48v lithium ion bms
- Thread starter Mtomo
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Chalo
100 TW
Get a BMS that can continuously deliver at least as much current as your speed controller demands.
In my observation, you are very unlikely to find a BMS that matches your old plug. You will most likely have to splice your new BMS plug leads onto the old sense wires, or connect them directly to the pack bus. You will need a multimeter to verify where to attach the leads.
When I need a new BMS, I go to eBay and search "13S BMS lithium" or the like. If you get an extra at the same time, then you'll have a spare that matches your plug.
In my observation, you are very unlikely to find a BMS that matches your old plug. You will most likely have to splice your new BMS plug leads onto the old sense wires, or connect them directly to the pack bus. You will need a multimeter to verify where to attach the leads.
When I need a new BMS, I go to eBay and search "13S BMS lithium" or the like. If you get an extra at the same time, then you'll have a spare that matches your plug.
There are lots of BMS options these days. If you post a picture of your old one, it might help.
48v, I assume is a 13s pack.
Some BMS have a separate charge and discharge port. Some use a single port for both charging and discharging. From your description, it sounds like you have the separate ports.
Physical size has to fit in the space available.
As Chalo pointed out, it will be hard to find one with the exact same connector for the balance wires but you might get lucky.
Your BMS can be rated for much higher than the controller current limit. As long as it's higher, it should be OK.
48v, I assume is a 13s pack.
Some BMS have a separate charge and discharge port. Some use a single port for both charging and discharging. From your description, it sounds like you have the separate ports.
Physical size has to fit in the space available.
As Chalo pointed out, it will be hard to find one with the exact same connector for the balance wires but you might get lucky.
Your BMS can be rated for much higher than the controller current limit. As long as it's higher, it should be OK.
Chalo said:
I'm assuming that this can be done by chopping off the connector from the old BMS and splicing the new one to that connector; is that correct? I'm thinking about switching out my BMS in the future to a smart bluetooth model.
Chalo
100 TW
E-HP said:
If you mean splicing the wires from the new plug onto the leads that have been cut away from the old plug, yes that's how I usually do it. I cut, strip, solder, and heat shrink one at a time so I don't risk brushing them together.
The main wild card is that some BMSes have a separate sense wire for B-, and some use the main B- lead for voltage sensing. If it's the former, a 13S BMS plug will have 14 sense wires, if the latter it will have only 13.
docw009
1 MW
I've also found that if the battery has an on/off switch, that requirement further cuts down the number of candidates. You'll also find that if you want a BMS that can balance, you have to check the specs to see if the boxes for balance current are populated. A lot of chinese vendors say "balance BMS" but they have no balance circuits, and those specs are empty.
Oh, that's a blast from the past. I remember those. I see 13 balance tap wires, so the B- connection is done through the main B- wire.
Most of the newer boards use a smaller pitch on the balance connector so you may need to splice.
Here is one possible replacement:
https://www.ebay.com/itm/363378332645?hash=item549b0953e5:g:7CUAAOSwWrdgi2fB
I have used a couple of these with OK results. Hard to see their picture clearly, but appears to have 14 wires. One will just go to the main B-.
Most of the newer boards use a smaller pitch on the balance connector so you may need to splice.
Here is one possible replacement:
https://www.ebay.com/itm/363378332645?hash=item549b0953e5:g:7CUAAOSwWrdgi2fB
I have used a couple of these with OK results. Hard to see their picture clearly, but appears to have 14 wires. One will just go to the main B-.
Thanks for the info. This battery was on an Ebike that sat for 4 years and was never really used. I suspect now, that it got shorted or something early on, wouldn’t charge and then just parked. Was then given to me. I have another ebike but has been working flawlessly for I’ve 7 years. Dissecting batteries is a new thing for me. Realistically what can I expect from this 4 year old neglected stack of lithium? Worth salvaging? I’d like to use it for a small go kart but is that asking too much from it? Can I make a “big” 12 or 24v battery from it for an electric refrigerator? What degradation am I looking at?
Thanks.
Thanks.
You can measure the voltage of each cell group at the balance tap connector. If any of cell groups are below 2v, the battery may be unsafe to use. I have recovered over discharged cells by charging very slowly, but apparently the copper can dissolve and re-plate in random places when you do this. Once the cells get up to around 3v, you can charge at a normal rate. Charge in a fire-safe location as old abused cells are much more likely to burn.
Thank you all that chimed in to help me sort this out.
I just successfully transplanted a new 48v bms to this battery. It seemed extremely daunting at first, but slowly started making sense. Thanks so much. Now I need to get this electric vw bus wired up and rolling.
I just successfully transplanted a new 48v bms to this battery. It seemed extremely daunting at first, but slowly started making sense. Thanks so much. Now I need to get this electric vw bus wired up and rolling.
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