Balance charging: better done with room temp battery cells?

legsofbeer

Active Member
So, reading various posts about hypermiling one's charging regime to milk the most lifetime range out of your battery, I have to wonder if the standard practice (with some vendors) of balance charging is sub-optimal. The instructed practice is to, approximately every 30 days, charge your battery fully, then leave the charger connected for another six hours so the BMS can balance out cells once the battery has reached a nominal voltage. But... we are advised to not charge the battery when it is hot off a ride or from outside ambient temp (reduces longevity). Yet charging heats the cells. So in that vein, would it not be better to charge the battery to whatever near nominal it will do, then disconnect the charger, let it cool, then reconnect and let it have the balancing sesh at a less damaging temperature?

I'm not claiming this would increase battery lifetime range, just thinking that if one is that into hypermiling battery lifetime that one would make a point of keeping the battery's charge within the 20-80% range, this might be another consideration.
 
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Ravi Kempaiah

Well-Known Member
Things have improved vastly in the last 5-6 years. Balancing the cells manually is done when there is no BMS with LiPo packs or battery with a shoddy BMS.
Even an aftermarket battery maker like EM3ev, who doesn't charge a heavy premium, employs a BMS that balances the pack at <90%. Check this out:

See the whole specs here:

1614570612306.png
 

legsofbeer

Active Member
Good to hear there are chargers available to the hyperlifers that are less pricey than the grin satiator. But my question remains, for those of us who have an allegedly good battery with a cheapass 2 amp charger, when we are doing the instructed monthly extra six hours' balancing charge, would or would not we be better off letting the battery cool down from the 40-something volt to nominal charge before letting the balancing charge do its thing?
 

indianajo

Well-Known Member
My cheap switcher charger shuts off @ 53.6 v. So letting it go another 6 hours is not an option. The battery sags a volt and a half immediately after disconnecting the charger, so if plugged in again it starts all over again. I don't do that. I shut it off at about 52.5 v typically based on the meter on the throttle. I've been full charging only once a quarter. For full charge I just let it run until it shuts off. Battery has a BMS, I presume it does the balancing thing. I don't charge it the same day I arrive, so it is ambient temp when charged.
I have a transformer charger in town that gets down to 100 ma or less @ 53.5 v, since it is a 45 v transformer -4 diode drops. It is 4 A @ 45 v but takes forever over 52.5 v.
I charge to ~52.5 twice a week in warm weather, after each 30 mile trip. So my 1/18 battery has about 180 charges on it. It is holding up fine. Battery used to red LED & cut out up the last couple of hills with the DD motor or the ebikeling motor, but it never measured below 43 at destination. It freezes here, so battery spends Nov-March wrapped in a heating pad in the garage. Bike rides around w/o battery in winter.
 
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legsofbeer

Active Member
Good details, but if I can condense my question: if it is suboptimal due to cell temp (damaging to battery lifetime) to charge it to full and immediately go on a ride, or to bring it home after a ride with cells hot from discharging and right away plug in the charger, then wouldn't it also be suboptimal to charge it to nominal full voltage, then while the cells are hot from charging, let the balancing charge run go for another six hours?
 

harryS

Well-Known Member
Sure, there's a best temperature for charging. If you want to cool your batteries down to a 70F ambient, I'm sure they will last longer. Have at it.

By the way, do you know that your Rad batteries actually have a balance BMS? If their instruction manuals mention it, that's great. A lot of the chinese import batteries don't have balance circuits. I believe my Ecotric does, which surprised me. I have a few other batteries that do balance and a few that I know don't have balance, but all of them are in good shape, in my opinion,

Personally, I don't have the time or enough battery capacity to run my bikes at less than 100%.. We put the bikes on charge after each ride. Never leave then charging overnite. That's good enough for me.
 

legsofbeer

Active Member
By the way, do you know that your Rad batteries actually have a balance BMS? If their instruction manuals mention it,
They do, and the battery measures 54.2v after the monthly full balancing charge whereas it's 53.7-53.9 near the end of the month after a full charge. And yeah, personally I don't worry too much about hyperlifeing the battery, though I do wait an hour after getting home before charging, and try to minimize the charge cycles (eg. every 30 miles, not 10 miles). But I'm curious whether the folks who advocate for keeping a battery in the 20-80% regime have thought about the consequences of balancing a hot cell battery.
 

AHicks

Well-Known Member
Region
USA
City
Snow Bird - Summer S.E. Michigan, Winter Gulf Coast North Central Fl.
I'm with Harry on the room temp battery charging. In a perfect world, that's going to give you the longest life. That said, in more practical terms, if I come in from a ride in 40 degree temps with a low battery, I'm not going to wait for it to warm up prior to charging it. I'll willingly take any hit to battery life resulting from that practice. AND, the charger will be on it until the next day. If my bike is going to get a 100% charge (which I do often as not) I plug it in and leave it until the next day - just like I've been doing for years now on our other bikes. Heresy, I know....

I charge when standing voltage get's down to 45-46v or so.

