Off Road Battery Size recommendation for BBSHD
- Thread starter geosped
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Chalo
100 TW
TNC said:
If you're talking about the eBay item description in this listing:
https://www.ebay.com/itm/52V-14S-45A-Li-ion-Battery-Protection-Board-BMS-PCB-Electric-Bike-Ebike-14S-BMS-/303799457857
It says right in the title that it's a 14S BMS. The specifications include this:
It's not abundantly clear whether the specs are for either a 13S or 14S BMS, or a single BMS that can do either 13S or 14S. But it won't do 15S.
Doh!...LOL! But hey...who has time to look at the title?..LOL!
Man, I was so focused on trying to make sense of all the line items, I completely overlooked that in the description title. Besides, that's way too easy. Do people not like a good challenge anymore. :lol:
Man, I was so focused on trying to make sense of all the line items, I completely overlooked that in the description title. Besides, that's way too easy. Do people not like a good challenge anymore. :lol:
geosped
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Im still trying to figure out this BMS thing. So the vendor states LVC kicks in at 41v. However the BMS also kicked in if the voltage of an individual cell reaches a certain voltage. Independent of the total voltage. Is this correct? Is that an "if or".
From my perspective and not sure if this is correct but that valid value to pay attention to is the total voltage. Don't go below 41v. From what I can tell there is no way to look at the individual cell voltage. So this is not something I can control. Also although not a best practice in all situations it's a good idea to charge the pack to 100% ensuring each individual cell is balanced charged as opposed to the "best practice" of charging the battery to 80% helping to prolong battery life but not ensuring the cells are balanced charge. Is this a correct assessment?
What I've been doing is 80% charge for 5 charges and then 100% every 5th charge to ensure a full balance charge. This sounds kind of hoki can someone mention what's the best practice to maintaining good battery health. My charger (Luna 52v 3a) supports 80 90 and 100% charging.
From my perspective and not sure if this is correct but that valid value to pay attention to is the total voltage. Don't go below 41v. From what I can tell there is no way to look at the individual cell voltage. So this is not something I can control. Also although not a best practice in all situations it's a good idea to charge the pack to 100% ensuring each individual cell is balanced charged as opposed to the "best practice" of charging the battery to 80% helping to prolong battery life but not ensuring the cells are balanced charge. Is this a correct assessment?
What I've been doing is 80% charge for 5 charges and then 100% every 5th charge to ensure a full balance charge. This sounds kind of hoki can someone mention what's the best practice to maintaining good battery health. My charger (Luna 52v 3a) supports 80 90 and 100% charging.
geosped
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I'll try to explain the whole makeup of a battery in my non engineering not to technical layman's terms. So my pack is 14s2p meaning two collums of 14 batteries wired in Series connected by 2 rows in Parallel for a total of 28 batteries. You take 14 cells and wire from the negative terminal from one cell to positive terminal to the other cell for 14 batteries (-+-+-+ 14x). This increases the voltage of the entire pack (4.2v per cell x 14 cells or batteries equals 58.8v meaning this is the voltage of a fully charged 52v battery regardless of the capacity. The 2p represents (Parallel) how many strips the battery has. So in my pack we have two strips of 14 batteries wired in Parallel meaning these two individual strips are then wired positive to positive (++--)and negative to negative thus doubling the capacity of the two 52v strips. So the 21700 T40 Samsung cell ( these are the individual cells made of 4.2v with a capacity of 4000mah or 4ah.) If you take the two strips of 52v 4ah strips and wire them in parallel this doubels the capacity and you get an 8ah 52v pack. Not sure if that makes sense. There are other factors to consider but that's the gist.TNC said:
In order to understand your 17.ah we just do a little math 17/5=3.4. Your individual cells have a capacity of 3.4ah per cell thus why you have 5strips (5p) 3.4*5=17 look up the specs of you cells and validate if im right. It will probably say 3400mah they will all be 4.20v when fully charged.
MoneyPit
10 W
I didn't want any part of a backpack battery until a particular frame pretty much forced me to go there. I was amazed at how the cable disappeared from my awareness within the first few minutes of the ride, and having the battery on me where I could shift my weight to deal with the terrain on a bike that was no longer weighed down by a several pound lump...
Its worth not dismissing out of hand, which I did before I ended up trying it. I use a hard shell boblbee pack with a janitor's retractable key ring to hold the cable snug to me if I am standing or in the saddle.
