Alternator & Starter Battery Charging: Frequently Asked Questions
- Are alternator chargers worth the cost and headache?
In one hour of driving, a simple 30A alternator charger in a Class A, B, C, Van, or Skoolie will generate as much energy as a single 100W solar panel will in a day, and it will do it at a lower price per amp-hour generated. If someone is going to drive an average of at least half an hour per day, we strongly recommend adding this robust charging system.
- What is a battery combiner/isolator?
This is a device that connects your house battery bank to your alternator when certain conditions are met. The purpose of this device is to provide alternator charging to your house battery. Typically, the connection is made when an ignition signal is detected, or when an elevated voltage on the starter battery is detected, indicative of the alternator being active. The downside to a battery combiner/isolator is that it is just a direct connection, with no way to regulate the voltage or current flowing to the battery. This is usually fine when using lead-acid batteries, but can present challenges when using lithium batteries.
- What is a DC/DC charger?
A DC/DC charger is like a battery combiner/isolator, in that its purpose is to provide alternator charging to a house battery bank, but unlike a combiner/isolator, it is capable of regulating the voltage and current. DC/DC chargers are more expensive than battery combiners/isolators and don’t allow for nearly as much charging current.
- What is the difference between an Isolated and a non-isolated DC/DC charger?
Isolated DC/DC chargers have a separate negative connection for the input and the output. non-isolated chargers have just one negative connection. Isolated chargers are best for Trailers and 5th Wheels, while non-isolated chargers work with Class A, B, C, Van, and Skoolie applications.
- What is bidirectional alternator charging?
Bidirectional alternator charging is when your alternator can charge your house batteries, and systems that charge your house battery can also charge your starter battery. A DC/DC charger doesn’t have this feature, but a Victron Cyrix battery combiner does.
- What is a Boost?
Similar to bidirectional charging, a boost is when you manually combine your house battery bank and starter battery bank. This is typically used when your starter battery is dead and you need to use your house battery to turn your ignition.
- Can you charge a battery with solar and alternator at the same time?
Whether it’s shore power, an alternator, a generator, solar panels, etc., it doesn’t matter. Connect them all. Run them all at the same time. No additional protections or switching of any sort are necessary.
- How do you charge a house battery with an alternator?
This can be done via a DC/DC charger or combiner/isolator. AM Solar has kits to meet a variety of applications. It is important not overload the alternator or put too much current or voltage on the battery.
- Does a solar charge controller stop a battery from overcharging?
Yes, a solar charge controller prevents a battery from overcharging by regulating the voltage and current coming from the solar panels to the battery. After charging a battery, a solar charge controller switches to a maintenance or float mode to keep the battery at full charge without overcharging. It continuously monitors the battery voltage and reduces the charging current to prevent damage and extend the battery’s life.
- How far can a solar charge controller be from the battery?
The distance between a solar charge controller and the battery can vary, but it is generally recommended to keep it as short as possible, ideally within 10 feet (3 meters) to minimize voltage drop and ensure efficient charging. Longer distances can be accommodated with thicker gauge wires to reduce resistance and maintain proper voltage levels. However, it’s crucial to follow the manufacturer’s guidelines for wire size and maximum distance to ensure optimal performance and safety.
- What is a Customer Connection Point (CCP)?
A CCP is an electrical junction point on a vehicle where the alternator or starter battery positive can be accessed. For alternator charging, A CCP connection is prudent if the customer has a valid manufacturer chassis alternator warranty, which for most applications terminates after 5 years from the vehicle’s production date. If the manufacturer has a CCP, it is designed to limit the amperage drawn from the alternator for any auxiliary load demands.
- Where would I find a CCP and what are its specifications?
Here is what we have encountered:
-An older Mercedes Sprinter CCP is located in a Midi fuse box on the side of the engine battery-positive terminal and is rated for 40ADC
-A newer Mercedes Sprinter CCP is located in a Midi fuse box under the driver’s seat and is rated for 80ADC
-A Dodge Promaster CCP is located in the passenger seat belt pillar and is pre-wired with 8AWG to a proprietary connector rated for 50ADC
-A Ford Transit CCP 1 is a 1/4″ stud located in a plastic bezel mounted on the door side of the driver’s seat base and is rated for 60ADC
-A Ford Transit CCP 2 is a 5/16″ stud located in a plastic bezel mounted on the door side of the driver’s seat base and is rated for 175ADC **Note: Typically, a Transit with a CCP 2 has dual engine batteries under the driver’s seat and also offers a CCP 1 connection in the typical location**
- What If I don’t have a CCP? Can I make one?
If an application is not equipped with a CCP, or the chassis warranty is no longer valid (and/or a consumer is not concerned with voiding the chassis warranty), a consumer can create a CCP by simply connecting a lead (with a fuse or breaker inline) to the engine battery positive post. For good practice, we like to determine the chassis alternator output rating and then design an auxiliary system that does not exceed 50-60% of this rating. For example, a chassis alternator with a 200A output rating offers a 100A-120ADC auxiliary input source limit. One can choose to exceed this limit and the chassis alternator is likely to keep up, but for how long is unknown. We like to tell customers who request such demands are equivalent to redlining a car… It can handle it, but it will wear out much sooner, and a failed chassis alternator will leave them stranded.
- How can stay within CCP specification limits?
For many reasons, we are excited about the new 50A Orion XS, but one of the best features equipped on these new units is an adjustable input/output current limit. This feature allows us to maximize a CCP limit more easily and serves to be easily adjusted if/when the warranty is void and the consumer opts to maximize their chassis alternator output limit.
*The above data, information, and/or rule-of-thumbs are our opinion formed from the organic process that comes with being an installation shop. It is not intended to replace or supplant any information that OEM may give you or stipulate in their manuals. We encourage end users to do the due diligence with their vehicle’s manufacturer, when determining what items may or may not void a warranty.
Temperature Sensor for BMV-712
Support from AMSolar is definitely 5 stars. 1st line of support for Victron equipment provided through distributors. AMSolar likely one of the best when it comes to RVs.
Tom B