SLA type battery are they good???

Discussion in 'Electric Bicycles' started by john B., Sep 16, 2009.

  1. john B.

    john B. New Member

    (2) 12v / 10 AH valve reg. rechargable does any one know how they rate for life expectency and regular use for job commuting??? this is on an Izip bike. Im not sure about this to invest $$$ I need reliability not any more grey hair.

  2. safe

    safe Active Member

    The short answer is that lead acid batteries are not very good.

    The long answer is why...

    Most of the other battery types like NiCads, NiMh, LiFePO4 can be drained at rates that are adequate to power an ebike without any performance loss. However, for lead acid type batteries they have something called the "Peukert Effect" which is that they lose a percentage of their total capacity if you try to draw the current out too fast. As a consequence your (2) 12v / 10 AH actually start with:

    2 * 12 * 10 = 240 Wh (watt hour) of total capacity.

    But when you factor in the Peukert Effect you get:

    240 Wh * 50% = 120 Wh of actual energy. (which isn't much)

    Meanwhile you are carrying all the weight of lead which is bad too.


    However.... lead acid is CHEAP and so for a person starting with ebikes it's not such a bad deal.

    NiCads are selling pretty cheap these days because NiMh has mostly replaced them, but they work well.
  3. john B.

    john B. New Member

    buying a second battery

    If I opt to buy a second battery would you think I could get back and forth to work?? Im 200 Lbs. I live in a oven called Phoenix, and there are moderate hills, oooh 25miles one way to work??? Im not sure how employer will feel about recharge I start tomarrow. So this lead acid battery I can buy more of it cheeply to replace life to it right??? Where??
  4. safe

    safe Active Member

    25 miles... that's far by ebike standards unless you do most of the work by pedaling. My guess is that in the desert heat your hope was to be able to rely on the battery power to get you home and not get a workout with the ride.

    A recharge is required because you will barely be able to go 25 miles one way.

    However, if you were to buy something like NiMh batteries you could extend your range and make the trip easier. But the negative on that is the price.

    You are probably caught in a sort of loop where you don't have much money, so you need the job, and you need to get there cheaply, so the idea of spending big $$$ on batteries doesn't make sense.

    There are people that have spent $1000 or more for LiPO4 batteries and management systems. The guys that are spending the big bucks are usually in it for the thrills... it's harder to make the economic argument for ebikes over other options. (cheaper than a car however)

    I gave up on the purely economic argument for ebikes long ago and am focused on them for their potential sport value.

    Yes, you can find SLA batteries on the internet at decent prices, but the shipping is expensive. The best bet would be to find something local, but the sizing is pretty specialized.
    Last edited: Sep 16, 2009
  5. john B.

    john B. New Member

    test road in car

    It is 18 miles one way and only one hill thats will be a challenge. With 2 bateries one to use there one to use back,do you think I will make it with pettleing 25% or 40% ????? What do you think ??? And yes I aint got a whole lot of money and I am tring to do my best till I can get some checks in. Thank you soooo much for answering back!!!!!!! Can I buy just the lead acid and put it into the existing battery cases?????
    Last edited: Sep 16, 2009
  6. safe

    safe Active Member

    If you pedal and assist the bike you will probably make it.

    And if you select the correct battery (right size) then all batteries are generic so don't worry about any specific brand other than that there might be some differences in quality. (some are old when you buy them, you want them fresh like bread) Make sure you are buying "deep discharge" batteries for things like ebikes and not motorcycle starter batteries which are designed differently.

    Let me explain how SLA's (sealed lead acid) work...

    There are two reactions, a sulfation reaction and an oxidation reaction. Whenever the battery is stressed (like if you drain it deeply or rapidly) the battery will get permanent damage (wear) on the oxidation side. You cannot reverse that. If you let the battery sit and especially if you let the battery sit at low charge (which you never want to do) it will build up sulfation and that will weaken the battery too. You can usually fix the sulfation side somewhat with a pulsating charger, but oxidation is forever.

    The "bottom line" is that you:

    Don't ever want to drain the batteries any deeper than you have to.

    You must IMMEDIATELY get the drained battery on the charger. All time that the battery spends at low charge is killing it.


    The nice thing about NiCads is that they are "idiot proof" in that you can either leave them laying around charged or uncharged and it doesn't hurt them. For NiCads and NiMh they wear as a result of the charging process or extremely rapid discharge (rare).

    Good luck... I hope you can make it...
    Last edited: Sep 17, 2009
  7. AussieJester

    AussieJester Member

    Actually the Lifepo4s have come done a bit in price now Safe, for around 700 bucks you can get 48v 20ah Headways including charger. You will get in excess of 50 kilometers with these (my good mate has a set thats what he gets and no pedalling as he has now working pedals)

    If you can get your hands on Li-ion cells they are also very good. Makita and Bosh battery packs use these, they require now BMS A123 cells as per used in Dewalt 36v packs are also very popular amongst the ES crew they do require a BMS. Some people though will by say 4 Dewalt packs and leave them in tact buy a dewalt charger and charge them as if they were to be used in a power tool. If you have a service center for any of the mentioned manufactures hit them up for any faulty packs they have, you will get good cells from them one or two maybe iffy turf them keep the rest ...Just a thought.

    As safe suggests NiCads are an option but like the Li-Ions your need a **** load of them for any sort of range and they are heavy, not as heavy as Lead Acid but still heavier than the other alternatives.

