Multiple Battery Banks with different types?

[TomW]

Folks;

First, some info on my current setup:

[STORAGE]

Bank A: Trojan 105 6 volt cart batteries wired for 24 volts [440 AH] Main Bank. 4 years plus old.

Bank B: 4) 110 AH VRLA 12 volt batteries wired for 24 volts [220 AH]. Extended Run Bank. Supposedly new never installed over goods but no sure way to know.

Bank C: 4)  Trojan 105 6 volt cart batteries wired for 12 volts. Even older than the A bank batteries.

Bank C is used to run my Wireless Internet and is generally just charged with an automotive charger plugged into my inverter so it is not going to be integrated into my main storage.

[SOURCES (All are 24 volt nominal)]

300 watts of Siemens SP75 panels configured for 24 volts.

One Zubbly 6.5 foot [2 meter] Conversion [TM] that easily does 250 watts and can see over a KW in gusts.

One Danbilt [TM] 10 foot dual rotor [off line waiting for a tower solution].

[INVERTER & CONTROLS]

An Outback 2.5 KW 24 volt Sinewave Inverter. I use the inverter to mostly run our refrigerator. We probably get 80%+ of the fridge needs from RE right now. The fridge is not exactly high end on efficiency but thats another story. The % is higher when my tracking is working but we lost a large pile of electronics to lightning awhile back and the tracker was one of the items.

I have a "Mike Controller" that I modified to work on 24 volts. It is not used now.

I have a USB enabled digital Multimeter and software to read data into the computer. I have a module that can control a couple relays from the computer. "Computer" in this use is a Linksys network storage device with Debian Etch installed on it with USB, and network ports [very low power]. I have several mediam  capacity relays and motor start contactors some with 24 volt DC coils and some with 120 AC coils.

I am usually here so my controller is me [now].

[The Dilemma]

I want to integrate the VRLA bank into my storage scheme. I think I can use the mike controller to split out charging but with a potential of 100+ amps into the inverter I do not think I have relays that can handle that kind of current.

[The question]

Due to differing age, capacities and types I cannot sensibly just piggy back these VRLA on the Trojan bank.

I am looking for ideas on both ends of this situation. I am NOT interested in "buy this piece of electronics.." ideas. I prefer to use what I have onhand as much as possible.

I do Not want to see MPPT mentioned, either, unless you want to send a unit for me to field test.

Ok thats the question. And the parameters.

I may need to do something like Anderson power plugs for transferring the inverter from bank to bank but only seen those in a 60 amp rating. Big knife switches would be good too but I never see any of any size.

Thanks for any sensible ideas offered.

Cheers.

TomW

[fungus]

"Big knife switches would be good too but I never see any of any size."

Maybe something like what mitcamp did would be good for high current, but with less contacts obviously. IIRC it was made out of copper pipe; just thought of it when you mentioned knife switches:

[willib]

Hi Tom , i'm curious of the USB digital multimeter?

[TomW]

willib;

Well, it is actually an RS232 Radio Shack 22-812 serial meter with a USB to 9 pin adapter running zmeter on Linux to gather the voltage data. We did

have a USB analog to digital converter for voltage but it was kind of crappy and it got killed by lightning and will not be replaced.

Cheers.

TomW

[AbyssUnderground]

Id like something like that to measure my setup. Is it simple to do?

[TomW]

Abyss;

Well, "simple" is relative. It is pretty straight forward. In my case I use Debian anyway so it is installed on almost all my machines.

Get the source code from sourceforge for zmeter, compile and run after you connect the meter. Some simple shell scripts and you are logging data.

From there standard Linux tools will get you to where you can use the data to make decisions on how to control things, etc.

Best part is, it will run on almost any low end cheapie hand me down computer either full size or laptop.

Cheers.

TomW

[Nando]

You may be able to interconnect ( paralleling) A) and B) .

Charge both to float condition then let them rest for at least 4 hours without any load and read the voltages and if within 1-2 % of each other bank, you can parallel them without any problems.

We have done up to 4 % and have lasted years without problems.

Define the manufacturers difference and see the charging profile and voltage differences are within the 1-2 % band then you can charge them in parallel.

[zubbly]

hey T,

if its just a big amp capacity relay you need, i suggest you check local forklift repair shops.  most have a grave yard outside where the old units are put out to pasture and occasionaly supply an obsolete part.

the realys in those lifttrucks have massive contacts, and work with a wiping action.  24 volt is common.  they should handle hundreds of amps.  for a case of beer, they may even take them off for ya.

just a thought that i think might work.

zubbly

[TomW]

The Trojan 105 Spec sheet is here:

http://www.trojanbattery.com/Products/ProductSpec.aspx?Name=T-105

closest to the VRLA rating was 185 AH [5 hr rate]

The VRLA is listed on this site:

http://www.powbat.com/products/Telecom%20VRLA.htm

The TL-12120 12 volt 118 AH [8 hr rate] down the page a ways.

Just should of included that in the original post.

Cheers.

TomW

[WindChopper]

If you are really into manual switches, try the Battery Disconnects that they use in Fire Apparatus.

One source is DelCity.net .... prices are - well .... but you could also check the mechanic at your local Fire Department for other sources.