Our Rad is 4 years old now, with no obvious signs of degradation - yet.
 

fixercqi

New Member
Recent research into li-on longevity has discovered that a lot of damage occurs because of something similar to sulphation in lead acid batts. The cathode and anode are being coated, so to speak, and become less able to transfer electrons. They then discovered that there is an optimal voltage that should be applied to each cell during charge. Anything over or under that V was progressively detrimental. They say that 3.9v is optimal and that higher v will affect the cathode, and lower will affect the anode. I gather that most chargers run at 4.2v. I guess the idea is to shorten the charge time and increase the discharge time, apparently at our cost. I don't know if the Satiator mentioned above allows selection of charge v, but if it does, then it would seem a great option for anyone with 2 or more batts to charge. Optimal charge v was proven to increase longevity double fold. I like stuff that pays for itself quickly.
 

plugpedals240

New Member
Region
Europe
It always depends on the batteries. I charge it in my garage where it's above outside temperature with a slow charger. this way, they won't get damaged.
 

PedalUma

Well-Known Member
Region
USA
I have some batteries with an on/off switch. Interestingly I can charge these overnight with the switch in the off position. In the morning the charger light is green, showing a full charge, then when I switch the battery on, the charger light turns red and it charges the last 10% and turns green again when full.
1,000/52=19.23. These batteries are good for 1K charges. That is one charge per week for nineteen-years plus one season. These batteries will be obsolete in five-years, so I do not worry much about it. They work for me, I do not work for them.
 

JES2020

Active Member
Recent research into li-on longevity has discovered that a lot of damage occurs because of something similar to sulphation in lead acid batts. The cathode and anode are being coated, so to speak, and become less able to transfer electrons. They then discovered that there is an optimal voltage that should be applied to each cell during charge. Anything over or under that V was progressively detrimental. They say that 3.9v is optimal and that higher v will affect the cathode, and lower will affect the anode. I gather that most chargers run at 4.2v. I guess the idea is to shorten the charge time and increase the discharge time, apparently at our cost. I don't know if the Satiator mentioned above allows selection of charge v, but if it does, then it would seem a great option for anyone with 2 or more batts to charge. Optimal charge v was proven to increase longevity double fold. I like stuff that pays for itself quickly.
I use a outlet timer to shut down my charger at predetermined levels, (something you can figure out with trial and error).
When I balance my pack, the charger stops at 54.6v but by leaving it plugged in, the out of balance cells will be balanced by the BMS. This ONLY happens at top voltage, so the charger needs to "kick in"in the process.
One other thing I have learned is to let the battery sit for 1/2 hour after a ride, before charging.

One the point of gaining battery life cycles by under charging, I do what this guy does.
 

RickyE

New Member
So, reading various posts about hypermiling one's charging regime to milk the most lifetime range out of your battery, I have to wonder if the standard practice (with some vendors) of balance charging is sub-optimal. The instructed practice is to, approximately every 30 days, charge your battery fully, then leave the charger connected for another six hours so the BMS can balance out cells once the battery has reached a nominal voltage. But... we are advised to not charge the battery when it is hot off a ride or from outside ambient temp (reduces longevity). Yet charging heats the cells. So in that vein, would it not be better to charge the battery to whatever near nominal it will do, then disconnect the charger, let it cool, then reconnect and let it have the balancing sesh at a less damaging temperature?

I'm not claiming this would increase battery lifetime range, just thinking that if one is that into hypermiling battery lifetime that one would make a point of keeping the battery's charge within the 20-80% range, this might be another consideration.
 

RickyE

New Member
I am new to this forum and couldn’t find a place to comment ?
I am aware that storing a lithium battery at less than 50% is a bad idea.
I just made a foolish purchase of a 36 V 10 amp hour battery that was listed as ‘new’.
It only shows 3 V on my multi meter
Two questions : 1) Is this new looking battery dead in the water and won’t take a charge?
2) I can’t find a charger with a four pin connection to the four pin port on the battery!
I would appreciate any advice ! Thank you, Richard
PS: never buy ANYTHING from Populo Bikes !
 

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AHicks

Well-Known Member
Region
USA
City
Snow Bird - Summer S.E. Michigan, Winter Gulf Coast North Central Fl.
How handy are you? Would you be up for disassembling the case, installing some good wire, basically making your own charge lead - that doesn't use that charge jack?
 

AHicks

Well-Known Member
Region
USA
City
Snow Bird - Summer S.E. Michigan, Winter Gulf Coast North Central Fl.
I think that might depend on how handy you are? If you are able to come up with the number, arrangement, and type of cells, it's not hard to come up with a suitable charger.

That's not to say you don't need to be cautious though!
 

JES2020

Active Member
I think that might depend on how handy you are? If you are able to come up with the number, arrangement, and type of cells, it's not hard to come up with a suitable charger.

That's not to say you don't need to be cautious though!
My battery for instance is a black box w/ no information or specs on it. I would not be able to rest easy putting a charger that didn't come with that battery.


As Frankenstein's monster says 'FIRE BAD !"
 

AHicks

Well-Known Member
Region
USA
City
Snow Bird - Summer S.E. Michigan, Winter Gulf Coast North Central Fl.
My battery for instance is a black box w/ no information or specs on it. I would not be able to rest easy putting a charger that didn't come with that battery.


As Frankenstein's monster says 'FIRE BAD !"
No getting around that fact!

The picture of the OP's battery makes it look like it might be a little easier to figure out - IF he's even interested in doing that.

To be honest, with just 3v showing on a volt meter, I'm not real sure it's even worth messing with.