Battery Testing a mobility scooter -interpreting readings.

[ericmark]

Oh what a tangled web, I use a 12 Ah lithium battery for my e-bike and it will take me from Shrewsbury nearly to Welshpool, so around 18 miles, but I am peddling as well, and free wheel down hill, around same size motor (not saying how big as possibly over permitted size) and the scooter has two 36 Ah batteries at 12 volt each, so considering voltage the lithium battery is 24 Ah for comparison as voltage doubled. The scooter claims 25 miles, but it is heavier than the e-bike, although speed limited to 4 MPH not 16 MPH, but I would think 25 miles is a bit optimistic. Like my first Honda moped (P50) which stated 254 MPG on a level paved road, where does one find a level paved road, at 0.6 gallon tank that was 151.8 miles, but I could just about get 68 miles in real terms, we are seeing the same with an electric car range.

For lithium it is recommended store ½ charged, but for lead acid store fully charged and top up VRLA once every two months it says to recharge lithium before use.

I would expect around 10 - 12 miles from the lithium, which at 4 MPH is 3 hours riding, I would not really want to ride one for more than 3 hours, the 5 hours with lead acid can't see ever being required, but the big thing is as the lead acid discharges the performance drops, so after 15 miles the hill climbing ability is really reduced, the lithium also have a reduced output, I know very well the last bit to my house when going from the railway station to my house it does reasonably well, I do need to push hard, but I can make it, but to Welshpool and back, 16 miles, it has a problem with the last bit, how much is me being worn out, and how much battery hard to say, but often I end up walking the last 200 yards.

However the mobility scooter completely failed, it does not allow one to peddle, and I was lucky some young girl helped me push it the last 100 yards, I think is was the batteries being shaken, as after taking it apart to carry down the steps and reassembling it at the bottom, it worked. But have you tried pushing a mobility scooter, it's not easy, as you can't reach the tiller from the back and along side not easy to push.

Now the e-bike has walk assist, so not having to push the bike, and even when the battery completely fails, you can still pedal it. On that trip from Shrewsbury I peddled from railway bridge to MacDonalds roundabout, then retried the pedal assist, and it took me into Welshpool and the pub where my wife met me and I folded it up and put it in the car.

My wife's e-bike is fully legal, and that also can do around the same range hers is 36 volt, and rated in watt hours, but her bike is lighter, and does not have a throttle, she must peddle, and assistance stops at 15 MPH, have you tried cycling on a fast road with cars shooting pass you at 15 MPH, I think mine which I can do 20 MPH is far safer even if not legal. To H*** with the law, I want to arrive home on my bike, not an ambulance, so to h*** with the law.

 

[Taylortwocities]

I was curious to look at the options regarding using a Lithium battery in a scooter.

Others can advise on this, but I believe that you would not be able to use the original (lead acid) battery charger to charge Lithium batteries.

 

[ericmark]

Others can advise on this, but I believe that you would not be able to use the original (lead acid) battery charger to charge Lithium batteries.

I am sure you are correct, but the link given was a pair of batteries plus charger. But at £250 compared with £125 it seems rather expensive, and reduced capacity as well, if weight is a problem, as with my e-bike I can see the point in lithium, but the scooter I have splits into 5 units, seat, rear wheel, front, and 2 batteries, and the batteries are not the heaviest bit. And no way could I lift it without splitting, so battery weight is not an issue.

Also the volt meter to show range left will also likely be wrong with lithium batteries.

My biggest complaint is the scooter does not allow the batteries to be charged off the scooter, the e-bikes do, but not scooter, so one has to unload the scooter to recharge. Where with e-bike I can leave the bike in the car, and just take battery into house for charging.

 

[bernardgreen]

I believe that you would not be able to use the original (lead acid) battery charger to charge Lithium batteries.

I would agree.

Lead acid batteries tend to be dumb and rely on the charger to be smart enough to not overcharge the battery. Smart being as simple as having a fixed output voltage.

Lithium batteries invariable have built in "smartness" ( electronics ) to protect the battery from excessive charge and discharge currents.

 

[ericmark]

The problem with lithium compared with lead acid is likely all to do with the inbuilt protection. With the lead acid one realises the scooter is running out of power well before it actually fails, but with the lithium one minute it is driving the e-bike well, and next minute nothing.

