7 tips for installation of a charge controller

Most mobile homes’ basic equipment leaves much room for improvement in terms of self-sufficiency in your own power grid. Therefore, more solar panel battery capacity, a solar system, possibly an inverter, and perhaps a charging booster from Renogy will soon be an issue. After the daily drive, the starter battery is fully charged – but what about the onboard battery? This is where effective charging with a booster comes into play. Our article “Renogy charge booster – 7 tips for installing a charge controller” highlights relevant considerations for purchase and installation.

It should be mentioned as a preliminary remark that we have not received any discounts or other benefits from the manufacturers or companies mentioned. Ultimately, we installed a Renogy charging booster and can correctly only give our tips for this product. Generally, we always comment free of commercial interests and represent our personal opinion.

1. General considerations

Motorhomes suggest relaxed travel from pitch to pitch without worrying about electricity and water. Very soon, every WoMo owner notices that improvements are necessary for terms of self-sufficiency with energy and their own need for freedom. The price competition among the manufacturers does not allow for a reasonable expansion of the basic equipment to be on the road autonomously for as long as possible. The 100 Ah AGM RV battery, often installed as standard, is usually not enough for more than one night without shore power with a refrigerator, heating, and some light.

If you want more electricity self-sufficiency, you have to deal with your needs for free-standing, the technical framework of your vehicle, and the expansion options. An inventory of your electricity storage, electricity consumers, and electricity generation in the mobile home is necessary.

We recommend creating a hand sketch of these three influencing factors. You will also have to deal with your own camper’s mostly built-in electric block (EBL). Find out, for example, what capacity your onboard system charges the onboard batteries or what power consumption your refrigerator or heating represents per day. Don’t forget how the state of charge/consumption is currently displayed and whether that’s enough.

Here is a sketch as an example of our Adria Twin Supreme 640 SGX:

On a normal winter day/night with a refrigerator, running heating, hot water use, light, and charging of mobile phones, we have to reckon with a lithium-ion RV battery drain of around 40-50 Ah. The refrigerator draws the most electricity. Our Adria 640 SGX offers only a simple display panel for the charging status of the starter and onboard battery (in volts). Since AGM batteries should not be regularly drained below 50% for longevity, the “factory” AGM onboard battery lasts just over 1 – 1 1/2 days. This is what reality looks like off the shelf!

2. Needs considerations

The needs considerations seem almost the most important to us. From our experience, this should only arise after purchasing a mobile home. When you live in your mobile home, you precisely recognize your own (free-standing) behavior and energy needs. In addition, it is usually much cheaper to have the identified needs installed later … the manufacturers charge a lot for these extras, ex-works.

You don’t have to worry about a charging booster if you always drive your WoMo to the campsite with a shore power connection. A second 100 Ah AGM onboard battery can already cover all needs … and the charging capacity of the EBL is usually sufficient for full batteries.

The needs considerations are not primarily about free-standing behavior. Aspects such as route behavior, winter camping, pure sine wave inverter, e-bikes, or air conditioning must also be included. It is recommended that a power requirement capacity and a desired onboard battery capacity are also noted for each partial aspect. A charging capacity can then be calculated, which meets the considerations of the needs.

So if you are aiming for reliable self-sufficiency with electricity or want to live a distinctly off-the-grid life, you will have to upgrade. You need to know what off the grid meaning is. First and foremost, solar systems or lithium batteries come to mind. But that would only be half the battle. What if little solar power is produced in winter? Or how to charge the e-bike batteries without discharging the onboard battery via an inverter while riding? In such considerations, a charge controller quickly emerges as the optimal part of an overall solution.

3. When is a booster, and what design?

Technically speaking, a booster in the vehicle’s alternator pretends to be a consumer. This means that such charge controllers come into question as the optimum charge capacity while driving. However, alternators in modern vehicles are designed to be economical and sometimes switch off when a full starter battery is detected. But even if a built-in electronic block (EBL) in the WoMo can wrest some charging current from the alternator, then it is all too often not the charging values that bring enough yield for an expansion. For example, our EBL in the Adria delivers a maximum of 18 A. We would have to drive 12 hours for our almost empty 222 Ah 12v lithium-ion battery to be recharged.

A booster is justified if as much charging capacity as possible is achieved for the onboard battery over short driving distances. Or you have a large lithium battery, which would depend on a booster’s additional and high charging capacity, especially in winter. But a situation with an inverter, with which the e-bikes are charged via the 230 V mains supply while driving, is also a very useful booster. This is because the inverter’s current drawn from the onboard battery is immediately recharged.

