Help with new battery bank setup

Re: Help with new battery bank setup

BB. wrote: »

Welcome to the forum ITSki...

Thanks, and thank you for taking the time to reply.

BB. wrote: »

I will attempt to answer the questions--But we should try to keep the mix of wide ranging questions and answers from going everywhere.... I.e., take a path through each major step/component--It should be a little easier to understand.

Understand that, sounds good.

BB. wrote: »

I will be interested to hear what your other answers were--Many times, the answers are different because you (perhaps unknowingly) asked slightly different questions of each. Also, different people will approach a problem from different angles--Which can result in somewhat different system designs.

yes, I think there were two problems: my questions were too broad in scope and I did not properly clarify exactly what my ultimate goals were.

BB. wrote: »

The Honda 2000i is a very good pick for a smaller genset that is both reliable and pretty fuel efficient (especially if operated at partial power). If taken care of, you can get 2,000 to even 6,000 hours of use out of one with good maintenance (and scheduled oil changes). But, once they wear out/break, they usually don't seem to be worth overhauling.

Thanks, that makes me feel better, and is good to know on the repair piece. Honda generally makes good engines, so i was hoping that carried over into their generator line.

BB. wrote: »

And, can you confirm your "golf cart" batteries are 6 volt @ 105 Amp*Hours (at what C/XX discharge rate)? They should probably have higher AH capacity (we use the C/20 Hour discharge rate for our rules of thumbs designs). Nominally, I would have expected closer to 200 AH or so for a 6 volt "golf cart" sized battery.

Sure. I may have calculated wrong. The batteries came from Sam's club. They are Duracell GC2 6-volt. Instead of exact amp-hour, they come rated as "75 Amp rating 105 Min." So to get actual amp-hours, I calculated as (Amps * min)/60. So in this case, (75*105)/60 = 131 amp-hours. Sorry, it should have been 131 instead of 105....if this calculation is correct.

BB. wrote: »

If we do the design correctly, you should be able to use the same AC Charger on the grid and with your Honda. But knowing your battery bank actual voltage and AH capacity is important.

Yes, that's what I would like to do. 1 charger either plugged into regular outlet, or into generator if power is out.

BB. wrote: »

Loads are the first stop in Wind-Sun's design guide^TM.;)

I would suggest you look at getting a Kill-a-Watt type meter. Very handy to understand the basic requirements of your AC loads (voltage, current, Watt*Hour, etc.). Besides planning/running from your emergency power system, it is very handy for use around the home when looking at energy conservation projects... And, believe me, an off grid power system is firstly an energy conservation project.

Thanks, yes I've seen that meter. Will order it today. So far, I've just been trying to estimate power needs based on the watts or amps stamped on the various items that might be needed.

BB. wrote: »

For example, Hot water, hair dryer, hot plates are all "energy hogs". They use a lot of power (i.e., upwards of 1,800 watts, which forces you to use a "large battery bank" and a "large" AC inverter just to turn on.

Then there is the Watts*Hours of use... Use a microwave at 1,500 watts * 1/6th of hour (10 minutes) = 250 Watt*Hours... That is not a "lot of stored energy to use", so the battery does not have to be "large" for that reason--Just because of the peak power.

On the other and, a desktop computer that may run at 250 watts * 10 hours per day = 2,500 WH per day--That does not need a large inverter, but the computer may use 10x as much energy over the course of a day (vs the microwave).

Then we look at a laptop instead that may use only 25 watts, or 1/10th that of a desktop system (see how the conservation works?).

For heating, I use multi-fuel camp stoves that can run from gasoline/kerosene/diesel/alcohol... Usually much more efficient than resistance heating/cooking powered by a genset/battery bank/ AC inverter (although, we can size a system to do electric heating, if needed--it just pushes the power requirements up dramatically).

Makes perfect sense. I setup a spreadsheet to calculate watt-hours for various appliances, guesstimating time used. this has been eye-opening. I will get the kill-a-watt meter and make more accurate measurements of energy needed. I have other fuel sources...some propane and kerosene that i hope to use for most of the heating and cooking.

BB. wrote: »

Pumps can be real power hogs... But using a kill-a-watt meter and understanding the loads can save you a lot of money--For example the pump may only run 10 minutes out of every hour... Much different than one that runs for hours on end. Also, there are DC pumps (and other types of pumps) that may be much more energy efficient. We can look at your options and see were things work out (pulse a little kill-a-watt meter usage).

Yes, the pump was a big concern. It's a permanent installation. Originally, I had a 1/2 HP pump. When I began thinking about running essential systems without power, I realized that had to be changed. So I swapped the 1/2 HP for a 1/3 HP model that has the lowest start-up amps. Additionally, I bought a 1/4 HP Thermoplastic Submersible Utility Pump that I can hook a water hose to...this would be a backup for the permanently installed pump.

