Bumbo
New member
I wanted to do a write up on two different Blue Sea ACRs I have been playing with recently and talk about experiences with them for my applications.
The two ACR units I have been using are the Blue Sea #7610 and #7611
These two units are excellent for smaller applications where one might not need the manual control or higher amp limits of their ML series.
You can find specifications for both these units here:
7610
https://www.bluesea.com/products/7610/SI-ACR_Automatic_Charging_Relay_-_12_24V_DC_120A
7611
https://www.bluesea.com/products/7611/BatteryLink_Automatic_Charging_Relay_-_12V_24V_DC_120A
Both of these ACRs are pretty much identical except for their primary feature. The SI-ACR (7610) is their start isolation version. It offers the ability to wire a 12v+ trigger, like the starter, so you can instantly disconnect the aux battery during cranking.
The BatteryLink version (7611) has a feature called Auxiliary Battery Priority which essentially changes the open voltage threshold from 12.75 to 12.25v. You can have this wired into ignition so its always enabled when the car is running, but I have mine on a switch so I can control it manually... more on that later. I also understand if you wire this feature permanently on and don't have a dual battery setup, you can essentially use this as an LVD, but I have not tested that yet. More on that later, when I actually do another write up on LVDs as I am currently running a different one.
Each of those feature connections are located in the center of the ACR between the Ground (required) and the optional LED indicator.
SI is a good feature if you want to protect sensitive electronics that might power-cycle during cranking. This also protects the ACR or circuit from having starting currents go though it. If the ACR is closed and SI isn't used it will participate in starting the truck.
The SI unit has one additional feature which is NOT included in the 7611 which is low battery voltage lockout. If either one of those cells are below 9.5 volts, it won't combine. Some may look at this as a Con, but I think its a Pro. If you ran down your aux battery or had an internal short, it would potentially bring down the starter battery leaving you stranded. This ACRs goal is to protect the healthy cell. I found this very appealing for an adventure/overland type truck. At least this way it gets you out of the truck to actually check the system before hitting a manual switch and forcing it like you can do with the ML series or busting out the jumper cables to self jump...
The 7611 was a solution to a problem that I was experiencing in my own setup.
The problem I was experiencing was under high load conditions with all my lighting on... the voltage drop was right at the 12.75 open voltage threshold and there were times the ACR would go open on me. The Aux Batt Priority feature was nice because I was able to lower that open voltage threshold by 0.5 volts, solving the issue I was having.
Because I wired the feature manually to a switch, it ended up proving to be very useful for my needs in other ways. Even with the engine off I could control the open voltage and choose if I want to keep more voltage in the starter, or force the starer to participate in feeding accessory loads down to 12.25v before the Aux takes over the show.
This turned out to be an awesome little way to get a bit of extra run-time for my ARB 50. I can leave it unattended for a lot longer than I would even realistically need, and the headroom was welcome on hot days or when actually running it as a freezer.
Even with a 12.25v open on the starer, I have plenty of juice to start the truck. I do miss the Low Voltage Lockout feature, but I think the trade off is great. I generally keep good tabs on my system and maintain it's health.
All of my packs are about 1 year old, healthy, and when testing I never had my electronics power cycle / reboot when cranking... but that doesn't mean it wont ever happen. With higher loads or fatigued packs, it might start happening which makes the SI feature very valuable depending on what your applications are. Having GPS or communications equipment go down would really irritate me.
One thing I like about my time with Blue Sea is the quality of the product, simplicity of design, and the documentation / spec sheets are fantastic...
I get happy when I see stuff like that. I even got excited when I saw a torque specification for the studs and screws on various products like fuse panels too. Attention to detail...I appreciate it, so I actually take the time to do it. Makes me feel I am building a quality system.
I am excited to try an ML series when I have some higher amp requirements, and if anyone else knows of some other great ACRs for smaller systems that have special features please let me know... I am always curious to try other things, and I would be more than happy to buy/test/review for my own curiosity as well.