Rated at 600A continuous, 1000A intermittent  Off - A - A+B - B

http://www.delcity.net/delcity/servlet/catalog?parentid=789172&childid=789239&page=1&tab
set=1&pageitem=1&new=y

Rated at 360A continuous, 600A intermittent  Off - A - A+B - B

http://www.delcity.net/delcity/servlet/catalog?parentid=791777&childid=791779&page=1&tab
set=1&pageitem=1&new=y

Russ

[WindChopper]

Lets Try that again with Brain Engaged ....

Rated at 600A continuous, 1000A intermittent  Off - On

http://www.delcity.net/delcity/servlet/catalog?parentid=789172&childid=789239&page=1&tab
set=1&pageitem=1&new=y

Rated at 230A continuous, 345A intermittent  Off - A - A+B - B

http://www.delcity.net/delcity/servlet/catalog?parentid=791777&childid=791779&page=1&tab
set=1&pageitem=1&new=y

Rated at 360A continuous, 600A intermittent  Off - A - A+B - B

http://www.delcity.net/delcity/servlet/catalog?parentid=789171&childid=789234&page=1&tab
set=1&pageitem=1&new=y

Russ

[DanG]

Okay, I won't say you need to purchase the Outback Mate Controller - I don't know if your Outback charger section is active or whether you are pushing batteries direct... You have a first tier logic controller built into the FX2524 so it's just how to best utilize it... Though not having the RS-232 cable hooked into the inverter probably saved the unit from entering sky spark heaven, bet you already thought of that!

I seem to remember you bought the FX2524 locally - perhaps the RE vendor could/would/should "Demo" a Mate for you to program in an Aux - GenAlert - DivertDC scheme to toggle the batteries from A to B (to act independently of the Outback charger section if needed) though I think the Time/Date functions reside in the Mate, the stored raw input settings of the 2524 may allow you to force a fallback once solar goes away w/o the Mate attached...

The Winverter software to track Outback inverter depends on having a Mate - Oops, skip that, its for Windows98 or better...

[tecker]

Another option I think is viable is to configure the bank with lesser power for a greater voltage with the charger (Wind , solar etc ). Then a constant charge can be maintained over a longer period .As the charge is consumed the the higher voltage

through a regulator is used first before the main bank is taxed.

[ghurd]

Maybe this would create more problems than it solves.

Guessing the 100+A is the surge to the inverter caps?

What if 60A Anderson's were used to change over on dead circuits,

then big 100-150A IGBTs were used to turn the circuit on?

I might know someone who has a couple extras,

and a wife who wants them out of the dining room.

G-

[TomW]

Well, folks;

Thanks for sharing the ideas. Seems like most were basically "connect them together with this.." advice. I probably will end up just piggybacking them [parallel] with a provision to disconnect the VRLA bank occasionally to cook the flooded cells. I will also incorporate some method of letting them reach the same voltage slowly before hard connecting them. Like a headlight bulb on a light switch across the main connection switch. I found a 2 pole Square D plug fuse type service disconnect in my stash and I modified it to bypass the fuses. Its rated 30 amps per leg and sharing the load they should be fine. Seems that with the main bank being 2X as big as the add on it will provide about 60% of the current leaving 40% on the add on bank. The Outback is 2.5 KW so roughly 100 amps max steady draw split 60/40 will be OK.

Anyway, thanks again for the ideas.

I guess I figure I may as well use them like this even if its not absolutely the best way rather than let them sit drawing welfare. It will get me another 50% gain in storage which I could use some days for both absorbing and providing amps.

Cheers.

TomW

[coldspot]

Tom-

Have fun!

Anyway, windchopper's fire apparatus switch.

 Very much also used in boats, (I have one I hope makes it into my boat with the isolater, I got for it also) and RV's I'd think.

 Great for smaller sized banks or dual battery type of set up but, for a larger bank I also will want knife switches. My stash/collection only has duel or two switch set ups, great for the DC side but I'm still looking for a three knife one for use of shorting the mill out.

 Army  store has a lot of electrical box's but I never have time to look close at very many of them.

[PaulJ]

   Tom,

   For what it's worth, I run two battery banks, 500Ah and 350Ah at 48V, with the big one hardwired to the inverter. The smaller bank is not normally used much, so I keep it happy by floating it off the big bank through a 6A diode and a 50W headlight globe - this is connected permanently. This serves two purposes, the diode obviously stops the smaller bank being discharged when there's no sun or wind, and its voltage drop keeps the smaller bank from seeing the full absorption voltage of the larger bank when it's just sitting there fully charged. Crude but surprisingly effective.

   In your case, with different battery types, you might want to use two or more diodes in series if the max voltage of the T105's is much higher than the safe max for your vrla's, not too sure on this though.

   I use the smaller bank in summer by running it in parallel with the big bank (through a 50A Anderson connector) when I need to run the aircon, and in winter to boost the solar hot water with a 48V element.

   To recharge it when it's been substantially discharged, I usually parallel it with the big bank through the Anderson connector on a good sun or wind day and babysit it.

   Personally, I'd be wary of running different battery chemistries in parallel in a low or no load situation.

   Hope this helps,

   Paul.