Installing a Battery Tender wiring harness on a motorcycle may seem like such a basic idea that it’s not even worth writing about.
But, you never know…and new riders are coming in to the sport all the time (we hope), so why not post a quick article on installing this very important device?
It’s so important, in fact, the very first thing that happens when a new bike enters the webBikeWorld “fleet” is the installation of a Battery Tender wiring harness.
So here’s a quick overview covering some of the reasons why you should install a harness and some “how to” tips.
The focus is on the Suzuki GW250 (blog) but the concept applies to any motorcycle.
The Battery Tender SAE Harness
The Battery Tender harness is simple device that connects to the battery at one end and has a standard SAE connector at the other end, with a 15A to 25A fuse in the middle.
Once the harness is attached to the battery, a Battery Tender can be easily connected to keep the battery in top condition.
The SAE “hermaphrodite” connector used by Battery Tender is designed to prevent short-circuit if the unexposed end touches a metal part. SAE connectors of this type are also used for some types of other motorcycle accessories.
For example, a short harness is available with an SAE connector at one end and a round connector at the other end to attach a heated vest. This short harness would attach to the Battery Tender harness like the one shown below.
Also, many different motorcycle accessories can be connected to an SAE terminal on a harness attached to the battery. So buying and attaching a Battery Tender SAE harness to your motorcycle is a good idea.
Ol’ Reliable, the Battery Tender Plus.Using a Maintenance Battery Charger
Every new motorcycle owner should consider using some type of maintenance battery charger on their ride. It’s a cheap way to ensure that the motorcycle’s battery will remain fully charged and healthy and ready to go.
There are a couple of reasons why this is especially important for a motorcycle.
First, a motorcycle usually doesn’t get the same daily use as a car, so the battery may sit for days or even weeks without being charged by the bike’s electrical system.
A slow “parasitic” or “vampire” battery drain may occur, caused by power requirements from things like a motorcycle clock, LED lights on the anti-theft system (and the anti-theft system itself) and more.
The second good reason to use a maintenance charger is that many motorcycle batteries are very difficult to access underneath all the bodywork.
So it’s even more important to make sure the battery remains in excellent operating condition, which can minimize the time and effort spent in pulling the battery for charging, diagnostics or the always-expensive replacement.
A battery maintenance charger like the Battery Tender or any of the other maintenance battery chargers reviewed on webBikeWorld should be used whenever the bike is parked to keep the battery healthy and charged.
The Battery Tender Charger
Battery Tender Plus battery chargers (021-0128, approx. $45.00) have been used in the webBikeWorld garage on all non-LiFePo batteries for nearly 15 years running.
Three chargers are always on, 24 hours a day, 365 days each year and whenever the bikes are parked, they’re connected to the charger through the SAE Battery Tender harness installed on each.
The Battery Tenders have never failed. That’s pretty amazing and it gives us a lot of confidence in the product. So when the Suzuki GW250 (blog) found a new home in the garage, it got a harness also.
Battery Tender SAE cable harness.
SAE connector types.
SAE vs. proprietary connector types.
Battery Tender wiring diagram.Battery Tender Harness
A Battery Tender or most of the other maintenance chargers can be temporarily attached to the battery using alligator clips, but this usually means — at the very least — removing the motorcycle seat to access the battery.
Also, you have to use a certain amount of caution when messing about with alligator clips — sparks can fly even as you connect the clips to the terminals and that’s never a good thing with a battery and gasoline around.
So a few minutes work in connecting an “official” Battery Tender harness for around $5.00 is a smart investment. Battery Tender popularized the SAE terminal type, which makes it easy to connect the charger.
The harness has two ring terminals, red and black that, on modern bikes, are connected to the battery’s positive (red) and negative or ground (black).
An inline fuse adds protection and the SAE terminal can be routed out the side of the bike or somewhere easy to access to connect the lead from the Battery Tender or other type of charger.
Some charger brands use proprietary connectors but I’m fond of the SAE type because it’s generic, available, cheap, fairly safe and easy to use.
Battery Tender also makes 25 ft. long extension harness leads (~$11.00), also with SAE terminals on both ends, and that’s what we use in the garage.
