diy solar

diy solar

CALB 200 Amp smoke

emeraldcoastcamper

New Member
Joined
Dec 12, 2019
Messages
109
I have (4) CALB 3.2V 200AH cells connected to make a 12.8V battery, Terminal connections are with copper pipe I flattened and drilled. The cables to the inverter are 1/0 welding wire. During a 120 AH event I noticed a burning smell and then smoke coming from one of the terminals. The wires were very hot to the touch. This battery has been in use about 30 months in my travel trailer with no noticeable problems. I have removed the battery to my garage workbench and want to do some testing. How do I re-create the large amp draw that caused the smoking without using my 3000 watt Magnum inverter? Is there a bench test device that is capable of performing this test. Visually the cells look good, with no swelling, or discoloration on the terminals. Each cell is reading 3.33 Volts. Oh, the BMS is a Daly 12V 80 amp.
 
There are battery testers which compress a carbon stack as variable resistor.

Probably this was a connection that loosened or oxidized. Possibly bad crimp.

What I'm doing to make high AC current for circuit breaker testing, without high wattage, is use a current transformer. I wire a 240V/120V transformer in series. Connect that in series with 1800W space heater for 15A at 120V, short 120V winding to get 45A opening to 40V. Using that concept but more heaters for more current I produced 100A to fast-trip a breaker. I've just wired three transformers for 3-phase and am in the process of cascading them to boost current twice.

But that doesn't help for cell terminal, where you can't access both ends. If you had cells series/parallel so multiple busbars or busbar and cable on one terminal, it could test those connections. However, oxide of cell terminals would be a possible source of the problem, and not testable this way. Or maybe it is? 60 Hz micro-cycle of cell? Only at lower SoC to avoid over-voltage! (I disavow any responsibility for the risks of connecting a lithium cell to house wiring.)
 
Rather than attempting to recreate the situation simply go buy some proper terminals. Copper corrosion is much less conductive than pure copper which creates resistance to current flow thus heat.
 
Best to test in place with existing equipment. A no touch thermal sensor should be in your RV tool kit.

Temporarily disconnecting and moving the battery is enough to mask the issue of a loose connection. 3000w inverter seems a bit large for that battery.
 
I would just remove and inspect your buss bars. My bet is you will see the offending spot. If it is hot enough to smell it will leave marks.
 
So is your opinion that pipe can not be used with success? Because if that is the case YOU would be wrong.
I almost went down this road.
But then it occurred to me... $2600 worth of batteries, $1000 for various tools and parts, $1800 for inverters, et al.
Why am I trying to save $30 or 40 on proper, FLAT busbars.
Even experimented with several flavors of pipe. Hammered, used a vise. I was unable to get a flat enough surface on the copper.
Oh, they look great, flat until I put a stainless flat edge across them and inspected with a magnifier glass
No bueno. Especially with high current.

I suggest you get some proper bus bars between the cells.
 
McMaster carr sells copper bar stock...A 3kW magnum needs 4/0 wire. and an 80A BMS is way too smalll...
 
Back
Top