FAQ: Batteries

[Boxster1971]

Was looking at the Storyteller vans with the Volta system where there is a large 10000wh lithium storage battery. 3600w inverter and large 50 volt alternator to recharge in a couple of hours. The Volta system can apparently only be purchased installed in an RV or semi truck and does not look like you can buy components. Are there sources out there for the components from other suppliers? Any forum sites where this is discussed would be nice?

The Volta system is available for upgrades to existing vehicles. I think you may need to get to an authorized installer as the owner of an Airstream Interstate did in 2019. He had the work done by Holland Motorhomes in Holland, MI. See this thread on Airstream forum for details.

Volta Equipped New Interstate (aftermarket addition) - Airstream Forums (airforums.com)

 

[Prince of pixels]

In addition to the Wind-Sun site Icarus has a link to above the associated forum he has provided a link to below, I found the following sites helpful in designing and building the electrical system in my conversion.

http://handybobsolar.wordpress.com/. Lots of practical information about RV solar installations, wiring, and batteries from an electrical engineer who has been boondocking for 7 plus years without resorting to a generator and rarely having to plug in. He lambasts RV dealers and RV solar "experts". Well worth reading his blog.

http://www.vonwentzel.net/Battery/index.html. Lots of information about batteries from a marine standpoint. The author works through some of the myths and misinformation that abounds concerning batteries, battery types, and their use.

http://www.cruisersforum.com/forums/f14/. Link to the Batteries, Generator and Solar forum on Cruisers Forum. The information is geared to marine systems and sailing in particular but applies directly to RV systems as well. These folks' lives depend on their systems functioning properly and safely. Lots of information available using the search function.

http://www.amplepower.com/index.html Like Handy Bob these folks are iconoclasts. They manufacture and sell electrical system components and controls for marine electrical systems as well as land based solar PV systems. Click on the Technical Documents tab to get started. I ended up ordering their Ample Power CD which contains two books, Living On 12 Volts with Ample Power and Wiring 12 Volts for Ample Power.

Curt

Handy bob is a political hack, I read through ages of “the truth” and gave up. Dear readers: don’t click the link above looking for “practical information about RV solar installations, wiring, and batteries from an electrical engineer” unless you enjoy Fox News. You may have to scroll a ways to find anything related to batteries.

 

[Roamers]

Handy bob is a political hack, I read through ages of “the truth” and gave up.

I do think his 3 posts as you describe detract from the site, but if one is designing a solar system, it is a great site in my opinion. If batteries alone is the education one is looking for, probably would not go there.

 

[Lagom]

I just installed solar for the first time, 160w panel, cheap PWM controller feeding a pair of 6v FLA golf cart batteries. With my 12v refrigerator on, the system voltage goes up to 14.2v all day in the sun, then drops down overnight to 12.8 in the morning (edit: drops to 13.7 when compressor running). My battery case is sealed up to the vent pipe (Flo_Rite for watering) so I can't see if hydrogen bubbles are forming without going through a bit of work.

Will a cycle like this do the batteries any harm? Is it advisable to adjust it up or down?

 

[Lagom]

That's very difficult to read, largely due to white text on blue background. Anyone publishing white text on blue background online should be banned from the Internet.

Turn on the free Reader mode extension (from Chrome store) and it will convert to black and white when you activate it for a page. It also makes ads go away, which is helpful on low bandwidth connections. I think my iPhone Safari has it built in.

 

[autostaretx]

I just installed solar for the first time, 160w panel, cheap PWM controller feeding a pair of 6v FLA golf cart batteries. With my 12v refrigerator on, the system voltage goes up to 14.2v all day in the sun, then drops down overnight to 12.8 in the morning (edit: drops to 13.7 when compressor running). My battery case is sealed up to the vent pipe (Flo_Rite for watering) so I can't see if hydrogen bubbles are forming without going through a bit of work.

Will a cycle like this do the batteries any harm? Is it advisable to adjust it up or down?

12.8 volts is the standard, expected (and very happy) voltage for a fully-charged lead-acid battery after it's had a few hours away from any charger.

My HQST PWM controller offered 13.8 volts as its float (but was adjustable through the menu system).
I'd certainly be tempted to lower the float to that level.
Here's the HQST instructions on how to adjust that level:


A PWM controller doesn't really have 3-stage charging .... it can only "attach the panels" or "disconnect" (as the above paragraph implies).

When the battery is fully charged, the controller will occasionally blip it with the panel voltage when the battery drops below the "maximum allowed" voltage. The battery will instantly go above "maximum", and the PWM disconnects. Rinse and repeat.

added: the higher float voltage could also come from having the wrong type/chemistry of battery specified.

--dick

 

[Lagom]

... I'd certainly be tempted to lower the float to that level.
...
added: the higher float voltage could also come from having the wrong type/chemistry of battery specified.

This is a lead/acid only controller.

I guess my question is -- will 14.2 "boil off" my water? It's sort of midway between recommended float charge and equalization charge voltages.

I am inclined to dial it down, but I was hoping that a battery expert could chime in.

