Batteries & Related Systems
Battery Charging
Charging System
Charger Location
The battery charger is located under the rear seat.
Charging Operation
Charger outputs are connected to the furthest positive and negative terminals in the battery bank, providing the same charge to all batteries equally.
Charging is automatic. Once connected to shore power, the charger will sense battery bank voltage. If it is too low, it will begin a charge cycle after a few seconds. At the end of the cycle, it will stop charging and will not initiate another cycle until disconnected and reconnected to shore power again.
Charger output voltage is higher than the battery voltage in order to force a charge. It is important to have the key switch off whenever shore power is connected to avoid sending a higher voltage or voltage spike through your electrical systems.
Indicator Lights on Charger
It is common for chargers to have lights indicating charging status and error conditions.
Console "Charger On" Light
The Charger On indicator light on the instrument panel is powered by a
separate output from the battery charger. It indicates that a battery charging cycle has
begun. It does not indicate that it is successfully charging your batteries.
Caution: The original wiring between the charger and the light carries 120V AC high
voltage, but looks the same as low voltage wiring.
The original light is a 5/16" 125V AC neon panel light. These fail frequently. A good
replacement is an 8mm LED rated for the proper voltage.
Original Charger
Our original charger was a Zivan NG1 (user manual link).
Replacement Charger
If you are using the original Trojan T-105 batteries, here is
Trojan's advice for a charger 
In general, the charger:
- must match the battery chemistry (e.g. lead acid), type (e.g. flooded), have an output voltage designed to charge your battery bank (e.g. 36VDC), and an input voltage matching your shore power (e.g. 120VAC).
- should be a "smart" charger with three charging phases in order to maximize battery life.
-
requires an amperage rating sufficient for your battery bank and charging speed
expectations.
Per Trojan: "charge rate should be between 10% and 13% of the battery’s 20-hour AH capacity. For example, a battery with a 20-hour capacity rating of 225 AH will use a charger rated between approximately 23 and 30 amps (for multiple battery charging, use the AH rating of the entire bank). Chargers with lower ratings can be used but the charging time will be increased."A single Trojan T-105 has a 20-hour AH capacity of 225Ah. We have six batteries wired in series, so the total Ah capacity of our battery bank remains at 225Ah. If you have batteries wired in parallel, your amp hours will be higher.
Our original and replacement chargers were rated for a 20A output, which charges fast enough for us and likely has enough power for the charging cycles to properly maintain the batteries. A low amperage charger will not be able to perform each of the charging phases for proper battery maintenance.
Additional features you may want:
- A light or display on the charger that provides information about the charge mode and any errors.
- An output to power the "Charger On" light on the console.
- IP67 weather resistance.
- Ability to trickle charge if you leave your boat for long periods of time between uses. Most chargers run through one charge cycle, then stop. They sense battery voltage when initially plugged in, run through a charge cycle if required, then shut off until power to the charger is disconnected and reconnected.
When searching for replacement chargers, try searching for golf cart chargers. The Duffy Classic propulsion system is based upon standard golf cart components. As long as the charger meets the specifications above, it will work.