There's been mention of Bicycle Motor Works here. I have I think four of their packs. One of which is a 32ah 14S9P 21700 slab for a custom cargo bike build.
And I went with a 20ah pack for my backpack. That was inexperience doing the decision-making. You don't use anywhere near the power on singletrack as you do the street. At some point I will go to something a lot smaller.
Its worth not dismissing out of hand, which I did before I ended up trying it. I use a hard shell boblbee pack with a janitor's retractable key ring to hold the cable snug to me if I am standing or in the saddle.
There's been mention of Bicycle Motor Works here. I have I think four of their packs. One of which is a 32ah 14S9P 21700 slab for a custom cargo bike build.
And I went with a 20ah pack for my backpack. That was inexperience doing the decision-making. You don't use anywhere near the power on singletrack as you do the street. At some point I will go to something a lot smaller.
MoneyPit, I'm also a backpack battery rider too. I fully understand that battery mounting and/or location is a highly preferential issue. Some people don't even like using a small backpack for hydration purposes, so riders are all over the place on what they like and dislike. I come from off road dirt motor riding over all day distances around my home area and all over the western U.S., so I have to carry a fair amount of water and other items. I'm used to a decently heavy medium sized pack...not as big as true backpacking setups...so it was a natural jump to carry my battery in a small to medium backpack. I didn't like any of the potential spots on my Santa Cruz Nomad for a battery pack.
I notice you're using a retractable device for your power cable. I've seen these, but I though I'd try just running the cable without spring aid or retraction device. I put the two 10ga power cable wires into some of that automotive, plastic, wire loom cover. This offers some protection to the wires obviously, and it presents a more smooth surface that doesn't tend to hang up on things. Like you, I was surprised how unnoticeable the cable is while riding. I have about 4' of cable that plugs into the lead from the battery that sticks out of the top of the backpack. It attaches at the nose of my saddle between my legs, and this keeps the cable out of my way. I've had no issues with this system.
When I want to get off the bike, there is enough cable to easily step off and even move a little. I don't unplug each time I want to move away from the bike. I just slip the backpack off easily and hang it on the handlebar or set it on the ground...no big deal. My pack is easy to put on and take off. It's just not a hassle to me. What if I crash? The backpack is pretty well padded, especially to my back, so I'm not concerned about injury from the battery. The plug at the battery leads at the top of my pack is positioned to pop loose if I separate from the bike. I've mimicked coming off the bike to test it, and it works just fine. My Nomad weighs nearly 50 pounds without the battery...full coil suspension, dual crown fork, heavy wheels/tires, etc. I'm glad the battery is not on the bike in my case...LOL! While under pedal assist or throttle, the bike's weight disappears.
I notice you're using a retractable device for your power cable. I've seen these, but I though I'd try just running the cable without spring aid or retraction device. I put the two 10ga power cable wires into some of that automotive, plastic, wire loom cover. This offers some protection to the wires obviously, and it presents a more smooth surface that doesn't tend to hang up on things. Like you, I was surprised how unnoticeable the cable is while riding. I have about 4' of cable that plugs into the lead from the battery that sticks out of the top of the backpack. It attaches at the nose of my saddle between my legs, and this keeps the cable out of my way. I've had no issues with this system.
When I want to get off the bike, there is enough cable to easily step off and even move a little. I don't unplug each time I want to move away from the bike. I just slip the backpack off easily and hang it on the handlebar or set it on the ground...no big deal. My pack is easy to put on and take off. It's just not a hassle to me. What if I crash? The backpack is pretty well padded, especially to my back, so I'm not concerned about injury from the battery. The plug at the battery leads at the top of my pack is positioned to pop loose if I separate from the bike. I've mimicked coming off the bike to test it, and it works just fine. My Nomad weighs nearly 50 pounds without the battery...full coil suspension, dual crown fork, heavy wheels/tires, etc. I'm glad the battery is not on the bike in my case...LOL! While under pedal assist or throttle, the bike's weight disappears.
geosped
100 W
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I guess my biggest reservation about wearing a pack on oneself is the minute possibility of the pack catching fire while it's strapped to you. I'm sure you guys have seen what a lipo fire on YouTube and it's friggen scary.
