Battery Charging ?
- Thread starter Jimbo397
- Start date
wesnewell
100 GW
No load 36.5V. Set LVC to 35V. Watch the volts. It will likely be more accurate.
el_walto
10 kW
Where did you get your pack from? Or what brand is it if any?
dogman dan
1 PW
Lower depth of discharge cycles make batteries last longer in general. So if you can charge, do. You won't "waste a cycle" by charging early.
Most chemistries are discharged or nearly discharged when they reach thier nominal voltage. So a 36v pack is pretty much done when it reaches 36v. Most lithium chemistry batteries of 36v will charge to 42-46v, somewhere in that range.
Most chemistries are discharged or nearly discharged when they reach thier nominal voltage. So a 36v pack is pretty much done when it reaches 36v. Most lithium chemistry batteries of 36v will charge to 42-46v, somewhere in that range.
Thanks Guys
I guess what I am really trying to figure out is how far I can go on charge, without actually draining the battery.
I understand that one should never completely drain the battery, but leave a certain percentage of charge in the battery.
Thanks
I guess what I am really trying to figure out is how far I can go on charge, without actually draining the battery.
I understand that one should never completely drain the battery, but leave a certain percentage of charge in the battery.
Thanks
el_walto
10 kW
The battery BMS "Should" protect the battery from over discharge. The battery will actively cut out when it is at its minimum safe voltage. Fully charge your battery overnight. Reset your cycle analyst, ride until it cuts out. Your Cycle Analyst will give you your actual battery capacity in Ah . Might not be exactly 14Ah.
Most people will tell you to keep most of your cycles above 80% discharge in case the battery is out of balance etc. Every time you finish charging, reset your cycle analyst by holding down the right button for a few seconds. When your cycle analyst says you have used 11.2Ah, your battery only has 20% capacity left. Try to not use more than 11Ah on a regular bases
You should keep your battery topped up whenever you can. You do not need to discharge it like people used to do with NiCad batteries.'
The capacity of the battery is measured in AH, so if you have a cycle analyst you can easily see how many you have used. It will just count up, so you need to reset the CA every time you charge the battery.
Most people will tell you to keep most of your cycles above 80% discharge in case the battery is out of balance etc. Every time you finish charging, reset your cycle analyst by holding down the right button for a few seconds. When your cycle analyst says you have used 11.2Ah, your battery only has 20% capacity left. Try to not use more than 11Ah on a regular bases
You should keep your battery topped up whenever you can. You do not need to discharge it like people used to do with NiCad batteries.'
The capacity of the battery is measured in AH, so if you have a cycle analyst you can easily see how many you have used. It will just count up, so you need to reset the CA every time you charge the battery.
dogman dan
1 PW
Well, have we got a use of english problem? Without discharging the battery, you can pedal around the world if you never turn the battery on. :wink:
But I have a rule of thumb for 36v batteries. At typical full throttle speeds of about 23-25 mph, 1 ah will take you one mile reliably. You can go further with no wind and no hills, or less far with wind in your face or uphill. On the flat, you'd still be likely to have a few miles left in reserve, but less than 20% capacity.
Slowing to 20 mph, you will get noticeably further range. perhaps 1.2 miles per ah.
But I have a rule of thumb for 36v batteries. At typical full throttle speeds of about 23-25 mph, 1 ah will take you one mile reliably. You can go further with no wind and no hills, or less far with wind in your face or uphill. On the flat, you'd still be likely to have a few miles left in reserve, but less than 20% capacity.
Slowing to 20 mph, you will get noticeably further range. perhaps 1.2 miles per ah.
el_walto
10 kW
dogman said:
Agreed, You should be able to get at least 14 miles, depending on many factors.
el_walto said:
Thanks, that is what I was looking for.
Don't exceed 11Ah, now I know when to turn around and head home (5.5Ah).
On a side note, I often put on 50KM (31.25 miles) or better between charges.
I do rest the cycle analyst after each charge, just put it on the charger now, and it read, 50.2KM, 39.9V, 10.6Ah.
Of course I keep the speed down, and help it up the hills.
Still an awesome machine.
dumbass
100 kW
Nelson37 said:
Lets say your pack is rated for 2000 cycles. But if you constantly use say 80+% of the pack capasity it is unlikle that it will ever see 2000 cycles. that said though...if you discharged to only 25% of capasity and recharged the pack it would likely get far more then the rated 2000 cycles. Of course there are many things that can effect the true cycle life of a pack. So this is a very simple explination.
Bob
el_walto
10 kW
This is my opnion.
If your pack is rated 2000 cycle, i'd think that means drain 100% to LVC and charge 2000 times. If you discharge to 50% and charge, that would be .5 of a cycle.
Yes there are a bunch of other factors such as venders not giving accurate cycle counts. I think some venders only test with a single cell rather than an entire pack. Lots of this stuff is subjective.
