"Insert clever comment here"
Sorry. No one's said anything memorable, or witty of late.
It's often said amongst us EV'ers that one of the biggest barriers to production electric vehicles is idiot-proofing these cars. Even though it's quite easy to kill yourself or others with a gasoline powered car, electric vehicles hold a special fear in the American public's eyes. Aside from hazard-proofing them, the cars need to be self-destruction proofed so that the owners don't slag their motors, controllers and battery packs.
I haven't done any of this to my car but I've been wanting to. I've learned that my charger has a built-in relay that I can use to power a dummy light to keep me from driving off with the cord plugged in. I also want to dial down my motor controller to keep me from accidentally hammering my batteries with too heavy an amperage load. It'll be beneficial for the motor too.
I also abhor the way the builder wired in the DC-DC converter and the controller pre-charge circuit. I'm going to buy a terminal board and properly screw all this stuff down......IF the warm weather ever finally gets here.
I've replaced 10 of 16 of my damaged batteries so far. I only drive very gently on low speed roads. Once they're all replaced, I'll be back on the major highways.
Monday, April 07, 2008
Joke's On Me
"What's this solid crap?" -My comment after seeing metal chunks in my battery hydrometer.
That comment marked the very rapid failure of my battery pack. I managed to get 7,000 miles from them before I killed 'em. That's not very good for those of you who are wondering. Here's the how and the why:
1. In the early months of last year, I had no instruments and I was operating on the false premise that these golf cart batteries were good for loads up to 300-400 amps. Wrong-O. 8 volt golf cart batteries are good for steady currents of 120 amps and bursts of 180.
2. The winter here was very cold and dry. I ended up on a drive where I underestimated my range and really drew the pack voltage down past the minimum point. The result was dead battery cells scattered through out the battery pack. How could I tell? All the battery voltages were really weird so I used a battery hydrometer to check the electrolyte levels in the individual cells. A battery hydrometer has a weighted needle in it and a graph on the side. Where ever the needle floats to indicates how much charge that cell has. Lots of cells read "zero". I also sucked up a lot of metal bits. The metal is...was active material that was shed from the battery plates while I was pulling 350 amps from the batteries. Yummy...... so "don't do that".
An 8 volt battery has 4 cells. 2 X 4 = 8 volts. A single dead cell makes the battery 6 volts. Or, 8 volts with a lot less capacity if you prefer. I had dead cells in nearly every battery. My range shrank to 15 miles on the best of days.
I knew my ignorance of proper care would catch up to me. I was expecting to only get 10,000 miles from the batteries...but I didn't quite make it.
There is a correlation between how deep you discharge lead-acid batteries versus how many charge/discharge cycles you get from them. If you only discharge them 5%, then you get 1,000's of cycles from them. That can be years of life. If you drag them down to 80% discharged every time, you'll get about 800 cycles. If you hammer them down past the 80% safety threshold, then you lose even more cycles...600, 400, 200....until you might kill them in just a couple of months. Also, if you discharge lead batteries at rates they weren't designed for (which was my primary mistake), you'll have the same effect.
Ok, so I learned the expensive lesson. My cost/benefit analysis says that in the 13 months I drove the car, and the average cost of gasoline versus the cost of the batteries, I broke exactly even. Well...not exactly. I didn't recoup the cost of electricity which was probably only a couple hundred dollars. Half of my charging was done at the local mass transit parking garage for free.
So...I'm still not financially or technically ready to upgrade to Lithium Iron Phosphate batteries so I've settled on flooded golf cart batteries again. This time I've really cheaped out and bought Energizer 8 volt batteries from Sam's Club. How's this for global economy: The batteries are made by a Mexican company for Johnson Controls which then sells them to Energizer who slaps their label on them and sells them exclusively at Sam's Club. About the thing that makes me feel good about these batteries is the one year warranty. I've been in touch with technical support at Johnson Controls and they "assure" me that these batteries are durable and dependable.
I'm hoping that my increased knowledge will help me keep these batteries alive for 10,000 miles or better. Forewarned is forearmed they say...
