Charging System

Now I can get into the charging system, which for me is the fun stuff.  It has always excited me to deal with capturing energy from nature.  Solar power and wind power generation is like magic, the stuff amazes me!  Even though the expense up front is hefty, it always feels good to operate electrical devices without plugging into the grid.

What I am attempting is to be able to charge our propulsion batteries without having to plug into a common 120v plug, I would like to maintain the system completely off the grid.  My system will have the ability to plug into a common outlet should I have the need, but I am hoping that will not be the case.

Our charging system is a little more complicated than just a solar panel, solar charge controller and batteries, we have to somehow charge a 48 volt system from a 12 volt solar panel.  We are space handicapped and cannot put 2 - 4 solar panels on the cargo lid of the WattCycle.  We only have room for one 65 watt panel, and putting up a canopy of two or four solar modules above my head just seems ludicrous outside a carnival parade. 

How then do we plan to charge our system?  I will be using two small 12v AGM batteries with a higher amp hour rating than our propulsion batteries.  The AGM batteries, or charging batteries will receive the solar charge anytime I am riding or parked in the sunlight.  The solar panel will keep the charging batteries at full charge during the day and act as a buffer for power.  By using this AGM batteries and an inverter, I will then be able to create a useful 120 AC volts any time I like.  I just happen to have a 1000 watt inverter in the shop that can easily run the 48 volt charging system that I will use to maintain my lithium propulsion batteries.  Now, I am sure that there might be an engineer out there that is shaking his/her head, knowing that there was a better way to build this mouse trap, but I have not cultivated that brain cell yet.

Sunwize 65 Solar Panel

• The glass surface is impact resistant and allows maximum light transmission
• Polycrystalline solar cells are encapsulated and bonded to the glass in multiple layers of ethylene vinyl acetate (EVA) and laminated with a white Tedlar™ backing insuring long life in severe environmental conditions
• A weather resistant junction box accommodates all wiring methods including moisturetight strain relief connectors and electrical conduit
• Bypass diodes insure reliable operation
• Anodized aluminum tubular frames add strength and durability
• Rated Power: 65 Watts
• Rated Voltage: 17.4 Volts
• Rated Current: 3.7 Amps

Ganz 10 Amp Solar Charge Controller

The charge controller will process the 17.4 volts from the solar panel and automatically charge my secondary batteries as needed.  It will work with lead acid, AGM or Gel batteries.  I will be charging an AGM for this project.  This charger is capable of charging two battery banks should I need and it will auto switch between the banks as needed.  It also has protection for overcharging, reverse polarity and short circuit.

 

Ganz Remote Charge Meter

Monitors both solar voltage & battery voltage, charging current & load current
Displays Amp-Hour, watt-hour charge accumulation and percent of batteries charged
 






48 Volt Charger - Maintains the primary batteries

Searching online for a charging system was like looking for a ripe melon, if you know what you are looking for, you can always shuffle through the mess and find what you need.  In our case, I knew we needed a smart charger that can handle a 48 volt system.  When I say "Smart Charger", I am talking about a charging system that will sense the needs of the battery and  vary both the voltage and the amperage to keep the battery in the best state.  Overcharging and undercharging are both catistrophic to a battery system.  We happened to find a Soneil charging system that met our needs for the right price.


So, to sum up the charging system;

1. The solar panel charges the secondary battery system using a charge controller
2. The secondary battery powers a 120 volt AC inverter
3. The inverter powers a 48 volt DC charger and charges the primary lithium batteries

The inverter will also keep all of my cordless power tool batteries charged should I need.  Just an added bonus.