With all of the constant changing environment variables when riding off road less so on road it just seems like a risk I'm not willing to take. What if you crash or some one runs into you accidently and you fall, battery gets ruptured, punctured or whatever and it shorts and your knocked unconscious, being burn alive is not something I want to see on my obituary
I'm painting a very very unlikely situation but what if. At least having the pack on the bike wearing flat pedals you get ejected bike goes up and flames and your just pissed. I'd rather be pissed than toast :wink:
With all of the constant changing environment variables when riding off road less so on road it just seems like a risk I'm not willing to take. What if you crash or some one runs into you accidently and you fall, battery gets ruptured, punctured or whatever and it shorts and your knocked unconscious, being burn alive is not something I want to see on my obituary
I'm painting a very very unlikely situation but what if. At least having the pack on the bike wearing flat pedals you get ejected bike goes up and flames and your just pissed. I'd rather be pissed than toast :wink:That's why I wear a full face DH MTB helmet all the time. I will still be conscious when I smell the burning flesh...LOL!
But seriously, Geosped, I think the scenario you described might be the "more likely to get hit by a metor" scenario, but I understand some/most not wanting to tote their battery in a backpack. Karl Gesslein has touched on the issue of a battery backpack in the past, and indicated that even with the fire scenario being highly unlikely, the opportunity to detach the pack before any catastrophe is more likely. It's just recommended not to have a backpack that has some kind of Houdini level method of detachment if ejection is necessary...LOL!
You probably remember that I ride a dirt motor too, and I guess it's possible that I could crash, be knocked unconscious under the bike, and have a flaming inferno of 3.7 gallons of fuel roast me alive. It's possible.
But in all seriousness, I'm not poo-pooing anyone's concerns about how or where they decide to carry their ebike battery for whatever reason.
But seriously, Geosped, I think the scenario you described might be the "more likely to get hit by a metor" scenario, but I understand some/most not wanting to tote their battery in a backpack. Karl Gesslein has touched on the issue of a battery backpack in the past, and indicated that even with the fire scenario being highly unlikely, the opportunity to detach the pack before any catastrophe is more likely. It's just recommended not to have a backpack that has some kind of Houdini level method of detachment if ejection is necessary...LOL!
You probably remember that I ride a dirt motor too, and I guess it's possible that I could crash, be knocked unconscious under the bike, and have a flaming inferno of 3.7 gallons of fuel roast me alive. It's possible.
But in all seriousness, I'm not poo-pooing anyone's concerns about how or where they decide to carry their ebike battery for whatever reason.
MoneyPit
10 W
A pack would be faster to remove and it could be shucked and completely clear of the bicycle vs. sacrificing the bike (and then you die horribly in the resulting forest fire?geosped said:I guess my biggest reservation about wearing a pack on oneself is the minute possibility of the pack catching fire while it's strapped to you. I'm sure you guys have seen what a lipo fire on YouTube and it's friggen scary.
With all of the constant changing environment variables when riding off road less so on road it just seems like a risk I'm not willing to take. What if you crash or some one runs into you accidently and you fall, battery gets ruptured, punctured or whatever and it shorts and your knocked unconscious, being burn alive is not something I want to see on my obituary
). The XT90 connector would pop free immediately, and something you won't get with a frame bag - the case is hardshell. So you could take a hammer to it without touching the battery. Or fly off the bike and smash onto a rock etc. It also doubles as a spinal protector.I realize this backpack stuff is not for everyone. I thought it was the worst idea ever until I was forced to try it and figured out the benefits as I went along. But if we are cooking up worst case scenarios, there's plenty of them on either side of the argument. Your call on what you are comfortable with.
Chalo said:
Chalo, the term "port belt balance" used in geosped's link to the Bicycle Motor Works advertised BMS, does that refer to the component or feature in the BMS that functions to balance all the cells in the battery when one or more becomes unbalanced? Reading a thread on another forum, it appears some battery BMS units have that capability and some don't. Since the BMW one mentioned here has a data sheet, I was just wanting to know if that port belt balance was the balancing component or if it was one of the other line items in the data sheet?...or can one even tell?
Chalo
100 TW
TNC said:
I don't know. "Port belt balance" doesn't mean anything to me.
All the BMSes I've used or replaced (a lot of them, but not many fancy ones) only balance at the end of charge, by bleeding a small amount of current from the cells that have reached their top voltage.
On one of my batteries, I have an "active balancer" that isn't a BMS, but only a circuit that levels voltage imbalances between cells whenever they occur. This can be added to a pack that also has a BMS.
