You just invented new way for storage Amps on demand - keeping it in postal/courier service (response time is a bit long , tough)... LOL
The nimh battery build...
- Thread starter deacon
- Start date
I was my own bms circuit last night.
I took the pack apart and balance the cells. From what I understand the problem comes when you over charge one cell to bring another cell up to minimum charge. So what I did was charge them till the best cell hit max. Then I took the cells apart and divided them into groups. They pretty much fell into three groups. Then I charged each group to max but not over charge. Then I took them apart again and they were within a 1/10th of a volt of each other. I put them into 12volt battery packs of equal amp sized and left them to balance each other over night. Parallel batteries do that.
This morning i checked and each 12 pack was within a few 1/100ths of a volt of each other. I tried to run it but there are just not enough amps in the pack yet, It does move the bike, just very slowly like an almost dead battery would. That is why I think I'm on the right track, I just need more power in the battery pack. I have also ordered a new motor with less power but less amp draw as well. I'm going to play with it when it comes.
I took the pack apart and balance the cells. From what I understand the problem comes when you over charge one cell to bring another cell up to minimum charge. So what I did was charge them till the best cell hit max. Then I took the cells apart and divided them into groups. They pretty much fell into three groups. Then I charged each group to max but not over charge. Then I took them apart again and they were within a 1/10th of a volt of each other. I put them into 12volt battery packs of equal amp sized and left them to balance each other over night. Parallel batteries do that.
This morning i checked and each 12 pack was within a few 1/100ths of a volt of each other. I tried to run it but there are just not enough amps in the pack yet, It does move the bike, just very slowly like an almost dead battery would. That is why I think I'm on the right track, I just need more power in the battery pack. I have also ordered a new motor with less power but less amp draw as well. I'm going to play with it when it comes.
The man who said balancing batteries by hand was a pain in the butt please stand and accept the truth of the year award. Not impossible but a pain.
Once I get all the weak cells weeded out it should be easier... When I get a battery that won't come up to the others I usually find one aa battery that won't charge as well as the others. I usually rebuild the sting it's in using it to test the construction of the pack. So far it seems that the small battery that just won't charge at the same rate as the others. it probably is a chinese quality control issue.
Once I get all the weak cells weeded out it should be easier... When I get a battery that won't come up to the others I usually find one aa battery that won't charge as well as the others. I usually rebuild the sting it's in using it to test the construction of the pack. So far it seems that the small battery that just won't charge at the same rate as the others. it probably is a chinese quality control issue.
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I ordered 50 more cells from china and 30 arrived. I send them a note explaining the problem. There are not the same guys who I am fighting with over lost in the mail batteries. I expect these guys to replace the batteries since it is obviously their fault.
I just hate that it takes so long to get it here from china.
I just hate that it takes so long to get it here from china.
If someone can explain this please do. I assure you I am not falsifying this to make it difficult.
I meter the batteries before every ride. They always read 13.5 per unit or there abouts. The pack is not at all satisfactory at 36v. It runs way to slow. I have been assuming (Yes I know what that makes me) that it was a lack of amps going from the battery to the controller then to the motor. But adding batteries to the pack in parallel did little if any good
I tried the bike at 24v lots of amps today and it ran like a pregnant pig. Then on a whim I decided to try it at 48volts on the bike with no controller. The bike performs like it does with about 30 volts sla. Runs adequate but with pedal assist. maybe a little less pedal assist.
I read the battery before i left and it was 53 v. My question is, what the heck is happening. Why would the bike run slower on the same voltage nimh power pack than on an sla. I know it gives up its amps slower but adding more amps to the pack didn't really change anything. I have forty more cells coming so I will probably find a way to use this but its not going to be pretty I assure you.
I meter the batteries before every ride. They always read 13.5 per unit or there abouts. The pack is not at all satisfactory at 36v. It runs way to slow. I have been assuming (Yes I know what that makes me) that it was a lack of amps going from the battery to the controller then to the motor. But adding batteries to the pack in parallel did little if any good
I tried the bike at 24v lots of amps today and it ran like a pregnant pig. Then on a whim I decided to try it at 48volts on the bike with no controller. The bike performs like it does with about 30 volts sla. Runs adequate but with pedal assist. maybe a little less pedal assist.
I read the battery before i left and it was 53 v. My question is, what the heck is happening. Why would the bike run slower on the same voltage nimh power pack than on an sla. I know it gives up its amps slower but adding more amps to the pack didn't really change anything. I have forty more cells coming so I will probably find a way to use this but its not going to be pretty I assure you.
