The converting, maintenance, and operation of a Suzuki Samurai conversion to Electric power.

Friday, September 10, 2010


I had to send a 24V module out for replacement by the vendor. This means I have a 132V pack and a charger that has 144 and 156V settings. How to charge? I decided to try a "bad boy" charger. A bridge rectifier is connected to the 120V AC with the battery pack connected to the + and - of the rectifier. This bridge rectifier is about an inch square and consists of 4 diodes connected such that the AC is converted to DC. It works out to about 160V of pulsating DC. It can be used to charge batteries from 96V up to about 144V. 144V won't fully charge.

This is certainly not a recommended safe practice.

Bolt the rectifier to a chunk of sheet aluminum to act as a heat sink. Make the connections to the battery pack. Hook together all the extension cords you can find and plug in the rectifier. See what the charge rate is in amps. If it is over 10 amps, borrow some more extension cords. (The extension cords lower the voltage.)

Mine turned out to be 2 amps. I kept removing cords. One short cord worked fine. 10 amps when the batteries were low tapering down to 5 when the batteries approached full.

I recommend that you have a timer that will shut off the power when you expect the battery pack will be fully charged. If you don't have a timer, set an alarm clock to remind you to turn it off. I use the alarm on my cell phone to remind me to check on them every couple hours. Remember, the max voltage you should charge to depends on temperature.

A ways back I explained how to use a transformer in buck or boost mode to give better output voltage control.

Please be careful. I am not recommending anyone do this. Electricity is dangerous. Touching bare wires and connections can cause shocks which can be fatal. Don't set your lawyers on me! You've been warned.


Anonymous said...

You should also add that leaving a charging method like this unattended is just asking for a fire, cell phone alarm or not. You should have personal experience with that now. :)
Do you even know why an extension cord causes a voltage drop? I'm thinking you do not.

storm said...

Not sure why someone would post as "anonymous". Why would you make assumptions about what I know? What "cell phone alarm" do you refer to? The "bad boy" is not recommended practice. I obtained a Manzanita Micro charger after this bit on the "bad Boy" was published. The voltage drop in the extension causes an amperage drop in this battery charging application. Less amps means less heating of the cord. (But don't keep the cord tightly coiled because the voltage drop results from heating.)