A better SLA?

Hello chaps. Nice to see a forum with some technical rigour about it.
I've been lurking for a while.

I have a 3 year old Currie izip (ezip) trailz.
It has sat in the garage the last year, though I have kept the Yuasa NP7-12 SLA batts topped up.

I have started using the bike again, and it is clear that the batts are near the end of their natural.

I run them in 2s or 2s2p config using one or 2 Currie batt boxes.

NP7-12 batteries are 150mmx95mmx65mm = 6x4x2.5 inches.

Here's the spec for these batts:
http://www.yuasabatteries.com/pdfs/NP_7_12_DataSheet.pdf

Now I notice the spec for the Yuasa ypc8-12 looks a bit better:
They carry a bit more juice in the same form factor, even when run at higher currents
They can take a higher current and look as though they are generally a bit better for ebikes.

http://www.yuasaeurope.com/images/uploads/uk/downloads/datasheets/Yucel/YPC8-12_UK.pdf

I wonder what compromises have to be made to get the better spec?

So are there any other SLAs around that would do the job even better - in the same form factor?

I hope that the Lead-Acid industry is responding to the challenge of the new chemistries.

That's got to be good - for us!

Lead sucks. It's ah rating is based on a 20hr discharge, At ebike discharges of an hour or less, you'll be lucky to get half the ah rating of the battery. Time to leave the 18th century and come into the 21st. Replace those chunks of lead with smaller, lighter, more powerful, lithium batteries. 5ah 14.4V Turnigy hardcase packs are only $23 each. Four of them would probably fit in one of the currie cases with room to spare for 10ah @ 28.8V and only weigh ~4.5lbs and be capable of a 200A draw. IIRC the currie controller is only 35A max.

Yes, I've considered Turnigy packs, and Ping packs etc. I may well end up getting lithium.

But before deciding, I'd like to compare them with the best and most appropriate SLAs.

The Currie controllers are 25A.
When I'm riding, I mostly draw around 12A.
With NP7-12 cells:
If I'm running 2s SLA, then each cell is running ~2C and can deliver little more than 1/2 of its energy.
If I'm running 2s2p SLA, then each cell is running ~1C and can probably deliver >2/3 of its energy.

YPC8-12 cells should bump the total and deliverable energy up a bit.

If I could find SLA cells that were better still, then my decision would be easy.

Is there a simple, safe, cheap, charging solution for 4 Turnigy packs?

Hi

Please forget the idea about the best SLAs there's no best SLA's at all, those SLA's are about the same brand name for brand name no matter what the one you chose. That SLA battery new will give you about 4 amps off usable range if you are not to hard on them, with allot of weight penalty.

Cell_Man (a Vendor) for instance can sell you a complete solution with A123 battery pack with the voltage and amps you need for your ebike. If you are worry about charging Lipo battery "'Method" as the perfect charging/discharging solution for you.

And please gives you a chance to have a great ebike with a lithium battery pack and you will never regret this change.

Good day!
Black Arrow

Zippedy said:

Is there a simple, safe, cheap, charging solution for 4 Turnigy packs?

Click to expand...

Safest way would be with an 8s minimum balance charger. This is probably your best option.
http://www.hobbypartz.com/75p-1220-charger.html?gclid=CNa3z9_N57ICFayPPAod10MAPw
Cheapest way would be with a bilk charger of no more than 33v.
Both ways are pretty simple.

A better SLA is a lifepo4 with bms and plug and play charger. Just get a good enough cell for your needs or always buy a better cell than you need so is not stressed to it limits.

SLA batteries are not as cheap as they used to be. On the other hand, they won't burn your bike down like the RC lithium polymer packs wesnewell is recommending. There are some recent threads about that, so just page down a bit for more details. For those things to be safe, you have to treat battery monitoring and maintenance as a pastime. I don't think it's a very appealing pastime at all.

Changing your bike over to a different battery chemistry would require getting a new charger, too. Still, if you ride more than a little bit, it might be more cost-effective to switch to a lithium iron phosphate system now instead of re-upping your SLA pack.

If you decide to keep SLA chemistry, and at the amp loads you're discussing, I'd just seek out the cheapest freshly manufactured AGM type lead-acid batteries I could get my hands on. In my observation, the differences among SLA batteries are not so great as to warrant paying much more than the minimum, and the lowest priced commodity batteries are likely to be freshest due to quicker turnover.

A lot will depend on what you want to get out of your bike. If you need longer range, want the bike lighter, and WILL be riding it regularly, the extra expense of a lifepo4 pack would be well worth it. A 24v 20 ah lifepo4 pack would blow your mind. Ignore the lipo guys this time, you have no need for the high performance of lipo for your bike. Longer lasting lifepo4 would be better for your cost per ride.

If you want to have a battery that can stand storage for a year at a time, then be used just occasionally, a nicad pack would be just about ideal. Unfortunately good nicad ebike packs are not avaliable at Grin cyclery anymore. Nicads have a shelf storage lifespan measured in decades. They have dissapeared from the ebike world because of cost, high weight, and enviromental issues with nicad disposal. But it's still possible to paralell 4-6 , 24v nicad drill batteries to run an ebike. You need that many because the packs are only 2 ah or so in capacity. Not cheap, but they'd stand sitting in the garage for years.

But if you range needs are moderate, and funds are tight, some more sla's could be best. I agree with Chalo, don't buy the most expensive ones you can find. But I would like to add that they do need to be a type intended for EV use. The very very cheapest might be designed for a 5 amp draw, and your bike will be drawing up to 20 amps. The cheapest ones you can locate that are intended for kids toy electric cars should be fine. Cheaper ones intended to power emergency lights work, but just don't last so long as EV grade bricks that have thicker lead plates inside. Looking at the weight, if it's lots lighter, you get less lead and less range. Lucky you, if you find a source close enough to save on the shippping. Shipping lead bricks is pretty costly.

