Which SLA charger - slow or fast?

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Which is the best way to charge SLAs - very slowly or normal speed?

Slowly
1
17%
Normal speed
5
83%
There's no difference
0
No votes
 
Total votes: 6

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badnewswade
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Which SLA charger - slow or fast?

Postby badnewswade » Sat Mar 06, 2010 4:51 pm

We all know that fast charging is bad for SLAs. But what about slow charging?

I've got two SLA chargers- one "Intellect charger" from Ebay that charges up a 48v, 48ah scooter in around 27 hours (this is from a deep discharge - down to about 46.5-48v), and another that came with the bike, that charges it up in maybe 12-16 hours from a deep discharge. Which one should I use on a daily basis from the point of view of prolonging battery lifetime - the fast or the slow? And which is best to use after deep discharging the batteries?

PS: I've got two strings of SLAs - one at 21ah, the other at 28ah. The 28 ah one is about 9-10 months old and the 21ah string is brand new.
34 Watt Hours per mile, or > 700 MPG. What, me, smug?

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Peter Eggleston
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Re: Which SLA charger - slow or fast?

Postby Peter Eggleston » Sat Mar 06, 2010 7:45 pm

I find that it is best to charge lead batteries at the rate they can accept current. When mine are low, I start them off at a high rate, ie about 30 amps for the first 40 minutes to an hour, or until the batteries start to fiz. Then I switch to 8 amps for about 3 hours or when they again start to fiz. If the batteries are fizzing they are either being charged too fast to accept that current or are fully charged. I have charged in this way on the same set of batteries now for 7 years and they are still going strong.
Peter

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ChrisB
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Re: Which SLA charger - slow or fast?

Postby ChrisB » Tue Mar 09, 2010 10:51 pm

Personally I would like to chose the option thats not there i.e

As per manufacturers specification :wink:

ChrisB
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Deker
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Re: Which SLA charger - slow or fast?

Postby Deker » Tue Mar 30, 2010 4:11 am

Hi badnewswade.

Generally slow charge for SLAs is best, however 27 hours is too long if you need your bike next day.
The 12 to 16 hours should normally be OK.

Bear in mind. Always have your batteries fully charged before using your bike.

On my Lynch motor'ed bike I have two 12v * 30ah Sonneschein A500 SVLAs,
does about 7 miles per charge, but I like acceleration, the bike does pull wheelies :)
When doing wheelies I reckon the motor is drawing 150 amps or more.
I do not have to pedal my bike, it will climb any hill the back tyre can grip :)

Now for the really good bit - I bought the batts secondhand over 8 years ago and a fully automatic charger.
AND they are still good.

Many times I have discharged these batteries to the point the bike will hardly move under batt power (NOTE, No low voltage lockout on my controller)
So as long as the batt voltage can power the controller, the controller will supply electrickery to the motor.

As for charging my batts, if I recall correctly my charger supplies about 4-5 amps at 24v,
from normal usage takes about 3-4 hours to fully charge the batts.

More info - Occasionally I charge my batts using a 12v automatic charger on each battery in turn, this is to give a "Balancing Charge" to each of the 12v batteries.

HTH

Deker.

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badnewswade
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Re: Which SLA charger - slow or fast?

Postby badnewswade » Sat Apr 03, 2010 5:53 pm

http://www.barden-ukshop.com/sonnensche ... 1101-p.asp

Sadly, at a £131 a shot they're not much better value than Lithium. At least least lithium battereis are lighter.

Why are batteries always so insanely expensive?
34 Watt Hours per mile, or > 700 MPG. What, me, smug?

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ChrisB
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Re: Which SLA charger - slow or fast?

Postby ChrisB » Sat Apr 03, 2010 9:05 pm

I know what your saying but then I recon a set of these....
http://www.pingbattery.com/servlet/the- ... PO4/Detail would amaze you, yeah not cheap but then your sort of looking at buying all your fuel up front.

If it helps justify the expense try working out how long it will take you to recoup the expence of the LiFePO4's compared to filling up a scooter with petrol @ £1.19 ltr :shock: and how many miles you get for that. It would be interesting to see how quick you'll actually get your money back.

ChrisB
I reject reality and substitute my own !!!!!!