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We can only guess what happens...If you measure Amps on batts before ride and during and after , as well as consumption on the controller and motor (in same conditions) , we might be able to conclude something useful . With 48 V directly on the motor it should go noticeably faster (again , without measuring , it's a breeze on your face that makes a difference).
yes and how much I have to pedal and how hard. What gets me is that it performed so badly at 36v and did so much better at 48v. It wasn't the ah of the battery after all. I was dead wrong about that.
I felt like the bike was running at about half throttle, but I thought it was like when the batteries start going flat. I thought I had insufficient amps but actually it was insufficient voltage. Since i read the voltage after it left the battery resistance in the battery can't be to blame. I just don't get it.
Oh well maybe I can use it as a reserve tank kind of thing. I'll know the first nice day that I can ride. I have some very old batteries I can run down quickly to test whether or not I can kick in some extra amps from the nimh pack.
I felt like the bike was running at about half throttle, but I thought it was like when the batteries start going flat. I thought I had insufficient amps but actually it was insufficient voltage. Since i read the voltage after it left the battery resistance in the battery can't be to blame. I just don't get it.
Oh well maybe I can use it as a reserve tank kind of thing. I'll know the first nice day that I can ride. I have some very old batteries I can run down quickly to test whether or not I can kick in some extra amps from the nimh pack.
It is hard to think of batteries with different mind sets but I'm trying.
What I have observed so far about these cheap chinese nimh batteries. It seems to take about 1.5 times the voltage of an sla to get the same performance. As someone here pointed out to me its all about the amps delivered to the motor. A sla battery is like a coral full of horses dying to be free. It has this large gate. When you open the gate it doesn't take too much for a lot of the horses to get out quickly.
The nimh I am using would be a coral with a small gate. For the horses to get out in the same time it would take a heck of a lot of effort to pressure them all through. IE the volt difference required to get the same amps into the system. Maybe someone here can explain that better. AH seems to be the total number of horses in the corral.
48v nimh seems to run like 30v sla don't ask me why the experts will have to give you the mumbo and the jumbo for it. The 48v seems to act like 36v in the controller so far. I ran it piggy back with a depleted sla pack yesterday to bring th volts down some. I am going to charge it and run it 48 nimh today to see if it burns the controller. If not, I will begin thinking about how many ah I need to build a complete nimh battery pack.
What I have observed so far about these cheap chinese nimh batteries. It seems to take about 1.5 times the voltage of an sla to get the same performance. As someone here pointed out to me its all about the amps delivered to the motor. A sla battery is like a coral full of horses dying to be free. It has this large gate. When you open the gate it doesn't take too much for a lot of the horses to get out quickly.
The nimh I am using would be a coral with a small gate. For the horses to get out in the same time it would take a heck of a lot of effort to pressure them all through. IE the volt difference required to get the same amps into the system. Maybe someone here can explain that better. AH seems to be the total number of horses in the corral.
48v nimh seems to run like 30v sla don't ask me why the experts will have to give you the mumbo and the jumbo for it. The 48v seems to act like 36v in the controller so far. I ran it piggy back with a depleted sla pack yesterday to bring th volts down some. I am going to charge it and run it 48 nimh today to see if it burns the controller. If not, I will begin thinking about how many ah I need to build a complete nimh battery pack.
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well 48v did not blow the controller but it also didn't push the bike very well. I guess when all the batteries I have coming get here I will set up a 60volt pack and try that.
today's project is to reconfigure (easily done since I finally got the packs set up with bolt together figttings.) the pack to sixty bolts and try it on the bike with no controller. it won't last long since there are not enough batteries to make more than a make five ah pack. it should get me into the street where I can judge it's potential.
I made a post today on my other computer and it isn't showing up so I'll do it again I guess, I rode the new chain drive bike without a controller on the nimh battery pack at 36v it didn't do all that awful. it just lacked the hill climbing ability I'm used to. I had it set up all the batteries lumped into 36volts. So I reconfigured them to 48volts and tried it again pretty much the same performance as 36. Now this leads me to wonder if it isn't about the ah of the pack after you get the best voltage. I have more batteries on the way so I will be giving that a shot next.
I have a lot of time on my hands so I spend a lot of it balancing there batteries. I expect I'm a little anal about it since the early melt down. When I get a battery (ie 12volt subpack) that doesn't charge up like the others, I take it apart and check each of the strings of batteries in the pack. I repair it or charge it separately.
They say how the packs get ruined is over charging a good cell trying to bring a bad one up. So when they don't look just right I check them carefully. Actually it's kinda challenging and fun, Kind of like a mystery story. I love a good mystery even if I write bad ones lol.
They say how the packs get ruined is over charging a good cell trying to bring a bad one up. So when they don't look just right I check them carefully. Actually it's kinda challenging and fun, Kind of like a mystery story. I love a good mystery even if I write bad ones lol.
