battery issues

deacon · Mar 25, 2009

it would depend on the amp hour of the battery and the wattage of your bike motor.
remember a wheel chair only runs at one or two miles an hour. It is geared for slow but with more torque so I really don't know.

Now they say watt hours is what you need to know. try this for your math

ah of the battery x voltage of the batter to get watt hours.

Divide your watt hours in the battery by the watt of your bike engine, then you should have the hours your bike will run on that battery.

I would say figure half as an effective range so the battery isn't completely drained. I think that is the problem with not getting anywhere near the time the math would suggest. We seldom run the battery dead because the bike's performance gets so bad.

effectively a 12am batter is only about 7amp hours of usable current.

DOC BOLM · Mar 25, 2009

Deacon i saw a kid building an ebike in his dads shop.I guess he is 12 or 13.His dad had gotten some 24 volt lawn mowers from one of the local casinos.That thing would haul tail.The cover had a label saying 3 hp.He had a flat on the rear while he was on his first ride.I'LL see him later to see how he came out.Have you or anyone else used a mower motor & battery setup HD

deacon · Mar 25, 2009

I haven't but shoes mentioned it to me.

deacon · Mar 26, 2009

It's raining to beat the devil out there this morning and projected to continue all day. Tomorrow I might get a change to run some tests. Those batteries (flooded cell lawn tractor) ran down to 12.67 over night. They won't hold up that's for sure. I should have kept them charged, but I frankly never thought I would use them again.

I am still going to test them because I have them with which to work. I will leave them on the scooter charger until the last minute. The batteries will begin with a full charge but will drain quickly I'm sure. More so than a new battery would. If the test is promising, I will buy flooded next. I can get a set of tractor batteries for under 50 bucks locally. I can get a set of three times stronger car batteries for twice that I think. I need to keep looking for a reliable formula to convert cca to ah.

I mean a 56amp hour battery for 50 bucks would be a real deal if that were the case. I also want to pull these two batteries to see how the do on a trailer. They are really two very different factors. The power which I am sure will be significant and how they effect the bike.

deacon · Mar 26, 2009

I hear there is no reliable formula but I am going to search and post my findings as i go the see if I can verify any of them. It's something I personally want to know.

One guy on a form says he has one of those starter gizmos that uses an sla of 18ah and that it has a cca of 300. using these numbers it would be mulitpy the cca by .06... that would make a lawn tractor battery approximately 11amp hours. Thats about what I have in a much smaller sla. But last year I could get one for twenty bucks locally.

I just found another one that says its .04 which would make the battery 7ah which also could be. When I used these flooded cells I was also using a 7ah battery pack. I never really did a range test though. It certainly wasn't any less than 7ah.

I found another one who says the number is .12 which is a far cry from either of the others.

Pep boys gave a set of numbers that work out to .08 Which would make the lawn tractor batter 15ah.

this gives the formula I gave way back several post ago. Batteries

their formula would be simply... cca/5= rc then rc /2+16= ah this formula is way out of sync with the others. It would put the lawn tractor at 35amp hours.

deacon · Mar 26, 2009

As with most other things it's going to take a field test to know. I wish I had a couple of new flooded cells to test with but that's okay. I will run a test first of all to determine if

a. it is worth pursuing
b. lawn tractor batteries would be worth the money.
c. would auto batteries be worth the extra money.

using any of the formula on both types of battery would give a reasonable comparison if the SAME formula were used both times.

Let assume the .08 is a fair number. Then a 190 amp (assuming the lawn tractor batter gives cca)x.08 _15amp hours,

If that is the case then a 500 cca battery should be 40ah or at least three times larger... a 699 cca would be 48 ah. The ratio would be the same no matter which formula you used. If you found an auto battery on sale cheap enough it would be the better buy.

Of course there are so many factors involved it would be hard to tell exactly what is what for anyone but for yourself.

My first concern is weight and the effect of pulling on the bike's performance. I have one good trailer capable of pulling this large a load, so i'm going to strip it down for weight and give it a try for pull first. With of course trying to decide if it's worth the effort to go with the bigger batteries.

I bought my two sets of sla 12 /12 for about a hundred dollars. I have 24amp hours from them. For the same 100 bucks I might be able to get one set of 500 cca batteries. The weight would be the big difference I think.