    There are guys that have spent way less than a grand and get big kilometers, if you are strapped for cash though SLAs are the option to get you started, i have them on my first ride and they are going great, my absolute max commute though is under 10 kilometers, if i wanted range SLAs wouldn't be the best option. And yes they are hella heavy.

    Lipos are the other alternative but this tech is best left to the more experienced individuals as they can be very volitle if treated badly ...They are the most energy dense battery available though 4 22v 5000mah packs weigh the same as one 12v 18ah SLA..Surprised you dont use them safe road racing is all about HP to weight ratio, lipos would drastically decrease the weight of your bike.

    Best of luck...

    Last edited: Sep 17, 2009
  8. safe

    safe Active Member

    Well, I know that in a true racing situation I'd swap out the more reliable NiCads in favor of the Lipo's since they definitely have the best power-to-weight ratio. NiCads are good now because I'm still developing the rest of the bike and having to worry about the high tech fragile stuff is not what I want to do right now. But for racing they are the way to go. (I have no one to race yet)

    You can tell that I built the battery so that you can swap it out very easily with just a couple of bolts... ideally you would design some quick release so that batteries can be changed in a pit stop. Then you could race all day long...
  9. BikeMan

    BikeMan Member

    If the car batteries arnt much good or practical how is it this guy who builds e-bikes claims around 62 mile range on 3 car batteries? He has built a handful of different models using the car batteries.I'm curious is all since I'm just now looking into a practical and nice ranging e- bike for myself.Thanks.

    Attached Files:

  10. safe

    safe Active Member

    My old bike started off with similiar batteries.

    3 x 38Ah 12V SLA batteries

    ...and each one weighed 28 lbs, so the batteries alone weighed about 85 lbs.

    On the positive side the bigger batteries could run at lower "C" rates and get better more complete usage.

    The negative is obviously that the batteries are very heavy.


    I'm now running about 55 lbs of SLA's and 15 lbs of NiCads (total 70 lbs) and get about the same battery performance. I break fewer spokes now.

    The pure SLA solution is fine for economy... but for performance the lowered weight of other solutions makes it more practical. For speeds of 20 mph or less the SLA's would be fine. (I rode 3000+ miles on those original big batteries, but rode slowly with them)

    Attached Files:

    Last edited: Oct 17, 2009
  11. BikeMan

    BikeMan Member

    Thanks Safe for your reply.I have a gas engine motorized pusher now and really enjoy it.However I admit it would be nice to have a quieter rig.Its probably a fat chance but I was thinking of removing the gas engine and putting in batteries.I was under the impression electric was as cheap overall to run but after reading some of the threads here I guess I was wrong huh.Darn.It's hard though for newbies to go electric since as far as I can see there isnt a kit,at least not one worth anything for range and speed.Almost need a degree in this type of field to know how.
  12. safe

    safe Active Member

    Gasoline is hard to beat until prices rise back up into the $4 range.

    At $2.50 per gallon gasoline is an enormous amount of energy being delivered. (it's a great deal when you look at the bottom line)

    I gave up on the economic argument for electric a long time ago and now it's just about being clean and quiet and having better performance.

    The previous arguments of "Global Warming" has been so discredited that now it's called "Climate Change". Here in the midwest we've been getting much colder rather than hotter. Historical planetary cycles suggest that we are entering the next "Ice Age". (it's time for it)

    They keep finding more oil too... so the supplies keep getting larger and larger, so the "Peak Oil" argument is again probably 20 years away from being valid.


    At this point the reason to do electric bikes is because they are potentially a fun sport... that's about it. (in my view anyway)
    Last edited: Oct 17, 2009
  13. machiasmort

    machiasmort Active Member

    I agree, only to disagree on a few points here. Take a look at Safes Homemade battery packs... Great value to wieght... 100% serviceable!

    Go to harbor frieght and pick up a few 45 watt solar pannels!!! Your initial investment will be expensive but tou can make your battery packs break down and charge off of the 12V pannels.

    I won't argue Global warmming but will say that the next major issue will be water... The icecaps are melting and with that, we will soon run out of fresh water! People ain't thinking about where all that water comes from in the Great lakes and fresh water rivers in the World!
  14. machiasmort

    machiasmort Active Member

    Just an idea? Your running a push trailer already... How about a few deep cycle marine batteries on that thing... The wieght would help w/friction!
  15. safe

    safe Active Member

    NiCads are a great chemistry because they are pretty much unbreakable. They last for a decade if you are careful with them.

    The LiFePO4 cells are great on performance, but if you operate them outside a narrow band they will quickly age and you will lose your investment. (at least it's safer than LiPo's that can meltdown)

    I'm more interested in that liquid battery idea... it's safer than the idea of super capacitors (high voltage like 3000 volts) and it offers about the same speed of recharge / refill.

    We all seem to have started this electric vehicle thing back when oil prices got into a bubble. I started back in 2006. Once that bubble popped the price of gasoline came down and now gas is cheap again. In some ways it's like the housing bubble, once it popped it's hard to get people as eager to look at housing as the "next big thing" again.

    What is needed is a world war or something where gasoline supplies get cut... then having electric will be the way to go again.

    The strategy I'm focused on is fun... if a machine can be created that is in itself fun to ride then the technology becomes just a feature of the overall experience. It's easier to get people to "go" towards fun than "escape" from pain... but both carrot and stick can work, but the carrot works better in the long run.