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badnewswade
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Re: Which SLA charger - slow or fast?

Postby badnewswade » Sun Apr 04, 2010 1:34 pm

I've seen that site, and unless you're rich it doesn't make any sense. With shipping that battery costs arond £700. It costs me around £160 per year to run my bike on comparable SLAs.

So I'd have to use that cheap, gaffa-taped Lith for over four years just to break even. That's four years without an accident, theft, or simple change of circumstances - you're locked in to using it, if something better comes along or prices drop, you've wasted your money. If anything goes wrong with that very cheap battery, you've wasted your money, and worse still have to throw good money after bad repairing it...

When you take that into account, SLAs are miles better - I mean nobody pays their electric bills four years in advance do they? In fact people prefer the pay-as-you-go way of buying things, as it takes changing circumstances into account. Remember, I already have an electric moped, and the whole point of having the thing is that it's cheap, both up-front and in running costs. The high-cost, hope-it-doesn't-break-down-for-years-on-end economics of Lithium fly in the face of that.

At the end of the day, Lithium batteries are three or four times the price of SLAs but they aren't three or four times better than SLAs. The insane price of the technology is what's hampering take-up of them and of EVs- unless prices go down, EVs will always be a niche product and Lithiums a niche-within-a-niche.

Rant over! :twisted:
34 Watt Hours per mile, or > 700 MPG. What, me, smug?

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Jeremy
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Re: Which SLA charger - slow or fast?

Postby Jeremy » Sun Apr 04, 2010 6:25 pm

Well, I've been running a Ping 36V, 10Ah pack for around two years now. It has about 300 cycles or so on it, I think, and is still at close to 100% capacity as far as I can tell.

Based on it's performance to date, I'd be surprised if it doesn't do at least 1500 cycles, maybe more. I'd guess that 5 years is probably a pessimistic estimate of the life of this pack.

Bear in mind that this pack price also includes a decent battery management system and charger.

The other factors to take into account are ease of use and performance. The LiFePO4 pack delivers pretty close to 100% of it's rated capacity, whereas an SLA pack will struggle to deliver more than about 80%. I first ran my bike on 3 off, 12Ah 12V SLAs connected in series for a few weeks. The performance was dire, with incredible voltage sag (enough to trip the controller) and it was obvious that they weren't going to last long. I then switched to NiMH cells (a pack made up from 9off 12V sub-C size RC model packs from here: http://www.component-shop.co.uk/). These performed very well, until I blew them up in a charging accident (very dramatic, big bang, fire and lots of smoke). Where the Ping pack scores here is in ease of use, as the BMS and charger provided mean that it really is a fit, use and forget system, with no need to faff around trying to find the right charger.

There are alternative relatively low-cost LiFePO4 options open to you, but they are still more expensive than a Ping pack. For example, you could buy 32 off 15Ah A123 pouch cells, at $2.5 per Ah (plus shipping), but the total cost would be more than the Ping pack, plus you'd need to buy a charger and a BMS. You could look at using LiPo packs, although there are some risks associated with taking this route. HobbyCity (http://www.hobbycity.com/hobbyking/store/uh_index.asp) offer just about the best prices for good quality LiPo (look at their Zippy or Turnigy packs for best value), 12off of these, will give you 44.4V, 30Ah, at less than 9kg, for around $750 plus shipping, but you'll need a balancing charger and ideally some sort of low voltage cut-off system to protect the pack during discharge.

I'm afraid that there's no cheap answer to the battery conundrum. If ever there was something that the old adage "you pay's your money and takes yer choice" applied to has to be batteries.

Jeremy

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ChrisB
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Re: Which SLA charger - slow or fast?

Postby ChrisB » Sun Apr 04, 2010 8:03 pm

badnewswade wrote:At the end of the day, Lithium batteries are three or four times the price of SLAs but they aren't three or four times better than SLAs. The insane price of the technology is what's hampering take-up of them and of EVs- unless prices go down, EVs will always be a niche product and Lithiums a niche-within-a-niche.