But that said, Chalo does have it right. The lead is so low performance and short range to start with, that you might not notice all that much difference between high dollar top grade EV ones and lower weight ones that are cheaper. The difference might really make less impact if you have short rides in mind, then will park the bike too long using up the battery just sitting on the shelf anyway. Don't buy lead at all though, if you ride far enough to discharge them 100%. You can kill lead in weeks if you discharge them too deep enough times. Lead needs to be kept charged all the time as you know, but it also needs very light discharges to last. Like 50% depth of discharge. Lithium tolerates 100% discharges ok, and it really shines if discharged 80%.

dogman said:

But it's still possible to paralell 4-6 , 24v nicad drill batteries to run an ebike.

Click to expand...

But if you do, read these first:
http://www.endless-sphere.com/w/index.php/Batteries_NiMH_%26_NiCd

Thanks for input so far.

In the UK we are rather hamstrung by a 300W <15mph (under power) limit for ebikes on the road.

In that context, you can probably see why we are reluctant to splash out much.

But I might still be tempted... ...I can charge in the fireplace...

With 4 Turnigy 4S hardpacks, Could they all be balance charged at once with the above suggested charger?
http://www.hobbypartz.com/75p-1220-charger.html?gclid=CNa3z9_N57ICFayPPAod10MAPw

I think not, though I'm ready to be corrected.

Plus a 12v or 15v power supply so you can plug it in the wall.
Lifepo4.
Lifepo4.
Lifepo4.
Just charge once a month. And use it.

Zippedy said:

In the UK we are rather hamstrung by a 300W <15mph (under power) limit for ebikes on the road.

Click to expand...

but who is ever going to know? Unless you are planning on speeding up and down the M42or otherwise drawing attention to yourself, going up to 500 or 1000W and 20-25 mph, no one is going to even notice..

NeilP said:

but who is ever going to know?

Click to expand...

Anyone who reads your forum signature?

Though I'll assume that's your strictly off-road setup

I tend not to trust the numbers written on an SLA brick further than I can throw them, and I'm not that good at throwing big heavy bricks. If one's datasheet says it's double the capacity and current delivery of another, it seems more likely they are just lying about the performance by that much greater amount than the other battery mfg is lying.

Remember, that ABS lid on the battery doesn't resist whatever silk-screen text/numbers they want to print upon it. Just like the 18650's you can buy on ebay with shrink wrap saying 5,800mAh, when they are more accurately ~2,000mAh.

I know this is a slight deviation from the original subject, but is there any scuttlebutt about carbon foam SLA batteries these days? I was hopeful about Firefly Energy's technology, but after they went bankrupt I have not seen anyone else try to pick up where they left off.

SLAs would not have to improve nearly as much as Firefly were promising for them to become interesting again.

liveforphysics said:

I tend not to trust the numbers written on an SLA brick further than I can throw them

Click to expand...

Too true.
There are plenty of SLAs on the market of the same size quoting 9+ah, but they usually do not to have proper data sheets. Nor do they come from ranges that suggest they come from leading edge manufacturers.

But here's an optimistic spec for a chinese battery from a US reseller:
http://www.apeximg.com/spec/40748.pdf

Looks good, but perhaps too cheap to be true. And I cannot find them here.
Actually, the optimistic data sheets do tend to come from US resellers...
Perhaps resellers dare not show such sheets to the regulators in Yoorp. I dunno.

Carbon foam looks good, though I doubt it would be cheap.

price ?

I see them for 22 of your dollars on Am****n. free shipping in US.

I now reckon I can fit 12v 10ah SLA bricks in my Currie packs.
There are a few bricks around with the same 'footprint' but 18mm (3/4") taller.

They seem to deliver the juice and should sag a fair bit less than the ones I have now.
Downside is I'll be carrying an extra 4 lbs of lead with 4 bricks. Though 2 should do for most rides.

Upside - I can collect them locally and they are only GBP4 more each than the 7ah slabs.

http://www.ritarpower.com/upload/pdf/2012051111475380054823.pdf

But there's no rush. I'm still looking at Li.

22.00 cheap how about 15ah or 20ah ?. This for trailz bike ?

Is this a 24V system?

http://endless-sphere.com/forums/viewtopic.php?f=14&t=44100

circuitsmith said:

Is this a 24V system?

http://endless-sphere.com/forums/viewtopic.php?f=14&t=44100

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circuitsmith: Are you selling your BMS? If so, why don't you create a sale thread in the "For Sale" section and describe your product along with price and ordering information?

I spotted circuitsmith's BMS thread a few days ago, but being a lipo virgin, I can't quite get my head around it.

For instance, with a 7S3P setup, how do you balance the 21 cells? Are there 6 sockets under the board for the 6 Turnigy balance plugs?

Edit: Yes, the Currie ezip is 24v.

That sla is intended for standby service, like emergency lights. It's not an EV battery. Will it work? yes. For long range and long service life? No. But again, it depends on your use pattern whether it's best to buy a cheap battery every year to use only 50 cycles a year, or buy something robust like lifepo4 for 200+ cycles per year for many years. Two different needs, the heavy use pattern would not be cheap with low price sla's.

Currie ezip the bike ?

Repalce them with these.

http://www.amazon.com/K2-K2B12V10E-Lithium-Phosphate-Battery/dp/B0056BV43U/ref=pd_sim_sbs_misc_3/186-0269704-9099949

This is the new stuff and makes for a real easy upgrade.