Guide
Is it the charger or the battery?
A charger costs far less than a battery, so it pays to rule it out first. Here are the signs, and the one test you should only do with the right charger.
Quick answer
If the battery charges normally on a known-good charger of the same voltage and chemistry, your charger is at fault. If the problem stays, look at the battery. No light, instant full or never full suggest the charger; short range, cut-outs and heat suggest the battery. Never test with a wrong charger.
Signs that point each way
| Points to the charger | Points to the battery |
|---|---|
| No light and no fan noise when plugged in | Shows full quickly, but range is very short |
| Light shows full at once, even on an empty battery | Scooter cuts out on climbs or with a pillion |
| Never reaches full, even after many hours | Charge drops fast while parked |
| Charger very hot, smells or buzzes loudly | Pack is hot, swollen or smells |
| Battery charges fine on a known-good charger | Same problem with a known-good charger |
These are signs, not proof. A workshop test of both settles it.
Reading the charger
On many chargers one colour means charging and another means full, but this differs by make, so check the label or manual. A charger can show a normal light and still give too little current. A meter reading with nothing connected can also look fine on a weak charger. That is why we test the output under load in the workshop.
Trying another charger: only the right one
- Same voltage as your battery: 48V, 60V or 72V. Not one step up or down.
- Same chemistry: lead-acid, lithium-ion (NMC) and LFP chargers stop at different voltages.
- The same plug, fitted the same way round, and a current rating your battery accepts.
- If you are not sure, do not try. Bring both to us.
Why a wrong charger is dangerous
Lithium cells cannot absorb overcharge. A charger with a higher voltage, or one made for lead-acid, can push the cells past their safe limit. They heat up, swell and can vent or catch fire. The BMS is meant as a last line of defence, not a reason to use the wrong charger. A charger with too low a voltage will simply never fill the pack.
Questions
Frequently asked questions
How do I know if my electric scooter charger is faulty?
No light or fan, full at once on an empty battery, or never reaching full are typical signs. The surest check is a load test of the charger output.
Can I charge a 60V battery with a 72V charger?
No. It will overcharge the battery and can cause swelling or fire. Use only a charger of the same voltage and chemistry.
Can I use my old lead-acid charger on a new lithium battery?
No. A lead-acid charger works differently and can overcharge lithium cells. A lithium battery needs a matching lithium charger.
Is it normal for the charger to get warm?
Warm is normal. Too hot to hold, a burning smell or loud buzzing is not: unplug it and bring it in.
Not sure which one it is?
Bring the battery and the charger to Simada Naka. We test both for free, for any brand, and tell you the cost before any work.