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Onboard charging circuit??? Li-on - Lipo


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Hi, i have a model "Not plane" that is using a 3s lipo battery & i wanted to fit a 3 cell BMS charge protection board that is for a Li-on battery. Would this be ok with a Lipo battery. ?? Some advertisers say its a Li-on Lipo charger, but most refrancese when looking a little deeper only talks about Li-on. Any thoughts?? Thanks

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Just to be absolutely clear - we are talking about a Li-ion board and not a LiFe board?

A bit more information about the particular system you have in mind might help, but in general Lipo and Li-ion batteries are very similar voltages and are sometimes quoted as the same voltages, so the answer is that it would probably work OK.

When differences in voltages are quoted it is the Lipo that has the slightly higher voltage, so again you are on the safer side of the equation by using a Li-ion BMS on  a Lipo.

My approach would be to try it in a safe (fire resistant) location a few times before installing in the model.

Dick

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1 hour ago, Christopher Morris 2 said:

Hi, i have a model "Not plane" that is using a 3s lipo battery & i wanted to fit a 3 cell BMS charge protection board that is for a Li-on battery. Would this be ok with a Lipo battery. ?? Some advertisers say its a Li-on Lipo charger, but most refrancese when looking a little deeper only talks about Li-on. Any thoughts?? Thanks

Are you installing that so you can charge the battery in the mode itself? That is not recommended practise with lipos, you always want to be able to move the battery quickly in the event of anything going wrong during the charge process.

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Hi, thanks for the replies. It's actually for an RC train & i am fitting all the rc & power in a goods wagon with a simple 2 lead pos/neg to the train motor. The battery is a 1300mah lipo that is best at the lowest part of the carriage behind the loco to help with the center of gravity. So all the RC control & other lightweight bits will be on top of the battery. The carriage/wagon will come apart, but wouldn't like to keep doing this.  So what i am attempting is a jack plug socket for charging. Now this will give me the problem of at least one of the 4 jack terminals shorting as i connect the jack if wiring for a balance charge.  So! i am down to using a 2 pin jack & an onboard balanced charging board of some sort if i can work it out. 

Edited by Christopher Morris 2
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Hi,

I would suggest a small - high current not required - 4way connector.  The female part on the model and the male part shorting pins in pairs for pos and neg power.  It would act as an isolation plug. Charging can then be external as with the isolation plug removed the battery is completely isolated from the model electronics.  Just a thought.

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Do you have a spec sheet for the BMS?

I bought one for electric bike use, unused as yet. The spec sheet says it charges individual cells to 4.2V. that's spot on for Lipos. 

It also limits the charge current, I forget the figure. It limits the discharge current too, to 20A in my case. So both of these need to suit the battery and the use case. 

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4 hours ago, Chris Bott - Moderator said:

Do you have a spec sheet for the BMS?

I bought one for electric bike use, unused as yet. The spec sheet says it charges individual cells to 4.2V. that's spot on for Lipos. 

It also limits the charge current, I forget the figure. It limits the discharge current too, to 20A in my case. So both of these need to suit the battery and the use case. 

Not picked out a BMS as yet as i find one that seems good & read up on the tests & find out they are more of a protection than a true BMS. Nik's idea might solve it with a 4 way plug as i have a good balance charger. 

6 hours ago, Nik Harrison said:

Hi,

I would suggest a small - high current not required - 4way connector.  The female part on the model and the male part shorting pins in pairs for pos and neg power.  It would act as an isolation plug. Charging can then be external as with the isolation plug removed the battery is completely isolated from the model electronics.  Just a thought.

Nice idea. Would just need a 4 way plug that is an easy push fit as the train wagon is not the strongest. But it would solve any shorting out. 

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  • 2 weeks later...

Hi Chris, what gauge is the train? I run gauge 0 on a single cell 600 lipo with an inverter which takes it up to 12v . Last time I bought some inverters they were £1 each from China, on a tank loco it fits in in the coal bunker and for a tender loco the battery goes in the tender under a card plate with a dummy load of coal on top the esc is from Micron RC. Just un plug the battery when finished .

Eric r.

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On 24/02/2021 at 22:26, Eric Robson said:

Hi Chris, what gauge is the train? I run gauge 0 on a single cell 600 lipo with an inverter which takes it up to 12v . Last time I bought some inverters they were £1 each from China, on a tank loco it fits in in the coal bunker and for a tender loco the battery goes in the tender under a card plate with a dummy load of coal on top the esc is from Micron RC. Just un plug the battery when finished .

Eric r.

Hi Eric, sorry for not getting back, for some reason i am not getting notifications. I have got an ON30 layout & using a 3 cell 11.1 1300ma, only because its all in a goods van & i could get a 2500mah battery in this wagon. How much running time do you get from a 600mah lipo?? 

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Hi Chris, this is my set up the battery plugs into the inverter, I have on some used a switch mainly on a tender loco.  I have fitted the same small connectors to all my loco's so that I can take the whole system out and put it in another loco, The controller has a 12 loco capacity. I have not used it much over the last two years as I have gone back to model aeroplanes. Apart from the loft layout I have a track in the garden, as the loco's have such a small current consumption I have  not checked how long they last between charges . but the chap who put me onto the system does exhibitions and with an LNER tram loco it will run most of the day pulling 20 trucks on one charge. When I do go up to the loft I generally run something for about an hour  the leave it for a few days and there is still plenty of charge in the battery. I build my own loco's from kits or scratch, this one is scratch built in nickel silver, only items bought were the wheels , chimney , dome  and handrail knobs.

 Cheers Eric.

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