Insufficient Solar?!

[TomH]

You might consider replacing the batteries with Lithium. The attached page from Smart Battery states:

Bulk Charging is normally the only stage necessary to charge a Smart Battery Lithium Ion Battery. If your charger can be programmed to deliver CC (constant current) and charge up to 14.6V there is no need for an absorb phase.

My Sprinter on order will have a single 600Ah Lithium Ion battery from Lithionics, along with a second alternator and two 100 watt solar panels, solar controller, and smart charger.

https://www.lithiumion-batteries.com...y-charging.php

[arctictraveller]

Originally Posted by TomH

You might consider replacing the batteries with Lithium.

I think the OP's original issue is lack of charging capacity, rather than storage capacity. His current batterys may be adequate if he can get a full charge into them, but unless he ends up with excess amp hours available each day, a bigger battery (of any type) probably won't help.

[TomH]

Originally Posted by arctictraveller

I think the OP's original issue is lack of charging capacity, rather than storage capacity. His current batterys may be adequate if he can get a full charge into them, but unless he ends up with excess amp hours available each day, a bigger battery (of any type) probably won't help.

Hi arctictraveler,

Charging capacity is what my reply is actually about. I am not suggesting more storage capacity, but rather that an equal amount of Lithium storage requires much less power and time charging. Lead-acid and gel batteries require three stages of charge: bulk, absorb, and float. With the correct controller, a Lithium battery only requires bulk charging. All of the extra time and energy required for absorption and floating are not necessary.

Additionally, traditional batteries only allow 50% discharge without damage. Lithiums are closer to 85%. Replacing his existing batteries and charger with an equivalent number of Ah of Lithium would both reduce his required input power and time as well as increase his available capacity by 70%. Lithium is more expensive, but its life expectancy is 10 times that of traditional batteries.

[MountainBikeRoamer]

Hey, this is very likely a lot of already-understood info for many in this crowd.......but for anyone still beginning to grasp all of the finer nuances of off-grid battery charging/usage/monitoring/maintenance.......(or for the "perpetual learners" like myself....)

----- I've found these specific articles below to be invaluable when attempting to grasp the battery-charging "big picture."

Should be of use/interest to almost anyone when considering (or re-considering...) their battery and charger approaches/setups, especially with respect to:

1) solar
2) what amount of charging effect to realistically expect from your vehicle's alternator
and
3) The various "stages" of charging that batteries require to be properly fully charged and maintained.

I forget stuff often.....
......so I re-read these often!

STATE OF CHARGE: Your Camper/RV May Be Killing Your Battery Bank
State of Charge: Your Camper/RV May Be Killing Your Battery Bank | PopUpBackpacker.com

The RV BATTERY CHARGING PUZZLE
https://handybobsolar.wordpress.com/...ging-puzzle-2/

ALTERNATORS 101
alternators 101

RV BATTERIES 101
(& Why we use Trojan T-105 6V Golf Cart Batteries in our RV)
https://trekwithus.com/rv-batteries-...ies-in-our-rv/

EDIT: this one's also great --- especially for the original query about solar by B350 (The OP):

TENT TRAILER SOLAR SYSTEM
http://popupbackpacker.com/our-trail.../solar-system/

[arctictraveller]

Originally Posted by TomH

Hi arctictraveler,

Charging capacity is what my reply is actually about. I am not suggesting more storage capacity, but rather that an equal amount of Lithium storage requires much less power and time charging. Lead-acid and gel batteries require three stages of charge: bulk, absorb, and float. With the correct controller, a Lithium battery only requires bulk charging. All of the extra time and energy required for absorption and floating are not necessary..

Hi Tom, I do agree that lithium batterys have a lot of advantages. The question I have is about the total number of amp hours needed to return to a full charge. You said you can reach a full charge using "less power", does that mean fewer amp hours, or just the same number of amp hours in less time? Without the need for absorb and float charges, certainly fewer hours of total charge time would be needed, but can you reduce the total number of amp hours required? It seems to me that if you had consumed 100Ah, excluding any losses and inefficiencys, you need to replace that same number of Ah. With a higher charge rate allowed by a lithium, you could replace them more quickly, but without the ability to generate that higher charge rate (the situation I believe the OP is now in) just changing to a lithium wouldn't help. Should he be willing to invest in an improved charging system, lithium would certainly have advantages. Am I missing something?

[TomH]

Any time energy is converted from one form to another, some of it is lost through inefficiencies of the conversion process. Only a portion of the potential chemical energy in your car's gasoline (and atmospheric oxygen) is converted into torque at the wheels. Heat is lost from the engine, in the transmission, in the differentials, CV joints, tire/road friction, atmospheric drag, etc.

In this case, electrical energy is being converted into chemical potential energy in the battery. With traditional batteries, more of the electricity going into the battery is lost as waste heat. Lithium Ion is more efficient. Less energy is lost in the conversion process of electricity going in being changed to chemical potential energy.

Let's say you have a 200AH battery depleted to 50%. You don't just put 100 amps into it and it's full. These are going to be wildly made up numbers. (I am a retired teacher who once taught physics, but I am NOT an electrical engineer.) Let's just assume that during the bulk charge of a regular battery, you have to input 160 Ah to gain 80Ah of potential chemical energy. Now, however, the charger has to shift into absorb mode. Getting from 180 up to 200 (a difference of 20Ah) is going to happen at only 5% of the rate of bulk charge. Sun shining on those panels is mostly not utilized. Cloudiness, shade, and declining afternoon sun angle affect things too. Most of the solar energy hitting the panel is now turning to heat on the panel rather than changing into electricity in the panel. This phase of the charge is just very inefficient. Only a fraction of what you're trying to push in is getting in. And finally, there is the float charge. This is a trickle charge to keep the battery topped off as there is always a slight loss no matter what.

