Charging 12v cordless drill battery

[Chanz]

Can i charge 12v cordless drill battery the same way as SLA battery using the solar charge regulator? or is there even a way to charge with the SLA battery?

[Sunking]

Well the simple answer is yes. However it gets complicated.

In the off-grid solar power market, all the panels and charge controllers for that market are made to work with Lead Acid Battery charging algorithms and voltages of 12, 24, 36, 48, 60...

In the world of power tools there is no standard battery or voltage used. They may use Nickel Cadmium, Nickel Metal Halide, or any one of the many Lithium Ion chemistry. Voltages range from a few volts up to say around 24 with everything in between. They also use a different charging algorithm.

So the problem is there are no charge controllers made to do all that, and pointless for any manufacture to to try, there is just too many variables. That leaves you to do a custom design and build.

Now there is a way around that, and very easy to do, but very inefficient. You take a standard 12 or 24 volt solar power system with a standard lead acid battery of appropriate size, then use an inverter with the charger your Gizmo came with.

[Chanz]

Well the simple answer is yes. However it gets complicated.

In the off-grid solar power market, all the panels and charge controllers for that market are made to work with Lead Acid Battery charging algorithms and voltages of 12, 24, 36, 48, 60...

In the world of power tools there is no standard battery or voltage used. They may use Nickel Cadmium, Nickel Metal Halide, or any one of the many Lithium Ion chemistry. Voltages range from a few volts up to say around 24 with everything in between. They also use a different charging algorithm.

So the problem is there are no charge controllers made to do all that, and pointless for any manufacture to to try, there is just too many variables. That leaves you to do a custom design and build.

Now there is a way around that, and very easy to do, but very inefficient. You take a standard 12 or 24 volt solar power system with a standard lead acid battery of appropriate size, then use an inverter with the charger your Gizmo came with.

Thanks. Then why is it inefficient to use the inverter?

[Sunking]

It is just all the losses added up. To just charge up the first lead acid battery, using the best MPPT charge controller money can buy is around 66% efficient, So let's say you have a 12 volt 10 amp hour battery. That equates to 120 watt hours. So at 66% effeciency it takes 120 wh / .66 = 181 watt hours input.

Ok now you use that battery to power an inverter with 95% efficiency to power another charger with power power losses to charge another battery like NiMh that has a 80% charge efficiency . It adds up pretty quick especially the dollars to do it with solar.

I am a power tool junkie, and I got a few cordless tools like my favorite DeWalt Drill. It has a 24 volt 2500 mah battery, or 60 watt hours. It comes with a 3 hour charger. I can build a custom solar charger to charge the batteries in 3 hours, but to do so I have to way oversize the panel and be limited to using it between 10 am to around 3 pm window. Just in materials I am looking at $300 to $400. So for me it is just not worth the effort when I can use the manufacture charger, plug it in anytime, and cost less than a fraction of a penny for the electricity.

[Chanz]

It is just all the losses added up. To just charge up the first lead acid battery, using the best MPPT charge controller money can buy is around 66% efficient, So let's say you have a 12 volt 10 amp hour battery. That equates to 120 watt hours. So at 66% effeciency it takes 120 wh / .66 = 181 watt hours input.

Ok now you use that battery to power an inverter with 95% efficiency to power another charger with power power losses to charge another battery like NiMh that has a 80% charge efficiency . It adds up pretty quick especially the dollars to do it with solar.

I am a power tool junkie, and I got a few cordless tools like my favorite DeWalt Drill. It has a 24 volt 2500 mah battery, or 60 watt hours. It comes with a 3 hour charger. I can build a custom solar charger to charge the batteries in 3 hours, but to do so I have to way oversize the panel and be limited to using it between 10 am to around 3 pm window. Just in materials I am looking at $300 to $400. So for me it is just not worth the effort when I can use the manufacture charger, plug it in anytime, and cost less than a fraction of a penny for the electricity.

thanks. so solar charging is out. what is the outcome of charging using the inverter considering that its less efficient. will it damage the drill battery? need to know if it worth getting an inverter.

[Chanz]

by the way regarding the mppt controllers. i thought they are 95 to 98% efficient

[Sunking]

by the way regarding the mppt controllers. i thought they are 95 to 98% efficient

Well they are, but not the batteries they are charging and wiring losses.