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Powerchair & Scooter Batteries, and Disabled vehicle batteries.

See also:  Inverters and Chargers  &  All about Powerchair and vehicle batteries and  Powerchair Battery State of Charge & Which batteries to buy or Detailed PowerChair Only Menu

Almost "any" batteries will work
to a degree in most applications but which batteries do I really want, which are best for which job and why? 

Well for reasons that will become clear later you actually really want a GOOD deep cycle battery on your mobility vehicle as well as on your Powerchair or Scooter.  Nothing else will do. 
We don't do simplified dummed down answers on this site,

 

There is actually a HUGE difference between all those different battery types.

3 major sealed types of battery in powerchairs... This describes them all.

Sonnenschein + MK gel = same thing. MK bought the rights to use the technology. Both are good and give exceptional service life in un demanding powerchairs, that don't pull many amps. for older people, low amp controllers, or mushy programming where you cant tell the difference anyway. So anything from Pride or similar then! They use starved acid by VOLUME to protect plates from deep discharge damage, so start ok when charged then go pretty "weak" (higher resistance) when discharging. They need a full 8+ hours, up to 12 hours at 14.1v MAXIMUM to FULLY recharge and return all the deep plate sulphate crystals to the acid. 14.1 is safe, more like 14.4 puts voids in the gel and you lose capacity as well as gain resistance, and it doesn't recover. Or they will not give full service life. Since mobility chargers seldom do this they have a shorter life than they should! Mostly they get too many volts, and cut off way too early before charge is really complete. Some mobility chargers (good ones!) are 3 stage. So go on to "float" after main charge is complete. So they should be left connected as long as possible AFTER charge to try and top up the missing couple of percent.

Odyssey and other pure lead plate batteries (Odyssey, Stinger, Exide, etc) can use stronger acid and so are lower resistance because they do not need to protect the pure lead plates (no added zinc, carbon, calcium etc for strength) as there's less corrosion deterioration on deep cycling. So these offer better performance, lower resistance even when discharged, less Peukert, so more of the actual Ah is available for use. And they naturally charge much faster. And they will start a truck in mid winter when half flat... They need 14.7v CC/CV until 100thC and high float for a few hours, or CV to 1000th C to get 450 to 500 cycles. Or they too will have a short life. These kind of batteries are easy to recognise by the huge CCA, CA, 14.7v charge voltage, cost, figures!

Deep cycle cheap batteries, there are loads, like the Full River, and Haze, Power Batteries etc are all usually AGM, are high resistance. Because they have to use a weaker acid as they use calcium or other metals alloyed into the lead plates for strength and cost reasons. Stronger acid causes them electrolytic corrosion when deeply cycled. So these are usually higher capacity, (more but thinner plates because of the zinc/calcium strength) but high resistance with low CCA figures (or none as they cant) because of the weaker acid and only suitable for low current or constant current operation. Or my grandma. They don't last as long either. 300 to 400 cycles max. 14.4v charge max usually. Or the alloyed metals cause gassing and venting.

 

In ALL cases fit the BIGGEST battery you can. Often you cant fit bigger though without serious modification. You cant do much about this limitation other than fit the biggest battery you can in the space provided. Sometimes in a car or van that's easy as the battery fitted may be pretty small compared to the battery mounting tray size. In a scooter or powerchair that isn't often the case so your stuck. (Well you actually can change this but its not easy!)


So what do you look for?  Read the batteries technical info sheets! Not available? Buy a different battery...

It will read something like this (Example data here is for the OPTIMA Deep Cycle & Starter battery shown):

Length:
Width:
Height:
Minimum weight (kg):
Nominal Voltage:
Cranking Amps (SAE):
Reserve Capacity:
Capacity (C/20 rate):
Internal Resistance:
Cyclic Capability:
YellowTop S-4,2L254 mm                  Optima Example
173 mm
198 mm
19,9 kg
12 V
870 CA
120 minutes
55 Ah (Amp Hours)
2,8 mOhm
400 @ 80% Depth Of Discharge (D.O.D) at 20 Hour rate.

