Need help finding a BMS

[samush]

I'm building a 72V, 20 ah battery out of 152 Samsung ICR18650-26F cells and am having difficulty finding a suitable BMS. The configuration I want is 19 groups in series. I have 8 more cells so I could do 20 groups but I'd prefer 19. I also want it to be able to output at least 40 amps.

I found a charger that would work for the 20 in series but am open to any suggestions
https://bmsbattery.com/ebike-charger-ev-charger/457-alloy-shell-900w-lifepo4-li-ion-lead-acid-battery-ev-charger-charger.html?

 

[dnmun]

you should use one of the D131 BMSs that i bot from Bestechpower and build out to 24S and 100V.

my lipo pack is 21S to match to a 24S lifepo4 pack and i use D131 BMSs on both of them. i can get 240A out of the two D131 on the lifepo4 pack and another 240A out of the two D131 on top of my lipo pack. i charge to 87.6V.

that is the best charger deal for the money. i think they are a little cheaper shipping from EV assemble or maybe alibaba. BMSbattery charges alot for airfreight.

 

[samush]

Unfortunately my controller and motor (C7240-NC and H3540) are rated for only 72V 40A so I don't think I should build a 100V pack. I think I'll try and get the 19S D131. I want have it in a sealed unit with the batteries, I think it wouldn't produce that much heat if I'm only running 50 amps max. Thanks

 

[John in CR]

While there's nothing inherently wrong with 19s, at some point down the road you'll probably wish you'd chosen an even number, even if for only practical reasons like splitting your pack in half. 20s of 3.6V-3.7V nominal cells is my favorite pack voltage for a number of reasons. The top of charge voltage is well below the 100V limit of components in 72V controllers. A 20s pack can consist of two 36V (a common voltage) packs in series. A 20s pack parallel's nicely with a 23s or 24s LiFePo4 pack to the mutual benefit of both. A 20s pack can be assembled from 10s, 4s, or 5s blocks of cells, so adding a range booster pack for longer than normal rides is simple.

FWIW, your motor doesn't have a firm voltage limit, at least not below 150-200V or so. It does have a torque limit though, so your practical voltage limit is determined by the size wheel you run and the aerodynamics of your vehicle.

 

[Ykick]

Unfortunately my controller and motor (C7240-NC and H3540) are rated for only 72V 40A so I don't think I should build a 100V pack. I think I'll try and get the 19S D131. I want have it in a sealed unit with the batteries, I think it wouldn't produce that much heat if I'm only running 50 amps max. Thanks

The thing about Bestechpower BMS is that they almost always can be used with lower cell counts if desired. In other words, if you buy 20S BMS you can use it with 16S, 17S, 18S, 19S, or even fewer cells. I've used Bestechpower 20S BMS on 12S packs with no issues.

Moral here is to buy the larger cell count and use it with lower cell counts if ultimately desired/needed.

 

[dnmun]

i should do another order of the 20S D167 i guess. lemme know if you are interested but like ykick said, you can use the BMS for any series count up to the number of channels on the BMS. it is not restricted to only the full serial count.

i find the 21S of lipo and 24S of lifepo4 are most closely matched. i got 4.18V for the balancing voltage on this last batch of D131 so i could charge both of my packs to the 87.6V level to balance the lipo pack.

 

[samush]

Okay so I'll get the D131 20s. Is there anything you need to do when using it in 19s ? Or do you just hook up the cells and charge with the respective voltage?

 

[dnmun]

you should order the 24S D131 if you order from henry. they will expect you to order two of them since they are a manufacturer and don't really like having to deal with the selling of single items.

if you order 20S or 19S then it will have to be a special order. they have to leave off 4-5 channels so it will take a few days to insert your order into their production flow.

they can sell you the 24S version from stock since that is what they keep in stock since that is what people normally order.

 

[wesnewell]

Anyone try this 24s bms?
http://www.aliexpress.com/item/24S-lithium-battery-protection-board-BMS/1930156282.html

 

[samush]

Dose anyone know what site I can get the 20s D131 off of? Also can you give a link to henry?

