Keeping Lithium Batteries Warm

As you probably know, it is harmful to a lithium battery to charge it when it is at freezing temperature or below. That means 32F for us normal people…and 0 centigrade for those folks who don’t understand regular science and measurements.

Ok, ok…yes, I know that was pretty much rude and arrogant on the part of this American…typical…right!? But kinda funny from my perspective 😉

Back to lithium batteries…you can safely discharge lithium batteries slightly below 32F but you are not doing the batteries any favors. Charging lithium batteries at or below 32F can actually damage them. The lower the temp at which you try to charge it, the more damage is done…until you destroy it beyond recovery. So simply don’t do it.

However, in our area more and more folks are putting their solar equipment in CONEX containers or stand-alone, unheated sheds. And then winter rolls around, the temp inside the CONEX drops below freezing and they lose power. And then of course they are upset with someone…other than themselves. Why? Because they didn’t understand that most LifePO4 batteries, the good ones at least, have a temp sensor that will shut the battery down to prevent damage to the battery when the battery cells temp drop close to 32F.

And I have seen some real overcome projects come out of that…complex insulation boxes, propane heaters, heat lamps, etc. Ah, no need for all of that. And besides…a heat lamp uses an extraordinary amount of power…and that depletes your batteries pretty quickly during those long winter months.

So I did what many pros do…heat mats with thermostatically controlled outlets. Yup, that simple.

I looked on Amazon, and at my local hardware stone, looked for a high-quality thermostatically controlled outlet that turns on between 35F – 38F and turns of at 45F – 50F. I needed an outlet for each heating mat and a heating mat for between each set of batteries. Maybe consider a heating mat for the exposed side of each battery if they are in a block configuration.

If you are going to do this, the outlet units run from $15 – $26 or so for 1 – 3 outlets…just make sure you go for the best possible quality ones you can afford….you are protecting batteries worth thousands of dollars…you can afford quality outlets.

If you decide to do this, you can look at terrarium or seedling heating mats which run for $10 – $35. Or you can look at seedling heating mats as well which run about $12 – $18 each. Depending on how you have your batteries placed, you can place a mat between each two batteries, maybe one on the exposed side of batteries as well. Just make sure that the mat won’t overheat your battery. Batter should stay below 70F or so.

I would not place a mat over the face of a battery where there are terminals, wiring, controls, or displays.

Depending on your situation you might also need an insulated blanket over the batteries to keep the mat generated heat around the batteries. If that is the case I would suggest you move…you live in a far too cold environment 🙂

As with anytime you are working around electrical equipment, be very, very careful and follow all safety requirements and instructions. If you are hesitant or doubt your ability in any way…just call a qualified electrician or licensed solar installer. And naturally, you want to always follow recommendations and guidance from the battery manufacturer.

I am not a licensed electrician or a certified, licensed, bonded, or qualified solar system installer. The above information is not a recommendation or guidance for you to use in your system or with your equipment.


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Victron Energy Lynx Distribution System – Lynx PowerIn Part #2

Welcome to Part #2 of the Victron Energy Lynx PowerIn article!

In Part #1 < click here to read Part #1 > I shared a bunch of information, here in Part #2 I will show you how I attached a Class T fuse and how I turned a PowerIn into a fused distributor/connection point.


The battery side of this is pretty simple –

Adding a Class T fuse to the PowerIn.

The PowerIn external terminal hole is 8mm, the Class T fuse is 3/8″ stud. Yup, won’t work. I drilled out the external terminal with a 3/8″ drill bit.

Once I had it drilled out, it fit nice and snug.

Added the Class T fuse holder plastic protective cover and all was good. The cover protects any accidental contact with the terminals. Yes, I used a Bluesea Class T fuse…you can’t get much better quality than Blesea.

On the distribution side of things it can used a bit differently –

I have two charge controllers and two inverters that need hooked into the system.

I could have used a Lynx Distributor, but it costs $66 more and I didn’t need the monitoring capability, nor the pretty lights on the cover. But, I did need fusing capability. So here is a great “hack” for you…you can turn a PowerIn into a budget (a.k.a. “poor man’s”) Lynx Distributor with 4 simple additions…nuts, washers, and bolts. Here is how you do it…

PowerIn Hack –

First thing, buy:

  • Four (4) M8 x 25mm Hex Head Screw Bolt, Fully Threaded, Stainless Steel 18-8, Plain Finish
  • Eight (8) M8 Hex Nut M8-1.25, 65mm Height, 304 18-8 Stainless Steel
  • Twelve (12) 316 Stainless Steel Flat Washer, Plain Finish, Meets DIN 125, M8 Hole Size, 8.4mm ID, 16mm OD, 1.6mm Nominal Thickness
  • Four (4) M8 Copper Split Lock Sealing Ring Spring Washer Fastener

Important note: Use stainless steel and copper only as mentioned. Do not use any regular steel, etc.