There may be more information available but this is what we actually need. 
Detail below -- what it means to us:

 

  • Ah (Amp Hour) Rating.
    An "Amp" is a measure of current. An Ah rating is a measure of the batteries ability to deliver this current over time.
      In other words a 50Ah battery can theoretically deliver either 50 Amps for 1 Hour or say 1 Amp for 50 Hours. Or 25 amps for 2 hours etc. Its a measure of the size of the "fuel tank".  Don't worry too much about a few amp hours difference when choosing a battery as long as its a sensibly close figure. There are some other more important considerations.   The capacity of the Optima batteries I use in both my powerchairs and in my van are 55Ah although these expensive batteries are not the best solution for most people.  

    For pure engine starting duties capacity alone is pretty much irrelevant and all that really matters is CA (Cranking Amps) or CCA (Cold Cranking Amps) where more is always better. For for average powerchairs that actually use this store of energy Amp Hours are more important.

    Make sure you use the 20 Hour rate though to compare (there are others like 10, and 30 etc) because the faster you try to get the power out the smaller the amp hour rating and the opposite is also true. All because of the next important measurement below...
  • Internal Resistance or impedance. This is VERY important. It controls the amount of voltage drop under load. Its rated in Ohms. It can be found in the manufacturers specifications. The optima shown above is 2,8 mOhm which is very low. That's good! We want low! 3.0 mOhm is worse...  mOhm is Milli Ohm. (The wiring also has some resistance as does the controller itself too.) This figure is very important. if either resistance figures or engine starting figures are not available I would look elsewhere as it (the battery) may not like big currents and you cannot know...  Decent batteries will have a figure. It will only relate to the fully charged state though and it gets worse (bigger number) as the battery is discharged during the day...

  • Where the above "Ah" rating tells you the size of the fuel tank, the Internal Resistance tells you the size of the fuel line! It tells us how much power we can get out and how fast you can get it.  But its a little more complicated. The internal resistance gets worse as the battery charge decreases during use.  In other words your engine may "sag" more being starved of fuel before your tank is anywhere near empty.

    Obviously then for engine starting duties you NEED a very low internal resistance to provide the literally hundreds of amps required to fire up your car! engine  Especially a disabled converted car with many extra electrical devices like ramps, doors, extra lights, on board computers etc. The battery has a very hard time. You may be starting your car up with a half used up battery on a regular basis and a half used battery is even less able to deliver the big currents needed for engine starting...

    On a Scooter or powerchair "Some" types of 50Ah rated batteries will take you further than some 75Ah batteries will.  For the simple reason that depending on the batteries internal resistance (which actually increases as it becomes discharged and used up) then the actual "usable or accessible" capacity may not always be available at the high loads that powerchairs and scooters demand at difficult times.  The internal resistance of my favourite Optima batteries is a very very low 2,8 mOhm. 

    That's low enough that it can deliver HUGE currents with almost no voltage sag. Even when almost flat. They use these Optima's to start big trucks in cold climates and also its a true deep cycle battery as well... Most deep cycle batteries can't be used for serious starting duties because they just cannot supply the amps. With a few exceptions. (Hawker Odyssey, and others) But this is all way over the top for most power wheelchairs and wheelchair users. There are better solutions with a slightly larger capacity and adequate current capability as well as "more 80 percent deep cycles" before the rubbish pile claims them.  I do have one on my van here and I often use them in MY OWN powerchairs too because I use bigger controllers and taller gearing than most and get sick of "normal" wheelchair gel batteries failing me. But that's me I am not an average user.

    The relatively high loads a scooter or powerchair puts on the battery at times demand a battery that has a low internal resistance or it may not deliver enough power (voltage falls) under load just when you need it most on a ramp say, as your battery becomes more discharged.

