Re: #ubitx Powering options? #ubitx

Michael Hagen
 

It is really not a good practice, why would you want circulating currents eating up batteries until equilibrium is met?

Ford made the decision to do it?  They had their reasons.

For Me, I would have never done it.  And I worked for Ford Aerospace for  a lot of years.  Yep, wonderful Newport Beach, Ca.

I did not to get in on that decision, they probably would not want my comments!.  It is not the right thing to do?

I guess if it works, OK?  They have sold lots of trucks.

Just buy  both batteries when you change.  Hope they are matched?  $150 ea.

Mike, WA6ISP






On 1/15/2018 5:47 PM, Jerry Gaffke via Groups.Io wrote:
You're right, it's not a good idea to blindly parallel a bunch of batteries. 
But it can work just fine if they are of the same size and age and charge state.

If one has more internal resistance, that just means the other one will be doing more of the work.

However, if you connect them when not equally charged, one will charge the other.
In some cases the currents involved while the charge states equalize are excessive, far beyond
what either battery is rated for.  Could easily have an explosion.
Something to keep in mind, especially with Li-Ion batteries or large lead acid batteries.

Once the batteries in parallel reach the same charge state, there won't be any 
currents bouncing around. 
 
I have several of LED headlamps I bought on the web. 
Each has two 18650 Li-Ion batteries in parallel, they feed the LED through a resistor.
I doubt these particular 18650's have any kind of over-current protection, as the headlamps were quite cheap.
Use them all the time, work great.  And keep their charge just fine when sitting on the shelf.

We're off grid, I started out with  used golf cart batteries, wiring up multiple banks in parallel.
Around 10 KWH worth total, all having different histories and ages.
If anything, any extra internal resistance due to aging would have helped prevent excessive currents
if I had connected them in parallel without first bothering to check if the voltages were reasonably close.

Jerry, KE7ER


On Mon, Jan 15, 2018 at 04:14 pm, Michael Hagen wrote:
You do not want to parallel batteries, difference in internal resistance will cause one to try to charge another, and around we go, a circulating current between the batteries that will run them both down.  And we don't even get to use the power!

-- 
Mike Hagen, WA6ISP
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