Tranzx BL03 rebuild

[alanterrill]

I have a Tranzx BL03 battery from a Rayleigh Forge that is showing reduced capacity, although its voltage is holding up at 41V. I want to replace the cells and I've bought a pack from China that says it is specifically for this battery pack.
https://www.ebay.co.uk/itm/36V-12Ah-for-Tranz-X-PST-JD-PST-I2C-BL03-Battery-Li-Ion-E-Bike-electric-bicycle/333556846789?ssPageName=STRK:MEBIDX:IT&_trksid=p2060353.m1438.l2649
However, it has no instructions and no pre-soldered wires on it. I can identify the + and - terminals, but having dismantled the original I can see there are a whole strip of thin wires in addition to the main pair which go the length of the pack and go I assume to each individual cells for testing purposes. I have no way of connecting these. Has anybody done a rebuild on this pack and could advise whether these are critical or whether I could just ignore these extra wires?

 

[vfr400]

You'll have to desolder the sense wires and BMS from the old pack and resolder them to the new one. It doesn't have solder tags, neither does it have ring insulators on the positive ends of the cells, so you will have to be very careful when you solder the wires. Aim for the position on the strips between the cells to solder the wires.

You will also have to think about protecting the cell-pack with some sort of insulation and stabilising medium because the cells are not in holders. Heatshrink would be ideal, otherwise gaffa tape should do it.

You can't ignore any wires. They all have an important function.

 

[MontyPAS]

You'll have to desolder the sense wires and BMS from the old pack and resolder them to the new one. It doesn't have solder tags, neither does it have ring insulators on the positive ends of the cells, so you will have to be very careful when you solder the wires. Aim for the position on the strips between the cells to solder the wires.

You will also have to think about protecting the cell-pack with some sort of insulation and stabilising medium because the cells are not in holders. Heatshrink would be ideal, otherwise gaffa tape should do it.

You can't ignore any wires. They all have an important function.

With respect to the OP, it is clear that he was aware of the BMS and its importance as a safety feature.
The very fact that the Chinese seller has sold it without any instructions (let alone specifications of the supplied batteries used), and the buyer is unsure how to assemble it, is clearly a "possible" recipe for disaster!
Probably would ultimately been better off getting the battery re-celled in the UK by a reputable repairer.
You are dealing with 12Ah, not only a possible "clock stopper" to yourself..... but others by a mistake.
High amperage DC is unforgiving (from experience)

 

[Andy-Mat]

I have a Tranzx BL03 battery from a Rayleigh Forge that is showing reduced capacity, although its voltage is holding up at 41V. I want to replace the cells and I've bought a pack from China that says it is specifically for this battery pack.
https://www.ebay.co.uk/itm/36V-12Ah-for-Tranz-X-PST-JD-PST-I2C-BL03-Battery-Li-Ion-E-Bike-electric-bicycle/333556846789?ssPageName=STRK:MEBIDX:IT&_trksid=p2060353.m1438.l2649
However, it has no instructions and no pre-soldered wires on it. I can identify the + and - terminals, but having dismantled the original I can see there are a whole strip of thin wires in addition to the main pair which go the length of the pack and go I assume to each individual cells for testing purposes. I have no way of connecting these. Has anybody done a rebuild on this pack and could advise whether these are critical or whether I could just ignore these extra wires?

Firstly, soldering will most likely damage your cells, as soldering takes too long, and may overheat the cell.. They need to be spot welded, almost instantaneous.
There is a reasonable video here, with links to other information and about the welding:-

DIY Lithium Batteries: How to Build Your Own Battery Packs: Toll, Micah: 9780989906708: Amazon.com: Books

DIY Lithium Batteries: How to Build Your Own Battery Packs [Toll, Micah] on Amazon.com. *FREE* shipping on qualifying offers. DIY Lithium Batteries: How to Build Your Own Battery Packs

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The Ultimate Do It Yourself Ebike Guide: Learn How To Build Your Own Electric Bicycle [Toll, Micah] on Amazon.com. *FREE* shipping on qualifying offers. The Ultimate Do It Yourself Ebike Guide: Learn How To Build Your Own Electric Bicycle

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I hope that it all works out for you.
regards
Andy
PS. I just saw this ad, which might also help you further:-

The $16 battery tab spot welder

I’ve been looking for a cheap battery tab spot welder for 18650 lithium-ion cells for awhile now. The usual ones just aren’t worth the cost. For example, for half the cost of a welder, …

scottiestech.info

 

[vfr400]

With respect to the OP, it is clear that he was aware of the BMS and its importance as a safety feature.