The design of a charging booster depends on the one hand on the desired charging capacity. On the other hand (and very importantly), the design must be selected to ensure safe operation in the given power grid, the electronic block, and the onboard battery in the mobile home. Other aspects of choosing a booster can be battery type, size, cost, features, etc. Combined charging boosters (charging while driving & on 230 V shore power & solar controller & pulse function) are also available on the market. You will find many providers, such as Renogy, Victron, Büttner, Schaudt, Dometic, etc., in the market. Ultimately, the choice depends on the given framework conditions and the desired range of functions.

Our situation was such that we could head towards a pure charging booster from Renogy since our Victron MultiPlus inverter already covers such additional functions as charging “on the 230 V shore power” or “permanently on the shore power.” So it was important for us to efficiently close the possible charging gap of the solar system for our 200 Ah LiFePO4 Liontron battery.

4. Which model?

We decided to buy a Renogy product because of the very good price/performance ratio, the given functionality, and the manufacturer’s high “Made in US” quality. In discussions with installation experts, these charging boosters were recommended to us repeatedly. The installation is also well documented, with good instructions for different variants. Matching changeover relays with an EBL or by-pass relay for operation with a heavy consumer can also be purchased. The models VCC 1212-30 (compact design) and the series from VCC 1212-50 were up for discussion.

With the pure B2B charging boosters from Renogy, both housing variants offer all the desired functions at first glance. This way, all common onboard batteries can be charged with the (almost) optimal charging curve. There is also problem-free parallel operation with other charging sources (EBL, solar controller, etc.), the connection of a temperature sensor, or a recharging branch for charging/charge retention for the 12 V START battery. There is also a port for a separate display module. Both device types also have a separate fans so that there is no overheating, even in cramped installation locations.

Anyone who needs a very compact charge controller for smaller charging capacities (30A output) is well served with the Renogy charge booster 1212-30. The price is also very attractive at around $ 165.00 (approx. CHF 190.00). Nevertheless, we advocate the VCC 1212-50 for the following reasons. Not only because charging capacities of 50A and more are possible. The series from VCC 1212-50 can respond to significantly more charging characteristics via dip switches. Especially with the LiFePo4 batteries, 4 preconfigured charging characteristics are already available. In addition, these charging boosters from Renogy also allow more settings for the input (e.g., “in the limit” with the 1212-50: 33A, 42A, 49A, and 68A). The solid metal housing, the larger connection sockets, more status lights, the connection to a BUS, and of course, the higher charging power speak for the choice of this device. This also gives you the flexibility for later expansion. Of course, this type costs more at around $ 295.00 (CH prices around CHF 360.00), but the better functionality justifies this. We chose the charging booster from Renogy, type VCC 1212-50 because this model is ideal for the recommended max. 75A charging current of our Liontron lithium battery (= booster with 50A + charging current of the solar system).

5. Considerations for installing a charging booster

The installation of a charging booster from Renogy is not extremely difficult. Nevertheless, some aspects need to be considered for safe operation. The installation location should leave enough space for air exchange. In addition, the cable lengths caused by the location of the onboard battery/starter battery should be included in the placement. The longer the distance, the larger the cable cross-section to be installed. The tables in the instructions provide perfect information on the necessary cross-sections. When integrating with the EBL, note the maximum current load possible with the given wiring (possibly working with a changeover relay). Overall, we recommend having the installation carried out by an experienced workshop/specialist (approx. 2 working hours should be taken into account).

We installed the Renogy charging booster directly behind the ventilation grille under the passenger seat. The onboard battery is also mounted under the passenger seat and, therefore, very short cable routes with us. With regard to EBL, there was no integration with us. Charging the onboard battery while driving is entirely delegated to the inverter charger (plus, of course, with the support of the solar system). Functions such as “charging the onboard battery with 230V shore power” or “managing the 230V circuit” are routed directly through our Victron MultiPlus inverter. We have laid a recharging branch from the charging booster to the starter battery. For specific considerations regarding the temperature sensor, see Tip 7 below.

Christopher Stern

Christopher Stern is a Washington-based reporter. Chris spent many years covering tech policy as a business reporter for renowned publications. He has extensive experience covering Congress, the Federal Communications Commission, and the Federal Trade Commissions. He is a graduate of Middlebury College. Email:[email protected]

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