Then place the four M8 bolts in slots as pictured…

Then place a stainless steel washer on each bolt as pictured…(the washers reinforce the bottom part of the plastic to prevent damage to the plastic when you reinstall it).

Next you will replace the plastic cover and insert/tighten the 4 retaining screws that you previously removed.

Then add another stainless steel washer and stainless steel nut as pictured…(the washers again strengthen the plastic from damage, the nut raises the working surface to a level point for the fuse).

Then you can add your lugs and fuses…

PowerIn with hack completed, fuse installed and both positive and negative wires installed.

Important Note: There are other websites who do kinda the same hack…but they mostly get it wrong. They do not add the nut on top of the washer that sits on top of the plastic piece and before the fuse & lugs. Not putting that nut on creates a very disjointed angle for the fuse that could damage the internal fuse connections.

So there you have it…a Lynx PowerIn has many uses including that of a stripped down, economical Lynx Distributor.

Let me know if you have any questions!

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Victron Energy Lynx Distribution System – Lynx PowerIn Part #1

The Victron Lynx Distribution System is a modular busbar system that incorporates DC connections, distribution, fusing, battery monitoring and Lithium battery management.

The system consists of the following components:

  • Lynx PowerIn
  • Lynx Distributor
  • Lynx Shun
  • Lynx Smart BMS

Each component’s main part is its 1000amp positive and negative busbars. And each component’s primary feature is the ability to connect together via the 1000amp busbars. However, each component has a separate function, they are:

  • Lynx Smart BMS – Only for use together with Victron Energy Smart Lithium batteries. If you don’t have Victron batteries, then you won’t ever need this component.
  • Lynx Shunt – Operates much like a smart shunt to monitor system energy usage. It connects to a Victron GX device to display that information, and the information can also be accessed via the VictronConnect app.
  • Lynx Distributor – Along with positive and negative busbars, there are 4 fused connections for batteries or DC equipment together with fuse monitoring.
  • Lynx PowerIn – Is essentially a Lynx Distributor without the computer board, fuse holders, and monitoring.

And the PowerIn component is the subject of this post. Why? Because I love it and I am using it in my upgraded glamstead solar power system. And most of all…you might find it useful as well!

There are 6 connection points on the positive bus bar and 7 connection points on the negative busbar, one of which is a ground connection. And remember, the busbar is 1000amp, made from solid copper with plating…making it even better than copper only. You can connect batteries, loads, chargers, etc. to the busbar as needed/required.

Connection points…

Wiring diagram…My use of the PowerIn is two-fold; 1) using it as a busbar to connect my LifePO4 batteries in parallel, 2) using a second one as a distribution/connection point for my inverters and charge controllers. I also use a Lynx Shunt, but that is a post for another day.

Use #1 – Battery busbar system:

My batteries are “rack mount” batteries, but I do not have room for a racking system. So I am placing the batteries on a very low 3″ floor stand; batteries will be 2-high, 2-wide (when completed). If I had a rack system then I would not use a PowerIn, I would use a busbar built into a rack system mounted vertically.

With the PowerIn each battery will have equal length 2/0 cables capable of carrying at least 200amps. When complete, each battery will also have a Bluesea 175a high current MRBF Terminal Fuse mounted on the positive terminal to each battery. The MRBF fuse will isolate/protect each battery in the case of a high-current dead short. Yes, I know I am over-engineering the system. But, I am trying to give it as much redundant protection as I realistically can.

Also, connected to the external positive busbar “prong” (for lack of better description) I will attached a 400amp Class T fuse to protect the battery bank from an external high-current dead short, or, protect the system from a high-current dead short in the battery bank. Yes, I know…that means I am over-engineering again with a battery bank fuse protection and each battery fuse protected as well. But if you have ever seen a high-current dead short…well, you would want a lot of protection…a lot.

