This is more posted for educational experience, We've already solved the problem. No Photos or Video's to document this.
I was at the campground, and I was helping a friend that had just bought a used camper this year.
His complaint was the battery doesn't last long (maybe 4 hours) and even fresh off the charger, it doesn't have enough reserve power to get the slideout all the way out without leaving his truck connected. Diagnosis: Dead Battery. I (Incorrectly assumed) the battery was original to the 2016 camper. 5-7ish years is the average lifetime on a standard sealed lead-acid battery. No big deal.
The battery died at 9pm on his first night. We took photos of how the camper was connected, and he purchased two new Group 24 batteries, and some 2/0 cables to wire them in parallel. When we reconnected to the new battery, Immediately the 30amp fuse on the camper tongue blows. Weird?
We take battery out of parallel, to simplify. Still blows the fuse Immediately. (and with some pretty large sparks) We play with order of operations for a little bit. (Let's try putting the fuse in first, then connecting,. Nope. Let's try connecting, then putting the fuse in, Nope. Try turning EVERYTHING in the camper off, nope).We hook the old battery up, still works normal (just with no real power)
Now we start examining everything. In the dark at 10pm.
The fuse was on the cable connected to negative terminal. It was manually spliced in after the fact (with green wires), and we hypothesized that it was being used as a disconnect switch. (It's the only thing that made sense).
We tried a 40amp fuse, just incase the 30amp's were flaky. Nope, blew immediately.
We compare the pictures, we're hooking it up exactly the same way. We examine the "old" battery. It's dated 2019. Huh? It shouldn't be this bad off.
It's time to phone a friend. We call a friend who works on Semi's, and usually does the 12V systems on them.
We explain everything. We get silence for almost a minute. Then he asks us to take a voltage reading off the "old" battery, and send him a photo of it.
It's -12.76.
Negative 12.76 volts.
We missed the - sign on the multi-meter, because it's not backlit, and really, who expects your battery to put out negative power.
We reverse the leads (positive to negative, negative to positive), and Voilà! it works!
Semi-Guy has heard stories. If you get a battery discharged enough, and then get it on the charger backward, you can reverse the polarity of a battery. We can only assume it's incredibly dangerous to do.
Friend is going to get some colored electrical tape, and correct the wire color when he get's back. But now the fuse makes total sense, since it's REALLY on the positive side.
Just figured I'd share a fun story from the weekend.
I was at the campground, and I was helping a friend that had just bought a used camper this year.
His complaint was the battery doesn't last long (maybe 4 hours) and even fresh off the charger, it doesn't have enough reserve power to get the slideout all the way out without leaving his truck connected. Diagnosis: Dead Battery. I (Incorrectly assumed) the battery was original to the 2016 camper. 5-7ish years is the average lifetime on a standard sealed lead-acid battery. No big deal.
The battery died at 9pm on his first night. We took photos of how the camper was connected, and he purchased two new Group 24 batteries, and some 2/0 cables to wire them in parallel. When we reconnected to the new battery, Immediately the 30amp fuse on the camper tongue blows. Weird?
We take battery out of parallel, to simplify. Still blows the fuse Immediately. (and with some pretty large sparks) We play with order of operations for a little bit. (Let's try putting the fuse in first, then connecting,. Nope. Let's try connecting, then putting the fuse in, Nope. Try turning EVERYTHING in the camper off, nope).We hook the old battery up, still works normal (just with no real power)
Now we start examining everything. In the dark at 10pm.
The fuse was on the cable connected to negative terminal. It was manually spliced in after the fact (with green wires), and we hypothesized that it was being used as a disconnect switch. (It's the only thing that made sense).
We tried a 40amp fuse, just incase the 30amp's were flaky. Nope, blew immediately.
We compare the pictures, we're hooking it up exactly the same way. We examine the "old" battery. It's dated 2019. Huh? It shouldn't be this bad off.
It's time to phone a friend. We call a friend who works on Semi's, and usually does the 12V systems on them.
We explain everything. We get silence for almost a minute. Then he asks us to take a voltage reading off the "old" battery, and send him a photo of it.
It's -12.76.
Negative 12.76 volts.
We missed the - sign on the multi-meter, because it's not backlit, and really, who expects your battery to put out negative power.
We reverse the leads (positive to negative, negative to positive), and Voilà! it works!
Semi-Guy has heard stories. If you get a battery discharged enough, and then get it on the charger backward, you can reverse the polarity of a battery. We can only assume it's incredibly dangerous to do.
Friend is going to get some colored electrical tape, and correct the wire color when he get's back. But now the fuse makes total sense, since it's REALLY on the positive side.
Just figured I'd share a fun story from the weekend.
Comment