BB. wrote: »

Again, goes back to loads--A small system is easy to run off a Honda eu2000i and a 12 or 24 volt battery bank. A larger system, they tend to range more at 24 or 48 volt battery bank+inverter+charger controller(s) (and keeps the DC wiring from getting too thick/expensive/difficult to work with).

I would put this off until you size the system... Large AC inverters have lots of neat options--But if you can keep the system size small, 2-4 golf cart batteries plus a 300-600 watt inverter may be all you need (small system keeps your costs way down, and you will have to replace the batteries every 3-5 years or so--so ongoing maintenance costs are a factor too).

Yes, perhaps my process and goals should be better defined here. In some ways, I think I've put the cart before the horse. Like everyone else, what it boils down to is "what i would like" vs "what i can afford". If I had infinite resources, my objective would be to be able to live off-grid indefinitely. I'd have solar panels, a large battery bank, some generators, a big garden, etc. But that's not my reality, and with the idea of "you have to start somewhere," i set a more reasonable objective for our current situation.

My objective: "provide food, water and power for essentials so that our family could be decently comfortable during an extended power outage of 4-6 weeks". A 4-6 week power outage is not especially typical in this day and time. But I'm a good scout, and I'd like to have this ability..."just in case". Bad winter storms, natural disaster, etc.

What I'm NOT doing: connecting my generator or battery bank to the grid.
i'm also not expecting to power my entire house off the generator/battery bank. When i created the spreadsheet to calculate watt-hours for appliances, it opened my eyes to how much stored energy would be required for all the "comforts of home." Allowing for only 50% battery drain, my initial battery bank size was something like 30 batteries. YIKES! Hence my objective of only providing power for "essentials" during an outage.

My essentials are:
- sump pump (if it's raining). in a recent 6-day continuous rain, the pump cut on about every 5 min 24/7 for the entire 6 days plus about 2 days after the rain stopped. each cycle of the pump was about 5 seconds. BUT, that was on the 1/2 HP pump. i have not had opportunity to test the 1/3 HP pump yet. i will do that with the kill-a-watt meter next rain....or fill the basin with water from a garden hose to test.
- charge communication devices like telephones, ipads, small TV/radio
- power some low watt LED lights ( have some LED xmas type string lights and a few lamps with 4 watt LED bulbs)
- plug in a small chest freezer 2-3 times/day to keep food cold.
- run a laptop computer, modem and router (assuming internet is available)
- perhaps run the microwave for a few minutes 3 or 4 times a day

i plan to take a weekend very soon and simulate a power outage, to find out exactly what all we would need/miss. This should help cement the list of essential items and how much energy we would use.

To meet my objective, I tried to figure out what setup would give me to most power for my $$. That eliminated solar, as it was too expensive for my wallet and too complicated for me as a DIY at my current knowledge level. I wanted the battery bank so as not to waste fuel running the generator when i only need to power smaller loads. This will stretch the fuel supply and the life of the generator.
- After evaluating generators, I landed on the honda. from your feedback, looks like that's a decent choice. thankful!
- after evaluating all the different kinds of batteries, i landed on the lead/acid golf cart style. They were easy for me to buy locally and seemed cheapest for the power they put out.

I had a plan, then, to setup a battery bank, consisting of 8 GC2 batteries (because that was how many i could afford) and wire them up 12-volt. I bought the generator and the batteries, then started having doubts about how to charge them and how to wire them. So i stopped and started digging more. as vtmaps noted "stop spending money until this is figured out". So this landed me here for more help.

Sorry for the novel, but maybe this will help explain where I am and where I need to be.

BB. wrote: »

When you first get started--You may be checking specific gravity a few times a day. After the system is commissioned and stable--You should be checking electrolyte levels about once a month, and needing to add electrolyte every couple of months (lots of "it depends here").

thanks, that helps.

BB. wrote: »

You should box and vent the battery bank for two reasons... One is hydrogen gas is generated during charging (and charge controllers have been "known to run-away")--So safety is one reason. (as well as to protect the wiring/battery terminals so somebody does not drop a piece of metal on top of the battery bank (all around, a very bad idea). Hydrogen gas will probably not collect and blow up your basement/house--But if there were some sparks into the battery caps, you could have a nice little H&O explosion and spray chunks of batteries and sulfuric acid around (also not a good idea).

The second is flooded cell batteries will generate some acid mist. You can reduce it to a degree with "water miser" battery caps (if you use them)--But both the sulfur smell and the acid mist can be irritating to some people (and cause rust/corrosion/deterioration of nearby equipment/articles in the basement).

ok, makes sense. i will start working on that.

BB. wrote: »

So--We can either design a system around your loads--Or, in your case, you can give us your battery bank spec., and then we can define the system's capabilities (see if it meets your needs) and design the balance of the hardware to support the bank.

I think in this case, i've already go the batteries, so let's design the hardware to support the bank. And I will be sure to run within the limits of this system if/when the power is out.

Re: Help with new battery bank setup

Thanks for the information and good resources. I'll keep studying.