If your pack is rated 2000 cycle, i'd think that means drain 100% to LVC and charge 2000 times. If you discharge to 50% and charge, that would be .5 of a cycle.
Yes there are a bunch of other factors such as venders not giving accurate cycle counts. I think some venders only test with a single cell rather than an entire pack. Lots of this stuff is subjective.
dumbass
100 kW
Lets simplify it this way. First off if you use the bike on a regular bases then charge on a regular bases. So if you use 10% everyday then charge if for that 10% recovery everyday. But don't get overy excited if you forget it because at the end of the second day you'll still only be down 20%. But if you only use the bike "now and then" it's best not to leave the battery fully charged until you need it. Then charge it to fully. If you live in a cold area and will be storing the battery for a long time try to run it down to half. And check it monthy. It will likely only loose a few % per month in storeage.
When you do charge always try to do a full charge so the pack has time to balance. If you do very light usage everyday it might be good to ocationally run the pack below 50% so it has a long charge period to retain cell balance. Full charge on most lifepo4 cells is 3.65v and will settle (at rest) between 3.2 and 3.45 depending how long they are resting and the type of cells you have. But they should all be in the same area of voltage.
You may want to consider getting a CA or simular meter to monitor the usage as you ride. Remember the only way to know how full a lifepo4 cell is is by knowing how much you used. You can not monitor them by their current voltage like other cells.
Bob
When you do charge always try to do a full charge so the pack has time to balance. If you do very light usage everyday it might be good to ocationally run the pack below 50% so it has a long charge period to retain cell balance. Full charge on most lifepo4 cells is 3.65v and will settle (at rest) between 3.2 and 3.45 depending how long they are resting and the type of cells you have. But they should all be in the same area of voltage.
You may want to consider getting a CA or simular meter to monitor the usage as you ride. Remember the only way to know how full a lifepo4 cell is is by knowing how much you used. You can not monitor them by their current voltage like other cells.
Bob
john7700
100 W
Nelson37 said:
dumbass
100 kW
If I were starting over I would be very tempted to go with A123 Prismatic cells. I think the biggest they offer are 20ah but they are very expensive and hard to find. But I could build a killer 48v 20ah triangle pack that would be nothing weight wise.
No there is nothing wrong with not using the extra power just because it's there. It does not effect the cells at all. But if you do not need high amp draw there are a lot of good cells for a lot less.
Can I, can I, can I answer the last question................. please!!!! LOL
Bob
No there is nothing wrong with not using the extra power just because it's there. It does not effect the cells at all. But if you do not need high amp draw there are a lot of good cells for a lot less.
Can I, can I, can I answer the last question................. please!!!! LOL
Bob
dnmun
1 PW
totally hijacked now.
the OP originally said he had a 37V polymer pack.
i assumed he meant he had a 10S lipo pack.
he refused to tell us what he has for a pack so i don't know how anyone can answer his questions until we know. the other guys should start their own thread about their stuff if they wanna, but this guy started this thread to get some info and so far he has nothing useful.
and we still know nothing about what pack he has.
the OP originally said he had a 37V polymer pack.
i assumed he meant he had a 10S lipo pack.
he refused to tell us what he has for a pack so i don't know how anyone can answer his questions until we know. the other guys should start their own thread about their stuff if they wanna, but this guy started this thread to get some info and so far he has nothing useful.
and we still know nothing about what pack he has.
dumbass
100 kW
Of course your correct we now have mixed technology questions. But Jimbo397 indicated he had the info he wanted and hasn't posted since. The problem with mixing the thread is the info given can be confusing for some. But if you notice Nelson37 (the other guy as you called him) is new here and I'm sure he didn't relize he should have started his own thread. Nor did he know he was talking about a different type of technology. I guess I should have ignored him or told him we can't answer his questions until he figures out how to start his own thread.. But when he does we'll all be very happy to help him. OPPs...my bad (I guess)!! Alls good in ESville now.....so we can all sleep safe tonight :lol:
Bob
Bob
dnmun
1 PW
i guess it doesn't matter since he never came back with info about his battery. there are good reads in the reference section.
conventions are that 12S was 36V for lifepo4 but now people use 37V for 10S lipo, or whatever the ad says on the ebay ad. there is 41V limno4 too which is used the same way, and knowing what type of chemistry is important to help him if he has problems.
conventions are that 12S was 36V for lifepo4 but now people use 37V for 10S lipo, or whatever the ad says on the ebay ad. there is 41V limno4 too which is used the same way, and knowing what type of chemistry is important to help him if he has problems.
dumbass
100 kW
He also posted the same exact thread on another site. And of course dropped off the face of the earth there too.
