Charging Drill Batteries From Inverter Bad?

[SV Demeter]

I have mananged to kill my makita 18v lithium ion cordless batteries and Im wondering if it is from running the charger from my inverter? Inverter is an older Freedom 25 which I believe is probably not pure sine wave. It could be just a coincidence and i only charged them once this way. Im not even entirely sure if I charged both batteries or just one. One died a last week and the other this week. The charger just flashes both the green and red lights saying the battery is bad. Stinking batteries cost more than the drill...

Anyway Im sort of confused as to why the charger would care since its converting back to DC to charge anyway? If this is in fact the cause I guess I need to consider a pure sine wave inverter. Are there small ones out there? Maybe just get a small one for charging sensitive things like these drill batteries?

[djmarchand]

The Freedom 25 is definitely a modified sine wave inverter.

The chargers associated with power tools don't like MSWs. I tried using a 150W cigarette lighter inverter and it would buzz loudly and trip out when plugged in to one of those chargers.

But I agree with you, if it didn't trip (and 2,500 W shouldn't trip) then the DC output shouldn't be affected.

And FWIW look online for replacement batteries. Google makita battery and your model number. You can probably find one for $40. I found one for this price for a DeWalt drill.

David

[capn_billl]

I would have to see the internals of the charger, but typical of modern inexpensive electronics, they probably use an SCR or equivalent to control output voltage. The sharp square wave of a non sine wave inverter is not able to be controlled this way, leading the charger to misread charging voltage and under or overcharging battery.

There was another thread in which charging options from a 12v battery bank was discussed.

I often charge my battery tools, from a pure sine wave inverter no problems.

If you have 12v tools, or can take a 30% power drop on an 18v tool, just make a cord directly to your house bank.

[SV Demeter]

Yeah it didnt trip. In fact it charged just fine. Its was a few days later I went to charge the battery again this time off shore power and I got the lights blinking telling methe battery was bad. Im starting to suspect the makita charger now. Thanks.

[Vamonos]

Makita makes an "automotive charger" for their lithium ion batteries. However, it's pretty pricey at $102.

Amazon.com: Makita DC18SE 18 Volt Li-ion* Nickel Metal Hydride Optimum Automotive Charger: Home Improvement

[SV Demeter]

Originally Posted by Vamonos

Makita makes an "automotive charger" for their lithium ion batteries. However, it's pretty pricey at $102.

Amazon.com: Makita DC18SE 18 Volt Li-ion* Nickel Metal Hydride Optimum Automotive Charger: Home Improvement

Ha ha $102. The batteries cost more than that! Well the 3ah ones do anyway. This is probably the way to go then. Seems silly to run the inverter to make 120 AC only to convert it back to 18v DC to charge the drill.

[senormechanico]

I doubt the charger's bad, it just barfs with MSW.
Sine wave inverters aren't as expensive as they used to be.
I'm happy with this one:
OSP 1500W Pure Sine Wave Power Inverter DC-AC 3000 Watts Peak (759681010234) | eBay

It's not auto start, but otherwise it's great.

[AnchorageGuy]

Using an inverter for rechargeable batteries can be challenging. A quick and easy check is to look to see if the charger carries warning of dangerous voltage at battery terminals. If it does, then don't use it on an inverter. Some chargers for nickel-cadium batteries can be damaged using them on an inverter. If the charger produces a low voltage of 30 volts or less AC or DC output, it should work fine. Another note on rechargeable batteries with an inverter, if the appliance plugs directly into the outlet to recharge, it should not be used with an inverter. As others have stated, the pure or true sine wave is the preferred, however, we have used a modified sine wave for decades, including now, with no ill affects to any of our equipment or appliances. Chuck

[SV Demeter]

Originally Posted by senormechanico

I doubt the charger's bad, it just barfs with MSW.
Sine wave inverters aren't as expensive as they used to be.
I'm happy with this one:
OSP 1500W Pure Sine Wave Power Inverter DC-AC 3000 Watts Peak (759681010234) | eBay

It's not auto start, but otherwise it's great.

You are probably right. Maybe a pure sine wave inverter is the way to go for items like this? Probably dont need a 3kw unit though. Im wondering now about my laptop? I have been running that on the MSW freedom off and on for about a year now. I guess if the battery was going to **** the bed it would have done so by now? My plan was to get a 19v DC converter to run the laptop but havent bought one yet. I have a small 150watt inverter I use for charging iPhone and other small devices as their draw was too small to kick on the main inverter. Pretty sure it is MSW too.

[AnchorageGuy]

Originally Posted by SV Demeter

You are probably right. Maybe a pure sine wave inverter is the way to go for items like this? Probably dont need a 3kw unit though. Im wondering now about my laptop? I have been running that on the MSW freedom off and on for about a year now. I guess if the battery was going to **** the bed it would have done so by now? My plan was to get a 19v DC converter to run the laptop but havent bought one yet. I have a small 150watt inverter I use for charging iPhone and other small devices as their draw was too small to kick on the main inverter. Pretty sure it is MSW too.

We ran our laptop on a MSW inverter for years and it never gave us any issues with the computer or battery. But not every laptop make will do the same. Running a laptop from an inverter is a very inefficient use of power so a DC to DC converter is the best solution for your computer. They are very cheap also. Chuck

[BeRad]

Hi All,

I know this is an old thread but it is a top hit on google so I figured I'd add one bit of insight. (I came here wondering about the ills of charging off MSW so nothing to add there.)

In terms of lithium batteries suddenly not charging - I do highly suspect the charger.

We had a Ryobi charger fail in almost exactly the same way as the OP describes. I immediately suspected the charger since the batteries all going dead at once seemed highly implausible.

I disassembled the charger and scrubbed the circuitry with a stiff toothbrush and isopropyl alcohol, and it worked again for a few weeks until we could source a replacement. Hope this helps somebody out there.

[LoudMusic]

Originally Posted by SV Demeter

Ha ha $102. The batteries cost more than that! Well the 3ah ones do anyway. This is probably the way to go then. Seems silly to run the inverter to make 120 AC only to convert it back to 18v DC to charge the drill.

I've considered buying the Dewalt version of that. It seems to make a lot of sense. But why does that little box that only changes DC voltage cost twice as much as the ones that invert from AC to DC? That's so frustrating to me knowing we're getting gouged based on low demand. In fact, it's probably not a difficult task to use the body of one of their AC DC chargers and put a DC DC voltage converter inside it effectively building your own.

https://www.lowes.com/pd/DEWALT-20-V...ger/1002979866

So annoying.