I have been forced to sit around thinking about the nimh battery pack, because I am awaiting parts for the chain bike and for more batteries to arrive. I'm about to go out on a limb and will probably have to eat my words since I have before, but here goes.
I think it is going to end up being that I have to buy the highest number of amps for my pack which my controller will handle. I think the batteries I am working with have a 1/1 draw rate. I also think the batteries are over rated on the packaging. So here is what I think will happen.
I think that I will eventually get to a point where the pack pulls up a hill effectively. At that point, I think I will be able to count what I have and get an idea of what it takes to run my bike. Since shipping is so slow from Hong Kong, the only place batteries come from, it might take a month or two more, but I think I am zeroing in on it.
If the factory rating were honest, I would be on the money now. According to the label I have right at 30 ah of battery. I'm thinking that the pack runs at about 2/3 throttle of the sla pack. That is just a guess, but I wouldn't be surprised if the pack is over rated by that much.
I am rough figuring the AA cells at 2ah real figures, the C cells at 5ah more or less. That would make my pack about twenty amps. two thirds of the max draw of the controller. If that assumption is true, I need five more battery strings to make the total of thirty. I am hoping that I am right and that more batteries will increase the pool of amps available to the motor. If not I am throwing good money after bad.
This battery pack is not going to be cheap but it is going to have a few real advantages. If it draws at one to one from the battery pack, then the pack should outlast anything around. It should deliver the full load for an hour, that is about fifteen miles on my bike. Plus it won't be pulling max amps the whole time so that should even increase the range by say 25% more.\
According to the claims (most likely over rated) the batteries can be charged up to a thousand times. Even if that is 30% over rated it is still two years. It is also easy to find the bad string, then the bad cell inside the string. In other words repairing the pack will be cheap and easy. I have a pretty good handle on charging them now.
I use three battery tenders from Wally mart. They are on a 1 hour timer from home depot. I am still getting the charging times down, but they charge roughly 1/3 amp per hour. So I charge them until the first battery reaches 13.5 volts (+/-.1v) Then I remove it from the charger and keep charging the others until the next one reaches 13.5. Then if the last one doesn't seem to be responding I remove the nut and bolt holding all the wires from the strings together and check to see if they are all the same voltage. They should be at that point. Usually I find one that is open or not taking the charge for some reason. i find and repair the problem and reassemble the pack. It is ready to go again.
Now this is NOT for everyone. I have lots of time and love mysteries. When the pack won't charge right up, it's like a great murder mystery for me. I just take over the kitchen table and start to eliminate the usual suspects.
So far it has been quality control by the assembler (me) or a bad cell left over from the great melt down. I have this pack set up so that it can easily be charged on the three battery maintainers from Wally Mart which I use for the sla. For the nimh I use the timer, but for the sla I just plug them into the wall. But I can also change the wiring quickly to set them up parallel, so that I can use on my car battery type charger. I increased the number of leads from the car battery charger to three. If i remove the wires from the pack that makes it a series connection, I can charge all three batteries at once with the one charger. I do that when I want to charge a lot of batteries at once. Three on the tenders and three on the car charger. It sounds like a lot of work but it works just fine once I got used to it. The car type charger works at 2amps minimum but spread that over a couple of batteries and each is getting less than the full load. It doesn't seem to have hurt them any yet.
I think it is going to end up being that I have to buy the highest number of amps for my pack which my controller will handle. I think the batteries I am working with have a 1/1 draw rate. I also think the batteries are over rated on the packaging. So here is what I think will happen.
I think that I will eventually get to a point where the pack pulls up a hill effectively. At that point, I think I will be able to count what I have and get an idea of what it takes to run my bike. Since shipping is so slow from Hong Kong, the only place batteries come from, it might take a month or two more, but I think I am zeroing in on it.
If the factory rating were honest, I would be on the money now. According to the label I have right at 30 ah of battery. I'm thinking that the pack runs at about 2/3 throttle of the sla pack. That is just a guess, but I wouldn't be surprised if the pack is over rated by that much.
I am rough figuring the AA cells at 2ah real figures, the C cells at 5ah more or less. That would make my pack about twenty amps. two thirds of the max draw of the controller. If that assumption is true, I need five more battery strings to make the total of thirty. I am hoping that I am right and that more batteries will increase the pool of amps available to the motor. If not I am throwing good money after bad.
This battery pack is not going to be cheap but it is going to have a few real advantages. If it draws at one to one from the battery pack, then the pack should outlast anything around. It should deliver the full load for an hour, that is about fifteen miles on my bike. Plus it won't be pulling max amps the whole time so that should even increase the range by say 25% more.\
According to the claims (most likely over rated) the batteries can be charged up to a thousand times. Even if that is 30% over rated it is still two years. It is also easy to find the bad string, then the bad cell inside the string. In other words repairing the pack will be cheap and easy. I have a pretty good handle on charging them now.