Lithium batteries are just more efficient. With a smart charger, the battery goes almost directly to full capacity in bulk charge mode. You just don't have nearly as much energy lost to the inefficiencies while you are trying fill it up.

The following is a crude and incomplete analogy, but it does illustrate the point. Let's just say your car's gas tank had a fuel port with a diameter smaller than the nozzle of the pump. Also, the pump has one speed-wide open. You aim the nozzle at the hole and manage to get a third of the gas into the tank. Also, once you hit 80% full, some of the gas eddy-flows back out, wasting even more gas. Your neighbor has the same sized fuel port opening, but he has two advantages-a funnel that fits into the opening and a pump that can throttle down. Both of you can fill your tanks, but your neighbor manages to fill his faster with less of the gas spilling on the ground.

[1der]

TomH - Has the above freezing, 32F, charging requirement for Lithium batteries changed? The environmental control necessary for Li has kept me from going to them. I also do not want to dedicate in cabin space for the battery in order for it to be heated for charging. Our van based ski excursions create problems for Li.

Re battery monitor - this will require a shunt (to monitor Ah used) and careful wiring so house loads go through the shunt. Otherwise, measurements of charge/discharge will be inaccurate.

[arctictraveller]

Tom, I stand corrected. I was not aware that Li batterys had such a high charge efficiency. Lead acid is pretty low, with 85% being a good average at the 50% discharge level, but it looks like Li's are around 99% So, if the OP was able to provide a correct charge profile for Li's, he could end up with more available amp hours. Now if the price wasn't so high for Li's, I might switch too. Back to the OP's original question, how can he get a full charge with his current set-up? I think adding another solar panel will be the least expensive way to gain more amp hours in a day. If he were willing to spend more money, a bigger alternator, or second alternator, a better charge regulator, and a monitoring system or a lithium set up would certainly help. Or, a small generator. A 1000W Honda is small, light weight, fuel efficient, very quiet and can be purchaced for around $699.

[TomH]

Yea, the Lithiums do have to stay inside due to the freezing problem. I used to ski, but am too old. We will always be in moderate temperatures. For a rig regularly going to ski areas in winter, I would not want Lithium. They also have to be in a battery box that's vented to the outside, due to RVIA regulations, even though on this particular type of Lithium battery, it is simply impossible for any toxic gasses to be created (this is a different type Lithium compound than the batteries that caught fire on the Boeing 787 airplanes). I have been on the phone with Lithionics, who was not aware of the requirement. Their batteries are currently in testing with UL labs. RVIA doesn't want to lift the vented box requirement because they say the battery hasn't been "tested," which is absurd as saying you shouldn't carry water unless it's in a biohazard box because it hasn't been tested. This Lithium compound is incapable of making toxic gas, but these bureaucrats are calcified in their mindset. Lithionics told me they would call RVIA as well as arrange to get UL data to them. Lithionics already arranges discreet individual cells in a sealed container (that's what battery means to begin with). Their chief engineer was out of the office Friday. I'm going to ask him next week if the container it's already built in can't simply be given a vent hole. The thing about the commercial battery boxes is that they have flanged edges and protrusions that make the thing take up even more valuable real estate. Backcountryguy and I have been PMing and emailing each other a lot, with both of us talking a lot with Fresno's Brian F., who has been on the phone several times with RVIA as well.

Now the thing is, SMB is an RVIA approved upfitter. Insurance companies give you better rates if your rig is RVIA approved. But, there are no legal restrictions against unvented Lithium batteries inside any category of RV. SMB just won't do it 'cause they don't want to lose their certification. Backcountryguy is a mariner, captain of a ship in fact. He has a marine contact (seagoing, not USMC) in WA who upfits yachts. He can pull out old batteries and replace with Lithiums and the correct type charging regulator. BCG is in WA and I'm moving there in 2 weeks. Both of us are considering creating a space for the size Lithium battery we want, finding a battery box of that size, putting a cheap battery inside the box, completing the SMB build in that configuration, then having the marine upfitter swap out with the bigger unvented Lithium.

For people who want to swap out lead-acid or gel from an existing rig, all you have to do is find someone who knows how to do it and puts in the correct type charge regulator, and you're good to go.

1der, re. the monitor and shunts, I really don't know.

Yea, they are expensive, but they last 10 times as long and weigh only a fraction as much (lead is #82 on Periodic Table; lithium is #3). I hope to have a cable installed that isolates at both ends. If I'm camped in the boonies and the starter battery fails, flipping connector switches at both ends would provide an instant jump from a massive and long life house battery to a failed starter battery. I used to be a wilderness guide, but I am way too old to hike out of the backcountry now and this (along with a sat-phone) will give me huge peace of mind.

[B350]

Lithiumion batteries sound great. At about half the weight of an AGM and 4 1/2 times the cost the van should get better fuel mileage and with no money to spend I shouldn’t get fat off tacos and sweets.

After speaking to a great tech rep at Renogy I plan on adding 2 more Renogy Eclipse 100W panels with a 40A charge controller. If I’m feeling ambitious and end up somewhere with the right tools I think I’ll go from the current 12AWG wire coming from the panels to 10AWG. Ambition and tools will also likely be the deciding factor in adding a battery monitor.

So, I may have everything shipped to Sacramento in mid November or just go to Renogy in Ontario, CA late Nov/early Dec.

If anyone can offer a place to work on the van and a few electrical tools (heavy crimp tool and such) that would be greatly appreciated.

Thanks again everyone.