Li-ion Charger recommendations

[DouglasXK]

What should determine the size of charger is the parallel configuration of the battery. A battery with 5 or more cells in parallel will have a maximum charge of 800mAmps per cell which any cell likely to be used these days should be perfectly happy with. Otherwise a battery with say 10ahr capacity is likely to be made from Samsung 25R cells in a 4P - 4 parallel cells - arrangement and that handles a 4 amp charge but a 2 amp charger would be better.

For your application which must be in excess of 6P a 4 amp charger is going to take at least 5 hours and 10 hours if 2 amps. Assuming the cells are Li-Ion.

The exception to this is a non-uniform cell structure in a battery pack. A mixture of different capacities virtually dictates you use a low amperage charger because the battery management system uses very small balancing currents which won’t allow the BMS to balance charge fast enough - it chucks too much current at it.

The same applies to packs which use sub-standard cells. When a Chinese pack is offered at a very cheap price that is generally too good to be true.

The answer is build your own then you know what you’ve got but if you can’t, buy from a reputable UK supplier.

 

[Nealh]

25R is one of the top cells with a 20a rating, I doubt that many common 10ah batteries would have these inside.

 

[DouglasXK]

You’re confusing maximum output with rated capacity. The OP describes rated capacity of 20AmpHr

 

[Robert Stanford]

What should determine the size of charger is the parallel configuration of the battery. A battery with 5 or more cells in parallel will have a maximum charge of 800mAmps per cell which any cell likely to be used these days should be perfectly happy with. Otherwise a battery with say 10ahr capacity is likely to be made from Samsung 25R cells in a 4P - 4 parallel cells - arrangement and that handles a 4 amp charge but a 2 amp charger would be better.

For your application which must be in excess of 6P a 4 amp charger is going to take at least 5 hours and 10 hours if 2 amps. Assuming the cells are Li-Ion.

The exception to this is a non-uniform cell structure in a battery pack. A mixture of different capacities virtually dictates you use a low amperage charger because the battery management system uses very small balancing currents which won’t allow the BMS to balance charge fast enough - it chucks too much current at it.

The same applies to packs which use sub-standard cells. When a Chinese pack is offered at a very cheap price that is generally too good to be true.

The answer is build your own then you know what you’ve got but if you can’t, buy from a reputable UK supplier.

Hi Douglas,

I used to be a fairly dab hand with a soldering iron and am reasonably confident in building a charger (though I've not had much experience of surface mount components and multiple layer boards). I am not up to designing one.

Where would I start (kit or pcb template to photo etch)?

Thanks for your help,

Rob

 

[DouglasXK]

Rob, I’m referring to building your own battery packs not chargers. I’ve used AnnPower (AliExpress) 4 amp chargers for several years without any trouble. I couldn’t build one for the £30-40 they charge for them. Building battery packs is more testing and mechanical engineering (keeping the cells in place) than electronics.

 

[Nealh]

You’re confusing maximum output with rated capacity. The OP describes rated capacity of 20AmpHr

I am not, In post 21 you stated:

Otherwise a battery with say 10ahr capacity is likely to be made from Samsung 25R cells in a 4P - 4 parallel cells

As I mentioned the 25R cell is a pucker 20a rated cell and very few 10ah batteries will have these cells inside and more likely will have far inferior/crappier cells then these.

 

[Robert Stanford]

Rob, I’m referring to building your own battery packs not chargers. I’ve used AnnPower (AliExpress) 4 amp chargers for several years without any trouble. I couldn’t build one for the £30-40 they charge for them. Building battery packs is more testing and mechanical engineering (keeping the cells in place) than electronics.

My mistake, I'm pretty sure that the cells in my battery are of the inferior variety so I have decided to play safe and go for a 2A charger. I have followed your lead and gone for a metal cased one, with a fan and a fuse on the output made by AnnPower. It claims to be CE compliant but we will take a peak in side just to make sure it looks OK (not possible with a welded plastic case).

I will report back once it arrives.

Thanks for your help

 

[Paultr]

https://bmsbattery.com/search?controller=search&orderby=position&orderway=desc&search_query=Charger&submit_search=


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Off topic and possibly stupid post but just want to be certain. The prices on the above site look very reasonable. Many of the chargers say they are suitable for lead acid batteries so would this one for example be suitable for charging a 12v conventional lead acid leisure battery (these are not true deep discharge batteries but can be partially discharged and are used in caravans and boats) ? The label on the one in this link shows that they do a 12v 20A version.
https://bmsbattery.com/ebike-charger-ev-charger/795-s600-300watts-lifepo4li-ionlead-acid-battery-charger.html?search_query=Charger&results=149

 

[Robert Stanford]

Off topic and possibly stupid post but just want to be certain. The prices on the above site look very reasonable. Many of the chargers say they are suitable for lead acid batteries so would this one for example be suitable for charging a 12v conventional lead acid leisure battery (these are not true deep discharge batteries but can be partially discharged and are used in caravans and boats) ? The label on the one in this link shows that they do a 12v 20A version.
https://bmsbattery.com/ebike-charger-ev-charger/795-s600-300watts-lifepo4li-ionlead-acid-battery-charger.html?search_query=Charger&results=149

I have not used BMS Battery and can't vouch for them.My understanding is that when you order you need to specify the battery chemistry (e.g. lead acid) and they will customise the charger to match it.

 

[Paultr]

I have not used BMS Battery and can't vouch for them.My understanding is that when you order you need to specify the battery chemistry (e.g. lead acid) and they will customise the charger to match it.

Thanks Robert. I have since looked at the site again and I was being over cautious and I am sure the chargers would be suitable if I specify the lead acid option. It was all the references to the lithium ion chemistry that put me off. They make the chargers sold by that well known multiple car accessory retailer seem woefully under powered and over priced !