It at some point in time it might be desirable to add additional batteries to the battery bank (more than 4). If so, I will simply add another PowerIn by connecting it to the existing PowerIn and thus extending the busbar connection system. That is one of the true beauties of the Victron Lynx system…it is scalable and expandable.

The economics of a PowerIn –

First off, a PowerIn can be found on Amazon for $156.00…seems a little expensive to you? Well, let’s look at it in real terms compared to just a simple plain busbar set-up.

  • Good quality busbar with cover $110.58 (this is a 600amp vs Victron 1000amp) with only 4 connections vs Victron’s 6.
  • And you will need two of these, 1 for negative connections, 1 for positive connections = $221.16. And it isn’t modular.

The Victron PowerIn is $65 less expensive, more connections, more features and a very cool pretty blue cover.

But you say…I can buy two 250amp busbars for $37.99 on Amazon! Yup, you can…but look at the details…it is 250amps at 12v not the 58.4v that the solar batteries can operate at. (Oh, and other busbars are only rated at 48v maximum NOT 58.4v that the batteries can operate at.) Oh, and the busbar is plated brass NOT plated copper!

So go ahead and buy the cheap low-priced busbars and see how that works for you! If you choose this route…have plenty of fire extinguishers on hand and really good home owner’s insurance.

For those of you that want to see more of what you can do with the PowerIn…Part #2 will give details on attaching a Class T fuse to a PowerIn and how to turn the PowerIn into a fused distributor. And that info comes tomorrow!!

Let me know if you have any questions!

< click here to read Part #2 of the Victron Energy PowerIn >

Send me your thoughts, ideas, comments, questions, and concerns…

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TRAP: Solar – More Growatt Problems

 I have previously written about Growatt issues before, and I am not a fan of the company…at all. I have worked directly with some of their company folks and I don’t like what I see in the way they conduct business and how they react when confronted with problems regarding their products. So here are two more additional problems.

One of those problems is their ethics in how they conduct business, the other problem is dangerous to US customers.

First, let me explain something…when you see most of the YouTube video reviews of solar equipment you are watching a money making machine. Most companies whose products are being reviewed pay to have those products reviewed by the person doing the video…not all, but most. And each time the video is watched the person who made the video is paid as well. I am not opposed to people making money by providing information on products.

However, some companies whose products are reviewed are quite demanding of the reviewers…such as Growatt. They have a very strict and company-friendly contract. In the case of Growatt the contract requires a pro-Growatt outcome of the review as well as extensive control of the content of the video…almost a script approved by Growatt. And do you think that would influence the person producing the review? Yeah, either its a favorable review or you don’t get paid.

The next issue is with the Growatt 5000ES inverter/charger. In simple terms…it is unsafe. There are two version of the 5000ES; 1) is sold in the overseas market, 2) the other is for the US market. Problem is with the different electrical standards between the US and overseas countries…and it is a potentially deadly difference.

The problem revolves around 120vAC vs 230vAC and the potential of the ground in the US version being energized with 120v and possibly 230v. Ah yeah, the ground being energized…and potentially without a person knowing it until they touch it!

So the same exact model label, the same exact model identifier, and the potential to cause serious problems.

For the most part Signature Solar sells the 5000ES that is safe to use in the United States…but I can’t confirm that 100%. The 5000ES overseas version is mostly sold via eBay from what I can tell. Again, I am not 100% sure that all eBay sellers are selling the overseas version here in the US…or that there are not other Growatt dealers selling the overseas version as well.

And here is the biggest problem with this issue…from what I can see Growatt hasn’t done anything to correct the situation. It would be as simple as redesignating the US version as 5000US or 5000ES-US and put the correct label on the box with the corrected manual inside.

Be very, very careful with Growatt products…if they are this negligent with something this obvious and simple…then what other problems are there with their equipment? And if they are so worried about negative reviews that they have to bribe some reviewer…then who else do they bribe and what reviews of their equipment are legitimate?

For you…who are looking to purchase equipment…is it worth the risk to deal with equipment from Growatt when there are lots of companies out their that you don’t have to really worry about?

note: No company pays me to review, comment on, or discuss their products or the company itself.

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TRAP: Solar – Bad Professional Connections

Last month I was contracted to do some work for a local solar company. Part of that work was to salvage parts from old solar installation equipemtn that had been removed. Residential customers had hired this solar company to repair or replace their existing solar systems. The equipment I was salvaging was the stuff that had been removed and replaced with new equipment.

