Author Topic: Daisy-chain GHurd controllers?  (Read 3115 times)

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bcalmed

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Daisy-chain GHurd controllers?
« on: December 07, 2016, 04:36:53 PM »
Maybe this has been discussed, but I wonder if one can use a GHurd controller to dump to a second/third/fourth battery, etc?

It seems one could keep several, different 12V FLA's charged and use the final controller to dump to a resistance load....

...any thoughts?

Bruce S

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Re: Daisy-chain GHurd controllers?
« Reply #1 on: December 08, 2016, 09:33:40 AM »
Short and quick answer?
YES.

I've done this , since I use recycled NiCds. The trick is to not hurry and get the voltage right.
 I set mine to the max I wanted my NiCds to get to, then next set of batteries the same way. I think I only had 3 battery sets, didn't really have enough panels to go any further.

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OperaHouse

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Re: Daisy-chain GHurd controllers?
« Reply #2 on: December 09, 2016, 10:50:09 AM »
On another site they were talking about one of those 50,000ma Li packs for power. Talk about specmanship. From the weight of the pack I figured they were in the very low 20's of 18650 batteries.  That would get my CPAP through the night and I have plenty of Li from town recycling just hanging around. Just under 12V will work with my inverter.  Always use a 3 or 4 pack BMS system to charge these in a balanced way, these are cheap on ebay.  Voltage is critical and slightly undercharging leads to longer battery life.  I have a second lead battery I switch in and out now by monitoring the voltage on the primary battery.  I am a fan of the GHURD controller, but those cheap buck controllers would be better for Li.

Bruce S

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Re: Daisy-chain GHurd controllers?
« Reply #3 on: December 09, 2016, 01:42:54 PM »
OperHouse;
I am trying to be a fan, but ATM I cannot get those single Li chargers to be shipped to me.
How well are you finding the BMS packs on ebay working out? I'm thinking of trying those setup for my 12V airpumps.

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OperaHouse

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Re: Daisy-chain GHurd controllers?
« Reply #4 on: December 09, 2016, 04:43:28 PM »
Not sure what you are referring to.  I use these TP4056 cards for single
cells and they are about $3.50 for 10.  I can build them into a flashlight
for that price. Factory spec says to put 0.5 ohm in series with supplied
power.  Otherwise the IR loss is in the silicon. They run quite cool with
a resistor and seem to work perfectly fine at up to 4 ohms. Shut off voltage
is exactly the same. This resistor can be used to limit the maximum charge rate
instead of changing the resistor on the board.  The board still limits final
charge current of .1A, but limiting max current with a resistor is added safety
with unknown trashed cells out of laptops.

Your post reminded me that I have been looking at the 3 cell $2 board for a
week. I'm tripping over cells all the time, except when I go to look for them.
I did have these 6 cells handy in pairs and hooked them up to this board. This
exactoard in looks is available in the 3 and 4 cell version.  Just a couple
resistors are changed.  You actually have to search multiple listings to figure
out which pad you skip in the three cell version. Like the other board, it
seems to work well with a 1 ohm resistor in series. I just don't trust all
this crap from CHINA. With the resistor it charges at about 1A at 13.5V. A
good match for tieing it into a battery and that still gives me enough time
to charge in a day. So far it seems to automatically shut off when charged.

There are a number of Li chemistries. Supposedly you can tell by the color of
the plastic liner of a 18650 cell.  One thing for sure is these pack a lot of
energy. If any cell shorts out, there is massive current and heat.  That is
not much of a problem with two cells in parallel.  Putting seven or eight
in parallel is dangerous.  I would put a 2A fuse or PTTC reset-able fuse
supplying each each pair of cells from the controller board.

For me this will a good way to insure power for my CPAP machine and eliminate
the need to buy another lead acid battery. The batteries are free so I will
use what I got.  I'll be reporting my experience a year from now after I've
had a chance to use it. It has been reported these have a life expectancy of
1,000 charges.  Being used, I may only get another 200 charges before failure.
In a laptop it is fairly obvious when a cell fails.  Having multiple batteries
in parallel will make finding bad cells challenging. The fuses may give a way
to isolate each string. I may find that buying another 4 cell charger and
having 7 or 8 cells in series is much easier to diagnose. With my 50V DC buss
it is easy to use isolated wall warts and power individual charge boards.

Note the board has a location for reverse polarity protection diode.  I have added that
at the in/out connection.

I smell UNO li battery tester.



« Last Edit: December 10, 2016, 03:22:52 PM by OperaHouse »

Bruce S

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Re: Daisy-chain GHurd controllers?
« Reply #5 on: December 10, 2016, 10:47:23 AM »
Basically meant the same thing.
I've been recycling the battery banks sold around here ~$2/ea. The batteries in them are the worst possible. SO when people pitch them , I play catch  :).
Along with small 6 and 12 volt solar panels, I can replace the battery with one from an old Laptop battery bank , and charge them. WE have cute little clear wine bottle lights around the house that are charged in this manner.
When I am given laptop batteries, split them up into single batteries, put them on the solar charger for about a week, then let 'em sit for a few days to see if they're holding a charge. IF they're within 1 volt I keep them, if much lower they're carted off to a recycler

My current project is build up a 12Vdc battery bank with these cast off laptop batteries so I can run my 12V 0.750a (750ma) LED grow light setup off of these. Plus I have airstones that run only 60mins a day. Those are currently 110Vac and I use a cheapo 12 100 watt inverter that runs it.

I am looking at the 3~4 board on ebay . I figure that with one of the older H.F. 15 watt solar panels I can let it charge and run everything from it.  I know the panel is old and output sucks,,, better than just throwing it away.

Thanks for the info on the resistor info too.
Cheers
Bruce S
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Bruce S

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Re: Daisy-chain GHurd controllers?
« Reply #6 on: December 12, 2016, 10:29:50 AM »
 I've found yet another source of these, the Black n Decker 19.2 unit are what I'm now finding at the big-box DIY recycle dropoffs. I take in older 12V 7Ah and swap them out. Takes a little bit of extra work to get at the batteries, but the ones they use are a good grade of batteries.


Here's what one looks like with the covers off

Here's how the batteries are setup in the drill set
« Last Edit: December 12, 2016, 01:23:37 PM by Bruce S »
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george65

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Re: Daisy-chain GHurd controllers?
« Reply #7 on: December 12, 2016, 07:44:31 PM »

I have seen quite a few people on YT making their own " powerwalls" using these recycled batteries.
They seem to put a huge amount of time and effort in them but I always wonder about their longevity. If they are using old cells and merely removed the crap ones  from the packs, whats to say that the next one won't fall over in a week or a month or that they wont' get to a point in a few months where one is falling over a day.

They seem to put a lot into testing then building the packs but nothing to diagnose bad cells or replace them easily.

Bruce S

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Re: Daisy-chain GHurd controllers?
« Reply #8 on: December 13, 2016, 09:41:32 AM »
George65;
This is why Operahouse's sketch over in the other post can be so valuable.
I take the log way around. I setup my banks, then let them take days , charging then draining with say a LED light set. Rinse n repeat.
I'm still learning to spell when it comes to writing programs. and will be years before I can get close to his level.
I learn by doing, so investigative work , like finding a bad battery is both fun and educational for me. Plus the LED lit up water bottles are kinda cute :).

Here's my latest with the test battery just visible in the back ground. I first test them with cheapo common batteries.
 
 
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