My Roadtrek originally came equipped with the Sure Power Battery Separator Model 1315-200, a 200-amp solenoid version. While the separator functioned properly, it drew approximately 1.5 amps when the solenoid was energized, resulting in a significant loss of solar energy.
I decided to replace it with the Blue Sea ML-ACR Model 7622, a 500-amp magnetic latching (bi-stable) automatic charging relay featuring manual and remote control capabilities. Although it comes with a higher price tag of around $200 USD, the investment has proven worthwhile for me. According to the manufacturer, it draws very low current (<40mA to monitor terminal voltage) in both the "ON" and "OFF" states, with a moderate current draw for a very short duration during state transitions.
The Blue Sea ML-ACR is dual-sensing, detecting charge levels on both batteries. It also includes a start and engine isolation feature, though I opted not to utilize those functionalities. With the addition of the remote switch, I can manually isolate and combine batteries from the driver's seat. Typically, I leave it in auto mode and only switch it off (isolate) when the house battery is charging from solar panels.
For most applications, the more affordable 120-amp continuous rated Blue Sea SI-ACR should suffice for alternator charging.
The replacement process is quite straightforward, using the same wiring as the old Sure Power isolator. The ML-ACR terminal studs for the batteries are interchangeable, eliminating the need to trace which wire goes to the start battery or house battery. I only had to run three new wires (red remote, red [+], and yellow LED wire) to the remote switch, which I mounted on the dashboard next to the headlight selector switch. Additionally, I slightly enlarged the ring terminal holes on the [+] cables as the ML-ACR terminal studs are slightly larger (size 3/8") than the old isolator. If preferred, you can also change the ring terminals on the [+] cables at this point.
Blue Sea ML-ACR automatic charging relay wiring diagram.
Blue Sea ML-ACR automatic charging relay wired and mounted on passenger side firewall.
The remote switch location has a factory cut-out and was covered with a plastic snap cover. You can easily access the area by removing the light grey dash panel below it. With the panel removed, the plastic hole cover can be easily pushed out from the back. The factory cut-out has to be enlarged to accommodate the much bigger auto charging relay switch. I use a box cutter to slowly enlarge the hole.
Remote switch wired and mounted. The switch LED indicators are little too bright for me, that is the only thing I did not like with it.
Remote switch ground connection.
Wires were routed from cab to engine compartment through this factory firewall opening with weather tight rubber sleeve.
(+) wire to remote switch with 2 amp inline ATO fuse. All wires to remote switch were 16 gauge size as per Blue Sea manual.
One of the best mods I have done to our RV!! I did not modify the dash. I used one of the switch blanks already in the Sprinter to mount the switch. Again, best mod that I have done to our RV/MH.
ReplyDeleteNice idea using the switch blanks. Thanks.
DeleteI'm about to do the same swap on our 2010 Roadtrek 210P. The Sure Power still works fine but it gets hotter than blazes due to the constant current flow needed by the solenoid. I'm assuming that since the 7622 is a magnetic latching relay requiring mA to remain energized it's going to generate a much lower temperature. Have you found this to be true?
ReplyDeleteThanks
It is a bi-stable latching relay, it only requires current during latching. It does not warm/ heat up unlike the battery separator relay.
DeleteOn my 2008 Roadtrek 210 popular there is a large red wire coming from the Alternator to the center pole of my Isolator what did you do with it?
ReplyDeleteI have a battery Separator, which is not the same as an Isolator. The separator has only two connections, one from the alternator and one from the coach battery + connection. The separator has three connection posts: one in the middle from the alternator, one on each side from your chassis battery, and the other from your coach battery. You can replace your isolator with a separator or an ACR relay; connect the wires from the alternator and the chassis battery to the same terminal post of the separator/or ACR relay “B” post then connect the wire from your coach battery to the “A” post. Hope that helps.
DeleteGREAT blog post. It really is helping me to make the same move from the 1315-200 to the Blue Sea 7622 on our 2015 RT CS. However, I don't see where you connect the Isolation #1 (brown wire) to in the photos. Did you connect it to the starter as you diagram shows or to the start key switch? Do you have a photo of that connection? I just don't see the wire identified, like the other wires, in the photo with the Blue Sea installed on the firewall.
ReplyDeleteThank you. The start isolation is optional. I did not think the need
ReplyDeletefor it at that time, so mine is not connected.
I love the blog and RT upgrades you've made. I too am upgrading my 1315-200 to a Blue Sea 7622. However, I didn't see in any of your photos/discussion where you connected the Isolation #1 (brown wire). Did you connect it to the starter solenoid or the start key switch? The photo of the installed Blue Sea ACR n the firwlewall doesn't identify that wire on the device. Any info/photos on where you attached this wire would be greatly appreciated.
ReplyDeleteAgain, great blog.
Thanks for this great post. I'm on the verge of installing the Blue Sea SI-ACR (the cheaper device) which you suggested "should suffice". I'm having second thoughts and wonder if I'm being too much of a cheapskate. Anyway, if you have time would you kindly elaborate on the choice of the SI-ACR version.
ReplyDeleteAlso, your photos are extremely helpful. How did you attach the device to the firewall, sheet metal screws or something more elaborate?
Thanks again for your help.
Jim
Thanks for asking. The RT alternator wiring and breaker are limited to 80 amps, whereas the Blue Sea SI-ACR is rated for 120 amps continuous, exceeding the capacity of the existing wiring and breaker. The main difference between the SI-ACR and the larger 500-amp ML is the ML’s higher current rating, remote switch, manual override/shutoff, slightly lower current draw when changing state, and other features that are generally unnecessary for a single engine/alternator system.
DeleteI just use screws to mount it on the firewall.
Very helpful. Thank you. Jim
DeleteInstalled and working.
ReplyDelete