Trojan L16 REB bank - cell issue

BB.

Ideally, you want the 4 cables to be the same length.

If, you have one paralleled GC battery that has longer connections, the cables will have higher resistance and tend to limit charging/discharging current for that one battery.

Matched cable lengths (resistance), and both batteries will share current much more equally.

-Bill

Surfpath

Today we will get the 2 new golf carts. This is the present bank. Mr bad cell battery is on the left row. 3rd from front.

Surfpath

The existing cables are 2/0. Will keep this in the new batts, right?

Surfpath

Got them. They were supposed to be topped up last night, but I found SGs to be 1.225 across all cells. Sigh.
So, the plan is to remove the bad battery (the one the Orange level is on). It will leave an awkward spot to replace it with the GCs. So, the plan is to put an old but good L16 (see blue flashlight) in place of the baddie, and then put the new GCs in the new spot which has more room around it. A 6" block will make up the height.

We got four 2/0 cables made just a few inches longer, in other to accommodate the slightly longer distance between L16 and GC. We now have to read up on how to shut down the inverter and CC.

BB.

You can always reorganize your battery bank and put a "good battery" in the back (to replace the bad battery) and install the 2x GC batteries at the front for easier access+cabling.

If you start with the GC batteries at the (roughly) same SG as the rest of the battery bank, that should work fine (you want "all batteries" to be at the "same" state of charge in the series string).

-Bill

Surfpath

Ready to make the final bank hookup. New batts in parallel as per the diagram in thread above. Any final thoughts?

BB.

Looks good. There is a small black wire next to the wall (thermal sensor?). Make sure is not pinched by the batteries. And longer term, get a open end/box wrench to do the cabling (not a Crescent Wrench which is bigger/more clumsy and more likely to round off the flats on your hardware).

For tools working on battery banks, remove rings/jewelry, wrapping the handles/rest of the tool with electrical tape to reduce the chances of accidental shorts is highly recommended (many electricians re-wrap the tools every time time they do a new job just to be safe). And use a face shield/goggles/glasses to protect against acid spills/battery explosions (lighting off hydrogen inside the cells).

Good luck and let us know how "patching" your battery bank works out for you.

Take care,
-Bill

PS: If you have corrosion issues, using Vaseline or some sort of battery terminal compound will help keep the terminal ends clean and electrically connected.

Surfpath

Thanks. Good advice. Here's where we are now. Our Flexpower system does not appear to have a battery breaker between the bank and the charge controller. ?? The manual sucks.
We went to attach the main positive lead that goes to the inverter to complete the circuit, and got a spark that was a little unsettling. Could just be the 48v. Calling outback now to confirm. Hopefully they are open on a Sunday.

Surfpath

Outback service is not open.
Nowhere on the unit is there a battery disconnect. Just an inverter disconnect. That's the big breaker in photo. When I turned that off to shut down the system earlier today the controller stayed on, meaning it still got power from the bank. So technically there is no breaker from bank to controller. Battery status is For the FNDC, battery monitor.
Grrr. Maybe you just have to get sparks as you connect the final lead.

Aguarancher

You definitely want a breaker between the controller and the battery bank. Good news is you already have a place for it. Also make sure the solar panels are off before you connect your controller.   

Estragon

+1 on adding a breaker. One failure mode for charge controllers is apparently a short, which absent the breaker could make for a really bad day.

Making sure pv breakers are open and opening inverter breakers should minimize sparking, but charging CC caps etc may still spark a little.

Surfpath

Update. I have held off making the last connection, ie. between the negative post of the last battery in the series and the cable that goes to the flexpower unit (FP1). I'm Going to wait until I have confirmation that there really is no CC to battery breaker on the FP1.
The thing is, I remember vaguely, that when I last did this 6 years ago when installing the new unit, we had to connect the bank by attaching the cables, as opposed to flipping a breaker. Again, grr

Surfpath

Agreed.The unit should have come with a battery to cc breaker. It's an all inclusive thing. Perhaps I'm just missing it??
In the attached photo of all the DC breakers on the unit, just to the left of "controller disconnect" is a "pv array gfdi". So not really a controller disconnect.
I tried turning off the battery status breaker (which i am pretty positive is for the fndc battery monitor, but it still sparked.
So taking a pause. May have to call outback in the morning, PST.
The fridge is on the genny..

BB.

Check the wiring for the Ground Fault Breaker... It could be on the PV to Controller input, or it could be installed in the wiring between the controller and the battery bank (your "controller disconnect" breaker--Either is "legal", but the second gives you both ground fault and controller to battery disconnect).

-Bill

Surfpath

Hi Bill,
Yes, we also thought that, because the wiring for the "battery status" breaker does go to the gfdi, then to the controller. So we (the wife) flipped off the battery status breaker and tried to connect the last lead....but same thing. Sparks, and the controller fan came on. She removed the lead. That's when we took a break from the solar room and came up for lunch.

BB.

Yea, the "fun" of making up "hot" battery bank connections. There are always capacitors somewhere in the system that need to be charged up--And can give you a healthy spark when you make the first connection.

And why you need to be really careful around the Lead Acid Cells, that spark can be enough to touch of the hydrogen in the cells. I cover the cells nearby with a damp towel/scrap cloth to help prevent that issue.

Just expect the spark and make the connection (as long as it is not a big plasma flash, like arc welding, you should be fine).

-Bill

Surfpath

Bill
Duh...of course it was the green Gfci breaker that is also the controller to battery breaker. Just like you said, it was "installed in the wiring between the controller and the battery bank". Silly me. The wife figured it out when she read your post.
So everything is now back on, 50.2 volts. Looks ok. Will let it bulk then will check SGs too make sure the new batteries are roughly the same as the old.Will perform a short eq if necessary, if we still have sunshine left.
Thank you, thank you..

BB.

We must never admit our mistakes to our wives... I will keep it secret if you will. We will never hear the end of it.   

-Bill

Surfpath

Amen, brother Bill, you speak the gospel.

JRHill

Wow, there is a lot it this thread. I got here from the Outback Forum. Nothing to do with the OB stuff but I've had my Trojan problems and the 8uckins from the dealer on warranty. Sigh.

I'll have to read and reread this thread.

Saggys

Your wife sounds like a "keeper" to me, smart gal.