With a little luck I can get at least one run from the old lawn tractor batteries so I can get a feel for the performance change in the bike. That will be a big big factor.

cvpsmith · Mar 26, 2009

deacon said:
I am still going to test them because I have them with which to work. I will leave them on the scooter charger until the last minute. The batteries will begin with a full charge but will drain quickly I'm sure. More so than a new battery would. If the test is promising, I will buy flooded next. I can get a set of tractor batteries for under 50 bucks locally. I can get a set of three times stronger car batteries for twice that I think. I need to keep looking for a reliable formula to convert cca to ah.

Deacon,

I found this on another forum w/ regards to CCA/AH:

GaryInOz (Vic) posted:

"CCA's are related to the total surface area of the plates in the individual cells. Starting or Deep Cycle relates to the thickness of the individual plates.

For a given volume, either the number of plates may go up (ie., Starting, high CCA battery, but not much metal to get through before the plates disappear altogether) or the thickness of the individual plates goes up (ie.,Deep Cycle, lower CCA but able to withstand continuous discharge without mechanically dissolving the plates away). The starting battery is capable of high currents over a very short timespan (= high CCA, and generally lower A/H capacity), related to the high surface area. Deep Cycle have a lower surface area but more "meat" in the plates (= lower CCA, but generally higher A/H capacity), enabling the chemical reaction to occur to a greater depth in the plate.

THERE IS NO CONVERSION RULE FOR CCA's TO A/H's. Apples and oranges.......

Before I get shot down, please take note. I said "FOR A GIVEN VOLUME...". There will obviously be differences in size and construction that will affect CCA and A/H ratings of individual batteries."

A lot of people on the forum seemed to agree with this conclusion...

cvpsmith · Mar 26, 2009

Here is a link to the forum:

Battery CCA/amp hours formula @ ExplorOz

deacon · Mar 26, 2009

cvpsmith said:
Here is a link to the forum:

Battery CCA/amp hours formula @ ExplorOz

Actually I read this when I was trying to find a way to calculate the ah of a battery. Even though there is no direct correlation from one to the other. I have also read that european batteries if not now at one time were sold in AH and those were used to start automobiles.

I may be totally wrong, I usually am, but I think there is a way to get at least an estimate the value of a cca battery. It is my believe that a battery will last a given amount of time based on any measure of it's storage capacity. It might be more for a deep cycle battery, but I'm almost sure there is some way to figure one from the other.

For instance It is my understanding that cold cranking amps is actually a measure of the discharge of the reserve amps of a battery. The discharge rate is determined by the thickness and number of the lead plates in the battery. So if the discharge rate is 550 amps in 30 seconds there had to be a rate for discharging it at 1 amps for an hour.

I know there is a wide price difference between batteries as well. I think that is more about the number of plates than it is about the reserve amps in the battery. though I could well be wrong. I might have to take into account the quality of the battery I purchase. But I do know that I have three lawn tractor batteries and they all have different amp values. I am sure they are expressed in cold cranking amps. It's confusing I do know that much.

We have all experienced what happens when a car won't start. The battery will crank a while then it will get slower and finally die. It is discharging at max capacity for an amount of time that should be consistent with temperature ect. So if the battery discharges at 1 amp instead of 550 it should last roughly 550times longer. So if we know how long a battery will turn the car over at 550amps we should know how long the battery would last at one amp an hour...... I'm not smart enough to factor in all the variables but I think I might be able to get an idea from the field testing. At least it is worth a try for me. If for no other reason than idle curiosity.

P's there may not be a formula that will work, but the battery will last a predictable amount of time once you figure that out for Saturday, it should be the same for Monday. At least that is my assumption.

cvpsmith · Mar 26, 2009

On this subject, here is a very interesting device:

Digital DC Ammeter, Amp Hour & Watt Hour Meter

Digital DC Ammeter, Amp Hour Meter, Watt Hour Meter

I might have to pick one of these up. This should help me keep track of a lot of factors. What do you think? Price seems right, too...

deacon · Mar 26, 2009

cvpsmith said:
On this subject, here is a very interesting device:

Digital DC Ammeter, Amp Hour & Watt Hour Meter

Digital DC Ammeter, Amp Hour Meter, Watt Hour Meter

I might have to pick one of these up. This should help me keep track of a lot of factors. What do you think? Price seems right, too...

