batteries for mobility scooters



The bit about not keeping them topped up is interesting - after all that's what a car does on a long journey. And my last battery - Bosch - did 11 years. By far and away the longest ever in some 50 years of owning cars.
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Dave Plowman snipped-for-privacy@davenoise.co.uk London SW
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On 29/07/2014 16:01, Dave Plowman (News) wrote:

Quite different requirements, resulting in different designs. A car battery has to withstand a single deep discharge (not normally more than 50% of capacity) followed by trickle charging. They spend much of their life at or near full charge. Traction batteries have to withstand regular very deep discharge, possibly close to fully discharged, but have to provide full power at all normal levels of discharge. They spend much of their time partly discharged, but routinely get fully charged between uses.
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Colin Bignell

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Dave Plowman (News) wrote:

I've had six batteries (three pairs). These were the originals, the new ones, and the replacements. They are all SLA and they all say 'max charge rate 3.5A.' and they also specify the starting and trickle charge voltage. The charger I use for these batteries is rated 2.5A and the voltages are correct. It's actually the one supplied with the machine.
By the way it's interesting that the industry standard charger connector is a 3-pin XLR?
Bill
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snipped-for-privacy@care2.com wrote:

My wife's new machine has splendid suspension!
Bill
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Why?
Bill
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On 29/07/2014 18:32, Bill Wright wrote:

The life of the battery is defined in terms of the number of charges it receives. If you charge it once a day, a life of 1,500 charges is about five years, assuming 300 working days in a year. If you charge it twice a day it is two and a half years.
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Colin Bignell

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My understanding of the situation with lead acid batteries is that charging from 50% charge to fully charged only counts as about half a cycle, and from 75% is only about a quarter of a cycle. This would also seem to agree with the experiences of a lot of boaters I know of who use lead acid batteries. If they run them to 25% charge each time, then fully charge them, they don't last as many cycles as when they're run to 50% charge and replenished.
It certainly quoted that on my first mobile phone, which used a 2Ah SLA battery.
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John.
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On 29/07/2014 20:50, John Williamson wrote:

Not all lead acid batteries are the same. Car batteries, which I suspect most closely resemble boat batteries, are designed to discharge to around 50% before getting a continuous trickle charge. Traction batteries, as used in fork trucks, are expected regularly to go to 70%-80% discharged and then be recharged in a single (usually overnight) charge. That results in different internal designs.
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Leisure batteries on boats are more akin to traction batteries than starter batteries, being designed to deliver a low current for long periods. The normal installation is one starter battery for the engine and navigation lights and such, and at least one leisure battery for domestic power. These are the ones that get the deep discharge on a routine basis.
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snipped-for-privacy@care2.com wrote:

Yes, that machine has solid tyres and no suspension.
Bill
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Dave Plowman (News) wrote:

The two 100Ah batteries on my motorhome that are the 'vehicle batteries' have been in use since 1998. They are completely isolated when the vehicle is parked. Obviously the vehicle is only used for about three months in the year.
Bill
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They're made by the zillion, so cheap. I've just bought a 7 pin version. From the same maker, exactly the same body etc, but approx 6 times the price.
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Dave Plowman snipped-for-privacy@davenoise.co.uk London SW
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I don't think that answers the question; it just restates the situation. What I mean is, why should a partial charge do as much damage as a full one? And since deep discharge is said to be harmful, isn't it better to avoid it by starting to charge when the battery is not deeply discharged, even if that means the total number of charges is more? What about regenerative braking, which subjects the battery to constant short discharge then charge periods during the day?
Bill
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On 29/07/2014 21:45, Bill Wright wrote:

You might have to ask the designers of traction batteries that. I am only going by the advice they give to fork truck users. Whether that also applies to mobility scooter batteries, I have no idea.

Deep discharge is only harmful if the battery is not designed to handle it. Traction batteries are designed regularly to go down to around 80% discharged.

AIUI, it seriously shortens the battery life, although that is, in part, due to the high rate of the charging it may involve. OTOH, it increases range, so the user has to trade that against battery life.
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I don't believe a partial discharge followed by a recharge is an issue in terms of reducing the life by one cycle if:
a) you keep the level of charge retained in the battery above a certain threshold, maybe 90%, possibly a bit lower
b)the charging regime used at that point of the discharge curve is one recommended by the battery manufacturer with appropriate temperature compensation
c) the charging is terminated at the correct point
Two or more decades ago one of the first manufacturers of SLA's used to produce a very good reference book that explained all, not sure if it was ever published as an electronic version, I might have a copy about somewhere in my library but i won't be at home for another couple of months.
The top left image on this page indicates a typical cycle life in relation to depth of discharge.
http://www.yuasaeurope.com/images/uploads/uk/downloads/shortforms/NPC_shortform.pdf
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The Other Mike wrote:

    I see that lithium batteries are now available for golf carts.
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Was going to suggest similar, convert to li-po batteries, the appropriate charger and BMS, if you really want to do the job properly, fit a brushless motor and controller,
the buggy should then be able to travel about 6 times the distance on a charge and weigh uch less than with the lead acid batts, or if you put in the same weight of li-po batteries as the lead acids, you could prolly get half way from lands end to john on gorats on a charge :)
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On 30/07/2014 10:14, The Other Mike wrote:

It is mostly violations of either leaving the battery flat and totally discharged or gratuitously overcharging that shortens service lifetime. Temperature variations are a factor in high power or fast chargers but some typical cheap domestic chargers are generally not that smart and so need timing discipline to avoid damaging the battery accidentally.
This heuristic applies to most rechargable batteries to a greater or lesser extend. The only chemistry that could tolerate enormous abuse was the old wet plate NiFe cells which were almost indestructible provided that you followed their top up maintenance procedures.

Yaesu are as good as any although for less demanding roles you can find other acceptable brands. The key is not to buy the badged ripoff priced ones that the sharks who sell mobility scooters have on the shelf.
I found the 17Ah SLAs about the best price last time I was looking. You have to be careful to make sure the physical dimensions and connnectors are compatible with the enclosure they have to fit into. In general a higher capacity battery will just last a bit longer on a single charge.
Regards, Martin Brown
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I'd guess you could buy several new scooters for that cost. ;-)
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* I like you. You remind me of when I was young and stupid

Dave Plowman snipped-for-privacy@davenoise.co.uk London SW
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On Mon, 28 Jul 2014 13:33:30 +0100, Dave Liquorice wrote:
<snip> > Since the near fire incident I've "got at" my UPS and reduced the

Dave,
Could you provide more details please?
I'm looking at the replacement of a number of UPS battery sets and would like to prevent the overcharging. The fan/ventilation I can sort Ta!
Reply to should work
Nick
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