 

[autostaretx]

The T1N Sprinter itself (i.e. the Bosch alternator) runs at 14.2 volts for the first few minutes, then drops to 13.6 to 13.8 for the long haul.

Quoting from "BatteryStuff"
---

1. The first step is bulk charging, where up to 80% of the battery energy capacity is replaced by the charger at the maximum voltage and current amp rating of the charger.
2. When the battery voltage reaches 14.4 volts this begins the absorption charge step. This is where the voltage is held at a constant 14.4 volts and the current (amps) declines until the battery is 98% charged.
3. Next comes the Float Step. This is a regulated voltage of not more than 13.4 volts and usually less than 1 amp of current. This in time will bring the battery to 100% charged or close to it. The float charge will not boil or heat batteries, but it will maintain the batteries at 100% readiness and prevent cycling during long term inactivity. Note: Some gel cell and AGM batteries may require special settings or chargers.

---

--dick
p.s. i'm surprised it's FLA-only... even the $25 PWMs handle FLA ,Gel and AGM

 

[Lagom]

The T1N Sprinter itself (i.e. the Bosch alternator) runs at 14.2 volts for the first few minutes, then drops to 13.6 to 13.8 for the long …

p.s. i'm surprised it's FLA-only... even the $25 PWMs handle FLA ,Gel and AGM

likewise with my NCV3, although when the house battery is at 50% SOC it will stay at 14.1 for 15 minutes or so before dropping into the mid-13’s.

Lead acid only, not just FLA, supposedly auto senses which type.

 

[Lagom]

I got out my magnifying glass and read the instruction sheet. The autosense had read my FLA batteries as SLA, and was applying 14.2v equalization current to them (a solid arrow from panels to battery on the display). Float voltage was appropriately set at 13.7, and it eventually went into float mode (a blinking arrow from panels to battery on the display).

I changed the setting to FLA, which will trigger even higher equalization voltage (battery type is the only way to change this).

I have no idea what triggers equalization current to flow. I'll keep an eye on it when it gets sunny again, but today it is drizzling and the display is reading 12.7v in float mode. The fridge is still turned on but I didn't stick my head down there to hear if the compressor was running.

 

[autostaretx]

Some controllers run through an "equalization" process based on a calendar. One cheap PWM i had did it every 30 days.
(without looking it up, i think it was a 2-hour or 4-hour process)

--dick

 

[Lagom]

Some controllers run through an "equalization" process based on a calendar. One cheap PWM i had did it every 30 days.
(without looking it up, i think it was a 2-hour or 4-hour process)

--dick

I wonder if the company that built mine stole that software. No indication in the minimal documentation, but a friend who makes his living setting up high tech companies in China led me to believe that the intellectual property of every company he worked for was stolen. In the more esoteric disciplines, the theft was accompanied by raiding the staff and hiring away key personnel.

 

[autostaretx]

I wonder if the company that built mine stole that software. No indication in the minimal documentation, but a friend who makes his living setting up high tech companies in China led me to believe that the intellectual property of every company he worked for was stolen. In the more esoteric disciplines, the theft was accompanied by raiding the staff and hiring away key personnel.

Whether or not a design was stolen, or locally produced, or produced under license (or beyond a patent expiration date), it is quite common for one company to make "the same thing" that is boxed/labeled/sold by dozens of "brands". Instead of multiple small companies making copies, it's all one company making everybody's product. Much more efficient (read: profitable on small margins).

Thus the $25-to-$80 PWM controllers are pretty much the same under the hood ... form/function/buttons. Downloading their manuals reveals much. Sometimes the cute icons on the screen may have varied, but other stuff didn't.

In the 1990s-2010s, one factory in China was the producer of low-to-middle-end amateur telescopes for all of the US (and some Japanese) brands. Somewhere i've got a photo showing crates of Meade/Celestron/Orion/etc telescopes sitting in one room waiting to be crated and shipped.
Quaintly enough, the *quality* of the different brands' builds *varied* ... if the company (let's say Meade) didn't have a Quality Assurance guy on-site, somehow their scopes ended up with mounting castings that had voids, screw-ups and warps.

Here in the US the same thing played out with "White Goods" (fridges, washers, dryers, stoves). There were maybe 3 companies building 12 brands.

--dick

 

[Midwestdrifter]

Whether or not a design was stolen, or locally produced, or produced under license (or beyond a patent expiration date), it is quite common for one company to make "the same thing" that is boxed/labeled/sold by dozens of "brands". Instead of multiple small companies making copies, it's all one company making everybody's product. Much more efficient (read: profitable on small margins).

Thus the $25-to-$80 PWM controllers are pretty much the same under the hood ... form/function/buttons. Downloading their manuals reveals much. Sometimes the cute icons on the screen may have varied, but other stuff didn't.

In the 1990s-2010s, one factory in China was the producer of low-to-middle-end amateur telescopes for all of the US (and some Japanese) brands. Somewhere i've got a photo showing crates of Meade/Celestron/Orion/etc telescopes sitting in one room waiting to be crated and shipped.
Quaintly enough, the *quality* of the different brands' builds *varied* ... if the company (let's say Meade) didn't have a Quality Assurance guy on-site, somehow their scopes ended up with mounting castings that had voids, screw-ups and warps.