    In other words the battery "feels" run down and your scooter or powerchair it will be "sluggish" even though there is a fair bit of energy actually left in the battery. But its not "accessible" energy when high currents are demanded. 

    Its just that to use what's left in it you need to be able to take a smaller steady current out of it for longer periods of time as in a UPS system or similar use. Or if its easier to understand it may that with some battery types that the voltage falls very low under load early on in the discharge cycle.  Now a battery that has a very low internal resistance will keep on going and will still provide large currents on demand without much voltage drop even when almost exhausted.  In this way a smaller battery can give greater range and performance than a larger one. This equates to more usable range on your powerchair and a Motor Vehicle that will still start even after repeated use of suspension lowering and ramp and door operating mechanisms and extra time with lights left on etc.

    One more huge advantage of the really low internal resistance batteries (like the Optima, Hawker Odyssey ranges is that as well as being able to deliver huge currents they can quite safely be recharged at a much higher rate than normal deep cycle batteries. I fast charge my wheelchair for example at 30 amps from 50 to 70 percent discharged  to 95 percent charged in around an hour every day without any problems. The recommended rate for normal deep cycle batteries is about 20 percent or their capacity or less.  The reason this is possible is because the low internal resistance means almost no heating and wasted energy. Fast Charging -- about half way down!

  • Size -- Length, Width, Height is is all pretty obvious, it must be able to fit the space provided.

  • Weight -- Heavier usually means more lead. Deep Cycle Batteries and combined Deep Cycle and Starter batteries all NEED thick heavy plates. Weight is a good indicator of quality. Thicker plates are required in most Deep Cycle Batteries to prevent distortion and survive deep discharges better.

  • Voltage -- Almost all Lead Acid batteries are 12 Volts. There are some 2, 6, 8 Volt variations and the odd 16 Volt specialist batteries available used in motorsports but these are for unusual specialist applications. The batteries in your Powerchair or scooter are 12v They are connected together in most cases in series to give a working voltage of 24v.  Your car or van is 12v.  If it has two batteries then they are usually connected together in parallel so that you have double the starting current but still only 12v total.

  • Cranking Amps (CA) and Cold Cranking Amps (CCA). This is the number of Amps the battery can supply while the voltage stays above a pre defined level for a few seconds  It simulates the best your battery can do while trying to start an engine. This typically takes hundreds of amps and is very punishing to a battery. Standard car or truck Starter batteries have many thin plates with just a lead "sponge" coating.

    This gives a huge surface area allowing equally huge starting currents but they cannot be deeply discharged without damage. Normally a Deep Cycle battery wont have this information on it or in any documentation because it both isn't intended to be used for this sort of duty and most couldn't do it anyway. If you try then you could actually damage the battery permanently.  Much of this isn't really relevant to your Deep Cycle PowerChair batteries since most powerchairs and users don't need these huge current capabilities. 

    There are one or two that do though and they know who they are! Usually big hotted up reprogrammed powerchairs with heavy users that have noticed the batteries "sagging" when asked for more acceleration, or while climbing curbs and ramps.  Fortunately for use they make batteries like the Hawker Odyssey and the Optima "yellow top" batteries. Both of these are true Deep Cycle as well as excellent high current Starter Batteries  You don't have to choose one or the other

 


Deep Cycle, Starting only (actually called SLI for Starting Light & Ignition), Deep Cycle and Starter Battery.

What is the difference?

  1. Starter batteries. Starter batteries are designed ONLY to fire up your cars engine.  This typically takes hundreds of amps 500 or more Amps in winter to start a big engine is normal. It starts in a few seconds and your battery then has only been discharged by a few percent. Five percent or ten maximum for a very hard start in winter, Its then charged right back up again by your cars charging system very quickly.  Used in this way your Starter battery will last many years and many thousands of starts.

