What are battery tenders?
A battery tender is a device that slowly charges and maintains your car/motorcycle battery used if you’re not going to be driving it for a long time or are storing it in cold weather.
Battery Tenders are a name-brand product made by Deltran. They’re available in two models: Battery Tender Jr. and Battery Tender Plus.
A few months ago, I had just gotten back home from being out of town for 4 weeks. I went into the garage to fire up my bike, but to my dismay, the bike just wouldn’t turn on when I turned the keys in the ignition.
The bike had been lying unused for so many weeks in the cold weather, and the battery had drained. Oops.
After a bit of research, I realized that I should have invested in a battery tender.
I found a company in the United States called Deltran. They make battery tenders, which are effectively smart chargers that maintain your battery when you’re not using it.
Most batteries will gradually lose their charge if you don’t use them for too long. In very simple terms, you may have noticed that the alkaline batteries you buy for your remotes and what not come with an expiration date!
The battery tender keeps the battery healthy by monitoring and maintaining its voltage at an optimal level.
Alternatives to Battery Tenders
The Schumacher SP1297 is a smart battery maintainer. It auto-detects voltage from 6V to 12V, and will maintain and charge your lead acid battery.
It’s rated at 3 amps, so even if you have a very large capacity battery, it will still charge it fairly quickly.
There’s also a neat hook system to hang it on your garage wall or wherever you keep your vehicles.
Battery tenders vs battery (trickle) chargers
While the basic function of battery tenders and battery chargers are quite similar: they both apply charge to a battery and prevent it from getting too discharged, there is a huge difference between the two devices which is very important to keep in mind! You can’t necessarily use one in place of the other.
1) Tenders are smart, trickle chargers are not
Battery tenders are smart devices – that means they monitor the charge that is currently held by the battery, and maintain the charge accordingly. Tenders have a built in threshold that they look out for. If the battery charge is above a certain voltage, the tender will not charge the battery. Once it falls below that level, the tender will charge the battery back to the threshold.
This means you can leave a tender plugged into the battery for as long as you want and you don’t have to worry about checking up on it.
Trickle chargers, on the other hand, are not smart. They will keep pushing small amounts of current into the battery and don’t monitor how full the battery has become. This means it is possible to overcharge your battery with a trickle charger if you leave it plugged in for too long.
Overcharging a battery will damage your battery at best, and cause a fire at worst.
2) Tenders are more expensive than chargers
Since tenders are more advanced pieces of tech, it follows that they will be more expensive than trickle chargers, which can be found for quite cheap.
3) Uses for tenders and uses for chargers
At this point, you may be wondering what situations battery tenders are good for, and what situations trickle chargers are good for.
For the most part, a battery tender will do what a trickle charger will do – maintain your battery’s voltage so it doesn’t lose its charge.
However, battery tenders are more useful for when you’re storing your bike or car for a long period of time, such as in the winter. This is because tenders are set and forget devices. You can leave them plugged in all throughout winter and not worry about anything.
A trickle charger is useful for short periods of charging, like overnight. These are useful if you don’t need to store your battery for long, but just need something to give the battery a little boost before your next use.
If your vehicle’s battery is old and loses charge very quickly, or something is causing the battery to drain even when you are not using it, the trickle charger will keep pushing some current to keep the battery going.
Get a trickle charger if you can’t justify the higher cost of the tender. However, if you’ve got the extra few $$ to spare, then the tender will do what the charger does, and you’ll have the peace of mind of knowing you can’t overcharge the battery.
How to use a battery tender
Step 1: Set up the tender
Make sure your battery tender is turned off, and find a good spot to plug it in, preferably as far away from the car as your cables allow. You also need to make sure the voltage of your battery(6V, 12V, etc) corresponds with the rating of your Battery Tender.
Step 2: Connect the terminals
Connect the positive and negative terminals from the tender to the corresponding terminals on the battery.
Step 3: Turn on the tender
Turn on the tender and you should see the red light come on, which indicates the charging cycle has started.
It will take about 3-5 hours to complete an entire charge cycle.
If the red light is blinking, it means there is something wrong with the connection, or your battery voltage is too low and it must be replaced.
If the red light is steady, it means your battery is charging.
If the green light is blinking, it means your battery has reached a suitable voltage and can be used.
If the green light is solid, your battery is fully charged.
Can you use battery tenders with a lithium battery?
Some bikes use lightweight lithium batteries, and naturally, you may be wondering if it is possible to use your Battery Tender with a lithium battery.
I fly drones as a hobby, and I work a lot with lithium batteries – so I’ve got double firsthand experience here.
DO NOT USE BATTERY TENDERS WITH LITHIUM BATTERIES!
The Battery Tender device is meant to be used with lead acid batteries, which have a very different chemistry from lithium ion batteries. The charge levels and cell counts are also different, so if you hook up a Battery Tender to a lithium battery, it won’t be able to recognize how much charge is in the battery.
Lithium batteries also do not like being over-discharged or over-charged, so to maintain your lithium battery, you must use a charger that supports them!
Don’t cheap out on a good battery charger – you’ve invested so much into your bike, so it’s totally worthwhile to get a good charger, too.
If you’re storing your bike for the winter, an easy solution to make sure your battery is not unnecessarily drained is by simply unplugging it.
Yes, it’s that easy.