Brown discharge on Bumper - Dual 6volts

Lawrence A · 07-12-2021, 12:01 PM

I recently added a SAE solar port directly wired to the batteries on my 2018 17B. This connects a 180W portable with its own controller in addition to the factory 170W panel on the roof. Checked to ensure polarity is correct but I'm a neophyte when it comes to electricity so not too sure I've done it correctly. Went to Tofino, BC recently and it all seemed to work really well. Batteries recovered much better with the additional panel. However, after I returned home I noted this brown discharge on the back bumper. It's clearly dripping via the battery cable outlets on the cover of the battery boxes and is about the same below both batteries. The battery posts themselves do not show any corrosion.

Is this something to be concerned about? Have I got the wiring wrong? Is it a result of a high charging rate? The only other thing I can think of is, being Tofino, humidity was often very high, with occasional drizzling rain. Could excessive moisture inside the battery box cause this?

Any help would be appreciated. Thanks.

Lawrence

Brian B-P · 07-12-2021, 12:15 PM

It's possible that's not a brown discharge, but rather an acid discharge causing rust on the steel bumper. That would suggest an excessive charging rate, or maybe just loose battery caps and spilling acid due to the rough ride.

Lawrence A · 07-12-2021, 12:36 PM

Thanks for the quick reply, Brian. Yes, it's a pretty rough road to Tofino. Tossed the trailer quite a bit. On a second look I see the "discharge" was splashed quite a bit around the inside of the battery box. A while back I had the box covers off for a few days and rain got in there. Maybe just sloshing from a wet/dirty battery box? I wiped the stain off the bumpers and it did not appear to have affected the paint. Would that be an indication is not likely to be battery acid, or is it too early to tell?
Also, the electrolyte levels do not seem noticeably down which would indicate not an acid spillage issue.

MVA · 07-12-2021, 12:47 PM

Agreed - It appears that you are over charging the battery. If so, hydrogen and oxygen are are produced at the battery plates via water electrolysis. These gases are facilitating evaporating sulfuric acid (battery acid) out of the battery via the vent holes. Sulfuric acid is extremely corrosive to steel/iron.

In addition to checking for overcharging, check water level in battery. Use a baking soda water solution (1/4 cup in a pail of water) to wash the bumper, bat box, etc., then sand bumper and paint with a rust inhibiting paint (e.g. rustoleum).

2 cents

edit - just say your comment on the rough road. Still would clean up with soda and paint.

noblets · 07-12-2021, 12:47 PM

The dual battery boxes on our 17A had no drain holes and accumulated water inside, which spilled out onto the bumper and rusted like yours. I drilled a couple a small holes on the back bottom corners of the boxes, which helped.

cpaharley2008 · 07-12-2021, 01:09 PM

I drilled some drain holes in the bumper, it was was full of liquid also.......

noblets · 07-12-2021, 02:34 PM

Quote:

Originally Posted by cpaharley2008

I drilled some drain holes in the bumper, it was was full of liquid also.......

Well. that's interesting!

noblets · 07-12-2021, 02:34 PM

What about the frame?

cpaharley2008 · 07-12-2021, 02:35 PM

Just do not lay underneath when drilling.........you may get wet........

the frame is attached to bumper. I assumed the liquid came from the frame. Maybe I did both, my chemo brain is not too clear these days.

MVA · 07-12-2021, 03:04 PM

Thanks for the info. I thought (incorrectly) that the frame/bumper was sealed. Clearly not.

Brian B-P · 07-12-2021, 05:47 PM

Quote:

Originally Posted by Lawrence A

Thanks for the quick reply, Brian. Yes, it's a pretty rough road to Tofino. Tossed the trailer quite a bit. On a second look I see the "discharge" was splashed quite a bit around the inside of the battery box. A while back I had the box covers off for a few days and rain got in there. Maybe just sloshing from a wet/dirty battery box? I wiped the stain off the bumpers and it did not appear to have affected the paint. Would that be an indication is not likely to be battery acid, or is it too early to tell?
Also, the electrolyte levels do not seem noticeably down which would indicate not an acid spillage issue.

That's good news. A relatively small hole in the paint can lead to a large rust stain, but if the paint appears to be intact then it's not the acid and rust situation.

Lawrence A · 07-13-2021, 02:09 PM

Thanks for your help, everyone. I think for now I'm going to go with the theory that the issue was water build up in the battery box that picked up a rust-stain colour and then splashed out onto the bumper during a rough ride. I don't think it's a battery acid problem. It may be an over-charging problem, but I've no idea how to test for that and both controllers seem to be working/reporting just fine. It will be at least another month before I'll be using my portable solar panel again so I'll have to wait and see if I get the same residue again then. In the meantime I'm drying out the battery boxes and will clean everything up which will help the diagnostic process in case this happens another time.

Vermilye · 07-13-2021, 02:15 PM

Quote:

Originally Posted by Lawrence A

Thanks for your help, everyone. I think for now I'm going to go with the theory that the issue was water build up in the battery box that picked up a rust-stain colour and then splashed out onto the bumper during a rough ride. I don't think it's a battery acid problem. It may be an over-charging problem, but I've no idea how to test for that and both controllers seem to be working/reporting just fine. It will be at least another month before I'll be using my portable solar panel again so I'll have to wait and see if I get the same residue again then. In the meantime I'm drying out the battery boxes and will clean everything up which will help the diagnostic process in case this happens another time.

You might be surprised by the amount of acid that gets splashed out of the batteries, even with the caps "securely" closed. I had to clean the tops of my 6V batteries in the 17 fairly often, I also had acid spots on the rear bumper. I wire brushed them & painted with Rust-oleum...

gbaglo · 07-13-2021, 02:21 PM

I'm using this stuff and their cleaner from Canadian Tire.

MotoMaster Battery Protector detects acid, neutralizes acid, and protects against corrosion
Protects batteries after cleaning with MotoMaster Battery Cleaner
Size: 170 g

Lawrence A · 07-13-2021, 02:58 PM

Aaarrghh! OK. So looks like wet cell batteries can be a pain, no matter what. I'll go get the battery protector Glenn has described. Based on Vermilye's and others' experiences of battery leakage, I'll seriously look at AGM batteries when it comes time to replace in a few more years. Maybe even lithium if the price comes down enough.

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