ACR and on board chargers? (1 Viewer)

[AimCOtaco]

What is a good single bank onboard charger/maintainer that won't freak if/when the ACR combines the batteries?

I'm considering a Blue Sea ACR for a dual battery system. One of the main drivers is the 'dual sensing' combine arrangement as I'm planning to have solar on the house battery side of things so allowing any excess juice to top of the main battery will be automatic. I figure having the solar able to maintain both will be a big plus:
-keep the starting battery topped of when boondocked and still using some vehicle systems like lighting after the house battery has come up.
-maintain BOTH batteries when parked at home waiting for fun time.

It seems the solar chargers are simple and just pump what they can when they can so should work well with the ACR I think.

I'm not so sure about a charger maintainer though as most have intelligent circuitry and having the ACR switch in another battery is probably ok with some maintainers and not okay with others. Anybody have any first hand knowledge or experiences on this?

Thanks all,

 

[JCruse]

My solar charge controller doesn't work that way I don't think. It puts out 14.2 bulk charge and then 13.4 maintenance. Of course if the sun is setting it wont make that much, but as long as the sun is up somewhere in the sky it'll make those numbers or very close to it. I also have a Blue Sea ACR and the two have no problems living together so I don't see why you cant run a small charger. I run my big 50 amp charger with both of the other units connected and working.

I often make use of the circuit breakers in the setup to force the batteries to separate. This leaves the house battery (125Ah) to run most things while getting fed from the solar panel. If it gets too low I can close the breaker and pull some juice from the starter (100Ah).

A LOT of people say the BatteryTender chargers are very good and I suspect they're right. My controller is a Battery-MINDER who also make good chargers.

 

[Cruiserdrew]

I use a BatteryMinder and it works fine with the ACR in the charging circuit. In fact, mine right now is charging/maintaining 7 batteries and 3 ACRs, in 3 trucks and one stand alone battery.

I think the BatteryMinders have better electronics than the Battery Tenders, and mine has been in full time use usually with 5 batteries/2 ACRs for 2 years.

Personally, I think Blue Sea ACRs are the shiznit for home brewing a dual battery system. As long as you are comfortable making cables, and fuse the (+) at the battery with the correct size fuse, all will be good. Great product.

 

[spressomon]

FWIW: After installing, using and speaking with a Blue Sea tech about my 7622 I was a little dismayed to learn when in charging mode it performs bi-directionally regarding current flow (between batteries); not a true battery system isolator (his exact words).

This doesn't really pose a significant issue assuming the batteries in array are similar voltage requirement or, like I have my 3rd wire leg laid out, where the trailer leg of wiring resides on the alternator side of my Powergate.

I run a separate controller (Morningstar PS-30) for the solar panel to LiFePO4 battery when the trailer/7622 is disconnected from the LC. And I also have a Morningstar Sunguard for the rare time the LC sits more than a couple days with the fridge/freezer running.

 

[Cruiserdrew]

@spressomon that's exactly what a voltage sensing relay is designed to do. It combines when either side of the relay is greater than 13 volts for 2 minutes. It opens (and thus separates) when the voltage is below 12.75 volts. So it isolates the batteries, not sure what else you are looking for.

I have mine set up so that the alternator charges the stock wiring, closes the relay, and then also charges the #2 battery. With solar it's opposite-solar charge comes in on the #2 side, and when voltage there is above 13volts, it also tops off the main battery. What additional function are you looking for?

 

[spressomon]

^ yes but when the, in this example, the house battery/batteries are at say 12.8v and the LiFePO4 trailer battery is above that voltage then current can flow from the higher voltage battery 'downstream' to the 12.8v battery/batteries.

 

[Cruiserdrew]

I do not know about Lipo batteries, but for all intents, a lead acid battery at 12.75 volts is fully charged. So the effect is, they are only combined during charging. When not charging, the least use of power, will flash off the surface charge, drop the voltage to 12.75 and the relay will open, isolating the batteries. All forms of relay type isolators are like this. I suppose you could install a diode, but that would defeat one of the principal advantages of the ACR-the ability to charge in either direction.

 

[spressomon]

The more I thought about it...the alternator's output voltage is above either anyway, so it should be a non-issue.

