Using my lawnmower battery to charge lipos

[Foamforce]

I own a Toro 60v lawn mower and the batteries have a lot of power. 60v and 5ah. That would be about the same as a 12v 25ah battery. Better yet, they’re always charged and ready to go. Up until recently, I brought it to the field attached to the 300w Toro inverter and ran my charger off it. It works well but I just switched to a slick Hota F6 charger which is DC only. So just for fun, I bought this inexpensive DC-DC converter. The plan is to gut a Toro charger (I have extra) and install this in the housing. So then I’ll have a 12-50v DC portable power supply.

So far so good! My charger takes up to 30v, so I set the converter to 30v and tried charging a big lipo. It seems to work perfectly! Now I just need to put it in the charger case.

Thoughts?

 

[Bricks]

It will work just not very efficient lose a lot of AH to heat.

 

[Foamforce]

It will work just not very efficient lose a lot of AH to heat.

I was checking for heat while this was running and the heat sink was barely warm. Buck converters are apparently pretty efficient.

 

[Piotrsko]

Don't forget to check for charging heat in the plane lipo. They get hotter charging more than anything else. Ever wonder why most lipo fires occur during or right after charging?

 

[Foamforce]

Don't forget to check for charging heat in the plane lipo. They get hotter charging more than anything else. Ever wonder why most lipo fires occur during or right after charging?

The charger itself is a standard lipo charger, so no difference there vs plugging into the wall.

 

[Piotrsko]

Your charger works on lower voltage DC? Way cool. All my stuff has a lower limit but it is all transformered. The 12v stuff emits magic smoke on my 18 v Ryobi packs

 

[Foamforce]

Yeah, this particular lipo charger operates on 11-30v DC, no AC input. I have a couple other chargers that are either 11-18v DC or 120v AC.

My lawn mower battery is 60v, so I need to step that down to 30v for the one charger or 18v for the other. The DC buck converter can be adjusted for 5-58v DC output. I opt for the highest voltage that the charger can take, because that should reduce heat in the charger because it will be running at lower amps. Also, it will provide a higher output on the charger since the output is amp limited.

At least that’s what I <think > it will do. I know just enough to be dangerous. 🙂

 

[Bricks]

My Hyperion charger is 12-24 volt and I got a 12 volt 110 to 12 volt transformer for rack servers, I could go to 24 volts but would only gain 3-4 amps . Brain fart cannot remember what they are called.

 

[Foamforce]

I finished last night! What you’re looking at is my Toro 60v lawncare battery sitting in a repurposed Toro charger housing. I gutted the Toro battery charger and installed an XY6020L DC step down converter to take the 60v from the battery down to a voltage that my RC battery chargers can handle. Two of my chargers can use up to 18v and one can use up to 30v. The converter is configurable, so I can set it as high as each charger will allow.

The converter fit nicely inside the old Toro charger housing with plenty of ventilation. I put an XT60 port on the side and made a nice 3d printed part to adapt it to the hole where the 120v cord used to come out. The screen embeds nicely into the back. Overall it came out looking very clean.

I’ve only done a couple short tests with it so far and it seems good. The converter has an onboard temperature sensor with a fan and it gets up to about 37c and stays there. The fan barely runs. That’s a nice change from using my inverter with these batteries which has a loud fan that runs constantly. Tonight I’ll test this in the field.