Bob
http://www.bikeforums.net/showthread.php/834358-Battery-Charging
Bob
http://www.bikeforums.net/showthread.php/834358-Battery-Charging
dnmun
1 PW
ok, you were asking about why a cycle is not a cycle if it is a small degree of discharge during the cycle?
you wondered why small discharges from the fully charged pack did not rank as high as deep discharges in terms of longevity?
you wondered why small discharges from the fully charged pack did not rank as high as deep discharges in terms of longevity?
dumbass
100 kW
Trust me vast majority o us are not so fanatical about thread hijacking. I for one could care less and have from time to time done it without thinking about it. Personally, I agree within limitation a nut is a nut. Remember like you everyone has a long day from time to time.
In my early days I too though the same as you. That a cycle was a cycle and was therefore, thinking to drain the pack before recharging it. But I too quickly soon learned that was incorrect. I think it's a common mistake based on how cells are rated. Keep in mind that we are always talking about a "pack" not an individual cell. A single cell within a pack could fail long before the others and require replacement. Just as several cells could become week while a few remain strong. So many times a "bad" pack can be revived by replacing a cell or a few cells. For this reason I tend to prefer cell that are easy to changeout. Like cells with screw connectors for example.
As for your verying comute the thing to remember is the total usage of the pack between charges. So if you need to use 10% in the morning and 20% in the afternoon your charge is still only 30%. A lot depends on what you expect the life of the pack to be. IF your happy with 1000 cycles whice many people are then there's no big deal. As we said generally it's better to short charge then to have a depleted pack requiring a long charge. As mentioned however, there are exceptions to this. Sometimes cells can come out of balance from short charge cycles. So a heavy discharge now and then may help keep them better balanced. I don't normally have this problem because I tend to use single cell chargers now and then to put all the cells back in balance. I don't use a true BMS for high or low voltage cutoff. I've been very happy using my CellLog8s for monitoring and controlling of both ends. It's just my preference.
Bob
In my early days I too though the same as you. That a cycle was a cycle and was therefore, thinking to drain the pack before recharging it. But I too quickly soon learned that was incorrect. I think it's a common mistake based on how cells are rated. Keep in mind that we are always talking about a "pack" not an individual cell. A single cell within a pack could fail long before the others and require replacement. Just as several cells could become week while a few remain strong. So many times a "bad" pack can be revived by replacing a cell or a few cells. For this reason I tend to prefer cell that are easy to changeout. Like cells with screw connectors for example.
As for your verying comute the thing to remember is the total usage of the pack between charges. So if you need to use 10% in the morning and 20% in the afternoon your charge is still only 30%. A lot depends on what you expect the life of the pack to be. IF your happy with 1000 cycles whice many people are then there's no big deal. As we said generally it's better to short charge then to have a depleted pack requiring a long charge. As mentioned however, there are exceptions to this. Sometimes cells can come out of balance from short charge cycles. So a heavy discharge now and then may help keep them better balanced. I don't normally have this problem because I tend to use single cell chargers now and then to put all the cells back in balance. I don't use a true BMS for high or low voltage cutoff. I've been very happy using my CellLog8s for monitoring and controlling of both ends. It's just my preference.
Bob
dnmun
1 PW
that comment about needing to do deep discharge to cause the cells to balance is incorrect. you should not use comments here as fact.
you should charge as often as is feasible. it is easier on the battery to produce power from the top of the charge than from the bottom.
the farther you discharge lifepo4 cells, the farther they tend go outa balance with the others in the pack and require longer to balance when you charge afterwards.
you should charge as often as is feasible. it is easier on the battery to produce power from the top of the charge than from the bottom.
the farther you discharge lifepo4 cells, the farther they tend go outa balance with the others in the pack and require longer to balance when you charge afterwards.
REdiculous
10 kW
Pillow, fist, knife or gun fight.
Pillows to balance the pack. Something between fists and knives for daily charging. Use a gun if you want it to die sooner/now.
...is my very basic understanding. :wink:
I don't think so...
If a cell gets out of whack, say 1v under the average of the other cells, you can't deep cycle the pack to bring that misbehaving cell up 1v so it's inline w/ the rest. I'm pretty sure the balance-charger needs to address each cell individually in order to balance them.
I could be wrong though....I'm bulk charging a small homemade lipo pack, expecting it to explode one of these days. :lol:
dnmun
1 PW
the cells balance while charging when charged on a bulk charger with a BMS.
REdiculous
10 kW
Good to know. I've no experience w/ BMSes, pre-built packs or fancy chargers. I'm crudely bulk-charging a small lipo brick I put together....I don't care if it's out-of-whack, or spontaneously combusts. 
dnmun
1 PW
you may not care if it ignites because the house is not yours and you rent it but there may be other people in the building who can also be hurt by the fire.
we were talking about using bulk charging to charge a lifepo4 pack using active balancing by the BMS.
we were talking about using bulk charging to charge a lifepo4 pack using active balancing by the BMS.
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