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Author's Note:
Deep-cycle batteries are the literal power behind a power wheelchair, and in this way, batteries are among the most vital components to a user's mobility. As power wheelchair users, it's important that we recognize batteries as “living” components, where they require consistent care and attention.  And, in giving our batteries the proper care and attention – tending to them on a daily basis – we dramatically improve the reliability, longevity, and performance of our power wheelchairs.  My hope is that you will use these Power Wheelchair Battery FAQs to better understand the use and care of your wheelchair's batteries, where your batteries will serve not as a limiting factor in your life, but as liberation, providing the power needed to continually move your life forward.


What type of batteries do power wheelchairs use?
Power wheelchairs use “deep-cycle” batteries, designed to be discharged and recharged time after time (a stark contrast to common automotive “starting” batteries that are not designed for repeated deep discharging and recharging). Deep-cycle batteries for power wheelchairs are of the gel or AGM types, and are commonly referred to as “sealed” because they cannot spill, nor do they require the periodic adding of water. (“Wet cell” or “flooded” deep-cycle batteries, which require periodically adding water, are not recommended for power wheelchairs, as they can spill harmful battery acid and do not meet many transit requirements.)

Is there a break-in period for new batteries?
Deep-cycle batteries must experience a “break-in” period to reach full capacity and ensure longevity. Firstly, new batteries should be fully charged before the initial use. Secondly, during the first ten uses, one should not to dramatically deplete the charge, only using up to approximately 30% of the power wheelchair's charge, if possible, before promptly, fully recharging. This process will maximize battery range and lifespan in the long term.

How often should I recharge my batteries?
After every day's use, without question, you should recharge your batteries – do not go multiple days before recharging the batteries. In fact, batteries discharged to 50%, then immediately recharged, have double the lifespan of batteries discharged to 80% over several days without charging – so, it's vital to recharge batteries after every day's use, even if you only use your power wheelchair minimally each day.

Should I fully discharge my batteries before recharging?
Deep-cycle batteries should never be fully discharged, as it will rapidly destroy the batteries. Only use a power wheelchair as much as needed, avoiding fully discharging the batteries, and always recharge the power wheelchair as promptly as possible.

Is periodically recharging for a short time during the day as a “boost” helpful or harmful?
“Boost” charging ultimately harms deep-cycle batteries. Most power wheelchair battery chargers function in three charging stages to optimize the capacity and maintain the batteries. Regularly plugging in the charger for short bursts throughout the day does not allow the charger or batteries to go through the proper charging stages and durations, ultimately destroying the batteries. It's important to only fully recharge your chair after each day's use, avoiding boost charging in-between full charges.

How long does it take to recharge a power wheelchair?
It varies toward how long it takes a particular power wheelchair to recharge, based on the size of the charger, the size of the batteries, and the batteries' level of discharge. However, most power wheelchair manufacturers match the charger size to the battery size, so that an 80% discharge takes approximately 8 hours to recharge. Nevertheless, again, there are variables where an individual power wheelchair may take 10 or 12 hours to charge accordingly. Also, it's important to recognize that older batteries take longer to recharge than newer batteries, so recharging time varies over the lifespan of the batteries.

Can my batteries be overcharged?
If using the battery charger that came with the power wheelchair, per the instructions, with appropriate deep-cycle batteries, the batteries cannot typically be overcharged. Power wheelchair manufacturers use automatic battery chargers that constantly monitor the recharging process, turning off the charger when the batteries are fully recharged. For this reason, only a battery charger specified by the power wheelchair manufacturer should be used.

Is it harmful to undercharge my batteries?
Undercharging a power wheelchair will cause reduced range, as well as rapidly destroy the batteries. If you continuously use your power wheelchair before it's fully charged each morning, the batteries remain in a depleted state, which will cause rapid deterioration of the batteries. Whenever possible, avoid using a power wheelchair before it's fully charged.

How long can I leave the battery charger plugged into my power wheelchair?
Most power wheelchair battery chargers turn off automatically when the charge is complete, so there's no direct harm in leaving the charger plugged into the power wheelchair. However, battery chargers are subject to other dangerous factors, such as power surges from the home's utilities service, which may damage the power wheelchair. Therefore, it's recommended that you unplug the battery charger from the power wheelchair as soon as possible after recharging.

Can I use a different off-board battery charger than the one that came with my power wheelchair?
Battery charger plugs and power wheelchair charging port wiring patterns vary among manufacturers, so when one plugs a different charger into a power wheelchair, although the plugs may fit together, the wiring pattern may not match. If the wiring pattern is not the same, not only won't the wheelchair charge, but the battery charger may receive damage. For this reason, one cannot assume that an aftermarket off-board battery charger is compatible with a particular power wheelchair, and one should always confirm a battery charger's compatibility with the manufacturer before plugging it into the power wheelchair.

