# Looking to replace/upgrade batteries, could use some advice



## typci (Feb 16, 2012)

New to the forum, and plan to do plenty of reading and searching, I assure you. I'm already pretty knowledgeable about batteries and such, but I've got an urgent problem.

I've got two electric motorcycles. Both are originally electric, not converted. The batteries on both are next to gone, and I need to replace/recondition/upgrade/do something quickly as I need at least one in decent condition to drive for work. I many be able to get through next week on what they have left, depending on my work schedule. But I'm going to push to have something done this weekend.

One is 72V 20Ah (6*12V 20Ah batteries)
The other is 48V 40Ah (two sets of [4*12V 20Ah] in parallel)

They are both sealed lead acid. The 72V batteries are just shot. I'm taking the 48V bike to my repair guy tomorrow to make sure none of the batteries are bad. Also, my repair guy has a long history working with batteries, so he'll help me with any problems I run into.

Oh, and I'm an American in China. And my Chinese isn't that great, just good enough to converse.

So, if you can help me here, I've got a couple of possible scenarios to consider:

1) Recondition the batteries. Don't know if this is really possible/worth it. I need range and speed on my bikes, and for that I need good batteries. Even if I de-sulfate, change the battery fluid, etc, I don't think I'll get the reliability/strength from the batteries that I need. Anyone got experience with this?

2) Replace the batteries. I could replace them with another set of lead acid batteries, or maybe silicate it I looked hard enough. I'm guessing about $200 for new batteries on the 48V bike. It would be easy and would take an hour or two tops. Also, I could just replace the batteries in the 72V bike, to buy some time, and then sell it after I upgrade the 48V bike.

3) Upgrade the batteries. As a chemist, I know to the obvious advantage to Li-ion. The problem I have is my bikes are set up for lead acid, and to change to Li-ion I know there will have to be some serious changes, and additional hardware will be needed. Also, if I change to Li-ion, I want to have the possibility to move the whole Li-ion setup to another bike, should I buy a new one. Everyone here uses lead acid, so selling my bike with Li-ion batteries won't go over too well. Plus if they last for a couple years, I'll want to buy another bike during that time. I can buy a bike without the batteries, and just drop the Li-ion setup in, assuming the voltage/wattage requirements are the same. I've currently got a 2000W motor, and I don't see the need to go higher that that.

I found these A123 batteries for sale: http://item.taobao.com/item.htm?id=13500022222

There about $9.5 a pack, 3.3V, 20Ah. I figure I'll need 30 to replace the batteries on my 48V bike, and get 49.5V 40Ah. It'll cost me about $280, plus shipping, which should be about $25. Plus I'll need a new charger and a few other things I'm sure to keep the Li-ion in order. Also it gets cold here. Lowest I've seen is -7ºC, but we get overnight freezing for two to three months. And during the summer it is hot, 33ºC and up. So I'll need to do something about the battery temperature.

Also, how long do Li-ion batteries realistically last? I'm guessing I'll do about 30-70% (Avg 50%) discharge everyday. Their is rarely a day I don't ride my bikes. When the range gets to half the original, I'll have to replace the batteries. I need to make sure that if I upgrade, it is worth the cost. I'm currently getting about 14 months out of the lead acid batteries.

So, there's my situation. Anybody got some advice/wisdom they can impart on me?

Also, if you want, I'll post some pictures of the bikes. It'll give you some insights into how the Chinese are doing their electric vehicles.


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## DIYguy (Sep 18, 2008)

typci said:


> I found these A123 batteries for sale: http://item.taobao.com/item.htm?id=13500022222
> 
> There about $9.5 a pack, 3.3V, 20Ah.


Is this accurate? $9.50 USD equivalent for a AMP20?


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## DIYguy (Sep 18, 2008)

BTW, if it were me, I would buy cylindrical lifepo for the bikes.


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## typci (Feb 16, 2012)

DIYguy said:


> Is this accurate? $9.50 USD equivalent for a AMP20?


that's what it says on the website. There were lots of other people selling them for $10-$11, but this seller undercut by a little. I see this kind of undercutting all the time on taobao. Also this doesn't include shipping, which should be $1-$2 a kilo. I have no idea how this relates to prices in the usa. Is $9.50 high or low?

also didn't see cylindral lipo for sale. I'll look for them. Any reason why to go cylindral? I already have my battery boxes and don't want to do any unessesary modifications.