Yes, inside the old equipment had perfectly good bits and pieces that could be used to repair other equipment or sold as “used” for discounted prices. And yes, I love to do salvage work…it is fun to rescue perfectly good equipment pieces vs seeing them put into a scrap pile.

So I was tearing this stuff apart and found this shunt; the shunt was perfectly fine from all appearances, but it would be tested later to ensure that all was fine. But it wasn’t the shunt that caught my attention…it was the negative wire attached to the bus bar that was attached to the shunt. Do you see a problem with the connection? Here, let me give you another view…

Even if you are not an electrician or a professional solar installer you can see the problem. It is a horrible connection. I would estimate that only about 75% of the diameter of the wire is actually in the bus bar hole and even then it is only hanging on at the very end. So only about 10% of the original wire is actually connected to the busbar.

And no, that didn’t happen when I was removing the shunt.

Now, I will say that the screw was tight enough and was holding the wire in place, but that isn’t the point. There are two points;

1) The wire was only hanging on by about the last 1/8th of an inch…the very tip of the wire. It should have been fully inserted the entire width of the bus bar.

2) Only about 75% of the diameter of the wire was actually in the bus bar hole. In this case the wire was 6AWG stranded wire. Based on 6AWG the wire should be able to carry 70amps of current, properly installed. Well, since only about 75% of the wire’s diameter was actually making contact, it was the equivalent of about 10AWG stranded wire. And that means it was only capable of carrying about 30amps of current…had the wire been fully inserted. And since it wasn’t properly/fully inserted who knows for sure how much current the wire was actually capable of safely carrying.

See the problem with that?

Bottom line…

  • If you are doing the work yourself…do high-quality professional work. Don’t get in a rush, do it right, be proud of your install.
  • If you are having a system installed, ask to see inside the “magic boxes” and look them over yourself. You can see if the connections and work looks right and professional. If the installer gets upset or won’t take the time to show you what they are doing…well, that is serious reason for concern! It is your money…you have the right to inspect it all.
  • If you are buying a house that has a solar system, have it inspected by a local quality solar system installation company or a licensed electrician that is familiar with solar. It will be worth the fee.

These kinds of situations occur all of the time…there is some very shoddy workmanship out there by unprofessional and/or ignorant folks. Don’t you do it and don’t tolerate it from others.

Why? Duh, you could find yourself at the losing end of a house fire.

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New Solar Home Page !

I have created a new Solar Home Page to make it a bit easier for folks to find all things solar related.

There is general information, Tips & Traps, our Glamstead project information, and the solar book project that I spoke of a while back.

The new page is a work in progress since I am trying out a few new ideas for page formatting so I am sure it will change…just not sure how as of right now.

So go take a look you might find some interesting information there even if you are all that interested in solar power.

< click here to visit the solar home page >



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Tip/Trap: Solar – LiFePOWER4 Batteries

I am hearing considerable feedback regarding a particular problem with LiFePOWER4 batteries. The problem seems to occur in larger parallel strings of batteries, 3 or more. If the batteries aren’t brought up to 100% State of Charge (SOC) every 1 – 2 days then the BMS’s begin to have significant problems reporting the correct SOC. They have also been known to have the BMS shut down a battery when it is actually above the low voltage disconnect, due to the BMS incorrectly reporting the SOC.

The only “fix” appears to ensure that the batteries are fully charged every day or two (at the most).

One of the problems I am seeing in systems are large battery storage capability but not enough PVs (solar panels) to adequately charge them on low sun days (i.e. cloudy or short winter days).

As an additional note, I looked at LiFePOWER4 batteries when I was assessing different batteries to explain my current storage capability. I was not impressed with the LiFePOWER4 batteries for a number of reasons, price being one of them, but mostly build quality and performance issues as well.

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LifePO4 Battery SOC Charts

Yup, those are actual LifePO4 battery cells with a Battery Management System (BMS) attached to the side. In other words…a LifePO4 battery…without a fancy case around it.

In my early days of solar system design and building I had questions about when batteries were charged or not…and how much life they had left in them. Generally speaking, the voltage of a battery gives you an idea of the battery’s State of Charge (SOC).

The state of charge (SOC) of a battery is the relative charge that is present in a battery relative to its total capacity. Like knowing the amount of fuel in your vehicle’s fuel tank. When using a voltmeter to test voltage to assess SOC, for this measurement to be trustworthy, the battery must have been “at rest” (neither charged or discharged) withing the previous 12 hours.