 

[kowalski]

I think your problem may lie in mixing chemisties.

lithium nominal voltage is higher then lead, and could be float charging the lead through the blue sea system.

 

[cme4lyt]

I just installed the Blue Sea 'add a battery' switch and acr. Have been monitoring my aux battery and the entire setup is working as advertised.

Pretty easy install, just a bunch of cables to make....or have made !

Regards....

 

[AimCOtaco]

Thanks for the feedback all and especially the first hand use of a Battery Minder with the ACR @Cruiserdrew.

I've had some feedback from a few manufactures I've reached out to which has led me to a new Battery Minder. I've long used and trusted the Battery Minder for lead acid so it seemed logical to move up to their fancy current 2A AGM model and just use the little old one for flooded motorcycle batteries.

I also tested my own battery minders re-cycling logic; I was keeping a dying battery alive with it and noticed that if it was in deslufation mode and then I drew down the battery a bit with some light loads it would go back to bulk charge mode. This alone makes me think the battery minder would self reset and behave correctly when the ACR draws it down by switching in the second battery.

Blue Sea: They were not a huge help and first suggested their own 25A onboard unit which was way off the mark for a 2 battery auto system but 25A is the smallest charger they sell. When I pointed out that I needed a much smaller, lower output charger they suggested I look at Marinco which is in the same family of companies as they offer smaller chargers. No real feedback on the mode switching or advice on how to charge with the ACR, just some sales links...

NOCO/Guest: These guys understood the question and advised that single bank smart chargers may indeed 'freak out' a bit when a second battery was switched in. They did say that any of their multibank chargers would be more likely to handle this correctly and that the multibank chargers should not be damaged or 'freaked out' when the banks are merged by the ACR.

Battery Minder: They gave a short and sweet response that this should not be an issue for their chargers.

If this was for continuous or frequent use I might consider a 2 bank quality marine maintainer but for my use I decided to simplify things by going with the 2A Battery minder. I may or may not hard mount the charger, if I do it will be easy to move around for versatility.
Another thing I'm now considering is interrupting the ground to the ACR with a switch; I assume that if there is no ground to reference or bias the relay then the system would be AUTO/OFF switchable. That way I could force any charger to just impact one battery unless I want the ACR to combine them.

Anybody running a switch in the ground lead of the ACR to provide full isolation when desired?

Thanks all,

 

[TrickyT]

...
I also tested my own battery minders re-cycling logic; I was keeping a dying battery alive with it and noticed that if it was in deslufation mode and then I drew down the battery a bit with some light loads it would go back to bulk charge mode...

The same thing happens when you're keeping healthy batteries alive. The charger can't immediately "know" what charge state the battery is in, so it resets to bulk charge and evaluates the state of charge from that point. If the battery is already fully charged it switchs to maintenance mode pretty quick

2X on BatteryMinder and Blue Sea ACR. Been working well for me too.

 

[AimCOtaco]

Got it done. Built a single stainless tray for a D34 or G75 size battery and added a heat shield that doubles as the mount for the Blue-Sea SI-ACR(7610) and Blue-Sea Maxi-Fuse block that feeds my rear 'radio and camping' fuse panel. There is a Bussman 150A breaker in the charge line at the main battery. The battery interconnects are #1GA Welding cable. I'm considering adding a #1GA ground cable between the batteries as well. Main is a D31 Yellow Top, 2nd is a D34/78 Yellow top. The Battery minder (2A AGM 2014 model) is maintaining both batteries when stored and the charge relay is behaving as expected. I have not hard mounted the charger yet, it's handy to have around and I haven't found the right spot for it yet but still intend to do a least a quickly removable mount for it to make battery maintenance as easy as possible so I don't go lazy. So far so good so off to the desert I shall go.

 

[Cruiserdrew]

Nice job on the stainless tray. Your lay out looks great.

I like those Maxi-fuses. Intuitive and easy. Not expensive. ACR fuses are similar and useful in the same way.

 

[george_tlc]

A nice red boot over the +ve terminal stuff would be a good idea... Less chance of a 'welding' incident if you drop a spanner etc in that area...

cheers,
george.