I think you should get one and immediately read your auto battery and let us know the ah. I for one would be very curious.

deacon · Mar 26, 2009

I burned up my 24v battery charger today. It is the second one so I'm going back to using my 12volt charger and do one battery at a time. I have enough time for that

toytime · Mar 26, 2009

An Izip is rated at 24 volts and 450 watts. The bats are 10 amps each.
when I use your formula, Deacon , amps X voltage , I get 480 so I have no idea about all this stuff. This electrical stuff makes my head hurt.
But anyways, lets just agree that an Izip is 450 watts. If a motor sucks 450 watts , the battery would last an hour. If I'm correct, I think I may be starting to understand this now.

Doc Bolm; I've heard that the lawnmower bats. are great because they aren't lead acid.

cvpsmith · Mar 26, 2009

deacon said:
I think you should get one and immediately read your auto battery and let us know the ah. I for one would be very curious.

I don't see how I could hook it up to do that. I can only measure the AH used. Am I missing something in the connection options?

rearengine · Mar 26, 2009

figure that out for Saturday, it should be the same for Monday. At least that is my assumption.

Deacon.. I imagine you figured that out for Eastern time.. What would it be for Central time?? I'm just funnin, Keep up the good work, I'm going to school on ya, and i'm a dammed sight older than you. THat's why I need help on the hills.. Take care... Bill

deacon · Mar 26, 2009

Im just trying to figure this out. I have no idea what I'm doing to be honest.

about the meter I have no idea how they work you probably are doing it right. I just thought you had to have a base line to start with for the ah thing.

I need a lot of help on those hills myself.

cvpsmith · Mar 27, 2009

deacon said:
I need a lot of help on those hills myself.

me 2

As far as I can see, there is no way to DIRECTLY measure this:

Support vector based battery state of charge estimator

EVDL Archive / Forum Interface - Electric Vehicle Discussion List

FTAs:

This paper investigates the use of a support vector machine (SVM) to estimate the state-of-charge (SOC) of a large-scale lithium-ion-polymer (LiP) battery pack. The SOC of a battery cannot be measured directly and must be estimated from measurable battery parameters such as current and voltage.

The only way that I know of to monitor state of charge for a LiFePO4
cell is through integrating the product of voltage and current over
time. There may be more complicated scientific ways to do this, but I
would stick to integration.

All of which tells me that the little battery percentage monitor in the taskbar on your laptop is not a direct measurement, but rather an estimation based on the AH rating of the battery and the amount of power already used over time since the last charge at or very near 100% (which spikes the voltage; a measurable effect).

This is my feeble attempt at understanding it, anyway...

cvpsmith · Mar 27, 2009

BTW, I went ahead and ordered the meter. I really want to see some of these things like typical amp draw with assist vs. motor only, etc. I plan to mount it on top of the handlebars so that I can monitor real-time.

It's been raining here the last couple of days, so no testing on the LiFePO4 as of yet. I got a chance to put 5.2 miles on it the other day, but of course it did that without even breaking a sweat...

deacon · Mar 27, 2009

It rained here most of the day. I found time to do a little welding. I got the small, low trailer built for the flooded cell batteries. Charging them for long slow periods might be helping I'm not sure.

I blew out my 24volt charger so I'm back to my 12 bolt trickle charger and doing one battery at a time. Bummer. I might take a look at ebay for a 24volt charger but I have terrible luck with them. They are not very robust since they were designed to be plugged in to a mounted pack and I do all kinds of things with mine. I do have two 12 volt chargers I could charge two batteries at at time. I wonder if you can hook two 12volt charges together to make one 24volt charger.

deacon · Mar 27, 2009

I should mention that this battery cart is different from the other in that since it has so much weight on it, I welded to together a frame that sets the batteries only a couple of inches off the ground. With a little luck it will be pretty tip proof. I have had the big wet cells tip over on me before. Not a good feeling to drag the trailer around on its side.

It also uses ten inch plastic lawn mower wheels with solid rubber tires built in. I had them and I wanted to see how they would do since I would hate to change tires on a trailer.

battery issues

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