May 9, 2008; The 150 mile Jeep Hybrid Marathon! - Fuelly Forums
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Old 05-06-2008, 10:01 AM   #1
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May 9, 2008; The 150 mile Jeep Hybrid Marathon!

Friday, the Hybrid Jeep will be leaving Lake Charles, LA and driving over 150 miles to Kemah, TX. The alternator will be disconnected and a total of three batteries will be onboard powering the 12VDC system, including the 16" Electric engine fan.
I originally intended to start posting my work on electric vehicles when I purchased the project truck, a Dodge Dakota.

However events in the past few weeks have made me realize how much can be gained by converting vehicles that were never intended to be full time EV's. My first run in the Jeep without the alternator and an electric engine fan yielded 19.5MPG a jump from the previous best of 16.5MPG. Even more surprising is how easy it is to do, just disconnect your alternator cables and recharge when you get home. Of course, one little problem creeps up: range!

My recent work on range focuses on a prototype battery charger built by Dan Gathright. Dan upgraded an off the shelf switching power supply to send out a maximum of 14.1VDC, the maximum desired charge voltage for Gel-Cel batteries. The main battery on the Jeep is a brand new Group 24 Gel Cel.

The problem was the battery charger has no voltage indicator, temperature guage or an amperage guage. Without these key features, I could never tell what was really going on inside. When I get to Kemah, I will have to recharge the batteries at a business that is 200ft away so the battery charger will have to do it's job perfectly and unattended. Switching battery chargers can produce a tremendous amount of power for their small size (2lbs max weight). The problem is that when pushing over 25 amps continously the circuitry can overheat or short out causing a dangerous situation. The prototype has only shown a tendency to heat up to 110F when left in the Jeep on a sunny day, not bad but definitely a cause for concern. Additionally, 25 amp or greater output only occurs for a minute at best because the battery chemistry itself cannot accept the rate of charge for long. What will happen with three batteries in parallel is anyone guess!
I ordered a 25 AMP Ammeter Ammeter and a Lascar Self Powering Voltmeter from Suni (Sonya Haney) @ Allied Electronics last week for this purpose.

The temperature probe came from
5VDC F Temp Probe

I spent most of the weekend wiring up the components and using my trusty Dremel tool to cut mounting holes for the new guages. I soldered all the connections but finding a resistor to provide 5VDC for the temperature guage took the longest time.

In this picture you can see me cutting the Lascar Voltmeter hole. In the background the Jeep is eagerly waiting a charge.

My trusty sidekick JR observing the progress and wondering when why I am not throwing his toys.

The completed install. Examine the circuitry for the battery charger closely, there really are not that many components to these devices. The challenge is tuning the transformer to achieve the highest efficiency. So far we can get an average of 85% out of this power supply. Notice the probe for the temperature guage is on top of the heatsink for the powersupply.

Here is the battery charger plugged into the battery only. I found it has two modes: quick mode will charge at 15 amps but if left unattended overcharge the battery, slow mode will peak at 15 amps settling down to 1 amp and never break 14.1 volts.

In this image you can see the charger heating up it's heat sink as a 15 amp continous draw is being pulled from it.

Work continues, I hope to post a picture of the two batteries and battery charger mounted in the rear of the Jeep later this week.

On a side note, I am looking for a 1997-1999 Dodge Dakota I-4 with a 5 speed manual gear box. If you know of anyone who is selling their old Dakota with these specifications, please PM or email me: rgathright @ gmail .com
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