Also, I took the 48V bike to the shop, and all 8 batteries were swollen and cracking. I'm not sure if it was due to the cold, or internal problems with the battery, or something else. I'll need to do some research on that. So I just replaced the batteries since I need the bike working ASAP and it was only $190 with a year warranty.

I'm going to start designing the Li-ion battery system and hopefully put it together during the summer. This should give me enough time to read design and source good parts. Also I found 48V 20Ah a123 packs (16 a123 batteries) with individual cell BMS built into the pack for $240 including shipping, so I may grab two of those and charger and be done with it. It would be a lot less work.

I still have the 72V bike to deal with. I looked at the batteries, and they seemed fine. So maybe winter didn't break the batteries in the 48V bike. It's charging now and I'll take it out for a drive tomorrow to test the range. If it is functional, I'll just sell it.


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## Yabert (Feb 7, 2010)

typci said:


> Also, how long do Li-ion batteries realistically last? I'm guessing I'll do about 30-70% (Avg 50%) discharge everyday.


Really long compared to lead. At 50% discharge, I guess over 5000 cycle based on this specs.... it's more than 15 years at 300 cycle a year!

But you can destruct it in few cycle if you don't use it properly.


10$ for this awesome cell is a pretty good deal... Are you interested to start battery selling business? I offer you 16$ a cell including shipping...


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## DIYguy (Sep 18, 2008)

typci said:


> that's what it says on the website. There were lots of other people selling them for $10-$11, but this seller undercut by a little. I see this kind of undercutting all the time on taobao. Also this doesn't include shipping, which should be $1-$2 a kilo. I have no idea how this relates to prices in the usa. Is $9.50 high or low?


People have been paying about $30 to $35, recently this has dropped to the $20 dollar range.



typci said:


> also didn't see cylindral lipo for sale. I'll look for them. Any reason why to go cylindral? I already have my battery boxes and don't want to do any unessesary modifications.


Cylindricals with screw connections are common for bikes as they can be built into different shape packs. They also tend to have a higher C-rate capability than most prismatics.



typci said:


> Also, I took the 48V bike to the shop, and all 8 batteries were swollen and cracking. I'm not sure if it was due to the cold, or internal problems with the battery, or something else. I'll need to do some research on that. So I just replaced the batteries since I need the bike working ASAP and it was only $190 with a year warranty.





typci said:


> I'm going to start designing the Li-ion battery system and hopefully put it together during the summer. This should give me enough time to read design and source good parts. Also I found 48V 20Ah a123 packs (16 a123 batteries) with individual cell BMS built into the pack for $240 including shipping, so I may grab two of those and charger and be done with it. It would be a lot less work.
> 
> I still have the 72V bike to deal with. I looked at the batteries, and they seemed fine. So maybe winter didn't break the batteries in the 48V bike. It's charging now and I'll take it out for a drive tomorrow to test the range. If it is functional, I'll just sell it.


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## sokon (Sep 15, 2011)

> People have been paying about $30 to $35, recently this has dropped to the $20 dollar range.


the cells people where/are paying 30$ for have tabs, quite an essential part of a battery


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## DIYguy (Sep 18, 2008)

sokon said:


> the cells people where/are paying 30$ for have tabs, quite an essential part of a battery


They are coming with tabs in $20 range now also. According to JR, one quote as low as $17.50


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## sokon (Sep 15, 2011)

ok, interesting 

they seem to be flooding the market...good for us!


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## typci (Feb 16, 2012)

Yabert said:


> Really long compared to lead. At 50% discharge, I guess over 5000 cycle based on this specs.... it's more than 15 years at 300 cycle a year!
> 
> But you can destruct it in few cycle if you don't use it properly.
> 
> ...


I don't know anything about the quality of the batteries or the legal stuff to feel comfortable to sell them back to the usa. Plus there is the whole transfer of money from the usa to china. The best i could do is help you negotiate with a seller here in china. If you cut out the middlemen, it will get your price down. If you want i could ask some sellers if they are wiling to ship to the usa. From there you would just need an alipay account, chinese equivalent of paypal. I could prob help you get that too.