    A starter battery is great at delivering big currents for a few seconds only. If you discharge it deeply as you would say in a Powerchair on a daily basis (or if you leave your cars lights on accidentally a few times) it will die a horrible death and last weeks only.  All lead acid batteries suffer when discharged. In the case of Starter batteries which use a lead "sponge" coating on the plates to increase surface area -- it literally falls to the bottom of the battery and the weak thin plates warp and deform. They love to be charged at 100 percent and seldom discharged much!
  2. Deep Cycle batteries. Deep Cycle batteries generally wont / may not start a car and trying to do so actually can damage some types. They have higher internal electrical resistance. You wont find a CCA or CA figure on them. They are designed not to suffer as much as most lead acid type batteries when discharged very deeply on a regular basis. A GOOD Deep Cycle Battery can be discharged say 500 times at an 80 percent discharge level. A starter ONLY battery as fitted to your car would typically give you 20 to 50 cycles under the same circumstances.  So why the difference?

    GOOD Deep cycle batteries use solid thick pure lead plates. This means that unlike the starter battery above it cant shed its Lead Sponge Coating. And its plates don't warp.  But it has less surface area in contact with the (slightly weaker) acid and so its electrical internal resistance is greater. That's why it cant easily start a car or is bad at high currents.  Which is a shame because modern cars and disabled converted vehicles with all the hoists, ramps, lowering suspension, on board computers and other equipment really need a battery than can be discharged like a Deep Cycle Battery can. So if you have any sense and you drive a modern car full of electronics, especially if its got ramps, lowering suspension etc then you really need a Deep Cycle and Starting battery. One that combines both of the above and there are a few at a price..
  3. Deep Cycle and Starter. These unsurprisingly are a combination of the two! A very clever trick pulled of by very few batteries. The Optima battery is an example of these. It is a true Deep Cycle battery (400 Cycles - some pure Deep Cycle batteries can do 500). But because of its odd unique spiral cells that are made from thin pure lead rolled up very tightly it can start a truck too!

    Instead of using thick lead plates for its anti distortion strength, it uses the fact that its rolled up tight. Because the lead can be much thinner there is masses more surface area. This means it can have a very low internal resistance and high Starting Amps (CA, CCA) without needing to resort to lead sponge coatings... It also spill proof, and can be charged at high rates.  Its for this reason I have them in my powerchair because unlike most users I actually need the big amps they can deliver and as a starter battery in my Van because I understand the benefits in such a vehicle.

Cycle Life of a GOOD quality Deep Cycle battery (for use in a Power Wheelchair or Scooter is displayed below). You will not match this with a "cheap and cheerful" Deep Cycle battery. This graph is for the likes of the Sonnenschein A500 or similar high quality battery as fitted by the manufacturers. Remember this is under ideal conditions and temperatures with a very carefully tailored multi stage charger and exactly the same discharge level every time. In REAL usage conditions this will never actually be achieved.   Powerchair Battery State of Charge

Deep Cycle Batteries

  • As you can see the average depth of discharge GREATLY effects the number of cycles a Wheelchair or Scooter battery can survive. Expect to get only 10 months out of a Powerchair / Scooter battery if its used every day and used a lot. I get typically 10 months (300 days) use only because I actually use 80 percent of my batteries charge every day, through shopping, dog walking, and going out in the evening etc.

  • If you don't go too far live somewhere flat and don't use many steep ramps etc and average 50 percent discharge daily then expect 1000 days use or nearly three years.

  • If you are one of the masses of not very active users or are sat in an old peoples home watching the TV all day expect a much greater battery life up to 5 or 7 years.  For these people a cheaper low quality deep cycle battery makes some sense.

In addition to the above also consider this:

  • Pure Quality branded Deep Cycle batteries like the Sonnenschein batteries will typically give up to 500 Cycles at a discharge level of 80 percent. (as above chart)

  • Cheaper pure Deep Cycle only batteries usually give around 400 Cycles (check the figures!)

