Video 2 - Off Grid On A Budget
Video 3 - Solar Made Simple
Video 4 - The Missing Ingredient
A spreadsheet calculator to assist you in sizing your battery bank.
A video tutorial on how to use the battery size calculator.
Quick specs for several popular batteries that will be helpful when using the battery size calculator.
Joseph D Shank
What effect would an EMP have on an operating solar array with charge controllers and every part of the system? Joe
Hi Joe, Great question. It all depends on the strength of the EMP, it's distance from you, whether it is line of sight to you, and whether you had any shielding deployed.
In addition, since we have (thankfully) not had much experience with widespread powerful EMPs in modern times, there are a lot of unknowns. I've seen a lot of information floating around about what an EMP would and would not do, but most of it is simply conjecture.
If you are asking for my opinion, I think it is likely that a strong enough EMP would take out an unshielded inverter and charge controller. It may also be possible that the diodes in your solar panels would be taken out (that one I am less certain about).
While it is possible to shield a system, there is no way to be certain that your particular method of shielding will work. So in my opinion, the best method of preparation for someone who is very concerned about an EMP would be to buy a cheap spare inverter and charge controller (cheap models can be had for not much money). And if you are concerned about the diodes in your solar panels and are unable to have spares and change them, then you could buy some cheap solar panels too. With your spares, you would want to store them preferably in a tight metal container and preferably stored down in the basement to get as much mass as possible between the equipment and the energy from the EMP. Then, if (God forbid) an EMP were to occur, you are not depending on some unproven shielding method and you just pull your spares out.
That is my suggestion for EMP prep, without being an EMP expert. Hope it helps.
Nick -- thank you for the video and calculator.
1. In the battery sizing calculator you hard-wired in 0.5 in the denominator. This is for 50% depth of discharge - right? If so, what if you only wanted to discharge 30% (not 50%) -- then change this number to 0.3?
2. Also -- the 0.8 number in the denominator -- what is this? Is this to account for battery losses over time (20% loss)?
3. You mentioned monitoring tool (Hydro-volt ?) -- where do you fine these? What do you recommend?
4. Equalizing -- doesn't the charge controller do this (assuming you have a decent one)?
5. Water -- what level of impurities are permissible? Thinking of water sources available during a grid down situation
Hi Joe, Glad to help...
1 - If you wanted to use a different depth of discharge then you could modify cell B9 by changing 0.5 to 0.3.
2 - That is a derate factor for lead acid batteries. For every 1000 amp hours you push into them, you can expect to only get out roughly 800. So this accounts for the inefficiencies in the batteries themselves.
3 - Yes, I really like the HydroVolt meter. There are a couple places that carry it:
4 - Any good charge controller can equilize your batteries (provided you have enough solar power to do so), but it is typically going to be something that you manually initiate. Some systems are set up where it will automatically try to equalize every X days, but personally I like to be a little more hands on and make sure the batteries actually need to be EQ'd. While you can do it based on a timeframe, you'll likely be putting extra wear on the batteries. In addition, equalizing causes the batteries to lose water much more quickly than normal and if you are not checking beforehand, you could end up with a situation where your water level gets so low that the plates are exposed and you damage the batteries. So it's always a good idea to check your water level before equalizing.
5 - While distilled water is highly recommended (and it is possible to distill even in emergencies with some distillers like the Survival Still), if you didn't ave access to distilled water then I would use any filters you can get your hands on and get the water as clean as possible. Just do the best you can. But I would much rather use sub-par water then to let the water level get so low that the plates are exposed.
Hope that helps!
my wife and I watched WEB presentation this morning ( we had unexpected company last evening). we would love to get your program for the $297 , if at all possible. we have a cabin in Northwest Arkansas and it is off the grid. THANK YOU for the videos and the one on batteries Lou
I was directed to your site by a friend. I saw your first video and wanted to know if the other videos in the series are available and where can they be accessed...thanks!
I'd be very keen to know your opinion(s) on the latest nickel/iron batteries - the ones with a 30 year life first time around.
Hello Nick, I've been thinking of going off grid for quite sometime now. My hobby has been electronics for almost 50 years now so, except for some of the finer points specific to charge controllers, I understand how most if not all of this works. I also have the added benefit of having the experience of operating and maintaining electric forklifts and their batteries for 19 years in a warehouse in Florida. I am embarrassed to admit that only last night did it occur to me that a forklift battery would be a good bet in a PV system. I know it is not good practice but I've seen a lot of times, on my job, among 30 or so forklifts, where they would have to be pushed to the battery shop for a change, (each had 2 batteries), as the operator had run it into the ground but the battery still kept coming back to be abused again. This is why I came to believe one would be a good choice as they are made for deep heavy discharge and also for the hard bumps and jolts in the life of a busy warehouse although I agree with you 100% about their care and maintenance. In a PV system, a forklift battery would be on a lifetime vacation comparatively speaking.This being said, I have a theory I would like to throw at you for your opinion. Assuming cost and storage space isn't a factor, in choosing a forklift battery, I've seen battery companies come to my job and check / replace worn / damaged cells in what would be an otherwise good battery. This wasn't a cheap process in the short run but it was convenient. Now, I live in West Virginia and the nearest quality battery supplier that I can find is in Ohio. Theoretically speaking, would it be easier maintenance wise to build a battery bank of electrically equal or larger size, (for less stress on the batteries), out of something like 22AH AGM batteries. If a cell goes bad in a forklift battery, it's as much as 100Lbs and it will cost several hundred dollars to repair even if one learns to do it and does it themselves. This added to the down time of the system waiting for a "heart transplant" to arive where as a 22AH battery could be isolated from the system temporarily while waiting for an 8Lb, $44.00 replacement from Amazon.com without missing it much. The reason why I ask is I'm getting up in years and down in health and am trying to make a reliable system but one my wife could maintain easily. AGM = no water, less to maintain and she can switch out 2 wires and lift 8 Lbs. Thank you for your consideration. Jeff M.