 

[dnmun]

Henry@bestechpower.com is the guy i have had all of my dealings with but he is really busy now that he has become a director. he uses lily to handle orders so you should send your email to both of them and include lily, lily@bestechpower.com, with your order.

if you are in the US i can add you to a small group if i can find a few others who wanna buy a BMS from them. that helps with the price since i get pretty good deals with them now that i bot so much from them. i still have 4 of the 24S lipo D131 here with a balancing voltage of 4.18V which i had to get through a special order.

if you only need 20S i would recommend you buy the 20S lipo D167 since it is much cheaper than the D131. you will have to buy two if you order from Bestechpower but it is best that you have a spare BMS and get it in the same order since that keeps shipping costs lowest. i try to warn people to be careful with them but most often they are damaged by accidentally shorting the BMS or the sense wires so having two is necessary in any case.

ask for the standard 2.8/4.25 LVC/HVC and balance voltage of 4.2V and they will ship right away.

 

[dbaker]

dnmun,

If you do an order, add 3 BMSs for me to use on 13s 18650 packs on the Bafang mid drives..

 

[dnmun]

i got two of the D127v2 on this last order. they are 15A and very small with a plastic cover. i have a13S calibike pack which had no balancing network in the BMS so i ordered these to test on it. i also have a 13S 8Ah nanotech pack to test it on too.

i have tested the D126 which is also rated at 15A and was able to carry 22A for awhile with it but burned it up at 25A. so i wanted to test these to see how they worked.

not sure how much current you need or which BMS you looked at. there are a lot of them that are designed up to 13S lipo.

the D141 has all kinds of software capabilities too. ability to monitor cell health like internal resistance and record it to data files you can download. i like that feature because i think that by collecting charging profiles over time it should be possible to isolate individual channels going bad. the charging profiles would show changes in internal resistance during charging. the most critical type of data imo.

 

[samush]

I live in Canada so I guess I'll just make my own order, thanks dnmun

 

[dnmun]

maybe you can talk someone close by to you in canada to join in the shipping costs. if you can buy up to 10 BMS at a time he will give you a discount on the price too. plus having more in the shipment reduces the shipping cost for each one.

 

[samush]

I ordered 2 and they are on their way. Now for a charger. I'm thinking about getting this https://bmsbattery.com/ebike-charge...ion-lead-acid-battery-ev-charger-charger.html. What chargers do you guys use?

 

[Ykick]

I ordered 2 and they are on their way. Now for a charger. I'm thinking about getting this https://bmsbattery.com/ebike-charge...ion-lead-acid-battery-ev-charger-charger.html. What chargers do you guys use?

I've been using the little cousin 400W BMS Alloy charger with good results. Do note, power-up the charger before connecting the battery pack so that the charger isn't attempting to push current into the pack before the SMPS circuit is up to speed and ready to deliver charge current. I believe this reduces stress on the ICL (in-rush current limiter) which is common failure on some of these Alloy chargers.

 

[bigbr1212]

I recently purchased a BMS unit called EMUS BMS by JSC Elektomotus. It's amazing, it has individual modules that attach to each series and has the ability to send information through its Bluetooth module to an app the company made that works on Andriod devices and it tells you the status of each cell sort of like a fuel gauge. It also balances the cells in a more efficient manor which makes for quicker charge times. Most Bms units charge all cells together and then discharge the cells that reach the peak voltage. The EMUS BMS only charges the cells that need it and doesn't waist time sending power where it isn't needed and will help with the longevity of the life of the battery.

I hope this was helpful
Brian

 

[dnmun]

not much help. it just sounds like an advertisement with no pictures or price.

if someone wanted to watch their phone while riding to see if the battery is charged it might be useful.

i consider texting and reading the phone in traffic to be the leading cause of death among bicycle riders but it is usually from drivers of cars and trucks running over unsuspecting bicyclists while the car driver is finishing their text.

i watched a car drive right through a red light yesterday while the guy was looking down in his lap to get directions off of his phone. at least the cross traffic stopped for him. he never saw them, never even changed his 15mph speed on a regular 35mph city street. took him 4 blocks to figure out where he was on the phone and look up and finally drive.