  • Dual Purpose batteries like the Optima, Hawker Odyssey batteries will give around 400 Cycles but also can make huge currents so no voltage drop under load and can be used in your car or truck with many advantages too. And they can safely be fast charged which I find essential (nr. bottom of page)

  • Leisure batteries labelled deep cycle are very cheap but will give about 90 to 150 Cycles.

  • Car starter batteries will give you about 30 deep cycles depending on quality. That's not their intended use! And its really false economy.

With batteries you really do GET WHAT YOU PAY FOR!


Charging (a motor vehicle battery).

Maintainance-chargerIf your disabled modified vehicle is driven daily then there is no need. The cars alternator charges at 14.4v (or close) as soon as you start it and charges the battery fast. The danger is if its left unused for say a week or longer. All modern cars have such things as immobilisers, remote locking, engine management computers, alarms, various radio memory and other electronics that drain the battery as the car just sits there.  With extra electronics such as remote start, or say the computer in the boot of my minivan that controls the ramp, electric doors, suspension lowering, the battery has double the drain on it while sat unused!

Plus every time you switch off and get out, the ramp and suspension lowering as well as the door opening and closing motors all use a lot of power. Your battery is then in a slightly discharged condition. Batteries store well fully charged. But sulphate internally if left in even a slightly discharged state. Sunforce 50022 5 Watt Solar Battery Trickle ChargerSo that's now happening...

Compounded by the fact that all those electrical systems mentioned above are gradually taking more power out. So if you leave your car/van for more than a few days or a week its a good idea to charge it. It doesn't actually need a full charge (although that wont hurt) but it needs a maintenance charger like this Optimate or similar connecting and leaving connected while you are not regularly using it.

It may well still start if you don't bother but your battery is suffering and will sooner or later let you down. Another alternative is a good solar charger of 2 to 5 watts. It wont "charge" your battery but it will keep it topped up and prevent it going flat or sulphating. Less than 2 watts is a waste of time unless you live in Arizona!  I leave one plugged into the cigarette lighter socket sat on my dashboard when I am not using my van. It keeps my battery fully charged and healthy!

Remember ALL lead acid batteries HATE BEING DISCHARGED!

Charging a PowerChair or scooter battery.

All Powerchairs and Scooters use Deep Cycle Batteries. These despite their name DO NOT LIKE  BEING DISCHARGED!

With this in mind its best to ALWAYS charge them every single night with the manufacturers charger or something equivalent with the correct profile. Even if you only used the mobility device for ten minutes. Every night. Don't Forget! even if you fast charge them during the day.  If you have not used it at all then charge it once every week over night. Once a week will help prevent the batteries becoming discharged which ultimately is what kills them. Never discharge Lead Acid Deep Cycle batteries on purpose to get rid of any memory effect! They don't have a memory effect! Even the original rumour that NiCad batteries has a "memory" was not actually true. All deep discharge does is damage your batteries.

If you get chance during the day it IS BENEFICIAL to plug in the charger to lower the average daily discharge level. This is called opportunity charging. Contrary to what you may read elsewhere it is beneficial.  Anything that lowers the average discharge level helps your batteries live longer. It still needs the full overnight charge however every night just the same.

Are you fed up with waiting hours for your chair or scooter to charge? Well depending on your battery type you CAN fast charge them. I use Optima Deep Cycle and starting batteries partly because it allows me to charge them up in the middle of the day to 90 percent + in just one hour. See here It still needs the full overnight charge from the normal slow (8 amp or 20 percent of battery capacity) charger however every night just the same or your batteries never get properly charged and will become unbalanced.

See also:  Inverters and Chargers  &  All about Powerchair and vehicle batteries and  Which batteries to buy & Powerchair Battery State of Charge

Detailed PowerChair Only Menu

Lithium Ion Batteries for Powerchairs and Scooters

 

 

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