On another note:
If i'm going to switch to lifepo4, i need better data to convince me to switch. Right now, my lead acid batteries come with a year warranty, cost 2/5 the price of lifepo4,maintenance free ( i did just buy a desulfanator, but i just plug it into my bike once a week), and are tried and tested.

Lifepo4 are supposed to be great, but the technology is still new. Do i need a bms, top or bottom balance balance, and plenty of other questions are still being discussed. The one thing people agree on is that there is maintenance. Is it worth it to get better life out of the batteries in exchange for maintenance and other possible problems?

Today was a great example of my point. My batteries were dead, so i took it to the shop, walked to the restaurant next door and ate lunch, paid for the new batteries, and went home. And next year i will do it again. That's what is required of me to maintain my lead acid batteries. What if i was using lifepo4? What will i have to do to maintain my bike. My mechanics don't have much experience with lifepo4, so i may have to do the work. Which i can do, but then i'm spending my time which has to be factored into the cost in to the batteries, and my time is expensive.

Does anyone have any data on the failure rate of lifepo4 cells with or without bms? If my battery breaks, i still have to go to work/school and i need to know the probability of my battery having a problem. With lead acid, that probabilty approaches zero. Even when i had my recent problem, i drove the bike for over a week before i took it to the shop, meaning that the problem didn't interfer with my life.


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## dougingraham (Jul 26, 2011)

typci said:


> Lifepo4 are supposed to be great, but the technology is still new. Do i need a bms, top or bottom balance balance, and plenty of other questions are still being discussed. The one thing people agree on is that there is maintenance. Is it worth it to get better life out of the batteries in exchange for maintenance and other possible problems?
> 
> Today was a great example of my point. My batteries were dead, so i took it to the shop, walked to the restaurant next door and ate lunch, paid for the new batteries, and went home. And next year i will do it again. That's what is required of me to maintain my lead acid batteries. What if i was using lifepo4? What will i have to do to maintain my bike. My mechanics don't have much experience with lifepo4, so i may have to do the work. Which i can do, but then i'm spending my time which has to be factored into the cost in to the batteries, and my time is expensive.
> 
> Does anyone have any data on the failure rate of lifepo4 cells with or without bms? If my battery breaks, i still have to go to work/school and i need to know the probability of my battery having a problem. With lead acid, that probabilty approaches zero. Even when i had my recent problem, i drove the bike for over a week before i took it to the shop, meaning that the problem didn't interfer with my life.


In my opinion LiFePo4 are less fragile than Lead Acid. If you just use lead you get about a year of life out of them. If you pay a lot of attention to them you can double that. With Lithium there are people who do pretty much what you are talking about. Plug it in and charge it and then use it. To get there you oversize your pack. This is easy because all you need to do is use the same ratings as on the Lead Acid batteries. The ratings on the LiFePo4 are real at the currents used in EV's and generally not even close with Lead Acid. You don't need a BMS if you bottom balance the pack and then set the charge termination voltage down a little so the batteries end up undercharged. You won't get full capacity but you won't have problems either.

If you know exactly the voltage the charger you use right now terminates at you can probably pick a cell count that will work with the existing charger. This would't be my first choice but you can probably get away with it. Probably 23 cells for a 72v system and 15 cells for a 48v system.

If the charger you are currently using just tapers off to a low current and does not stop charging this would not be suitable for the LiFePo4 cells. With a bottom balance and undercharging (3.45v per cell) I would expect almost zero maint.


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## DIYguy (Sep 18, 2008)

typci said:


> Today was a great example of my point. My batteries were dead, so i took it to the shop, walked to the restaurant next door and ate lunch, paid for the new batteries, and went home. And next year i will do it again. That's what is required of me to maintain my lead acid batteries. What if i was using lifepo4?


Today was a great example of your point, I agree. replacing lead acid batteries. Next year you get to do it again. Exactly the point. With LiFePo4 u don't need to. Ur bike will likely wear out first.
If ur a techy guy, bottom balance and check them once a month with a volt meter.
If ur not, use a bms. A simple one like the mini-bms.

BTW, u may not realize it, but if you want ur SLA to last, you need a balancing BMS. For floodies you don't. 