The best way to accurately measure battery DOC is to continuously monitor voltage, amperage, and ampere hours remaining. This is a complex calculation of the energy available, energy consumed, and the energy returned to the battery in charging. It also adds the important element of time to the equation.

And to make things a bit more exciting…there is “charging voltage” and “resting voltage” that both can mean 100% SOC. Yeah, go figure right. Resting voltage is the more accurate reading to use to know the true condition of the battery. And resting mean…12 hours without a charge or discharge taking place. And in most solar systems that simply doesn’t happen because the system is constantly discharging (i.e. 24-hours a day) and/or charging (i.e. 6 – 18 hours per day while the sun shines).

So the most accurate way to gauge SOC is the continuously monitor method…and that takes special instruments. But, not too special, nor too complicated.

And here is another curve ball…

  • a 12v LifePO4 battery is correctly/fully charged at 13.6v and at 12v the SOC is just about 9% and the battery close to being ruined.

  • a 24v LifePO4 battery is correctly/fully charged at 27.2v and at 24v the SOC is just about 9% and the battery close to being ruined.

  • a 48v LifePO4 battery is correctly/fully charged at 54.4v and at 48v the SOC is just about 9% and the battery close to being ruined.

So why do they call them 12v, 24v, and 48v batteries when they don’t actually run at those voltages? I have no idea.

And another curve ball…there are “16-cell” 48v batteries and “15-cell” 48v batteries. The 15-cell version of the 48v battery is not real common and generally a good indicator of a battery manufacturer trying to hit a better price point by building a battery with one less cell and still calling it, misleading as it may be, a 48v battery.

If you are gauging a 15-cell battery you would deduct 3.4v from the fully charged, at rest, voltage of a 16-cell battery. And do so for each % rating of the 16-cell version.

To maintain a battery in healthy condition you don’t want to drop its SOC below 20%. Dropping the SOC below 20% damages the battery, meaning you are reducing it usable lifespan. Dropping the SOC below 14% damages the battery, meaning you are seriously damaging the battery. Good news is…if the battery has a BMS it should turn off automatically before damage is done. Bad news is…the battery BMS may not be set right to provide adequate protection. Good news…you can also protect the battery by setting the inverter to automatically shut down at a given voltage.

Also, charging a LifePO4 battery to 100% SOC doesn’t do the battery any favors. To keep a LifePO4 battery healthy and happy it is a good idea to charge to about 95% and don’t discharge below 20%.

In the following charts it shows the “voltage chart” displaying the voltage “curve”. Notice that the voltage curve will stay fairly flat between 110% SOC (resting) and 20% SOC, there is only .8v difference. And that is one of the huge advantages of LifePO4 battery…stable voltages throughout the discharge curve.

IMPORTANT NOTE: Always refer to your battery manufacturer for specific data, voltages, SOC, etc. regarding your particular battery. The information provide is only general information regarding LifePO4 batteries.

Individual Cell SOC & Voltages –
12v Battery SOC & Voltages –
24v Battery SOC & Voltages –
48v Battery (16-cell) SOC & Voltages –

note: you can download each image by right clicking on it.

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DC Wire – Types, Size Chart, and Fusing

One of the things that can get confusing, but is extremely important, is knowing what size of wire to use when working with DC circuits. And once you get the wire size figured out…then trying to figure out what size fuse should you use.

So I’ve included a wire sizing chart at the bottom of the page for you to download. And I will provide a couple of tips as well. Finally, I will provide a link to a great little sizing and fusing calculator that I think makes everything much easier when trying to calculate all of this. But first, some good information to know…Also, it is important to note that when dealing with DC currents in solar power systems (SPS) you need a high-quality wire with a good insulation rating; 105 degrees centigrade is commonly referred to as the standard. Voltage rating should be “600V”. Also, stranded wire is best when using wire in the DC side of SPSs…the more strands the better. But, a good measure would be as follows, with each strand being 30AWG wire…

6AWG – 260 strands
4AWG – 364 strands
2AWG – 624 strands
1AWG – 767 strands
1/0 – 975 strands
2/0 – 1196 strands
3/0 – 1547 strands
4/0 – 1950 strands

Most wire wire/cable will come with rubber or rubber-based insulation. Silicone-based wire insulation is generally considered superior to rubber-based wire insulation for a number of reasons, one being a higher heat rating, up to 200 degrees centigrade. Silicone is the most fire-resistant of common insulation material, it is also highly resistant to extreme environments. Then we also see silicone as being more flexible and more compression resistant. And yes, silicone is more suitable for outdoor applications, but when running wire outdoors it’s always best placed inside a protective conduit.

