# Off grid living battery bank issue



## handcrafted (Jul 13, 2014)

:bouncy:Hi All, I'd forgot I was a member and haven't logged in for some time just stumbled back across this great website through google search and wow :bash:my user name and password workded VOILA. So anyhow getting back to why I'm posting. I have a bank of T-105's in parallel series 12v putting out about 700ah on a zantrex 1000/2000 surge. I use a generator to power the charger 12v 12amps for couple few hours warms em up and switch over to 50amp for few more hours. So while working (I am a cabinet maker with my own shop) an 8 hour day the batteries are charging and reach anywhere from 13.5 to 14.25 with sg of 1250 1300. Schedule, genny shut down at 19:00 battery power on, only thing on at night is cordless phone and modem, network extender, cfl light if needed, and maybe couple hours watching tv and computer on for Netflix, my son living back home in his rv with 50' 12ga. cord to his power strip powering his tv and cfl light and ps3, early morning wake up make coffee with electric coffee pot, turn on office computer, cfl lighting, when coffee is done I pour it into my good ole Stanley thermos and don't leave coffee warmer on, around noon to oneish the genny runs my shop while charging the batteries. It's a great working system for the past 11 months while I design and build my solar system. My problem I experience from time to time with the batteries registering 12,4v when I turn on my computer with the coffee pot going and nothing else except for the modem,phone,network extender, the inverter will trip and then I can't get it to reset, Zantrex have a cutout at 10.5 v why does mine occassionaly cut out while still at 12.4v maybe I'm wrong but I would think with the amh of my batteries I should be able to go two maybe three days on battery say if I were to take a three day weekend and not want to hear the genny going. Well thank you all in advance for your comments and contributions and any living a similar way I'd love to hear your situation. And now that I found this website again I'll be updating my profile over the next few days and post some pictures of my set up and beautiful mountainous fews. ciao for now


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## 12vman (Feb 17, 2004)

Sounds like the battery isn't supplying the inverter with enough current. The initial surge demand is causing the battery voltage (seen by the inverter) to drop to or below 10.5 volts, shutting down the inverter. If it worked for 11 months, something has changed..

Check battery connections. Equalize the battery bank. (Could be stratified) Or, possible bad batteries if you allowed the voltage to drop until the inverter kicked off at 10.5 volts several times..


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## handcrafted (Jul 13, 2014)

Thanks 12vman I see what your saying and can agree to the possibility although my battery bank I purchased new last June 2014 and keep up on water level, charging and periodicly blast each cell in a circular fashion with my hydrometer just to keep the bottoms stirred up. So if I get what you're saying correctly, the draw is causing the bank to drop below 10.5 just long enough to trip and then the bank almost immediately returns to what reads 12.5 or regular read. hmmm to me that translate to "surge" now the question why only once in awhile. In case I failed to mention this is only an occasional happening.


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## buenijo (Jun 14, 2012)

Check the battery connections to the inverter. In addition to ensuring the connections are excellent, also consider using both shorter and fatter cables to connect the inverter to the battery. Place the inverter as close as practical to the battery to make shorter cables possible. Basically, I suspect there is high resistance in the connections between battery and inverter, and this is driving down the system DC voltage on high DC current.


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## wy_white_wolf (Oct 14, 2004)

Sounds to me like your loads are using more then you expected. Have you done a full evaluation of your loads? By what I see as your loads I'd guess you've been taking them down to 50 to 60% SOC daily. I really dought you could go more than 1 day without running the genny.

12.4V would put you at about 70 to 75% SOC if that was taken after they've had no charge or load for a couple hours. The 13V+ readings are meaningless since they are taken either during charging or right after charging. It is a surface charge reading. You really need to check them at least 2 hours after charging to get any kind of accurate reading. A fully charge battery after resting should be about 12.8V. Or better yet get a quality hydrometer. Then you don't have to wait.