Why did I buy a cheaper, maybe questionable replacement battery? Because the price of "commodities" has shot up in the last several months. The batteries I had were $83.00 each. Now they're $100.00 each. Trojan, the Cadillac of golf cart batteries are $140-180 EACH. The Energizer batteries were $74.00 each.
I'm hoping that the higher and faster that gas prices climb, the quicker I'll recoup the cost of my less expensive battery pack (and the cost of the car). Fuel prices are $1.00 per gallon higher than they were over the last year of driving with my old pack. It's all about cost/benefit analysis.
That comment marked the very rapid failure of my battery pack. I managed to get 7,000 miles from them before I killed 'em. That's not very good for those of you who are wondering. Here's the how and the why:
1. In the early months of last year, I had no instruments and I was operating on the false premise that these golf cart batteries were good for loads up to 300-400 amps. Wrong-O. 8 volt golf cart batteries are good for steady currents of 120 amps and bursts of 180.
2. The winter here was very cold and dry. I ended up on a drive where I underestimated my range and really drew the pack voltage down past the minimum point. The result was dead battery cells scattered through out the battery pack. How could I tell? All the battery voltages were really weird so I used a battery hydrometer to check the electrolyte levels in the individual cells. A battery hydrometer has a weighted needle in it and a graph on the side. Where ever the needle floats to indicates how much charge that cell has. Lots of cells read "zero". I also sucked up a lot of metal bits. The metal is...was active material that was shed from the battery plates while I was pulling 350 amps from the batteries. Yummy...... so "don't do that".
An 8 volt battery has 4 cells. 2 X 4 = 8 volts. A single dead cell makes the battery 6 volts. Or, 8 volts with a lot less capacity if you prefer. I had dead cells in nearly every battery. My range shrank to 15 miles on the best of days.
I knew my ignorance of proper care would catch up to me. I was expecting to only get 10,000 miles from the batteries...but I didn't quite make it.
There is a correlation between how deep you discharge lead-acid batteries versus how many charge/discharge cycles you get from them. If you only discharge them 5%, then you get 1,000's of cycles from them. That can be years of life. If you drag them down to 80% discharged every time, you'll get about 800 cycles. If you hammer them down past the 80% safety threshold, then you lose even more cycles...600, 400, 200....until you might kill them in just a couple of months. Also, if you discharge lead batteries at rates they weren't designed for (which was my primary mistake), you'll have the same effect.
Ok, so I learned the expensive lesson. My cost/benefit analysis says that in the 13 months I drove the car, and the average cost of gasoline versus the cost of the batteries, I broke exactly even. Well...not exactly. I didn't recoup the cost of electricity which was probably only a couple hundred dollars. Half of my charging was done at the local mass transit parking garage for free.
So...I'm still not financially or technically ready to upgrade to Lithium Iron Phosphate batteries so I've settled on flooded golf cart batteries again. This time I've really cheaped out and bought Energizer 8 volt batteries from Sam's Club. How's this for global economy: The batteries are made by a Mexican company for Johnson Controls which then sells them to Energizer who slaps their label on them and sells them exclusively at Sam's Club. About the thing that makes me feel good about these batteries is the one year warranty. I've been in touch with technical support at Johnson Controls and they "assure" me that these batteries are durable and dependable.
I'm hoping that my increased knowledge will help me keep these batteries alive for 10,000 miles or better. Forewarned is forearmed they say...
Why did I buy a cheaper, maybe questionable replacement battery? Because the price of "commodities" has shot up in the last several months. The batteries I had were $83.00 each. Now they're $100.00 each. Trojan, the Cadillac of golf cart batteries are $140-180 EACH. The Energizer batteries were $74.00 each.
I'm hoping that the higher and faster that gas prices climb, the quicker I'll recoup the cost of my less expensive battery pack (and the cost of the car). Fuel prices are $1.00 per gallon higher than they were over the last year of driving with my old pack. It's all about cost/benefit analysis.
Subscribe to:
Posts (Atom)
Posts
