Blue Sea Systems 7650 Add-A-Battery Kit - Dual Circuit Battery Management System, 120 Amps

After much reading and actually calling and talking to Blue Sea's tech support I'm very impressed with this product and their support. I know others have worried about the small voltage drain from the ACR unit. The ACR unit uses a small amount of current and over a VERY long time and it can drain the batteries it’s monitoring. I talked to the Blue Sea's Tech about this, and they had estimated about 4 months of just sitting there monitoring the battery voltage before the voltage drop would start to cause problems starting the engine. (This would depend of course on the condition of the battery and size/rating of it). However, when talking to the tech about this, there are a few things you can do to completely turn off the ACR. First if you hook it up like they show in the product picture you will need to hook up a small toggle switch to one of the three spade connectors on the unit to turn it off. Or if you are like me and want to KNOW everything is turned off when you put your boat away, you can wire as I have diagramed in the picture attached. By putting the ACR on the "downstream" side of the switch, you can turn everything off when you turn off the main switch. This will still allow the ACR to monitor the batteries when you have the boat in use and will function normally. The only thing would be if you put a charger on one of the batteries when in storage, you would want to leave the master switch to the “on” position so the ACR could function and allow current from one battery to the other. Otherwise, if you had the master switch in the off position you would only be charging the one battery that the charger is hooked up to. The batteries would be isolated from each other and from the ACR. Also, when I was speaking to the tech I mentioned I was I was worried about the 120 amp rating of the unit when the ACR engages. If there is a big voltage differential between the two batteries, there would be a surge of current across the ACR when it connects the two batteries. This 120 Amp is a continuous rating and the ACR will not engage the circuit if there is too big of voltage difference. This would be a case where one battery is bad, has a bad cell or has an extremely high load on it and cannot maintain a high enough voltage. The ACR will disengage and will try to isolate the batteries in that case. In continuous operation the ACR would really only see the total amount of output that the alternator could generate. In my case this is about 100 amps so the 120 amp ACR unit is sufficient. For the product itself, it is very solidly made, and has been working flawless. I had a Pergo basic 1, 2, 1+2, Off switch in my boat, and got tired of trying to remember to flip the switch to 1 when anchored out, then back to 1+2 when cruising around. With this no need for any of that. Just turn the main switch on when I’m getting all the stuff loaded in, and off when we put it in storage. SIMPLE SIMPLE SIMPLE.

This is an excellent kit for adding a battery to your 4x4. While it is designed for marine use, it's perfect for mounting under the hood and controlling a second battery. The smart relay is particularly clever, being able to sense a charging voltage on either side of the relay. So for instance, when it senses charge from your alternator on your #1 battery, it will close the relay and and charge the #2 battery. Similarly, if the solar system is charging the #2 battery, once it's full the relay will sense a charging voltage and close the relay and charge the #1 battery. The relay can also be turned off with the charge isolation circuit, so this is a very smart relay indeed. The switch is actually optional, but it allows some particularly handy options. Depending on how you wire it, you can use the switch to turn off the whole system, to use both batteries independently and to electrically combine both batteries through the high current switch. Combining the batteries would allow a self jump start in the event of a dead battery, or to increase the power available when winching. Realize with this kit you will still need appropriate wiring, fuses at the batteries, a ground bus, and several hours to install properly. You will also need some understanding of electrical circuits and how they work. There are several equally good and safe ways to install the add a battery kit. There is a recommended circuit diagram in the included instructions, and there are several other slightly different variations on Blue Sea's website. I thought both the included instructions and the website information very helpful. In summary this is a high quality and robust kit from a high quality company. HIGHLY RECOMMENDED.

I kept having problems once I switched this no problems occurred at all. It is really awesome piece of equipment.

Decided it was time to upgrade my boat to a dual battery setup with an automated way to keep the batteries charged by the alternator and juiced enough to start the boat if my accessories used up to much juice with anchored. Following the instructions the system was easy to install. Took me right around 4 hours. I spend the first hour trying to figure out the manufacturer’s wiring job. Once I labeled what wires went to the starter, bilge, trim and to the house accessories it was smooth sailing. Made my own battery cables for a cleaner look and to save a few bucks. Took the boat out the next day and after almost a full day on the lake listening to the radio and charging multiple devices from the accessories outlet the boat fired right up. In the past I would shut the radio off after a few hours to keep a start reserve. Now I no longer worry about that and enjoy myself. Update - This device is a life saver and its already paid for itself by keeping me from paying for SeaTow or a high priced battery at a marina. I accidentally left the boat ignition key in the on position while the boat was unattended for an extended period causing the starter battery to drain to about 6V, to low to crank. Realizing my mistake and that I completely drained the starter battery I turned the battery selector switch to Combine Batteries and was able to start the boat right up since the second battery was isolated and had not drained at all it was fully charged. Having this kit installed let me utilize the second battery during the day out on the lake until I could get back home to fully recharge the first battery.

Cela fonctionne très bien et c'est efficace. L'ensemble est monté dan la cale de cabine sous un panneau à proximité des batteries. Forcement la led est difficile à surveiller du fait de ne pas pouvoir être déportée au tableau de bord. les possibilités de montage en façade, avec ou sans support sont appréciables (montage sans pour moi, façades affleurantes). Il faut faire attention avant montage à prendre les bons diamètres des cosses serties. Entre le coupe circuit et le relais ce n'est pas le même diamètres... C'est un très bon ensemble.

Just what I am looking for

I used this to add a second battery to my 23 year old boat... it was pretty straight forward, but if you're confused there's plenty of videos about it on youtube. You'll need some fuses to go between the battery switch and the voltage sensitive relay... they recommend "battery post fuse blocks", "Blue Seas Systems" make them, but you can get cheaper clones on here.

great product, quick delivery

Blue sea electrical equipment is always well made. This is no exception