With the e-bike not so much a problem, but with the mobility scooter you have no pedals, I went with my mother along the cycle path from Shotton to the Wirral likely around 2 miles between motor vehicle access points, and had it failed, it would have been a problem, the same is true on the tow path on the canal, some 5 miles in places between assess points, however cycling 5 miles without assistance is doable, but pushing a mobility scooter would be very hard, remember if you are not disabled you should not be riding one, so a companion may be able to push you, but if you can push it, you should not be using it other than to test it.

With the e-bike when it failed at level 4 I was able ½ hour latter to switch it back on at level 1, but the mobility scooter is limited to 4 MPH if it can be used on a walkway, 8 MPH used on a vehicle road, above that looking at a quad, I think around 28 MPH, only know of one, made by Citroen the Ami, which is more like a small car than mobility scooter, reminds me of the Invacar of the 50's to 70's but electric rather than petrol. Again the 46 mile range is a problem.

 

[Harry Bloomfield]

With the e-bike not so much a problem, but with the mobility scooter you have no pedals, I went with my mother along the cycle path from Shotton to the Wirral likely around 2 miles between motor vehicle access points, and had it failed, it would have been a problem, the same is true on the tow path on the canal, some 5 miles in places between assess points, however cycling 5 miles without assistance is doable, but pushing a mobility scooter would be very hard, remember if you are not disabled you should not be riding one, so a companion may be able to push you, but if you can push it, you should not be using it other than to test it.

I still have the little used scooter of my deceased partner stored in the hut, which I put on charge very occasionally. The charger goes to green, immediately, or very soon after I have used it. I have used it at times, as an alternative to the bus, locally, both are quicker/easier than getting the car out, but I'm always wary of the batteries giving out and having to push it - I keep a rope stashed on it, so it at least can be towed home.

As said, it rarely gets an outing, but plan A would be to call (none driving) partner to come and watch scooter, whilst I nipped home for car to collect it, or park it in someone's garden for collection - if there was a handy / willing one near. I wonder how often unattended scooters are stolen?

It has never been run to completely flat, probably no further than 3 miles. What I really ought to do is test it, by doing circles around the local area, but how do you determine the 50% exhausted?

 

[Rodders53]

So, if I had a scooter with, say 2x32Ah batteries which apparently give a range of 20miles (give or take). Would I be correct in picking lithium batteries that were rated around 16AH?

2 x 12 V 32 Ah I assume.
That will most likely be a scooter capable of 6 or 8mph for on road (user must speed limit down to 4 mph when on a pavement) rather than a pavement/shopping scooter that goes in a car? Note that higher speeds use more power.

WE have a Pride Go Go 4mph pavement scooter with 2x 12V 22Ah batteries (replacing the original 18Ah ones). That weight 48kg and has a 15 mile range. It will typically do a full 'day out' wandering around a town, parks and within a holiday hotel complex. We do also have a spare battery pack should it run down to swap over to carried in the car.
The linked lithium cells will fit in the battery pack(s) we have {with some wiring modifications} - but I'd only expect them to supply a very similar range and no more than the current lead acids. They may be a bit lighter in weight.

We've recently acquired a lightweight (24 kg) folding power chair that has two Lithium batteries one 10Ah and the other 13Ah. Neither last as long as the Lead Acids do, so far, we find doing similar outings. Time will tell if their capacity improves as the makers suggest they will. Maker claims up to 15 miles on a charge (on the flat).

Each lithium battery in it's pack is priced at £95 ex vat cf around the same inc vat for lead acids (and one has to dismantle the battery housing to swap them).

I'm not sure what benefit there will be going lithium over lead acid on the OP's scooter other than a weight saving if removable battery pack(s)? The claims made on that SLX website are to be taken with a large pinch of salt.

Lithium batteries discharge evenly over their cycle unlike lead acid, AGM or Gel mobility batteries. You will not only get at least 2-3 time more range but your scooter will not slow down and labour up hills any more. The speed of your scooter will not be altered by Lithium batteries, it will just be more even and consistent.