Aluminum wire should not be used…period. Copper wire is the standard for DC applications due to its high electrical conductivity. However, there is even better wire than standard copper wire, tin-plated stranded copper wire. Tin-plated copper wire is noted for its longevity because of its anti-corrosion properties. And, studies show that this variety of copper wiring is able to withstand adverse weather conditions and end up lasting far longer than the standard copper wires. It’s also preferred in applications where the wire will be exposed to a high degree of humidity. And lastly, tin-plated copper wire has more electrical conductivity as compared to other varieties of copper wires. And yes, it is more expensive.

Here is a little tip for you…up-size wire recommendations one size. Yup, look up the recommended wire size…then go with one size larger. This gives you a measure of safety when deciding on your wiring. Better to have a wire/cable one size too large than one size too small. One size too small can result in more resistance and potentially melting the wire itself. And obviously, if you melt wire it is a bad thing, a very band thing…which could result in a fire.

And that brings me to another tidbit of information that should be, will be, important to you…protecting your wire from over-current. The reason you protect your wire from over-current to prevent melting wire/cable and the possibility of fire is plain and obvious. So you put a fuse in the circuit.

Quality equipment manufacturers (Tier 1 companies) will provide fusing and/or circuit breakers internally to the equipment to protect that equipment. It is the installer’s responsibility to protect the wire connecting the equipment with fuses and/or circuit breakers.

Looking at a fuse and its job is pretty simple…the job of the fuse is to melt its wire or plate element at a lower current (amperage) than the wire can handle. That breaks the circuit and stops the flow of electricity. If the fuse is rated for a higher current than the wire, then the wire become the fuse by failing before the fuse blows.

Here’s an example: 1AWG wire is rated to handle 150amps at a total circuit of under 15′ (up-sized one size). Now, if you wanted to protect that wire from failure and put a 200amp fuse in the circuit…the wire would theoretically fail at 150amps before the fuse “blew” (a.k.a. opened) at 200amps.

To avoid this problem in our example you would use a fuse of slightly less that 200amps…say 125 – 150amps. That way the fuse would do its job before the wire failed and caused a potentially serious problem.

And here is another thing to consider when deciding on the correct fuse to use…its different ratings. So take a 125amp/58v BF-2 fuse from Littelfuse. It is rated at 125amps, yes? But does that mean it will blow as soon as the current hits 126amps? No. If you review the chart that accompanies the fuse you will see it will maintain integrity for different lengths of time at different currents (amps).

At 100% of rating, in this case 125amps, the fuse will maintain integrity for 4 hours. If the current rises to 135% of its rating (169amps) the fuse will still be good for approximately 2 minuets before it opens/blows. At 200% of its rating (250amps) it will open/blow at about the 1 second mark. And at 750amps it will open/blow at about 1/10th of a second. So before you decide on the right fuse looks closely at its ratings.

In our 1AWG, 200amp wire circuit at a full 200amps of current, the 125amp fuse would blow in 2 – 3 seconds

Also, notice the fuse description in the example, “125amp/58v”, that means it is rated for 125amps only up to 58volts. Meaning, if you try to employ it in a circuit above 58v it will not function correctly…as in fail.

What???  And why is it rated at 58v, sounds strange, eh? That fuse is designed for 48volt solar power systems. So why the larger than 48 voltage rating? Remember that solar power system voltages can run as high as 56 – 58 volts +/- coming out of the MPPT charge controller.

Now, let’s return to the wire insulation rating. Remember I mentioned that wire should have at least a rating of 105 degrees centigrade? That means 220 degrees Fahrenheit. That is above boiling temperature of water before it fails. Silicone insulation can handle almost 400 degrees Fahrenheit before failure. So you can see one of the obvious benefits to silicone wire insulation. Now, that being said…if you are building a circuit counting on silicone’s ability to handle almost double the temps vs rubber-based insulation…you are building the circuit in dangerous country. Consider redesigning the circuit more for safety.

