Lipo Balancing advice

[Adyb]

Hi,

I have a Robitronic charger that can charge my Lipos no problem. It has no balancing function, so was wondering is it worth getting another charge with intergrated Balancer or just by an external balancer like Etronix Battery Doctor Balance/Discharger ? Has anyone else used one?


http://www.cmldistribution.co.uk/cml_product.php?range=RACING&productId=0000003637

Thanks.

[dale]

I'd go for one with integrated balancer, it's just less hassle. It's also becoming common to balance charge every run to avoid ever overcharging the Lipo cells; an integrated balancer is essential for this.

[gnr racer]

Balance charge 'every run'?? news to me

[neiloliver]

You should always charge with a balancer to ensure that no more than 4.20V is dropped across one of the cells. If your charger does not have a balancer then subtle differences in cell impedance will result in more voltage being dropped across one of the series elements and this will result in shorter life/safety risk.

N

[ch!3f]

when im racing between races i just top the cells up on balance as i only use 1800mah from my cells which are 4200mah ive gone before and not balance charged an had a dud cell at the end of the night better to be safe then sorry to be honest i use a imax b6 balance charger cheap and does the job!

[RogerM]

I always balance my cells every charge. The result is they are every bit as good now as they were when brand new a year ago!

[Adyb]

Ok thanks for the info, I have a budget of £80 can anyone suggest a good charger?

Thanks..

[gnr racer]

You do not need to balance charge every single charge,that is rediculous.
I balance to 3.80v per cell after every club day,then I balance charge a couple of hours before use,during a club day I just straight charge...all three of my lipo's are in tip top condition after more than a year.

[neiloliver]

Balancing down to a set voltage is not required in my view*, only using a balancer during each and every charge to ensure that no individual cell exceeds 4.2V. In a laptop computer battery this is done on each and every charge by shunting charge current away from the cell with the highest voltage to allow the others to 'catch up'. I assume the balancers inside the chargers we use work in much the same way although I have not tested their functionality.

*It is not good to keep your cells stored in a fully charged condition, storing them at around 40% is good and this is usually at about 3.80V (open circuit)... but given that we have such excess capacity in our batteries then it is easier to just race them and then leave them as they will be at or around this voltage. Then all you need to do is balance charge them the day before your next meeting.

[mark christopher]

Balancing down to a set voltage is not required in my view*, only using a balancer during each and every charge to ensure that no individual cell exceeds 4.2V. In a laptop computer battery this is done on each and every charge by shunting charge current away from the cell with the highest voltage to allow the others to 'catch up'. I assume the balancers inside the chargers we use work in much the same way although I have not tested their functionality.

*It is not good to keep your cells stored in a fully charged condition, storing them at around 40% is good and this is usually at about 3.80V (open circuit)... but given that we have such excess capacity in our batteries then it is easier to just race them and then leave them as they will be at or around this voltage. Then all you need to do is balance charge them the day before your next meeting.

I think this is top advice. If u have a balancer why not use it?

[Chris56]

Ok thanks for the info, I have a budget of £80 can anyone suggest a good charger?

Thanks..

The CORE RC chargers are quite popular, very reliable and an are excellent value. I use one of these and can't fault it:

http://www.modelsport.co.uk/index.php?product_id=36011

[Col]

I have your charger and wouldn't change it. I simply bought a cheap balancer when I changed from nimh to lipo (the trakpower one - not sure of they're available anymore)

[Benjy1]

I have the Balance doctor and it is great you can even balance your battery s without charging. It is a good bit of kit and if your charger does not have the balance facility it saves you buying a whole new charger at around 30 quid it is a must. Fully recommended.

:thumbsup:

[Adyb]

Again thanks for all the replies,

Was thinking the Doctor Balancer was the cheaper option. My Robitronic charger can charge Lipo's up to 10A ( I do follow the 1C rule). But if I got the CORE charger for example this can only charge up to 5A,so I would not be able to charge my 5400mAh Lipo pack at 1C....does this cause a problem?

Sorry if going a bit off topic but the 2 go in hand in hand for me.

Thanks.

[gnr racer]

Again thanks for all the replies,

Was thinking the Doctor Balancer was the cheaper option. My Robitronic charger can charge Lipo's up to 10A ( I do follow the 1C rule). But if I got the CORE charger for example this can only charge up to 5A,so I would not be able to charge my 5400mAh Lipo pack at 1C....does this cause a problem?

Sorry if going a bit off topic but the 2 go in hand in hand for me.

Thanks.
No,it wouldnt cause a problem at all.

[dpackster1980]

YOU MUST BALANCE CHARGE EVERY TIME.

IF YOU PLAN ON NOT RACING FOR A WHILE YOU MUST CHARGE THEM TO 3.5V PER CELL.

The reason for balance charging is to avoid a cell going beyond it's critical voltage (above 4.21v per cell) where they become extremely unstable and will eventually ruin the cell or they could catch fire.

The reason why you must leave charge in them is because they self discharge and everyone knows what can also happen below 3v per cell.

All as lithium polymer needs is oxygen to combust which is what happens when they swell because the sack splits in the case.

For the sake of an extra few quid for a balance lead or balance charger is ot really worth the risk? NO

The manufacturers recommendations are there in black and white. Some people assume they know better than the manufacturer and then they wonder why cells explode and catch fire.