WWW


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## Harry Chickpea (Dec 19, 2008)

"my son living back home in his rv with 50' 12ga. cord to his power strip powering his tv and cfl light and ps3" That means that the inverter may never get to go into sleep mode, even if the power draw isn't large. Depending on gaming and tv watching habits some days might end up with the inverter tripping out.


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## JeepHammer (May 12, 2015)

Very early on in my solar off grid days I had a similar situation...

After pulling my hair out, I got down to business,
Load testing showed that start-up can often demand TWICE the 'Rated' operational current draw.

Heating elements and electric motors in particular were my pain in the -----.
Start the coffee, throw a sandwich in the microwave, and I was in the dark until I went out and reset the breaker...

I *Should* have had plenty of amp hours and charge to run both,
Turns out the cables I was using wouldn't carry the amp load to the inverter,
And with just ONE corroded terminal, 
The batteries couldn't force enough amperage through to the inverter fast enough.

Testing comprised wiring in a set of 10 Ga. Wires parillel to the main cables,
Everything ran, which told me it was cable/terminal capacity.
New, larger cables, with better, CLEAN terminals solved the issue.

Like everyone else that builds their own power grid,
I made the mistake of using off the shelf, automotive style 'Battery' cables.
Those crimped on 'Flattened Tubing' type terminals that weren't soldered onto the wire...
Made in 'China' and worthless...

The 'Copper' conductor wire was ALLOY, not virgin/pure copper,
It was undersized, and it was large wire strand size, which conducts less amperage, letting voltage drop.

The terminals were flattened end tubing type with a connector bolt hole punched into the flattened end.
The terminal tubing was undersized (wall thickness) was undersized to carry the amp load from wire conductor to battery or inverter terminals.
Simply not enough terminal conductor to make a full amperage connection.

Another issue on the battery ends was the UN-SEALED tubing ends were allowing acid to creep into the terminal/wire unseen, causing hidden corrosion.

SO!...
Off to the welding store to get some FINE STRAND, VIRGIN COPPER, High amp load cable with good insulation,
And some 'BLIND' (closed) socket terminals that would carry full amperage load.

Blind wire sockets means the acid can't creep into the terminal,
Heavy lug means they WILL carry the amp load between cable and connection point,
Fine strand means more tighter packing/less air space between strands, better current carrying capacity for any given wire size,

Then CRIMP, Mechanical Connection,
SOLDER, Electrical Connection & Enviornmental Sealed connection,
HEAT SHRINK, fully Enviornmental Sealed, no hidden corrosion inside the terminal socket or insulation,

ROSIN CORE ELECTRICAL SOLDER,
Never acid core plumbing solder,
And if you want to make terminals 'Bullet Proof',
Use 'Silver Bearing' solder (not high temp 'Silver solder),
2% to 4% silver content,
The silver makes for a MUCH better electrical connection,
And it resists corrosion much better than regular tin/lead solder.

Now, when I'm pulling high amperage loads, I use a $20 heat gun to check terminal connections and cables for increases in temp/resistance,
Resistance builds heat, so it makes bad/undersized cables/terminals easy to find.


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## JeepHammer (May 12, 2015)

One other thing,
If you are going to use those flattened tubing terminals,
Drop some solder into the terminal cable hole and solder it shut before you install the cable in it...
Just because the end is flattened and has a hole punched in it doesn't mean acid/vapor can't creep into the terminal.
I learned about 'Capiary Movement' of liquids (battery acid) the hard way...


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## handcrafted (Jul 13, 2014)

JeepHammer said:


> One other thing,
> If you are going to use those flattened tubing terminals,
> Drop some solder into the terminal cable hole and solder it shut before you install the cable in it...
> Just because the end is flattened and has a hole punched in it doesn't mean acid/vapor can't creep into the terminal.
> I learned about 'Capiary Movement' of liquids (battery acid) the hard way...