The powerchair does slow and struggle in the same way on slopes and suchlike and definitely slows down noticeably as the gauge approaches the red (red, two orange two green leds on the gauge). Probably more so than compared to the lead acids on the scooter.
We swapped to the other battery at that point, no point in keeping going at half pace when there's a second on board the chair!

YMMV.

 

[Rodders53]

It has never been run to completely flat, probably no further than 3 miles. What I really ought to do is test it, by doing circles around the local area, but how do you determine the 50% exhausted?

Read the manual for the scooter.
Most (all I've seen) have a meter and that has red/amber/green to give an idea... Analogue needles or leds on more recent examples.
The typical rule is to note the meter reading while going flat out on the level.

 

[dishman]

Reviving this thread a bit.

Finally found a scooter I liked, and factored in the price of the batteries.

The existing ones do seem to be dead. They show 27-28v when tested with no load, but as soon as the scooter is turned on, this drops to 16v.
While moving, on high or low speed it drops to 14-15.5v.

Interestingly, without the multimeter there is no indication of such a low voltage. It seems to have good performance. But, i expect this was due to me just doing a short test run.

So, the replacement.

After looking through all the very useful comments again, I am musing the following:

The existing batteries were 34ah with a 19cm L and 13cm w

1) Replace with a random battery brand of similar or higher ah rating at around £60 x2 (£130+ in del)
Do gel batteries require a different charger?

2) Replace with a brand I know has a good reputation like Yuasa which at around £80 x2 (160+inc del)

3) Replace with a LifePo4 Lithium battery which for 25ah would cost £150 each (plus a new charger £30), so (£330-£340)

The main benefit of the last one is that assuming the allowable useful discharge of 80% (vs 50% of the lead acid) is that they actually have more usable Ah, despite a lower total Ah rating. Further more, they have vastly more usable cycles before dying.

There is also the weight saving. 11kg vs 4kg per battery.

But, after reading the comments again, I'm not sure the cost/benefit is potentially worth it.

So, is going with a good brand like Yuasa worth it vs any generic brand?

I might be able to fit 40ah Avon gel batteries to it. But have no idea as to their quality.

 

[Harry Bloomfield]

Reviving this thread a bit.

Tanya, in Wales, offer such batteries VAT free, if you have a valid claim to be disabled.

'The main benefit of the last one is that assuming the allowable useful discharge of 80% (vs 50% of the lead acid) is that they actually have more usable Ah, despite a lower total Ah rating. Further more, they have vastly more usable cycles before dying.'

You can use more than the 50%, but the more you use, the more dramatic the wear and tear on a LA battery. Unfortunately, the scooter makers claim the range, using the entire capacity of the LA battery, which if used a few times, would wreck them.

 

[Rodders53]

Those batteries are as dead as a Dodo...

My experience: With the Pride GoGo Traveller (we have had two).

First one was supplied with a charger that, when left on overcharged the batteries and killed them. Twice. Third set we switched charger off as soon as green. It developed control faults so was scrapped (keeping battery pack).

Second GoGo: May 2019 purchase.
Different charger make and model, now happily trickle charges after smart charging the batteries.

It came with Sail 18Ah batteries. Replaced those in July 2019 (So 3 y 2 m) with Yuasa REC 22-12. Have been charged 126 times (last charge 1st April), no noted loss of range or speed. So approaching 5 years of use.

Second battery box (from old scooter) by then had Lucas LSLC 22-12 batteries. My notes are they were fitted in March 2015. 63 charges by May 2017 and in July 2019 had low capacity (range). (4 y 4 mth life). Replaced with Lucas LSLC 22-12G (golf cart) from Tayna Batteries. They have since been recharged 125 times (the last a 1h 5m 'refresh' in April; last used 'in anger' in December).

Both those brands reckon on 300+ cycles to 100% discharge depth = 80% of original capacity in the spec sheets. Unknown brands often have no spec sheet at all. I am happy with both the brands I have used.

Mobility type maintenance free Ca/Ca lead acids are Absorbed Glass Mat or Gel construction and the same smart charger will suit either. Just be certain that the scooter charger is fully smart and the voltages match the battery spec sheets, especially for the long-term trickle charge use.

NB Batteries are NOT VAT exempt unless unique to the mobility scooter OR fitted by a mobility scooter service / maintenance company. So the size used in my GoGo also fits golf carts and has other uses in other devices.