Rant over! :twisted:


Ah now I have to disagree here.
I like you was very pessimistic about the whole Lithium thing, I still am to a degree when it comes to the really large ones, but since making my first purchase of a Ping 24v 15ah pack, the whole lithium thing has suddenly become a LOT more interesting :wink: I can safely say they ARE 3-5 times better than SLA's. Since fitting a set of these to my bike its just made the thing ridiculouse, its lighter by a 1/3 and the range has .........well I dont know what the range is, as I've yet to get to the point when it stops :shock: the orginal good SLA's would fade away after around 7miles, with a lot of care and a bit of pedaling I squeezed 11miles from them. Todate from the LiFePO4's I've ragged around 24miles out of them and at full bore the whole time and they didnt seem to even flinch, I'm sure you would be really surprised at the improvements.

badnewswade wrote:I've seen that site, and unless you're rich it doesn't make any sense. With shipping that battery costs arond £700. It costs me around £160 per year to run my bike on comparable SLAs.

So I'd have to use that cheap, gaffa-taped Lith for over four years just to break even. That's four years without an accident, theft, or simple change of circumstances - you're locked in to using it, if something better comes along or prices drop, you've wasted your money. If anything goes wrong with that very cheap battery, you've wasted your money, and worse still have to throw good money after bad repairing it...


I know what your saying but if you look at it in a slightly different way then your looking at 4 yrs of trouble free running, no more hunting out new SLA's to replaced dead ones every year, no more messing about swapping batteries in and out every year or sooner and lastly look at the investment, almost certainly you would be able to recoup a lot of the expense if you had to sell up.


badnewswade wrote:When you take that into account, SLAs are miles better - I mean nobody pays their electric bills four years in advance do they? In fact people prefer the pay-as-you-go way of buying things, as it takes changing circumstances into account. Remember, I already have an electric moped, and the whole point of having the thing is that it's cheap, both up-front and in running costs. The high-cost, hope-it-doesn't-break-down-for-years-on-end economics of Lithium fly in the face of that.



I agree with you ....to a degree, like yourself the main reason I drive EV's is due to their cheapness, however I also dont like driving a naff EV, I want mine to be fast, reliable and go a reasonable distance.
I know what your saying about paying your electric bills in advance but thats exactly what happens in a EV, its only we have become so pay-as-you-go with petrol that doing it any other way seems a bit odd, you have to pay for the energy somehow, while the energy is quite cheap the storage isnt.

I will admit I am still taking a slight gamble on them, but after doing extensive research I evaluated that it was a calculated risk and worth the potential gain, and gain I have got 8)

ChrisB
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badnewswade
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Re: Which SLA charger - slow or fast?

Postby badnewswade » Sun Apr 04, 2010 8:09 pm

Admittedly lithium is now cheap enough that it makes sense for light ebikes. In fact I wouldn't even think of running a pedal-assist ebike on lead to be honest.

But for anything else until Lithium drops in price by at least 50% I choose SLAs. What if I fail my MOT or am no longer able to afford insurance? What if the bike breaks down and can't be fixed? I'm still locked in to using it thanks to overpriced lithium technology.

Lithium is just too much of a gamble as it stands - as I say, if you don't get four or five years out of a pack you're basically wasting money. Also, I've heard too many reports of dead or dying cells and packs being shipped with faulty BMS, both of which require massive amounts of DIY to put right. As well as being affordable, my SLAs are literally plug and play- it doesnt' get much simpler than that. Seems it's really, really easy to screw up a Lithium pack and very hard to screw up an SLA - I've had SLAs sitting around three-quarters discharged for weeks on end while I waited for a charger to arrive, I've had them stored for a year and brought them back into use with no huge problems... I've had SLAs bouncing around on dirt tracks and rutted roads as well as in -5 degree snowdrifts and blizzards without ill effect. Would you risk taking a £700 Lithium pack out in conditions like that? I wouldn't - but because they only cost me £60 I was able to give my heavy ebike / ultralight e-moped just that sort of punishment this winter - and as it turned out, I'm still using that cheap £60 pack of SLAs today.

I really don't think Lithium has any kind of future at all unless it gets significantly cheaper. The question is, will the manufacturers sacrifice a massive per-unit profit on the whole economies of scale thing? And will supplies of Lithium hold out? I'm told that half of it is sitting under some hostile regime in Central America or something - much the same as oil really.
34 Watt Hours per mile, or > 700 MPG. What, me, smug?


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