:rock: Please note this is only my explanation of how I've made things work for me and is only offered as my Idea and is not to be tried nor relied upon by anyone for any reason. Work at your own risk assume your own responsibility. And wear a heavy set of gloves like welder gloves cause the copper heats up fast. 

I 've found that the "stock" terminal ends that come with most electrical (especially charger related) systems do not carry a load for long without heating up and becoming crispy fried. So after the first sticker shock of buying a copper terminal end, my brain said hey dummy you've been a plumber why not go buy a couple feet of various copper tubing and pipe and make your own. At which point I said hey brain ya know your right Again Two feet of copper and a little dielectric grease and few minutes of time and voila a new fitting and way better connection than the pre crimped. 
Here's what I do: determine i.d. of tubing or pipe (depends on wire size) cut off about 2" in length and ream both ends. Then cut back about 1 1/4" of insulation from wire. Coat liberally with dielectric grease. Place exposed wire into copper tube to the end and maybe even let 1/16" hang thru. Now place the first most 1 1/4" with the wire in it into your vise and squeeze the hell out of it shut. Now hears the part I found to be crucial to a good connection. Once flattened out take it over to your drill press (word of caution, clamp secure somehow to your plate the new fitting it can take off and spin out of control) (if you're not familiar with a drill press get someone that is) and drill the appropriate diameter hole in the flat THEN take it over to your vice and on the flat "anvil" of your vice use a hammer and begin to flatten it again and you'll notice that the wire begins to intrude on the drilled hole and then carry back over to your drill press (clamp in p[lace again) and with the same diameter bit clean out the wire. Now, you're almost done, now take the finished crimped end over to your grinder and clean up the end with the wires slightly protruding, if your good you can even radius then end to make it look good and when you're done you shouldn't even be able to tell from looking at the crimped end that there's wire in it. 
Now for you nay sayers, if ya don't have a drill press and the appropriate tools for this, well then find someone to help you. These are way far better connectors than any crimp on you can buy.


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## JeepHammer (May 12, 2015)

I would leave out the dielectric grease,
And fill the wire/tubing with electrical solder to PERMINANTLY seal the connection from corrosion.

There is no such thing as grease that won't eventually dry out,
Faster with heat and acid exposure.

There is also no such thing as copper that IS NOT going to corrode with direct exposure to lead oxide and/or battery acid.
All ends will eventually need to be changed...
Just a fact of life.

I don't see anything wrong with using the grease on the copper to slow corrosion.

Where two cables come together, use oversize tubing,
Stick both cables in one terminal.
This cuts down on terminal cost and terminal work.

Tinning the wire with solder, especially silver bearing solder makes the copper wire/terminals last MUCH longer, especially when standing up to battery terminals...

I cut my wires about 3" longer than I need, this allows for replacing terminal ends and still having the wire/cable long enough.
Copper cable is stupid expensive, and having to scrap a cable because its too short after an end replacment is adding insult to injury!


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## stevesmitty79 (Dec 25, 2005)

Do you have any fuses in the system? Have you checked or replaced them? I have a disconnect in my solar setup from my PV panels, pulling low current, maybe 20 amps. I pulled the 30 amp fuses and they disintegrated in my hand. Just a thought.


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## Bellyman (Jul 6, 2013)

wy_white_wolf said:


> Sounds to me like your loads are using more then you expected. Have you done a full evaluation of your loads? By what I see as your loads I'd guess you've been taking them down to 50 to 60% SOC daily. I really dought you could go more than 1 day without running the genny.
> 
> 12.4V would put you at about 70 to 75% SOC if that was taken after they've had no charge or load for a couple hours. The 13V+ readings are meaningless since they are taken either during charging or right after charging. It is a surface charge reading. You really need to check them at least 2 hours after charging to get any kind of accurate reading. A fully charge battery after resting should be about 12.8V. Or better yet get a quality hydrometer. Then you don't have to wait.
> 
> WWW


This is what I was thinking... only WWW stated things much better than I could have.


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