New EV owner needs help

1798 Views 7 Replies 5 Participants Last post by F16bmathis, Feb 19, 2011

chaz_fwb

Discussion Starter · Feb 18, 2011

I purchased a 71 VW squareback that has been converted to electric. It has 12 lead acid batteries. The car is 144 vdc?

It looks like the builder made a battery charger (looks like a bad boy) from a donut of wire (i assume an inductor), switches, and a bridge rectifier. The charger only puts out 120 vdc. Plus the 240v input side is now blowing fuses.
I was thinking of buying 4 three bank marine chargers and charge individual batteries. What do you think?

Also, three or four of the batteries need to be replaced. Some are walmart Maxx 29, some are marine "Mega Tron", some are unknown? I do not think its to ggod to mix batteries but I do not want to buy 12 batteries at $100 each. Any suggestions?

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F16bmathis

· #2 · Feb 18, 2011

chaz_fwb said:
I purchased a 71 VW squareback that has been converted to electric. It has 12 lead acid batteries. The car is 144 vdc?

It looks like the builder made a battery charger (looks like a bad boy) from a donut of wire (i assume an inductor), switches, and a bridge rectifier. The charger only puts out 120 vdc. Plus the 240v input side is now blowing fuses.
I was thinking of buying 4 three bank marine chargers and charge individual batteries. What do you think?

Also, three or four of the batteries need to be replaced. Some are walmart Maxx 29, some are marine "Mega Tron", some are unknown? I do not think its to ggod to mix batteries but I do not want to buy 12 batteries at $100 each. Any suggestions?

You've got 144V if they are 12V batteries.

If the charger only puts out 120V and your pack is 144V you've got problems. Sounds like you need to figure out the charger. As far as getting the marine chargers, depends on how fast you want to charge. And buying new batteries, I'd buy what I want for batteries. You may even find some re-furbished like I did at SMS battery. Brand new, nothing wrong, but half price.

Although, having had the cash, if I were to do it all over again, I'd have gone lithium from the start. Expensive, getting cheaper every day, but way better than FLA.

Also check into the 12V BMS, thought it was here somewhere. Simple two diodes and a light bulb. Worked great on my 144V pack.

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Nathan219

· #3 · Feb 18, 2011

How long do you plan on keeping your electric car? If you keep your car for more than 3-5 years buy some Litium Batteries and a good charger.
Good Luck

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EVfun

· #4 · Feb 19, 2011

I know this isn't pleasant, but you need 12 new matched batteries and a good charger than can charge 144 volts.

You can make a bad-boy if you are comfortable working with line voltage electricity. The short of it is the transformer from a cheap dumb 12 volt charger reused as a boost transformer. If you are not comfortable with tasks like changing outlets and light switches, or installing an electric water heater in your home, you really shouldn't attempt to build your own charger.

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DJBecker

· #5 · Feb 19, 2011

Note that twelve 12V lead-acid batteries is really a 168V pack that quickly sags to a bit under 150V under load.

The final charge voltage will be in excess of 170V.

These are important numbers to keep in mind when doing calculations. "144V" is almost never the number you want to use.

Mismatched batteries are a challenge because you can't use total pack voltage as a capability indication. You have to change which batteries you are monitoring to limit current and depth of discharge. A battery with low capacity and low internal resistance will initially "overload" a high resistance battery and make it appear that a high current draw is OK. Later that low capacity battery will be the weak point and could easily be destroyed by deep discharge.

On the plus side, lead-acid batteries allow a modest overcharge without damage, allowing all to come up to a full charge. Using mis-matched cells with other chemistries would quickly lead to a badly unbalanced pack. (A balancing BMS helps, but doesn't solve the problem.)

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chaz_fwb

Discussion Starter · #6 · Feb 19, 2011

I was thinking of purchasing a ELCON 1500 watt, 144 volt charger. It seems reasonabily priced. I do not think the ELCON has reprograming otions though.

I was going to replace my bad batteries with similiar walmart or Sams batteries.

My first objective is to get the car on the road. I do not want to get into lithium right now.

My other option is to buy four 3 bank 5 marine charges sold at Sams (these are about $115 each). They are 15 amp chargers, but rotate the three batteries during charge.

The person who built this car did a great job, I just do not understand why they were using a 120v bad boy charger.

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F16bmathis

· #7 · Feb 19, 2011

Seriously look into Trojan batteries. They are probably half the price you'd pay at Walmart. I had 24 Trojan T-105's (6V) before I went lithium. Seemed like a good size for the 40 miles I wanted. I installed Trjan (???) (12V) into the Probe.

You may want to look around for a good charger. The vehicle will only be as good as its parts. I had a buddy buy $25 chargers from E-bay for each of his batteries, then set them up on timed power strips to alternately charge. Seemed to work, but for a few more $$$ he could have had a Zivan or Manzanita. Someone is always selling something. I tore the Probe apart and sold the Zivan for $1000, to a buddy building a Ranger.

I chose the manzanita for the S10 cause you can charge from 6 to 400? volts, so if I ever upgrade, I don't have to buy another charger.

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F16bmathis

· #8 · Feb 19, 2011

Also, try craiglist. Had another buddy got a load of 12V for free!

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