Yes, really clear when he asked about ignoring the sense wires!

 

[MontyPAS]

Firstly, soldering will most likely damage your cells, as soldering takes too long, and may overheat the cell.. They need to be spot welded, almost instantaneous.
There is a reasonable video here, with links to other information and about the welding:-

DIY Lithium Batteries: How to Build Your Own Battery Packs: Toll, Micah: 9780989906708: Amazon.com: Books

DIY Lithium Batteries: How to Build Your Own Battery Packs [Toll, Micah] on Amazon.com. *FREE* shipping on qualifying offers. DIY Lithium Batteries: How to Build Your Own Battery Packs

www.amazon.com

The Ultimate Do It Yourself Ebike Guide: Learn How To Build Your Own Electric Bicycle: Toll, Micah: 9780989906791: Amazon.com: Books

The Ultimate Do It Yourself Ebike Guide: Learn How To Build Your Own Electric Bicycle [Toll, Micah] on Amazon.com. *FREE* shipping on qualifying offers. The Ultimate Do It Yourself Ebike Guide: Learn How To Build Your Own Electric Bicycle

www.amazon.com

71.33￡ 15% OFF|Spot Welder With Led Light Battery Welder Applicable Notebook & Phone Battery Precision Welding Pedal 787a+ Battery Spot Welder - Spot Welders - AliExpress

Smarter Shopping, Better Living! Aliexpress.com

www.aliexpress.com

I hope that it all works out for you.
regards
Andy

Good info! But.....
Cost of battery pack + Cost of spot welder (OK if you are making a lot of packs) + Factor in the "FU" factor.

Probably? Cheaper and safer to get the original pack re-celled.
At least you would get a limited guarantee, unlike with the bare pack from China?
Not gospel just my view.

 

[wheeliepete]

I think it's pretty clear what you are getting from the photos on the Ebay ad. If you don't feel able to carry out the work needed yourself, Jimmy at eBike Batteries may be prepared to do it for you.

 

[Andy-Mat]

Good info! But.....
Cost of battery pack + Cost of spot welder (OK if you are making a lot of packs) + Factor in the "FU" factor.

Probably? Cheaper and safer to get the original pack re-celled.
At least you would get a limited guarantee, unlike with the bare pack from China?
Not gospel just my view.

I don't disagree with you, but I thought that at the price of a cheap welder, he can use what he has already paid for.
And he might be able to "sell on" the welder to someone doing the same, when he does not need it anymore.
The $16 one must be so cheap that it is easily covered by his savings.....
Just a thought.
Andy

 

[Nealh]

One thinks that Alan is in over his head a bit on this one.
Connect the BMS incorrectly then it will be toast, do you have soldering iron

That battery pack has little in safety in it's construction, no extra insulators under positive cell ends and between the strip (nickel ?). Glued packs need support usually heat shrink or use fibre Glass packaging tape, also top and bottom of the pack 1 would tape in place 0.4mm fibreglass sheet for protection as well.

If you think you are capable and post battery pics we can super impose on them where wires need soldering.

 

[alanterrill]

Thanks for all the help - I've obviously bitten off more than I can chew -I have replaced batteries in an older battery pack before but they were NiMH cells and there is a higher level of complexity here. What I wasn't sure about was all those little wires ending at a strip that wasn't connected to anything - I thought perhaps these just went to each individual cell and were for the manufacturer to test a faulty battery pack with, but if they also go to the BMS then I've obviously bought a cell pack that doesn't allow for this. I'll call one of the re-celling firms instead.

 

[vfr400]

It's not difficult to do. Basically, solder on 12 wires and put some heatshrink or gaffa tape around it. We can tell you which wires go where if you show us what you have. This pack might be the best solution if you like to learn new things and you take pride in doing things yourself.

The photo shows a cell-pack that would probably be OK, though not the best. What you actually get could be better or worse.

A re-cell would get you a better pack with a guarantee, but will cost you at least £100 more. A re-cell would be the best solution if you can afford it, though it would be worth checking what a whole battery would cost. they often have clones on German Ebay for not too much.