Is this "active balancer" an exterior component or something that requires entry into the pack to install. I use one of those Luna advanced 52V chargers that allows you to change amperage and charge percentage, but in my limited knowledge I think I understand they do nothing for cell balance, as that has to come from the BMS. Did you go to this active balancer because your BMS did not have this function or is it just a more sophisticated balancing device?
The reason I'm trying to get informed on all this battery tech is because it seems pretty apparent that cell balance and good charging components and techniques are what make these expensive packs last a lot longer. Thanks for your input.
The reason I'm trying to get informed on all this battery tech is because it seems pretty apparent that cell balance and good charging components and techniques are what make these expensive packs last a lot longer. Thanks for your input.
Chalo
100 TW
TNC said:
You have to connect one wire to each cell group in series. If there's a BMS plug, you can attach to that. The circuit board doesn't have to be anywhere in particular, but it does have to be attached by a bunch of wires. The maximum current mine will use for balancing is only 1.2A, so it doesn't require a large wire. Some of these boards will balance at higher currents, so night need bigger gauge connections.
https://www.ebay.com/itm/293338032675
Man, that's a well detailed ebay listing. I even get some of what and how that component works...LOL! So basically this component is superior to what is contained in a decent BMS as far as battery balance is concerned? And if I'm understanding this component, most sealed batteries like mine would require opening to install it.
https://bicyclemotorworks.com/product/52v-17-5ah-lg-mj1-lithium-ion-e-bike-battery/
Though you can't see it from the terminals side, there is no on/off switch or other ports...just the XT60 and XT90 charge and discharge cables. I don't see a specific detail about battery balancing capability other than this comment:
"Our 14s 50amp continuous BMS with temperature protection will ensure stability within the battery pack and keep all 70 cells juiced up properly."
https://bicyclemotorworks.com/product/52v-17-5ah-lg-mj1-lithium-ion-e-bike-battery/
Though you can't see it from the terminals side, there is no on/off switch or other ports...just the XT60 and XT90 charge and discharge cables. I don't see a specific detail about battery balancing capability other than this comment:
"Our 14s 50amp continuous BMS with temperature protection will ensure stability within the battery pack and keep all 70 cells juiced up properly."
MoneyPit
10 W
The seller is Matt Bzura in Pennsylvania. He builds packs locally per the specs in his store listings at the time they are ordered.TNC said:
You can email him and he will answer. I've also spoken with him over the phone although it was regarding details on orders already placed and not a general info inquiry.
MoneyPit said:
Yes, I have been very pleased with the performance of this battery. I had called BMW representing the shop I work at to get a feel for their ebike battery endeavor. We were familiar with BMW as we had seen their gas motor kits popping up in our area in the past. It appears to be a small operation, but his batteries seem to be very good quality.
Feraldave
100 µW
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- Jul 3, 2021
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i tangled up in the backpack battery when i tried it..
i have a lunamate 52v Mighty Mini Cube Ebike Battery 6ah 14s2p = 28 Genuine name brand grade Sony 18650 cells..
i get 45 mins of mtb single track with it..
i wanted more so im building a custom battery.. 14s3p 21700 molicel 5000ah so 10ah.. about 3kg total weight..
im custom building the pack and mount..View attachment Aurum batt2 Drawing v2.pdf
i have a lunamate 52v Mighty Mini Cube Ebike Battery 6ah 14s2p = 28 Genuine name brand grade Sony 18650 cells..
i get 45 mins of mtb single track with it..
i wanted more so im building a custom battery.. 14s3p 21700 molicel 5000ah so 10ah.. about 3kg total weight..
im custom building the pack and mount..View attachment Aurum batt2 Drawing v2.pdf
geosped
100 W
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TNC said:
I only ride trails mostly intermediate and advanced trails blues and blacks I get about 20miles of hard lots of ups and downs. All in the North Georgia mountains. I've also been charging the pack to 90% not 100% I've heard this is supposed to prolong the life of the pack and every 5th charge or so I'll go to 100%. I think that is supposed to balance charge the pack. What I don't understand is got the pack down to 11% still read 48v. It's a bit off though my multi meter is reading 48.4v. I've heard keep it above 44v and I should be safe. The vendor said BMS is set to 41v that sounds really low. I wish the EggRider had some sort of audible alarm that's adjustable. So im not really sure where im at other than just continue to monitor the voltage and don't go below 44v?? Or is there something else I should be doing.
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