Do cold temperatures affect my batteries range?
The standard operating temperature of deep-cycle batteries is room temperature, 77F. Accordingly, battery capacity – or, range – decreases with lower temperatures, where operating a power wheelchair at 32F will decrease range by approximately 20%. Additionally, varying temperatures can adversely effect the recharging process, which is why batteries should ideally be recharged at room temperature.

How do I know if my batteries are safe for air travel?
Most gel and AGM deep-cycle batteries are air travel approved, and feature a label on the battery that reads to the affect of: “Sealed, non-spillable battery. F.A.A., C.A.B., I.A.T.A. And D.O.T. air transport approved.” One should ensure that the batteries feature such labeling when traveling by commercial carrier.

How do I charge my North American power wheelchair on 220-240 volt AC systems in Europe and abroad?
Most power wheelchair manufacturers have 220-240 volt battery chargers available that simply plug in and recharge existing North American power wheelchairs when overseas. Alternatively, a heavy-duty transformer can be purchased from electronics retailers, allowing the use of a 110-120 volt charger overseas when properly matched.

Can I hook up a 12-volt accessory to one of my batteries?
A 12-volt accessory should never be hooked to a single battery in a power wheelchair. Power wheelchairs are 24-volt systems, with the batteries connected in series. If you drain one battery, the charger will not equalize the batteries. The result is one depleted battery, and one overcharged battery – a combination that will destroy the batteries.

What's the lifespan of deep-cycle batteries?
Battery life is directly related to how deeply they are discharged use after use.  If a battery is discharged only 50% each day, it will have double the lifespan of if it's routinely discharged 80% (this is why it's inadvisable to use a power wheelchair several days before recharging the batteries). In everyday terms, someone who dramatically drains the batteries everyday may only get a year or less out of a set of batteries, where as a light users, who recharges fully after every use, may get several years of battery life. (Of course, poor charging habits overall will reduce the lifespan of the batteries, as well.) Still, this doesn't mean that one can't occasionally dramatically drain one's batteries; however, the less one repeatedly discharges batteries over the longterm, the longer they'll last.

My provider says that he tested the batteries, and they're fine, but my chair still isn't holding a charge – why is that?
Bad batteries often pass all tests, showing a false capacity. If the plates are sulfated or damaged, the batteries can read as a fully charged, but be functioning with limited capacity, where range is greatly reduced.

How should I store my batteries?
It's recommended that batteries are stored in a cool, dry place, but not below 32F, and charged every one to two weeks, ensuring that they remain fully charged, preventing deterioration. Stored deep-cycle batteries, including those installed in a stored power wheelchair, lose up to 15% of there charge each month – and if left uncharged, sulfation will destroy the batteries. Also, extreme heat can cause the lead within the batteries to deteriorate, so storing them in room or cooler temperatures is important.

Can seemingly dead, sulfated batteries be revived?
The answer is, sometimes. If batteries are sulfated – for example, from sitting “dead” or from poor charging habits – fully charging them, then using them for 5 charge/use cycles can sometimes remove much of the sulfations, restoring substantial battery performance. To do this, fully recharge the batteries, which may take much longer than normal, then use the batteries, depleting them – then repeat the cycle 5 times. This process of charge/discharge can remove sulfation, restoring the batteries' performance if they're not critically damaged.

Where can replacement batteries be purchased?
Deep-cycle batteries for power wheelchairs are not only available through mobility providers, but also from retailers who sell a wide range of batteries. Some retailers have cross-references for deep-cycle battery applications specific to mobility devices, while others label deep-cycle batteries as RV/Marine (it is important not to confuse RV/Marine deep-cycle batteries with “marine starting batteries” – if the marine battery has a MCA or CCA rating, that typically means that it's a hybrid starter battery, not designed for true deep-cycle use). In any case, the vital factors to note in replacement batteries is that they are deep-cycle and sealed, of the proper Group size and physical dimensions, with compatible battery terminals.

Are there different qualities of deep-cycle batteries?
As with most product categories, deep-cycle batteries come in a varying quality, where higher-quality batteries have thicker plates, better quality control, and sounder overall construction for a longer-lasting battery. Unfortunately, it's all but impossible for one to look at batteries on a shelf, and tell their quality. Nevertheless, one typically gets what one pays for, where sticking to known, proven brands most often results in a quality battery.

Can new batteries be bad from the dealer?
Quality deep-cycle batteries have a shelf life of approximately 6 months, at which point shelved batteries should be suspect -- that is, batteries sitting on a dealer's shelf for too long can be sulfated when placed in a mobility product as "new." Also, off-brand, poor-quality batteries have failure rates, including bad cells, resulting in reduced range and abnormal charging.

Published 5/08, Copyright 2008, WheelchairJunkie.com