And there is one really misunderstood aspect of deciding on wire/cable size…the distance or length of the actual wire run. Most folks will look at the circuit and say there is 5′ between the pieces of equipment and then use that to choose the wire/cable size. WRONG!! You use the total distance of the run…round trip. The circuit is the round trip of the current. So 5′ between equipment is a 10′ distance/length.

OK, so here is the long awaited chart with one note before the displaying it…when looking at the “circuit type” use “Critical” and “3% voltage drop” and when looking at the distance, the distance is the maximum run. So when you see 15′, that means up to 15′ round trip. Notice the “round trip”…that means the wire going to AND from the two devices.

( This is a very large graphic chart. Click to enlarge or you can download it as well. )

< click here to download the DC Wire Selection Chart in PDF file format >

“Voltage drop”…don’t worry about it…just use “3%” when using the chart. But if you really want to know…voltage drop is the amount of voltage will be lost through “resistance” in the wire. Meaning the lower the quality of the wire, the more resistance, the more voltage drop, resulting in less energy being moved from one device to another. Yes, that is a bad thing, it’s a waste of energy. That is the reason to correctly size wire…to efficiently move current/power through the wire.

Now, let’s talk about the wire sizing and fusing calculator that is found on the “” website. I like it…I like it a lot! You input the “amps”, the “voltage”, and the round trip length between the devices…then it shows you the recommended size of wire/cable to use to safely and efficiently carry that current. I like to reduce the “voltage drop” to 1.5% when using the calculator. That gives an extra margin of safety and efficiency.

There is also an option “Show Fuse Sizing Recommendations ” it gives you a great bunch of fuse information; 1)Minimum Fuse Size, 2) Recommended Fuse Size, 3) Max Wire Capacity, 4) Max Fuse Size. That is great, and critical, information to help guide you through making those design decisions. But again, I like to up-size the wire/cable one size just to be safe…and it allows for a little system expansion should the need arise.

The calculator link is

And yes,, run by Nate Yarbrough, has a lot of great information for you if you care to look around, including some very good videos.

TakeAways –
  • Use high quality, well insulated, stranded wire in DC circuits.
  • Up-size the wire by one size.
  • Use the right chart and/or calculator to determine the correct fuse size.
  • Ensure that the fuse rating(s) always are lower than the wire rating.
  • If you don’t understand all of this…then you shouldn’t be doing it yourself.

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Donation for a Battery…? WHAT ?

Yup, a couple folks asked me about the whole hidden “donation” thing. And they wanted to know more about what is was, and why I was doing it. They had found it tucked away hidden at the bottom of the Solar Home Page.

So here is the deal…my plan is to upgrade our solar power system here at the ‘glamstead’ to, as my wife puts it, upgrade our standard of living. Don’t get me wrong, we are doing just fine at this point, we just want to add more capability to power own “grid” that provides power to our place. Yes, meaning we are 100% off-grid when it comes to electricity…we produce and store own electricity via a solar power system.

So here is what the “donation” thing is all about…

Some folks have been very, very kind to me; they have understood the effort, time, and money that I have put into this website over the last 10+ years. A couple people wanted to directly help out financially with our solar system as kind of a way of showing appreciation. And, in their opinion, our fourth battery purchase seemed like the right place where they could help out.

The only major part of the solar power upgrade we have left to buy is the last (fourth) battery. The reason for the fourth battery is pretty simple; 1) we want to be able to store more power to last another day when it is cloudy outside (or during winter months) while we aren’t charging the batteries as fast as we are using the power, 2) we want to be able to run more/different appliances longer into the evening/night when the sun has gone down, 3) we also want to be able to power an RV or camper, or two, should folks show-up when times get tough.

The fourth battery will cost about $4,000 for the battery, shipping, and the wiring to hook it up. These very kind folks wanted to make a cash donation…and they suggested I do a “donation campaign” to raise the rest of the funds so we could get the battery sooner. They thought all the effort I have been putting into the website and the solar information was, could be, would be of value to folks who also appreciated what I do.

I was a little resistant at first, felt kinda like begging, but then I felt I should follow the encouragement of those folks. And it would be a huge blessing to my wife and I since we are now living on a fixed income and $4,000 is a whole lot of money to us. All things being equal, it would be sometime late next year till we had saved the funds to make that large of a purchase.

I want to thank everyone in advance for supporting the website and our efforts…regardless of whether you donate towards the battery purchase or not…thank you! You guys are the absolute best…and I am glad there are folks like you to help others.

Here is the button to do to the donation page…


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