Here in the US the same thing played out with "White Goods" (fridges, washers, dryers, stoves). There were maybe 3 companies building 12 brands.

--dick

I would point out that products made on the same assembly line are not always the same quality or even identical designs. To save costs quality assurance steps can be skipped, or components left off completely. Cheaper components can also be used.

As you mention, multiple brands having the same design isn't necessarily a bad thing. Economies of scale keep prices down, and make quality assurance easier. You would be amazing how many cars of completely different manufacturing origins, use nearly identical components under the hood. Sensors, pumps, etc.

 

[Robb57]

My question is related to an existing system and how I read the info display panel. I read through this post and have read through most of the links but they don’t really address my very basic question - how do I determine how long my house batteries will last with my A/C running (as an example).

Here’s a pic of my Victron Multiplus display panel taken with my Nomadic 3000 A/C running on “Cold” which is the highest setting;

I

I get that I am using 35A (I have 600AH capacity) and I my solar system is charging at 108W - and I am using 576W - but honestly I don’t know how to calculate how my charging input is offsetting my usage output. Appreciate any helpful input here.

I do get that I have about 7200WH capacity (12V/600AH) but how do calculate the 576W of usage against the 108W of charging?

 

[Eric B]

Your AC is currently drawing 576Watts to run
Your Solar panels are making 108Watts

Your battery bank is being depleted by the difference between the two, namely 467Watts

Your battery bank has a total capacity of 7200WattHours

If nothing changed (like the sun didn't move, and the power coming in off the solar panels was constant), then it would take 7200/467 = 15hours to run your battery bank down to zero

Since the sun moves and your panels are going to make less and less power, and if you keep running the AC at the same setting, then it will actually take less than 15 hours to run your batteries down

Drawing the battery bank down to zero is not a good idea though

 

[Robb57]

Your AC is currently drawing 576Watts to run
Your Solar panels are making 108Watts

Your battery bank is being depleted by the difference between the two, namely 467Watts

Your battery bank has a total capacity of 7200WattHours

If nothing changed (like the sun didn't move, and the power coming in off the solar panels was constant), then it would take 7200/467 = 15hours to run your battery bank down to zero

Since the sun moves and your panels are going to make less and less power, and if you keep running the AC at the same setting, then it will actually take less than 15 hours to run your batteries down

Drawing the battery bank down to zero is not a good idea though

Got it - thanks - and I do the see the -476 displayed on the panel. Not sure what the realistic max capacity of the solar charging is but the panels are rated at 180W and I took this pic at 5PM so the sun was getting low in the sky. I am planning on adding an aux generator.

 

[autostaretx]

If you started your test at 100%, you're now at 82%.

How much time elapsed between the two "readings"?

It's one fifth of the time needed (from 100%) to hit zero.
OR you have four more periods of that duration to reach zero.
(consider this a "back-of-envelope" (or cocktail napkin) cross-check on @Eric B's answer)

If you have lead-acid/AGM batteries, it's best to stop the draw at 50%
If you have LithiumFePO4, you can go to 10%

--dick

 

[Robb57]

If you started your test at 100%, you're now at 82%.

How much time elapsed between the two "readings"?

It's one fifth of the time needed (from 100%) to hit zero.
OR you have four more periods of that duration to reach zero.
(consider this a "back-of-envelope" (or cocktail napkin) cross-check on @Eric B's answer)

If you have lead-acid/AGM batteries, it's best to stop the draw at 50%
If you have LithiumFePO4, you can go to 10%

--dick

I started at about 84% - but I get your point - I should watch the time/% decrease ratio. I have Victron LithiumFePO4 batteries.

 

[Bill B.]

This is a dated thread I realize but it’s worth mentioning. Just about everything an R/V, boat, or off-grid owner ever needs can be found in these two books except perhaps LiPO batteries. For savvy techs well versed in the basics these are valuable from a historical perspective alone.
David Snead was a quiet, humble, yet genius engineer, computer programmer, and inventor. He in fact introduced the world’s first digital multimeter and much of what we take for granted with regard to battery management today came from David and his wife Ruth Ishihara. He coined the term and developed the standards for multi-stage charging of lead-acid batteries, high output alternator charging, built the first external smart regulators, and much more. He never filed patents to my knowledge and thus didn’t benefit financially and is rarely credited in developing much of what so many took advantage. I got the impression he was completely disinterested in such triviality. His wife Ruth was the driving force behind the start up and early yet brief success with their business Ample Power. David is no longer with us but Ruth is still living in Seattle last I heard. Their books are no longer in print but used copies are readily available on Amazon, eBay, and other online vendors.

‘Living on 12 Volts’ is more in depth/technical book(over 300 pgs.) and a great resource for principles of refrigeration(@80 pgs.). The later publication is over 200 pgs. dedicated to the principles of wiring and installation of a balanced power system. Both are well written and enlightening references that deserve a reservation on your bookshelf.