Battery bank voltage question...

Re: Battery bank voltage question...

Sounds pretty good... It is possible that you where undercharging before...

Wind-Sun has a very good Battery FAQ--if you have not read it yet--do read it in detail. Not only because it has numbers--but it also discusses philosophy of battery operation and care. Understanding what you are trying to achieve can help you figure out how to do that with the equipment you have...

So, some suggestions... More or less in order of importance (in my humble opinion knowing nothing else about your system):

1. Get the remote battery temp sensor for the Morning Star controller

• This will ensure your batteries are accurately charged to 100%

2. Get a hydrometer and thermometer...

• This will tell you very quickly the health of your battery bank--both overall level of charge/discharge and if individual cells/batteries are failing. Also can tell you when to force equalization. You will not use this every day--but checking a cell once a week (after you have checked/logged all cells for a day or two of use/charging to make sure everything starts out good) will help you keep the batteries in-charge.

3. Review your AC Battery Charger... Possibly get one that is designed for deep cycle batteries (and has remote temperature sensor, if IOTA--get the extra board).

• Many folks use just a plain old multi-purpose battery charger... Many do not output a high enough charging voltage to really fully charge a deep cycle battery. They also cannot equalize (although, usually the solar charge controller + panels will be able to on a sunny day). A good deep cycle battery charger will also, typically, output higher current for more time--so faster/better charging and less fuel wasted on running a gen set at low power usage by your charger.

4. How much battery water are you using... If a lot every month--you may be over charging (at times). If none--then you probably are not charging enough. If you think you are charging OK--but using excess water/mess on battery top--then look at some sort of "water miser" caps.

5. Sort of optional (because solution could be more money than you want to spend)... Get a Kill-A-Watt meter and put it on your generator output when charging your batteries...

• See if a eu3500i may be too large of generator for daily charging of your batteries--perhaps you are using a lot of fuel to only output a few hundred watts. Jacking up the charger size/output and/or using a smaller generator (like the eu2000i--although not electric start) may save you a bunch of money in gasoline. --If you only charge a little bit (during bad weather or when you are using other large loads--like washer/drier/saw/tools/etc... then you are using the generator probably to capacity (as a rough rule, using a generator below 50% capacity is not very fuel efficient--using the Honda euX000i family, if used below 25% capacity--with ECO Throttle On would not be fuel efficient).

Basically, the Honda family gives you, roughly, around 5,000 to 5,500 Watt*hours (5-5.5 kWhr) per gallon of fuel... Connect the kill-a-watt meter and run your load(s)... See how much power you use, how many kWhrs, and how much fuel you use...

6. I would also add--look at a battery monitor. Highly recommended, but not cheap. Allows you to see your battery state of charge at anytime under any condition... If it even saves you killing your battery bank once (and early replacement)--you will probably break even at the very least.

• The Trimetric TM2020 Battery Monitor System has had some love here (good $$/performance). The Xantrex LinkLite/LinkPro family I like a lot because you can set it up to turn off your loads (with a relay, control the inverter) or turn on a Red Light / Alarm on State Of Charge below XX%--really useful for the friend/worker that does not want/need to know to run your fancy off-grid system.

Home that this is useful--probably pretty repetitive for anyone that has been reading my "rants" over the last couple months (sorry)...

-Bill

PS: Probably I should answer your original question ( )--12.70 volts after the battery has rested for a few hours, and at 77F -- is 100% charged---And this also requires that you have an accurate/calibrated voltmeter. You will need to temperature correct the voltage up (if batteries are colder) or down (if batteries are warmer).

Re: Battery bank voltage question...

shortfatguy wrote: »

The Trimetric TM2020 Battery Monitor System has had some love here (good $$/performance). The Xantrex LinkLite/LinkPro family I like a lot because you can set it up to turn off your loads (with a relay, control the inverter) or turn on a Red Light / Alarm on State Of Charge below XX%--really useful for the friend/worker that does not want/need to know to run your fancy off-grid system.

I didn't know you could use LinkLite/LinkPro to control the inverter. Idiot proofing is what I'm trying to do so too. Does Xantrex sell the relay setup? Can the same setup be used with the Link 10/20?

SFG,

There is a "QUOTE" button at the bottom of each post--it will make it much easier to follow the cuts and paste between you and others... (you will see the world quote between a left and right bracket--and for the end [/quote] )

Your question--while you can get a big relay and set it up to control the DC power to your inverter... You are better off getting an inverter that has an on/off input (usually 5 or 12 volt signal) that can be driven by the LinkXxx controller (the LinkXxxx controller is just a small signal--12 volts at a few 10's of mAmps--IIRC). Controlling a big relay can actually waste 10 watts or so of power just turning it on (depends on the size of your system if 10 watts or so of wasted power will hurt you or not).

The older Link 10/20 does not have the external contact output--that I know off... I don't remember seeing this type of contact on any other of the Battery Monitors--but this was just recreational reading (:p)--I do not currently have any applications for this equipment--so I have not paid close attention (and I am not employed by NAWS or by anyone else in the solar industry).

If your needs are small--MorningStar makes a very nice 300 watt true sine inverter with very low losses.

Morningstar SureSine, 300 Watt Sine Wave Inverter 115VAC

Other brands, with small and larger inverters also have the aux switch control... You will probably need to pick a size, and read through the manual for the details:

For example, at least a couple Exceltech have a an AUX control (XP1100 & XP600 Complete Owners Manual + Specs PDF manual).

The other brands (such as available at Wind Sun / NAWS, also a good inverter FAQ if you want to learn a bit more), you will have to look up a manuals and search the web/mfg. site for details.

I do not have access to any of these devices--so I would be doing the same as you--picking a couple devices and reading the manual--Then make sure that the input/outputs are compatible--and calling the Mfg. if something is not clear.

If you are unsure--calling NAWS or the Mfg. directly should get the exact answers you need. We can certainly direct you towards possible solutions.

-Bill