Ah per day that included 32Ah. Using that ultra convenient number as a baseline, would mean 10,000 days of camping. Or somewhere in the vicinity of 27 years full timing on battery power.



YMM/WV (significantly).

Jon V's numbers look sensible to me.

Using the 32 Ah number, we could spend $625 on AGM's and be covered for 3,437 dry camping days. I'm pretty sure that our first set of AGM's will be running just fine long after we are done with this 19.

Otherwise, the only other benefit of lithium that I can see would be a 70# weight reduction and that certainly isn't worth an additional $1800 in up front cost.

[padlin]

Keep in mind that Jon is a pretty heavy power user, we use 10- 20 Ah a day.