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JPWright

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Reply with quote  #1 

I have two 70v panels connected in parallel. So I have 70v coming into the garage. There is an on/off switch before the 30 amp, 36 volt controller. That controller charges the six 6v batteries in my Elec-Trak tractor. It works fine but I collect more solar energy than I can use for mowing and snow plowing. I mow for an hour every week and a sunny day later the ET is fully charged and ready to go again.

My ET experience has been so good that I just bought an electric bike. The bike has a 42 volt battery pack. I will use it for 14-mile round trips 3 times a week.  I was thinking that I could get a cheap PWM programmable charge controller for the bike like this one that will work for lithium batteries.

http://www.ebay.com/itm/SL03-4830A-30A-36V-48V-60V-Wincong-solar-panel-charge-controller-regulator-LCD/261853355430?_trksid=p2047675.c100005.m1851&_trkparms=aid%3D222007%26algo%3DSIM.MBE%26ao%3D2%26asc%3D41376%26meid%3D80a82d0ce9d34dae8ec087ef1739b649%26pid%3D100005%26rk%3D3%26rkt%3D6%26mehot%3Dpp%26sd%3D262358882486

I would just hook this controller up to the pos and neg of the 70v wires coming into the garage. When one charge controller was not drawing current, the current could just go to the other charge controller.

Does this make sense? Or do I need to have a physical switch to choose between the two controllers?

Thanks for looking this over.

wireing for ET and Bike.jpg 


stmbtwle

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Reply with quote  #2 
Putting two controllers on the same array is generally not recommended, but you may get away with it, depending on the controllers (done that).  They will probably establish a "pecking order" with one taking priority but which one that will be I don't know.   I'd put in a second on-off switch for general principles and safety so you can shut off one or both controllers should problems arise.

Suppose you separated your two solar panels and put one on each controller?

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Solar is like the wind. It may be free, but putting it to work isn't!
Willie, Tampa Bay
Rick H Parker

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Reply with quote  #3 
The easy way would be to find a charge controller that will charge the bike's 42 volt battery pack from the 36V battery bank.

Before you get ahead of yourself, check the features on the charge controller you have. Some charge controllers can manage two battery banks, some have a dump load output which could be used to power a second charge controller.

What is the make and model of the the charge controller you have?



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Rick H Parker
Kansas, USA
Electronics Engineering Technologist
stmbtwle

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Reply with quote  #4 
I've never heard of a controller that could charge batteries of different types and different voltages at the same time.
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Solar is like the wind. It may be free, but putting it to work isn't!
Willie, Tampa Bay
Rick H Parker

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Reply with quote  #5 
Willie, you have now. Just follow the link.

This charge controller can charge two separate battery banks that consist of different type of batteries.



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Rick H Parker
Kansas, USA
Electronics Engineering Technologist
stmbtwle

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Reply with quote  #6 
Interesting, but wouldn't work for him. "For use with 12 volt systems only"

Pricey, too for a PWM controller.

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Solar is like the wind. It may be free, but putting it to work isn't!
Willie, Tampa Bay
Rick H Parker

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Reply with quote  #7 
"Does this make sense? Or do I need to have a physical switch to choose between the two controllers?"

Hooking two charge controllers to the same array, at the same time, can be done but it not easy to get them to play well together. It like defusing a bomb, if you got to ask it best you don't try.

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Rick H Parker
Kansas, USA
Electronics Engineering Technologist
JPWright

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Posts: 19
Reply with quote  #8 
Thanks Rick and Willy
I like the idea of separating the two panels, one for each controller. I never thought of that but seems like the simplest and safest solution. Thanks again for being there.
colinmcc

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Posts: 153
Reply with quote  #9 
Just a question about the ET.. Which one do you have? I have the baby of the family, the E8, wish I had a bigger one, but up here in Canada they are rare as hen's teeth!
stmbtwle

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Reply with quote  #10 
There should be a device that will sense when one battery is fully charged (or disconnected) and will switch that PV panel to the other charger. 50 years ago we had relays that could do that but I'm sure they've been replaced by solid state today. I'm not the one to design it though, maybe our resident expert can.
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Solar is like the wind. It may be free, but putting it to work isn't!
Willie, Tampa Bay
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