I use three battery tenders from Wally mart. They are on a 1 hour timer from home depot. I am still getting the charging times down, but they charge roughly 1/3 amp per hour. So I charge them until the first battery reaches 13.5 volts (+/-.1v) Then I remove it from the charger and keep charging the others until the next one reaches 13.5. Then if the last one doesn't seem to be responding I remove the nut and bolt holding all the wires from the strings together and check to see if they are all the same voltage. They should be at that point. Usually I find one that is open or not taking the charge for some reason. i find and repair the problem and reassemble the pack. It is ready to go again.
Now this is NOT for everyone. I have lots of time and love mysteries. When the pack won't charge right up, it's like a great murder mystery for me. I just take over the kitchen table and start to eliminate the usual suspects.
So far it has been quality control by the assembler (me) or a bad cell left over from the great melt down. I have this pack set up so that it can easily be charged on the three battery maintainers from Wally Mart which I use for the sla. For the nimh I use the timer, but for the sla I just plug them into the wall. But I can also change the wiring quickly to set them up parallel, so that I can use on my car battery type charger. I increased the number of leads from the car battery charger to three. If i remove the wires from the pack that makes it a series connection, I can charge all three batteries at once with the one charger. I do that when I want to charge a lot of batteries at once. Three on the tenders and three on the car charger. It sounds like a lot of work but it works just fine once I got used to it. The car type charger works at 2amps minimum but spread that over a couple of batteries and each is getting less than the full load. It doesn't seem to have hurt them any yet.
What kind of price are we looking at for the packs you've built and what AH are you at?
out of curiousity
If you were to believe the mfg (which I don't) I'm at 29ah at the moment. I believe it to be closer to 20.
I have no idea what I have in it but to replace it at the current prices and to get what I think it will take to get to the max draw of the controller is.... drum roll please. 315 to 350 bucks. However it is a truly 30ah not 20ah lithpoly. I'm not sure about anything till i get it on a bike and test it.
The appeal to me is the hands on build and maintenance of it. Plus I can replace and repair a little at a a time.
I have no idea what I have in it but to replace it at the current prices and to get what I think it will take to get to the max draw of the controller is.... drum roll please. 315 to 350 bucks. However it is a truly 30ah not 20ah lithpoly. I'm not sure about anything till i get it on a bike and test it.
The appeal to me is the hands on build and maintenance of it. Plus I can replace and repair a little at a a time.
Those of you who read this now and then know that I order batteries from several ebay sources. Well at least I thought I did. I have had trouble with two battery suppliers and honestly none of them send their names with the shipments. So I really can't tell which ones are doing what based on the battery shipment.
Last night I was trying to determine who was who from the ebay payment log. I found out that all my payments for batteries were going to the same two or three people. I was ordering from six or seven sources but only three people were receiving my payments.
It looks as though the sellers I have been dealing with are just agents. I think they are drop shipping them products to me and the payments are going directly to the real battery supplier. It would explain how the attitudes change from email to email from the same ebay seller.
I have to figure out now which are the reliable ones and which are inept ones.
Last night I was trying to determine who was who from the ebay payment log. I found out that all my payments for batteries were going to the same two or three people. I was ordering from six or seven sources but only three people were receiving my payments.
It looks as though the sellers I have been dealing with are just agents. I think they are drop shipping them products to me and the payments are going directly to the real battery supplier. It would explain how the attitudes change from email to email from the same ebay seller.
I have to figure out now which are the reliable ones and which are inept ones.
Also just for information purposes, it is best not to put the loose batteries you build into a soft pack. Especially true when the wires are laying around with connections exposed. It tends to get shorts and burn up the wires. Yes the house reeks of an electrical fire. The pack now resides in a plastic dishpan.
Okay I rigged the batteries I had to a well over 30amp battery pack at 24v and tried to use it. It was just too anemic to use even with the chain drive which I thought was more energy efficient. I have a few more batteries coming so I will test it with those but I don't expect much from them. After that it is a serious look at how to use it as a hybrid sla/nimh pack. I have already set one trailer up to hold both the 17ah sla and the 30ah (mfg numbers) pack.
Since it adds very little weight to the trailer, I might as well give it a try. I would not recommend this to anyone else period. My 17ah sla are about a year old so if I can stretch them out a little it would be nice. My 12ah set is about two years old I think. With them and the nimh pack I can do about four miles which is more than I could with them alone.
Since it adds very little weight to the trailer, I might as well give it a try. I would not recommend this to anyone else period. My 17ah sla are about a year old so if I can stretch them out a little it would be nice. My 12ah set is about two years old I think. With them and the nimh pack I can do about four miles which is more than I could with them alone.