Modification + dry battery charger

luck_gfb

Modification + dry battery charger [Copy link]

 

The sample has been received. Let me first introduce this boost board.

soso

Very clear, looking forward to the follow-up :)

qwqwqw2088

Dry cell charger?

Generally speaking, dry batteries cannot be recharged.

Is it okay? The charging current should be small, don't charge for a long time or multiple times, just play with it.

annysky2012

Dry cell battery charger? Generally speaking, dry cells cannot be charged, but ordinary cells can? The charging current should be small, and don't charge for a long time or multiple times. Just play with it, right?

Generally, they cannot be charged. Don't make the things come out. If they catch fire, it will be a big deal.

Gen_X

All of the above make sense. Let me share my decades of experience:

First of all, the charging of dry batteries is subject to certain conditions, and secondly, the charging current requirement is relatively small. The following are specific instructions:

1. For general 1.5V dry batteries, it is not recommended to charge if the voltage is less than 1.2V, which means they are close to being scrapped. It is best to charge them if the voltage is above 1.3V.

2. Strictly monitor the charging current. If the voltage rises quickly (soon greater than 1.55V), it means the internal resistance is too large, or the battery is dry and not suitable for recharging. If the battery is declared terminated, recharging is meaningless.

3. For No. 5 batteries, the charging current of a single battery should not exceed 120ma, the No. 7 should be kept below 60mA, and the No. 1 battery should not exceed 300mA, otherwise it is easy to leak or explode during the charging process.

4. The charging time should not exceed 1 hour. If it gets hot, it should be terminated in advance.

5. It is not recommended to charge silver ion (3V, 3.6V) button batteries. Generally, the control should not be easy to hear (the sound is quite loud). The current is below 30ma.

6. It is best not to try using disposable lithium batteries, as it is very dangerous and the charging process is equivalent to testing a detonator.

7. Generally, dry batteries can be charged 2-5 times, depending on the usage. The so-called charging is a simple repair "energy replenishment", which is not equivalent to the repeated energy storage of rechargeable batteries. As the internal resistance of the battery increases and the shell becomes soft, it can be declared that the battery life has ended and it is time to recharge it.

8. Only batteries that are used or replaced should be charged for "restoration". Batteries of micro-power devices that are not often disassembled should not be charged because there is still a risk of leakage and explosion. It is best to leave the batteries for a few hours after charging to allow them to "stabilize".

luck_gfb

Maybe you don't understand, my purpose is to use dry cell batteries as input, and use the boost board to boost the voltage to charge the mobile phone. Modern people cannot live without mobile phones, and they can be used to charge mobile phones in emergencies. I tested it today, and it is below 1.6V, this board cannot work, that is, a single battery cannot work. When the input is around 3V, the charging current is not very stable, and the output current fluctuates around 60-80mA. I tested it with a DC source, and the input current is more than 1A. I don't know if dry cells can output such a large current.

qiushenghua

Dry cell batteries are too inefficient as an energy source to charge mobile phones.

Taking No. 5 dry cell batteries as an example, the typical capacity of carbon batteries is 500mAh, and the typical capacity of alkaline batteries is 1500mAh.

The typical value of the dry cell output voltage is basically 1.4V. The Boost circuit in the circuit adopts a synchronous structure, and the efficiency is estimated to be 80%:

A carbon battery can release 1.4V*500mAh*80%=0.56Wh of energy.

A carbon battery can release 1.4V*1500mAh*80%=1.68Wh of energy.

Today's mobile phones have a capacity of 3000-4000mAh, with an average of 3500mAh.

The typical battery voltage is 3.85V, and the battery capacity is 3.85V*3500mAh=13.475Wh.

When the mobile phone inputs 5V, the efficiency of the Buck circuit is about 87%.

Battery charging also involves additional line losses, internal resistance losses, etc., and the efficiency is estimated to be 80%.

So if you want to fully charge your phone, you need dry batteries:

Alkaline battery 13.475/1.68/80%/87%=11.52

Carbon battery 13.475/0.56/80%/87%=34.5