Possible to charge one battery to another battery?

Question

Hello connection

I need your help regarding possible to charge one battery to another battery?

The requirement is if in our one battery dead then we might be not able to connect charger because we don't have AC plug at all places.

So the idea is there is another 2nd battery which can charge the battery in an emergency situation

Battery Specification:-

25.9 V 60 Ah

Lithium iron cell (18650) 7 cell in serise 24 cell in perellel

Charge mode:CC/CV

Charge Voltage:-29.4±0.02V

Nominal Voltage :- 25.9V

Capacity :- 60Ah

Discharge Cut-off Voltage :-19.25V

My question is can we able to charge one battery to another same battery?

Kindly share your valuable input regarding this question

michaelkellett · Answer

A good system would not attempt to charge the empty or failed battery from the back up battery(which will always waste energy and in the case of a failed main battery will not work at all). You should arrange a system to switch from the main battery to the back up battery when required. Since your system is using a main battery with 5.6MJ capacity you need to get this circuit designed by someone who knows what they are doing - ie who has experience and test equipment etc. A 7s24p lithium ion battery is a serious bomb waiting for an excuse to explode and must be treated with due respect ! What is the application of this system ? MK

Pavel.Simon · Answer

Generaly you can charge "empty" battery with the same "full" one.

But question is not about empty (or discharged) battery against full (or fully carged) battery.
You write: "if in our one battery dead" - if you mean empty (or discharged) then you can. Even you do not need charger or any electronics in betwen two batteries. You connect those batteries and energy will flow itself. Only you need to control when current isstill flowing fron new to old... If it stops, you need to disconnect - chcrging would not be possible anymore. At that time you need to charge your new one to be able give energy to old one.

Efficiency will not be good, but you can. More effective way is to replace one battery (empty one) with another (full one). Is it possible to physically change them?
Hovewer different situation is if the battery is really dead. Then it will not work. Old dead battery would not be able to recieve any energy, and then you cannot charge it in any way. Then replacement is only way.

Easy way is imagine it as two bottles: full one is able filling empty one. But any full one is not able fill broken (dead) one.

phoenixcomm · Answer

hardik.jani you are trying to swim upstream, it really doesn't work well. Case in point take my Smartphone and the battery pack. When I notice that the cellphone is at 50% I hook the small battery to the phone but that only prolongs the fact that the charger will lose power while the phone loses power. LOL Try this get a 12-volt car battery and run an inverter off it. This will work for a long time. then recharge the car battery. 1667.contentimage_3.png

hardik.jani · Answer

Hello Pavel Simon,

Thank you for your reply!!!!!

"The requirement is if in our one battery dead then we might be not able to connect charger because we don't have AC plug at all places."

Ans:- the fully dead means battery voltage is 23 V or 20 V and already integrated BMS circuit inside

Que:- my question is would need any isolate or protection circuit need between two batteries?

Pavel.Simon · Answer

for an emergency - no, but you need to control energy flow...

for regular use - of course, yes

so many other details are there:

1. are there load in the process?

2. any "strange" condition - humidity, temperature (high,low), ... - involved?

3. value of devices in load?

All of them is important in an estimate of protection. But really general are two rows of the beginning of this answer.

Possible to charge one battery to another battery?

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