You bring up a plausible scenario. There are pros and cons to everything, so really, it boils down to your personal priorities and the order of importance that you place on them.
If the best bang for your buck or the longest lifespan is your highest priority, then I think you’d be best served with a forklift battery. However, if the maintenance issue is a higher priority, then perhaps a sealed AGM battery would be your best bet, even though it won’t last as long and will likely cost significantly more when you factor out the lifetime cost.
I have not found it necessary to water my batteries all that frequently, but I do try to check them once every month or two. With the light duty usage that an off grid system puts on batteries (compared to the heavy duty usage of a forklift), you’ll likely not plow through water nearly as fast as warehouse forklift would. Another factor that affects water usage is proper charging practices. Years ago I found that I was plowing through water and realized I had my charge controller set wrong where the solar panels were pounding away at the batteries too much and overcharging them—thus using more water than usual.
And as far as a cell going out and needing replacement, yes—it is possible. Anything man made can break before it’s time, but I have very very seldom heard of this being an issue with big heavy duty batteries considering the way we use them off the grid (especially if properly used and maintained). I just think you would find the likelihood to be much much lower than what you were used to with warehouse forklifts (since forklifts are so hard on batteries and not all operators practice good maintenance).
So those are a few thoughts to consider. If you are still concerned with the maintenance and replacement issue and have the budget to go with a higher cost battery, then I’d say go for it and enjoy not having to worry about watering. You’ll still want to make sure your batteries fully charge at least once every 7-10 days and things like that, but you won’t have to deal with watering.
I’d be careful with cheap batteries (not sure which ones you are referring to on Amazon, but I wouldn’t be surprised if they are a sub par battery). Don’t skimp on the batteries—they are your weakest link. Go with quality and you won’t regret it. For a sealed battery, I’d stick with Trojan, Outback, or Concorde SunXtender.
Hope that helps. Take care,
Off Grid Boot Camp
Do you recommend tankless water heaters?
Any comments on energy demands for hot water slab heat vs. gas forced air?
Hi Bob, Tankless gas water heaters are a great option and typically use less gas than an efficient tank model. However they are more complicated and there is more to go wrong with them. If you go that route, I recommend Bosch and their pilot light model is an old off grid standby (the aqua spark model is a great idea that is non electric and uses no standing pilot, but in the past I heard from a dealer that they were having issues with it--perhaps they have those issues resolved by now).
Radiant floor heating would likely use less power than gas forced air as you can use a gas (or wood) water heater to heat the water and there are very efficient DC hot water circulating pumps made these days (March is one good brand that comes to mind). I still prefer wood heat, but if I had to choose between the two you mentioned, I'd go the radiant floor heating route for those reasons.
Hope that helps!
Thanks for your promptness Nick. Your comments are very helpful.
Thanks for making something that seems extremely complicated, understandable!
Wanda G. Krack
Thanks for this easy to understand video, and for talking at a reasonable pace! Great information!!
What do you think about the Tesla Powerwall?
I really enjoyed this video and learned some great information. Also, it was a boot to my backside which had me out there topping up my 48 volt battery bank. Thanks for the shot of inspiration and the new options to consider the next time around when battery replacement time comes again. I have the lowly T105s which actually serve me well but you have shown me some cool options to consider for sure.
Outstanding video. There are more educational videos than can be counted on line and your presentation is right there with the best university educational courses I have seen, Thank you very much for the pace and content.
I watched video1 and it was very useful for me.
Iam little confused about the battery discharging.
You said that it is better to discharge the battery to 50%, but how I do this?
Is there a relation between the capacity of the battery with the current discharged from it?
If I have a battery of capacity100AH and is stated as 20-hr rate of discharge, what is the proper discharge of current in order to keep the battery safe and not damaged?
Is your battery bank one forklift battery or more? thank you for all your help.
Curious where yo got your vent fan for your battery box?
The following videos are grayed out, can they be reactivated. Thanks
Video 2 - Off Grid On A Budget
Video 3 - Solar Made Simple
Video 4 - The Missing Ingredient
Hi Norman, The next video should be available to you in 2 or 3 days. As soon as it is available, it will not be grayed out anymore and you'll be able to access it. Same goes for the others as well. I'll send you an email to let you know when each one is ready for you.
Hope that helps. Thanks so much! Nick
Nick, Thank you for the very informative video on solar batteries. I am trying to get information on solar systems to use at a Mission Station in North West Zambia. Could you tell me if dust on the solar panel surface would effect the rate of charge to battery grid? also how many roof panels would be required to keep 12no. 1000ah - 2volt batteries at peak performance?
I look forward to seeing further videos on the subject of solar systems. Wilfred
Hi Nick, thank you so much for making these videos! We are in the process of building an off grid cabin and I am learning as much as I can about the solar world so I can size my system right and take good care of it. Do the next videos automatically come in few days or what is the process for accessing them? Thank you, Diana
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