What the Battery Tender lights mean
Solid amber or red means it is charging. Flashing amber or red means it is not. Flashing green means the battery is past 80 percent, and solid green means it is full and being maintained.
Checked against sources on by the TrueAmps editorial team.
The four states
| Light | What Battery Tender says | What to do |
|---|---|---|
| Flashing amber or red | Not charging. Voltage too low to start a normal charge, or a connection problem | Work through the three checks below |
| Solid amber or red | Charging, working towards 14.6 V | Leave it. A deeply discharged battery can take up to 72 hours |
| Flashing green | Above 80% charged, main charge done | Leave it to finish |
| Solid green | Charged, charger is maintaining the battery | Can stay connected |
| Alternating amber or red and green | Either the battery or the charger is at fault | Try the charger on a battery you know is good |
From Battery Tender's guide to its indicator lights, checked October 1, 2026.
Red or amber: it depends on the model
If you searched for a red light and your neighbour's unit glows amber, both are right. Battery Tender uses red LEDs on one model, the Plus 1.25 amp 12V charger (SKU 021-0128). It says every other Battery Tender and PowerTender charger uses amber. The colour does not change the meaning: solid is charging, flashing is not.
By that rule the Battery Tender Junior we cover is an amber model.
Flashing and not charging: three checks
Battery Tender lists these in order.
- Connections. Ring terminals fully seated on the posts, or clips on clean bare metal.
- The fuse. The quick-disconnect harness has an inline fuse on the positive lead, about an inch from the battery. A blown one gives the same flashing light.
- Battery voltage. The charger needs to see at least 3 volts. Below that, Battery Tender says the usual cause is a shorted cell.
That 3 volt floor is the practical difference from a NOCO GENIUS, which has a Force Mode for batteries under 1 volt. A Battery Tender has no such override in the maker's guide, so a battery sitting below 3 volts will not start charging on it. What Force Mode is, and why NOCO warns about it.
Solid for hours and still not green
The light turns green once the battery reaches 14.6 volts. On a small maintainer and a large or badly drained battery that takes a long time, and Battery Tender's own ceiling is 72 hours before it wants a call to support. The charge-time calculator gives an estimate from the battery size and the charger's amps.
Green the moment you connect it
Battery Tender's advice is to measure the resting voltage with a multimeter. At 12.6 volts or more the battery really is full. Under 12.4 volts with a solid green light, it says a bad cell may be stopping the charger from reading the battery correctly.
Jump starters and solar units read differently
The amber and green cycle applies to chargers and maintainers, including each channel of the multi-bank models and the solar chargers. Battery Tender's Jump N Start jump starters do not have it: their row of LEDs shows the charge left in the unit itself, like a power bank. The Charge N Start combination units carry both sets of lights, and the two work independently.
Questions people ask
Why is my Battery Tender flashing red or amber?
Battery Tender says a flashing amber or red light means the charger is not charging the battery. Its checklist is: the connections, the inline fuse on the positive lead, and the battery voltage. The battery needs at least 3 volts for the charger to recognise it.
What does a flashing green light mean on a Battery Tender?
The battery is more than 80 percent charged, according to Battery Tender. The main charge is finished and the charger is topping the battery off.
What does solid green mean on a Battery Tender?
The battery is charged and the charger is maintaining it. Battery Tender says the charger can stay connected at this stage.
Why does my Battery Tender have a red light and not an amber one?
One model uses red LEDs: the Battery Tender Plus 1.25 amp 12V, SKU 021-0128. Battery Tender says its other chargers use amber, and that solid and flashing mean the same thing in either colour.
How long should a Battery Tender stay solid red or amber?
Battery Tender says a deeply discharged battery can take up to 72 hours to reach the point where the light turns green. It tells owners to contact support if the light stays solid well beyond that.