The extension leads allow you to place the charger on a shelf somewhere in the garage near an electrical outlet and then route the lead to the bike, which can be parked some distance away.
Battery Tender warns that The UL-1236 standard requires a total of 12 feet from the electric outlet to the motorcycle’s battery terminals.
They measure this with the attached AC power cord on the Battery Tender as 6 feet, the attached SAE cable at 4.5 feet and the shorter extension cable with the alligator clips at 1.5 feet.
But obviously, it will be difficult to stretch everything exactly that far from the bike, thus you should probably always buy an SAE extension harness also — it just makes life a lot easier. (Note: They also make the 12 ft. long extension cable, part number 081-0148-12).
Follow the instructions on installing the SAE Battery Tender harness and be careful. The usual guidance is to remove the negative terminal on the battery first, then positive. Installation is the reverse; first attach the positive terminal, then the negative.
The screws or bolts on a motorcycle battery are usually small enough to fit through the ring terminals on the Battery Tender harness as shown in the photo above.
Route the SAE terminal end of the harness out under the seat or along the frame on the side or towards the rear of the bike or somewhere that is easy to access.
On the GW250, it was routed down the side and attached with a cable tie to a frame member along the side of the bike (photo below).
Under the seat of a Suzuki GW250. (L to R): Rear shock, battery, tool kit.
Single screw in rear of side cover holds the cover on the Suzuki GW250.
The side cover tabs hold the cover and fit into slots in bike. Be careful when removing!
Voltage regulator and electronic ignition under the side cover on the GW250.
Battery Tender SAE cable harness installed on the Suzuki GW250 battery.
Battery Tender SAE connector routed out the side and secured with a cable tie.Conclusion
Adding a Battery Tender harness is easy, simple and inexpensive and it can yield strong dividends over the life of the motorcycle.
Once the harness is installed, it requires almost zero maintenance; just keep an eye on it to make sure the wires aren’t getting chafed or worn.
You can use the harness to quickly connect a Battery Tender when the bike is parked and/or stored for the winter (if you’re unlucky enough to have a winter like we’re experiencing this year!).
The SAE connector can also be used for other accessories and I even connect my digital voltmeter probes to the positive and negative terminals of the SAE connector to take a reading on the battery once and a while.
It’s a lot easier than removing the seat and digging around for the battery terminals on some bikes.
Accessing the battery is very easy on the Suzuki GW250 but this isn’t always the case with other motorcycles. Just make sure you don’t forget your normal battery maintenance if you have a lead-acid or other non-LiFePo type of battery.
Publication Date: February 2014
wBW Motorcycle Battery & Charger Reviews | Maintenance & Repair Articles
Owner Comments and Feedback
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From “A.P.” (May 2016): “This article was great. However, any thoughts on troubleshooting when my trickle charges work only with alligator clips but not the SAE cable?”
Rick’s Reply: Has to be that the cable with the SAE connectors is broken?
Are you saying that this happens: You can connect the alligator clips to the battery and that alligator clip harness terminates in an SAE connector.
Then you connect the SAE connector leading from the charger to the bike and it works?
But then if you connect an SAE harness directly to the battery, it doesn’t work?
This sounds to me like the SAE harness is either broken or you’re not connecting it to the correct terminals on the battery.
From “K” (February 2014): “I enjoy looking at your website every few weeks, it’s high on my bookmark list, thanks.
I put the Battery Tender SAE Harness on my 250 cc dual sport so I could trickle charge easily and use a GPS if needed.
Afterwards during a day of trail riding my starter stopped working, luck got it to work on the trail, but at the lunchtime gas fill up it would not start again.
I pushed the bike a few hundred yards to the campground for lunch, but first took seat off to notice the battery positive terminal had jiggled loose, but screws were still in red rubber cover. Tip: Pay serious attention to lock washer arrangement with this option.
Hope this helps others.”
From “T.G.” (February 2014): “If you really want to dress up the install and make it look stock, get one of these Powerlet Luggage Electrix Connector and mount it on a plate or even through the fairing or trim parts on the bike.
That way it can’t get in the way and you have a rubber cap to seal it up. This is how I added mine to my K1200LT.”