Get VAT relief on certain goods if you have a disability

How to get VAT relief if you’re buying goods because of your disability.

www.gov.uk

If Tayna sell em with an exemption form both they and you could be in trouble but I don't think they will do that: https://blog.tayna.co.uk/2013/09/16/vat-exemption-mobility-batteries/

 

[Harry Bloomfield]

NB Batteries are NOT VAT exempt unless unique to the mobility scooter OR fitted by a mobility scooter service / maintenance company. So the size used in my GoGo also fits golf carts and has other uses in other devices.

Get VAT relief on certain goods if you have a disability

How to get VAT relief if you’re buying goods because of your disability.

www.gov.uk

If Tayna sell em with an exemption form both they and you could be in trouble but I don't think they will do that: https://blog.tayna.co.uk/2013/09/16/vat-exemption-mobility-batteries/

That is from 2013. I bought a pair of stairlift batteries last year, posted, and VAT free from them. I simply had to make a declaration that they were for mobility needs. The same applies to many mobility/health related items. 10 years ago, I bought a blood pressure monitor, from Argos I think. There was a downloadable form to reclaim the VAT, for that. I cannot recal whether I bothered to or not...

 

[dishman]

I did just ring Tanya actually. They said that they no longer apply the discount at purchase. It has to be reclaimed by me via HMRC and that they can be strict about whether it is reclaimable. To the point where it might have to say "mobility scooter battery" in the brand battery listing.

 

[ericmark]

I got my replacements from Tanya was called Manchester Batteries, never asked about VAT. Still in same town, but moved to new premises, at least parking easier now.

As to lead acid v lithium it is the recharge time which makes the difference, with lead acid looking at 16 hours, with lithium can be 2 hours with the right charger, however I would prefer to know the batteries are getting flat, my e-bike uses lithium and one is doing 16 MPH with light peddling then battery cuts out, at least I can still peddle, but now down to 6 MPH not 16 MPH. You have not got that with the mobility scooter, once dead your stuck.

Also a 35 Ah battery is heavy placed low down, it gives the scooter some stability, the lithium are a lot lighter, once you start to alter things, you don't know what else it will effect. Seem to have read the 35 Ah pair will take the scooter 25 miles, at 4 MPH that's 6 hours travelling, I would not really want to spend so long in the scooter.

I hired two scooters at Bemish about a month ago, and after a day travelling around the charge indicator had hardly moved.

I would go out with my mother as a run out, Shotton to Chester 8 miles each way, so 16 miles was not a problem, the problem was 4 MPH, to fast to walk with her, too slow to ride the bike.

I would not use anything other than the VRLA (AGM) as don't want acid to spill.

The biggest problem was the 24 volt charger charged them as a pair on the scooter, would have liked to have been able to charge them off the scooter, like I do for the e-bike.

 

[Rodders53]

That is from 2013. I bought a pair of stairlift batteries last year, posted, and VAT free from them. I simply had to make a declaration that they were for mobility needs. The same applies to many mobility/health related items. 10 years ago, I bought a blood pressure monitor, from Argos I think. There was a downloadable form to reclaim the VAT, for that. I cannot recal whether I bothered to or not...

Note the VAT guidance from .gov site is still current although last update was 2019.

No way to reclaim VAT as a member of the public from HMRC as far as I know: either supplier zero rates the sale or charges 20%. Section 2.2. of https://www.gov.uk/guidance/reliefs-from-vat-for-disabled-and-older-people-notice-7017

We've bought lots of aids with VAT exempt status... Including stairlift and maintenance contract for the same. The batteries inside are used in alarm panels... so not exempt if sold direct to me (but are if via the stairlift people when servicing).

I'd argue that a BP monitor is not unique to disabled and is used by many in good health so did not qualify anyway - just like examples of reclining chairs on that link are not.

If Tayna - or others - are selling outwith VAT man's guidance they will get caught sooner or later. See 5.5 of the earlier link, in particular wrt batteries in scooters (and should apply to stairlifts, too).

Now, buying the batteries already fitted inside a box that attaches to a scooter's unique docking system: that would be exempt. Sending your battery box to them to swap batteries: exempt.