Dumbest noob battery question of 2021?

mmcneil72

Hi T@B Nation:

Continuing saga of battery gremlin chasing enters a new and stoopid phase.

Reconnecting Interstate SRM-24 battery (OEM from 2017 perhaps?) and OF COURSE I didn't take a picture of the wires connected to the battery.

One red, one green (red goes to fuse holder, green comes out) and two white leads.  Pretty sure the two whites are NEGATIVE, but want to make sure before connecting.

Very likely this SRM-24 battery is dead anyway - failed a test at the Interstate dealer - just want to get this right in my head, since battery issues seem to cause a fair amount of problems in T@B world.

Contemplating an SRM-27 as a replacement, just hooking the old 24 up to check fuses etc. in trailer once shore power is connected.

TIA,

Mike Mc

Sharon_is_SAM

If you have a 2017 TaB with the solar port on the propane tub, you should have a red and white cable extending from that port to the inside of the tub.  The red is positive and goes to the “+” battery terminal and the white is negative and goes to the “-“  battery terminal. 

The main TaB battery cables are the green cable that holds the fuse holder and is spliced into a red cable - that also goes to the “+” terminal of the battery.  The other white cable goes on the negative terminal of the battery.  Here is a picture of mine. 

(Ignore the thin, red cable as it supplies the charge to an optional Victron  battery monitor.)

Make sure you put the main negative cable on last.

mmcneil72

Thanks Sharon!  The saga continues... trying to sort things out for a 3 day camping trip, our second.

Samrollseyes

@mmcneil72. Take an extra fuse to change if you mix the wires up. Not saying who but her initials are Samrollseyes crossed the wires and fortunately only blew the fuse. THAT was a cold evening. Pretty easy fix. But now I actually have it written in sharpie on my battery🤣🤣

Sharon_is_SAM

@mmcneil72 - your battery fuse should be 30 A.  Don’t forget to check the converter/fuse box Reverse Battery Protection fuse - just to make sure😉

pthomas745

If it makes you feel better, this "Dumbest Noob Question" gets asked quite a lot!  This is my 2017 battery setup.

tybladesmith

As @Sharon_is_SAM says, always connect the negative battery connection last, but also disconnect the negative lead first.

With the negative lead of the battery disconnected there is no circuit to cause an arc.

If the positive lead is being disconnected first and the wrench makes contact with any grounded surface -

all the amps in the battery are available to weld your wrench and burn body parts and arc flash your eyes.

Don't be that guy! 

Also, turning off the battery cutoff switch does not disconnect the negative wire from the battery.

This should be the first lesson in Electricity/Batteries 101
Sorry for the rant.

Ratkity

When dealing with battery connections, remember the negative wires are like the Marines - they are the first ones in and last to leave (works with jumper cables too).

BrianZ

But, @Ratkity, the Marines are a very positive bunch!

ScottG

Ratkity said:

When dealing with battery connections, remember the negative wires are like the Marines - they are the first ones in and last to leave (works with jumper cables too).

At the risk of appearing nitpicky, I've always found this time-honored statement confusing (and potentially dangerous).

If you are talking about battery terminals, the negative cable should be the first to leave the battery when disconnecting, and the last to arrive at the battery when reconnecting.

As @tybladesmith implied, mucking about with the positive terminal while the negative terminal is still connected may result in an impressive fireworks display and a prompt change of underwear.

You can learn it here, or you can learn it the hard way!  ;-)

Ratkity

@ScottG Yes, it's backwards when disconnecting, and then you have to be careful which battery to start connecting to if you are jumping a vehicle. Of course, here I am again, changing the topic! 

Lesson learned: Take a picture of the wiring before messing with it.
Another Lesson I learned: Before you leave the lot with your new camper, take a video of the walk-through. It goes really fast and you think you got it all (meh, I didn't ).