Making your own pack is not an option for making only one battery. The stuff is too expensive. It's not just the welder,. You also need wires, solder equipment, nickel strip, insulators, heatshrink and measuring equipment. Cut-proof gloves are also handy.

 

[alanterrill]

It's not difficult to do. Basically, solder on 12 wires and put some heatshrink or gaffa tape around it. We can tell you which wires go where if you show us what you have. This pack might be the best solution if you like to learn new things and you take pride in doing things yourself.

The photo shows a cell-pack that would probably be OK, though not the best. What you actually get could be better or worse.

A re-cell would get you a better pack with a guarantee, but will cost you at least £100 more. A re-cell would be the best solution if you can afford it, though it would be worth checking what a whole battery would cost. they often have clones on German Ebay for not too much.

Making your own pack is not an option for making only one battery. The stuff is too expensive. It's not just the welder,. You also need wires, solder equipment, nickel strip, insulators, heatshrink and measuring equipment. Cut-proof gloves are also handy.

Thanks -I've just sealed the original back up as I'm going on holiday next week and need the bike, so I was hoping to fit new cells before I went! However, I'll take it apart and photograph it when I get back. I certainly like to do things myself and have a soldering iron, multimeter etc, but I'm not willing to take the risk that I'll ruin the only battery I have for my wife's bike or I'll be in big trouble. I did look at buying a complete new battery before I sent off for the cell pack but couldn't find anyone selling one -one is listed on Amazon with 'currently unavailable' against it. I just looked on ebay.de and found a new there for 749 euros which is more than half the cost of the bike (£1250 five years ago).

 

[vfr400]

Thanks -I've just sealed the original back up as I'm going on holiday next week and need the bike, so I was hoping to fit new cells before I went! However, I'll take it apart and photograph it when I get back. I certainly like to do things myself and have a soldering iron, multimeter etc, but I'm not willing to take the risk that I'll ruin the only battery I have for my wife's bike or I'll be in big trouble. I did look at buying a complete new battery before I sent off for the cell pack but couldn't find anyone selling one -one is listed on Amazon with 'currently unavailable' against it. I just looked on ebay.de and found a new there for 749 euros which is more than half the cost of the bike (£1250 five years ago).

The largest and most affordable Online TranzX Battery Shop!

Are you looking for a TranzX Battery? Look no further! Hollandbikeshop.com is the most affordable and has the largest range of TranzX Batteries!

hollandbikeshop.com

 

[alanterrill]

It's not difficult to do. Basically, solder on 12 wires and put some heatshrink or gaffa tape around it. We can tell you which wires go where if you show us what you have. This pack might be the best solution if you like to learn new things and you take pride in doing things yourself.

The photo shows a cell-pack that would probably be OK, though not the best. What you actually get could be better or worse.

A re-cell would get you a better pack with a guarantee, but will cost you at least £100 more. A re-cell would be the best solution if you can afford it, though it would be worth checking what a whole battery would cost. they often have clones on German Ebay for not too much.

Making your own pack is not an option for making only one battery. The stuff is too expensive. It's not just the welder,. You also need wires, solder equipment, nickel strip, insulators, heatshrink and measuring equipment. Cut-proof gloves are also handy.

The largest and most affordable Online TranzX Battery Shop!

Are you looking for a TranzX Battery? Look no further! Hollandbikeshop.com is the most affordable and has the largest range of TranzX Batteries!

hollandbikeshop.com

The largest and most affordable Online TranzX Battery Shop!

Are you looking for a TranzX Battery? Look no further! Hollandbikeshop.com is the most affordable and has the largest range of TranzX Batteries!

hollandbikeshop.com

The largest and most affordable Online TranzX Battery Shop!

Are you looking for a TranzX Battery? Look no further! Hollandbikeshop.com is the most affordable and has the largest range of TranzX Batteries!

hollandbikeshop.com

And that one is out of stock of course, but thanks for the link.

 

[johnRN]

And that one is out of stock of course, but thanks for the link.

Bit of an old post now, but I was interested to hea how you got inside the sealed battery case?? I now need to do the same to check out cell performance, due to a crappy discahrge test! I belive it to have top/bottom halves glued together, and maybe the glue can be loosened using heat ...or maybe just cut it ope with a dremel ??