One last advantage... with the weight savings, u could put one of them cute little asian girls on the back and still go fast. ) Priceless.


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## typci (Feb 16, 2012)

DIYguy said:


> Today was a great example of your point, I agree. replacing lead acid batteries. Next year you get to do it again. Exactly the point. With LiFePo4 u don't need to. Ur bike will likely wear out first.
> If ur a techy guy, bottom balance and check them once a month with a volt meter.
> If ur not, use a bms. A simple one like the mini-bms.
> 
> ...


Actually I currently can fit two chinese girls on there and do top speed with about half the range, so your saying if I put lifeo4, I could have 3? That's the kind of benefits I'm talking about.

Anyway, I'm looking at 16 cells for 48V block. That seems to be the standard here in China. I can buy a charger specifically designed for 16 cell blocks. I can also buy a simple BMS that manages 16 cells for about $25. http://item.taobao.com/item.htm?id=13716851371 You will need to run it through google translate to make any sense of it. Or I can buy a prebuilt block with BMS already integrated: http://item.taobao.com/item.htm?id=13805031856.

So either bottom balance or BMS. I could do that. I'd rather not have to manually check the cells once a month, as I'd like them in a sealed unit. If I have a simple BMS like the one above, if there is a problem, how does it communicate to me that I have a problem? Maybe I can find a cheap BMS with an output that will tell me what is going on with the cells. That would be nice.

Also, I'm aware I need a balancing BMS for my SLA. I just can't find one for sale. All of them in China seem to be for lithium.


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## drgrieve (Apr 14, 2011)

If you set up the batteries correctly in the first place - good clean connections, no movement in the tabs. Top or bottom balanced (I'm in the bottom balanced, under charge, no bms camp) correctly. Count your ah and try to not below 10% soc (more important if top balanced of course)

Then from all end user reports I've read I would say that you have an excellent chance of zero maintenance for 10 years or more. You might want to check the voltages once in a while but you'll get bored of them being all the same.

If you can get A123 20ah at under $10 then that's a dead set bargain and even at $20 they are better deal than lead acid. At $10 it's a joke to consider lead acid.

I would seriously consider selling them you would make a small fortune. Certainly sell a few thousand units a month quite easily if the price is right.

Icing on the cake is if you could sell them packaged like a prismatic cell. No one is doing that yet. That would sell like gang busters. Easily $25 a cell for that.

People have thought them quite the deal at over $30 a cell plus shipping unpackaged with little info on them.


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## typci (Feb 16, 2012)

drgrieve said:


> Icing on the cake is if you could sell them packaged like a prismatic cell. No one is doing that yet. That would sell like gang busters. Easily $25 a cell for that.


What do you mean by packaged like a prismatic cell? 

The ones I'm looking at have: a123 systems with logo, made in korea, and a bunch of bar codes and serial numbers.

I will seriously discuss it with some business associates of mine, and see what I can do. I have a friend in the USA who can handle the business side of things there. My biggest concern is quality of the products, since they are coming from China.

Also, I think I found the cylinder batteries: http://item.taobao.com/item.htm?id=5505999704
2.3 Ah, is this right? I'd need ton of these if that is the case. But they're only $2-3 a piece.


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## drgrieve (Apr 14, 2011)

Well these particular cells (the 20ah pouch cell) would be the best cell you can buy for reasonable money on the market. The only issue with them as opposed to the next best cell I know of - the Calb 100ah cell - is that how do you actually package the cells so that it will last 10 years in a car?

In a car 20ah isn't enough. In the build I'm considering I want 4 cells parallel and 100 series for 400 total (4p100s). So currently I'd need to spend many hours putting them into an arrangement that would last the test of time. 

Packaged into a plastic box like the Calb 100ah cell would be perfect. But the cells inside would need to made immobile so the tabs don't break. The terminals made so they can handle over 1000 amps (this is not hard). Hopefully not impacting the 130 wh/kg too much ie not weighing a whole lot.

There are a few smart folks trying different methods currently - I'm following what they are trying. But something simple and cost effective is a key for on selling.

Certainly nothing out there yet to purchase and put in a car with no further effort over a normal large format prismatic cell.


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