WATCH PART 2 HERE - • Which Dual Battery Sys...
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Hi Guys, Briohny here from Accelerate Auto Electrics and Air Conditioning. If you are heading off road in your 4wd and going camping one of the must haves to keep your food and drinks cold and your gadgets powered is a dual battery system. Unfortunately, you can’t just come on in and purchase a 2nd battery and plug your fridge and devices into it, as you run the risk of running it flat and worse still running your starting battery flat so your car won’t start.
When looking at buying a dual battery system, we recommend that you do some serious research and planning before you install it, you need to ensure that you have enough power to keep your fridge cold and still start the car.
One of the most common questions we get asked when chatting to customers about dual battery systems is what is the difference between a Smart Isolator, DC-DC Charger and Battery Management System. We have put together this series of three videos explaining what each option is and the pros and cons to each of them.
Let's jump on in and take a look at the easiest and simplest option the Battery Isolator also referred to as a Smart Battery Isolator
The most common type of isolator is a Voltage Sensitive Solenoid
like this one here from Redarc the SBI12
On the front of this Redarc isolator, you can see these two connections. When we install the isolator we connect your starting battery to this connection and your auxiliary battery to the other.
The Isolator monitors the voltage of the starting battery, when the isolator sees your car is turned on and the alternator is charging (via an increase in voltage), the isolator connects the two batteries together, thus allowing your auxiliary battery to charge off the alternator.
When you turn the car off, the isolator continues to monitor the voltage of the batteries and when they reach a certain level, it will separate the two batteries from each other, this is how it gets its name as it is isolating the starting battery, which means you can power accessories like your fridge from your auxiliary battery and they will not draw power from the starting battery. This ensures your starting battery will always have enough life to start the car.
If you accidentally leave the lights on in the car or radio on overnight and manage to drain your starting battery you can bridge the connection between the two batteries and use the power of both the starting and auxiliary batteries to start the vehicle, this SBI12 from Redarc comes standard with this blue wire here which allows us to install a switch on your dash to jumpstart the car off the auxiliary battery if you need to. If you don’t want to use the jump start feature we would generally use a fuse between the isolator and starting battery to protect the system.
The battery isolator can be mounted anywhere in the vehicle, preferably but not necessarily in a dry area. We usually mount them under the bonnet near the starting battery.
In newer vehicles, that have a computer controlled alternator using a Battery Isolator will not work effectively as the car has a charging algorithm that is more concerned about fuel consumption and emissions so will regularly drop the charging voltage below the cut-off voltage of the isolator, basically the isolator will think the car is turned off when it’s not and will separate the two batteries and the auxiliary battery won’t charge. If you have a car with a computer controlled alternator you will need to look at installing a DC to DC Charger or more commonly known by Redarc as a BCDC.
If powering a fridge and a couple of small accessories, you will generally get about 2 days of power out of an auxiliary battery. One downside to the battery isolator is that it will only charge your auxiliary battery when the vehicle is turned on and will need to run for approximately a full day to charge the battery.
Another downside is your car alternator is designed to charge a starting battery, which is generally a lead acid or calcium battery, most auxiliary batteries are AGM batteries that require multistage charging. The alternator will charge the auxiliary AGM battery but only to roughly 80%. What that means, If you have a 100 amp hour battery the alternator and battery isolator option will only charge the battery to roughly 80% giving you 80 amp hours, not the full 100 amp hours that you purchased.
That’s a bit of a run down on smart battery isolators using the Redarc SBI12 as an example, there are plenty of other brands out there on the market and we do stock a full range in our showroom and online.
If you are looking at installing a dual battery system, check out the next two video’s in this series explaining the DC to DC Charger and a Battery Management System.
4 июл 2017
