Battery Care & Storage (Mobility Scooters & Power Wheelchairs)
Battery Care & Storage (Scooters • Power Chairs)
Batteries are the #1 cause of “won’t run” and “short range” problems. The good news: a few simple habits can add months (sometimes years) to battery life and prevent the most common failures.
Troubleshooting pages: Scooters • Power Chairs
What kind of batteries do you have?
Most common: Sealed Lead Acid (SLA / AGM / Gel)
- Usually 2 batteries (24V system): 12V + 12V
- Heavy, very common, works well when maintained
- Hates sitting discharged (sulfation)
Some models: Lithium
- Lighter weight, good cycle life
- Often uses a special charger + battery management system (BMS)
- Storage rules are different (don’t store fully drained)
Daily habits (best battery life)
Charge after use
- Plug in after each day of use (or after heavy use)
- Don’t run them “until dead”
Don’t store low
- If you haven’t used it in a week, top it off
- Low battery for weeks = sulfation
Keep connections tight
- Loose terminals cause voltage drop + heat
- Heat damage kills connectors/controllers
Charging rules (what to do + what not to do)
Do
- Use the charger made for your battery type and voltage
- Let it complete the full charge cycle
- Charge in a dry, ventilated area
- Keep the charger unplugged from the device when driving (obvious, but common)
Don’t
- Don’t use a random charger “that fits”
- Don’t store the unit discharged
- Don’t ignore a charger that gets unusually hot
- Don’t keep trying to drive if connectors are heating up
Storage (weeks to months)
For SLA/AGM batteries
- Fully charge before storage
- Recharge weekly (best) or at least every 2–3 weeks
- Store in a cool, dry place (not freezing)
- If the unit has a power switch, turn it off to reduce slow drain
For lithium batteries
- Store around 40–60% charge (not empty)
- Top off every 1–3 months (depends on BMS/pack)
- Avoid leaving at 100% for long periods (if your manual advises against it)
- Use only the correct lithium charger
Cold / winter tips
Lead-acid (SLA/AGM)
- Cold reduces available capacity (range drops)
- Charge indoors if possible
- Don’t leave fully discharged in freezing temps
Lithium
- Avoid charging when the pack is very cold (some BMS will block charging)
- Warm up indoors before charging if it’s been outside
- Cold can temporarily reduce output/range
Terminals, corrosion, and “hidden” voltage loss
What to look for
- White/green buildup on terminals
- Loose nut/bolt that lets the cable rotate
- Heat discoloration on connectors
- Cracked fuse holder / loose breaker
Why it matters
- Resistance causes voltage drop (weak/slow)
- Resistance creates heat (melts connectors)
- Voltage drop can trigger fault codes
When to replace batteries
Common “replacement time” signs
- Range is much shorter than it used to be
- It powers on but faults on hills/starts (after terminals are confirmed tight)
- Charger goes green too fast or never completes a charge
- Batteries test fine at rest but fail the load/sag test
Replace as a matched set
- Most 24V systems use two 12V batteries in series
- Replace both together (mixing old + new reduces life and performance)
- Confirm correct size (U1, Group 24, Group 34, etc.) and terminal type
Battery FAQ
Should I leave my scooter/power chair plugged in all the time?
Many modern smart chargers can maintain batteries, but not every charger behaves the same. If your manual says it’s OK, it’s usually fine. If you notice the charger running hot, batteries getting warm, or the charger never stabilizes, don’t leave it unattended long-term.
If you’re unsure, a safer routine is: full charge after use + top-off weekly during storage.
Why do batteries test “okay” but the unit still cuts out?
Resting voltage can look normal even when batteries are worn out. The real test is voltage under load (sag). That’s why the sag test is so useful.
Use: Load/Sag Test
How long do mobility batteries typically last?
It varies with usage and care, but the biggest life factors are: avoiding deep discharge, not storing discharged, and keeping terminals tight/clean.
Can I upgrade to lithium?
Sometimes — but only if your unit and charger/controller system support it (or the lithium kit is designed for your model). Lithium upgrades are not “one size fits all.” Use the correct charger and follow the kit/manual instructions.