Fuel Economy, Hypermiling, EcoModding News and Forum - EcoModder.com - View Single Post - DIY "Mild" Plug-in Prius Project: Grid-powering the 12v side w/ deep cycle batteries

orange4boy · 03-27-2010, 11:16 PM

Who needs a DC-DC up converter when you can hack a half destroyed battery to add a cell to a 12V to get 14?

Disclaimer: What I have done here is dangerous. Try this and you will die a horrible and painful death. Or at least you will be blinded, scarred and lead poisoned. You have been warned.

OK now I shall proceed with my story.

This winter I had a bit of an accident with the Elec-Trac in which one of my deep cycle batteries was damaged beyond repair. Or so I thought at the time. At some point I had remembered Darin mentioning a hillbilly battery mod in which a screw is drilled into a battery to tap one or more cells for an unusual application. Distilling hooch perhaps? I can't remember. Anyhoodle, I thought that since the battery still had three good cells why not save them and tap them off for the 14V. Much cheaper and more efficient than a DC-DC converter with enough juice since I had a worthless battery anyhow.

I drained the battery acid from the toast battery into a bucket while wearing a full hazmat suit. I then pried off the cover using a screwdriver and a flat scraper/chisel. I got it half off but then just busted it in half removing the vent side. I then could get at the bars inside to drill and tap them with a 1/4-20 tap. I cut one of the bars so I could split them into 3 separate cells. When I had carefully tapped the bus bars and removed all the lead filings, I hot glue-gunned the top back on. I poured the acid back in, hooked up the leads and, presto! Three 2V cells.

I have a nifty "Silver Beauty" battery charger which is blue. It has settings for 6, 12, 18, 24, 30 and 36V so I charged it up on the 6V setting.

That was last week. Today I finally had a chance to try it out. I loaded a good 12V battery and the hillbilly hack batt into the trunk and connected them together. 14.9V all up. Turned on the Prius and it dropped to 13.9V which is pretty much what it runs on from the DC-DC.

I tried the Silver Beauty and at the highest 12V setting it charges the "14V" battery nicely.

Disconnected the converter and bypassed the 12V battery so as not to boil it and did my regular commute on which I usually get 4.3-4.4 L/100Km. I was never able to beat 4.3.(54.7 MPG) First run I got 3.9 L/100! (60.3 MPG) I managed to end up at the same HV SOC so I wasn't "cheating"

We will see how it averages out but I'm thrilled with the result. It may turn out to be less of a gain because I have a hunch they just switched to summer gas here.

03-27-2010, 11:16 PM	#51 (permalink)
orange4boy Master EcoModder Join Date: Aug 2008 Location: The Wet Coast, Kanuckistan. Posts: 1,275 The Golden Egg - '93 Toyota Previa DX 90 day: 31.91 mpg (US) Chewie - '03 Toyota Prius 90 day: 57 mpg (US) The Spaceship - '00 Honda Insight Thanks: 100 Thanked 306 Times in 178 Posts	Ghetto 14V battery Who needs a DC-DC up converter when you can hack a half destroyed battery to add a cell to a 12V to get 14? Disclaimer: What I have done here is dangerous. Try this and you will die a horrible and painful death. Or at least you will be blinded, scarred and lead poisoned. You have been warned. OK now I shall proceed with my story. This winter I had a bit of an accident with the Elec-Trac in which one of my deep cycle batteries was damaged beyond repair. Or so I thought at the time. At some point I had remembered Darin mentioning a hillbilly battery mod in which a screw is drilled into a battery to tap one or more cells for an unusual application. Distilling hooch perhaps? I can't remember. Anyhoodle, I thought that since the battery still had three good cells why not save them and tap them off for the 14V. Much cheaper and more efficient than a DC-DC converter with enough juice since I had a worthless battery anyhow. I drained the battery acid from the toast battery into a bucket while wearing a full hazmat suit. I then pried off the cover using a screwdriver and a flat scraper/chisel. I got it half off but then just busted it in half removing the vent side. I then could get at the bars inside to drill and tap them with a 1/4-20 tap. I cut one of the bars so I could split them into 3 separate cells. When I had carefully tapped the bus bars and removed all the lead filings, I hot glue-gunned the top back on. I poured the acid back in, hooked up the leads and, presto! Three 2V cells. I have a nifty "Silver Beauty" battery charger which is blue. It has settings for 6, 12, 18, 24, 30 and 36V so I charged it up on the 6V setting. That was last week. Today I finally had a chance to try it out. I loaded a good 12V battery and the hillbilly hack batt into the trunk and connected them together. 14.9V all up. Turned on the Prius and it dropped to 13.9V which is pretty much what it runs on from the DC-DC. I tried the Silver Beauty and at the highest 12V setting it charges the "14V" battery nicely. Disconnected the converter and bypassed the 12V battery so as not to boil it and did my regular commute on which I usually get 4.3-4.4 L/100Km. I was never able to beat 4.3.(54.7 MPG) First run I got 3.9 L/100! (60.3 MPG) I managed to end up at the same HV SOC so I wasn't "cheating" We will see how it averages out but I'm thrilled with the result. It may turn out to be less of a gain because I have a hunch they just switched to summer gas here. __________________ Vortex generators are old tech. My new and improved vortex alternators are unstoppable. "It’s easy to explain how rockets work but explaining the aerodynamics of a wing takes a rocket scientist.