The two ACR units I have been using are the Blue Sea #7610 and #7611
These two units are excellent for smaller applications where one might not need the manual control or higher amp limits of their ML series.
You can find specifications for both these units here:
7610
https://www.bluesea.com/products/7610/SI-ACR_Automatic_Charging_Relay_-_12_24V_DC_120A
7611
https://www.bluesea.com/products/7611/BatteryLink_Automatic_Charging_Relay_-_12V_24V_DC_120A
Both of these ACRs are pretty much identical except for their primary feature. The SI-ACR (7610) is their start isolation version. It offers the ability to wire a 12v+ trigger, like the starter, so you can instantly disconnect the aux battery during cranking.
The BatteryLink version (7611) has a feature called Auxiliary Battery Priority which essentially changes the open voltage threshold from 12.75 to 12.25v. You can have this wired into ignition so its always enabled when the car is running, but I have mine on a switch so I can control it manually... more on that later. I also understand if you wire this feature permanently on and don't have a dual battery setup, you can essentially use this as an LVD, but I have not tested that yet. More on that later, when I actually do another write up on LVDs as I am currently running a different one.
Each of those feature connections are located in the center of the ACR between the Ground (required) and the optional LED indicator.
SI is a good feature if you want to protect sensitive electronics that might power-cycle during cranking. This also protects the ACR or circuit from having starting currents go though it. If the ACR is closed and SI isn't used it will participate in starting the truck.
The SI unit has one additional feature which is NOT included in the 7611 which is low battery voltage lockout. If either one of those cells are below 9.5 volts, it won't combine. Some may look at this as a Con, but I think its a Pro. If you ran down your aux battery or had an internal short, it would potentially bring down the starter battery leaving you stranded. This ACRs goal is to protect the healthy cell. I found this very appealing for an adventure/overland type truck. At least this way it gets you out of the truck to actually check the system before hitting a manual switch and forcing it like you can do with the ML series or busting out the jumper cables to self jump...
The 7611 was a solution to a problem that I was experiencing in my own setup.
The problem I was experiencing was under high load conditions with all my lighting on... the voltage drop was right at the 12.75 open voltage threshold and there were times the ACR would go open on me. The Aux Batt Priority feature was nice because I was able to lower that open voltage threshold by 0.5 volts, solving the issue I was having.
Because I wired the feature manually to a switch, it ended up proving to be very useful for my needs in other ways. Even with the engine off I could control the open voltage and choose if I want to keep more voltage in the starter, or force the starer to participate in feeding accessory loads down to 12.25v before the Aux takes over the show.
This turned out to be an awesome little way to get a bit of extra run-time for my ARB 50. I can leave it unattended for a lot longer than I would even realistically need, and the headroom was welcome on hot days or when actually running it as a freezer.
Even with a 12.25v open on the starer, I have plenty of juice to start the truck. I do miss the Low Voltage Lockout feature, but I think the trade off is great. I generally keep good tabs on my system and maintain it's health.
All of my packs are about 1 year old, healthy, and when testing I never had my electronics power cycle / reboot when cranking... but that doesn't mean it wont ever happen. With higher loads or fatigued packs, it might start happening which makes the SI feature very valuable depending on what your applications are. Having GPS or communications equipment go down would really irritate me.
One thing I like about my time with Blue Sea is the quality of the product, simplicity of design, and the documentation / spec sheets are fantastic...
I get happy when I see stuff like that. I even got excited when I saw a torque specification for the studs and screws on various products like fuse panels too. Attention to detail...I appreciate it, so I actually take the time to do it. Makes me feel I am building a quality system.
I am excited to try an ML series when I have some higher amp requirements, and if anyone else knows of some other great ACRs for smaller systems that have special features please let me know... I am always curious to try other things, and I would be more than happy to buy/test/review for my own curiosity as well.
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