dual battery bank auto switch found!!

[shadow44]

He Folks! I just wanted to share what I have found. I have been needing an automatic battery bank switch. Well I found a guy in Belgium. I know thats a ways off for us USA folks, but he is running them through ebay. His name is Victor. I sent him an email to ask him to build me a 24v 100 amp switch. He has been SUPER HELPFUL and is going to build me a custom configured switch for a fair price.

When bank 1 gets low, it will auto switch to bank 2. it will monitor bank 1, if it sees bank 1 go to 27.5 (charging) it will auto switch back to bank 1. it will also have an manual override. and in bank 1 mode only draws 50mW. To me this is the holy grail to have 2 battery banks and have them being switched intelligently automatically.

I have searched for something like this for some time now, and called a dozen solar outfits, with no results. I have not received my controller yet, but I am confident I will be pleased with what he builds. We have been bouncing emails back and forth for 3 days now, and he has been more than helpful in discussing what he can and can not do. I recommend if you need something similar, either contact me for his information, or go to ebay and search for user "new-eco-world"  or  battery switch automatic transfer.

Just thought I would take a minute to share this in case someone else needs one, or something similar. 

[Westbranch]

Just looked and I like the idea but those connection posts for 50A and above (looked at his store selection)  seem pretty small.
I know my 1500A 24V inverter calls for #4 wire for less than 6 feet. I used #2..

[dgd]

When bank 1 gets low, it will auto switch to bank 2. it will monitor bank 1, if it sees bank 1 go to 27.5 (charging) it will auto switch back to bank 1. it will also have an manual override. and in bank 1 mode only draws 50mW. To me this is the holy grail to have 2 battery banks and have them being switched intelligently automatically.
...
Just thought I would take a minute to share this in case someone else needs one, or something similar.

Thanks for sharing this info. Just last weekend I was discussing this with a new house owner who wants to go off grid. I will be installing a Classic, epanel and 2Kw PVs. He is really convinced that using two almost equal size battery banks based on L16s at 24v and having an auto switch to 'intelligently' switch between them is the optimal solution. I have recommended to just have both banks as one larger bank
and not bother with dual banks. I also thought that two seperate smaller banks would result in deeper discharge of one bank before switching to the other.
He will be using a 3kw inverter and I sort of cringe at the thought of a switching between the banks when the inverter is loaded up.
The battery switch would probably need to be capable of 250 amps to allow for power surges.
My logic is that if two banks become necessary then why is this of more advantage than a single larger capacity bank?
I would be interested to read why you consider two banks and auto switching  to be a 'holy grail'
thanks
dgd

[vtmaps]

He will be using a 3kw inverter and I sort of cringe at the thought of a switching between the banks when the inverter is loaded up. 

If switching banks while under load, I would imagine that the switch should be make-before-break.

On the other hand, regardless of load, switching from a discharged bank to a charged bank with a make-before-break switch can be exciting.

--vtMaps

[shadow44]

My logic is that if two banks become necessary then why is this of more advantage than a single larger capacity bank?
I would be interested to read why you consider two banks and auto switching  to be a 'holy grail'
thanks
dgd

that advantage is pure economics. Its much cheaper to buy and they dont have to be bought all at once and exact matches. 12 T105 purchased at separate times is a lot easier to buy than 24 at one time. And easier to charge up as well. plus if you have something bad go wrong with your bank you only loose 1/2. in my mind its safer and better to have dual isolated banks. But everyone has different opinions.

[dgd]

Ok... That sorta makes sense. If you are getting the changeover switch at a good price then it certainly would be a simple way of using new batteries with old in separate banks.
Probably would not apply to the new installation I am assisting with.
Anyway good luck with your setup and thanks for sharing the switch supplier info

Dgd

[shadow44]

Just looked and I like the idea but those connection posts for 50A and above (looked at his store selection)  seem pretty small.
I know my 1500A 24V inverter calls for #4 wire for less than 6 feet. I used #2..

That was some of the discussion I had with him. he added 8mm (5/16) bolts, they were as large as he could fit. They are standard for 100 amp load, I was concerned because I am running 04 monster welding cables. I have a 4kw inverter, but am not loading it up right now. 1.5 is about all I ever have on it. I will let you know how it works when I receive it, how it turns out.

[Westbranch]

one option is to have a Buss Bar close to the switch and use a short cable of smaller size to the switch.

hth

[shadow44]

one option is to have a Buss Bar close to the switch and use a short cable of smaller size to the switch.

hth

Thats what i was planning if my huge cables refuse to fit.

[Dad-07]

Not sure if anyone has used these,
http://www.newmartelecom.com/Automatic-Power-Selector/Automatic-Power-Selector.html

I have a 70A version and I am toying with the idea.

Peter

[Paulcheung]

Is there any good sense for this setup? I only see more bad and none good on this setup unless the batteries banks are far different on capacity or ages.

[zoneblue]

Do not underestimate the stress on relay contacts from 48V battery bank with something like 10000 amps interupt capacity. You pretty much have to build it in a vacuum, or with else with clever magnetics such as is found inside carling dc breakers. Also agree with vt, will need to be make before break to avoid dropping the inverter off, and this will cause more or less a full short from the high bank to the low bank. Breifly.