My Intellect cells are over 2 seasons old and still are going strong. Always balance charged and left with charge in them after each meeting.

[mark christopher]

YOU MUST BALANCE CHARGE EVERY TIME.

IF YOU PLAN ON NOT RACING FOR A WHILE YOU MUST CHARGE THEM TO 3.5V PER CELL.

The reason for balance charging is to avoid a cell going beyond it's critical voltage (above 4.21v per cell) where they become extremely unstable and will eventually ruin the cell or they could catch fire.

The reason why you must leave charge in them is because they self discharge and everyone knows what can also happen below 3v per cell.

All as lithium polymer needs is oxygen to combust which is what happens when they swell because the sack splits in the case.

For the sake of an extra few quid for a balance lead or balance charger is ot really worth the risk? NO

The manufacturers recommendations are there in black and white. Some people assume they know better than the manufacturer and then they wonder why cells explode and catch fire.

My Intellect cells are over 2 seasons old and still are going strong. Always balance charged and left with charge in them after each meeting.


no you Dont have to balance charge them, its advisable
no you DONT have to put them to 3.5 volts for storage....... try 3.8 to be nearer the manufactures recomendations. but after a 5 min run from full is fine.
NO lipo do NOT self discharge, or you would leave them full....

[dpackster1980]

no you Dont have to balance charge them, its advisable
no you DONT have to put them to 3.5 volts for storage....... try 3.8 to be nearer the manufactures recomendations. but after a 5 min run from full is fine.
NO lipo do NOT self discharge, or you would leave them full....

Mark you are so wrong please refer to link below, back of the net! :D

www.manoonpong.com/Other/main_page=page_2.pdf (http://www.manoonpong.com/Other/main_page=page_2.pdf)

I'd suggest you look things up in future instead of advising people on how to torch their house or shed. ;)

With a low self discharge rate (please refer to link) it is enough to over charge a cell in a pack, even though they are matched at the factory due to manufacturing you can't guarantee over time that one cell may discharge more than another.

So when you do not balance them you will over charge one cell. KAPOOOW!

[mark christopher]

Mark you are so wrong please refer to link below, back of the net! :D

www.manoonpong.com/Other/main_page=page_2.pdf (http://www.manoonpong.com/Other/main_page=page_2.pdf)

I'd suggest you look things up in future instead of advising people on how to torch their house or shed. ;)

With a low self discharge rate (please refer to link) it is enough to over charge a cell in a pack, even though they are matched at the factory due to manufacturing you can't guarantee over time that one cell may discharge more than another.

So when you do not balance them you will over charge one cell. KAPOOOW!


if you read my post i put its advisable! you do not need to ballance every time, i have never balance two of my packs as a trial for track tech and there still as near as when they were new.
i dont need to look it up cheers, i have been told by those in the know!
the very low discharge rate is very unlikley to effect packs, UNLESS they are left for an extended period of time, you will see more inballance of lower quality cells.

we dont balance them to when were discharging them in the cars by running them, the voltage cut off do not work on each cell, so ill let you tell all how you stop one cell going to 2.5 volts and one to 3.5 with a speedo cut off of 6 volts!

see what google brings you now :p

[Col]

I know a lad with an original gold case trakpower 4900 stick pack that's now 5 years old.
Last I heard (admittedly about a year ago...) this pack was running fine and had never been balanced in it's life. Wouldn't advise it though.

Personally I balance charge every time at home and sometimes (approx 50%) at the track. I have 1 pack (my only pack) of 18month old IB4200 35c saddle lipo's and they are as good now as when new.

[Adyb]

Ok got myself the Battery Doctor and have a question.

I will be balancing whilst charging, I have the option to set the lower voltage limit before the balancing starts...do I leave this at default value of 3.30v or change it to another volt limit, range is 2.5v to 4.2v.

In previous post people have mentioned not to charge over 4.21 volts and give the impression their balancers can stop this...the Battery Doctor does not have a upper balancing voltage i.e. preventing it going over 4.21...is this another problem?

Thanks.:confused:

[Col]

no longer relevant.

[dimblum]

Leave the lower voltage limit to 3.30v per cell.. That is the minimum voltage you want your cells to be at (lipo cutoff uses the same or slightly higher voltage range). I never really heard of a minimum voltage to start balancing, but I guess each manufacturer is different..

If you were to discharge your cells below 3.30v (i.e. run an ESC without an active lipo cutoff), then there may be no way to recover/recharge the cells in the future. Especially if you bought a really cheap lipo battery that uses sub-par cells..

I am not familiar with the Battery Doctor since I have only used chargers that have integrated balancers; but your charger should have a setting for lipo voltage peak detection of 4.2 to 4.21v per cell. The charger should cut off when it detects this per-cell voltage. You charger should also let you configure the Mah setting (3300Mah, 5000Mah etc) of your battery as a backup to the voltage detection. Just in case your battery capacity peaks before the cell voltage is topped off.

Hope this helps.

Ok got myself the Battery Doctor and have a question.

I will be balancing whilst charging, I have the option to set the lower voltage limit before the balancing starts...do I leave this at default value of 3.30v or change it to another volt limit, range is 2.5v to 4.2v.

In previous post people have mentioned not to charge over 4.21 volts and give the impression their balancers can stop this...the Battery Doctor does not have a upper balancing voltage i.e. preventing it going over 4.21...is this another problem?

Thanks.:confused: