Does ACR exist to charge start battery bank only if the volts drop below 12.45?

Discussion in 'OnBoard Electronics & Controls' started by sdowney717, Jul 9, 2021.

  1. sdowney717
    Joined: Nov 2010
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    sdowney717 Senior Member

    I have been thinking as to why charge the start battery bank all the time even on a small charge, it is not needed.
    And if the charger has issues, the start bank can be overcharged.
    So does an ACR exist that would allow charging like below 12.45 and stop charging when volts are fully charged like around 12.7?

    A start bank can sit a long time and the battery is fine unconnected to a charger.
     
  2. fallguy
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    fallguy Senior Member

    I gotta admit confusion by your post.

    short answer, no

    the acr exists to combine battery banks, it basically kicks in if one battery has enough voltage to kick over to the other one

    For a boat with dual starts, the acr keeps one battery that may be low 'strong' enough to go

    the thing to do for a third bank is to bleed off start batteries with a charger, like a 24-12 or a 12-12 'smart' charger that goes to a other bank, like the house

    Orion-Tr Smart DC-DC Charger Non-Isolated - Victron Energy https://www.victronenergy.com/dc-dc-converters/orion-tr-smart-non-isolated
     
  3. sdowney717
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    sdowney717 Senior Member

    I use one battery to start 2 engines, that battery is always charged by the port alternator. The house bank by the starboard alternator.
    I do have a relay rated for 80 amp continuous duty to join house to starter banks for charging when engines are running. (it is a simple combiner relay that turn on when ignition turns on, it works good, I can also turn it off with a switch and can add to cranking power)

    An ACR wont do what I want. I only want the starter battery charged if it needs charging, like the battery volts are low, and when it does not need charging have it not be charged. And AC charger charges it all the time.
    I dont want a starter battery cooked by my charger which it always does. I get only couple years from start batteries, they eventually get dried up by continual charging even at 13.8v and the last ones I got were welded top. No way to add water.

    You dont plug your car start battery into an AC charger when your not driving do you?

    If you have to do that, it's bad.

    All I can think of to do for now, is turn the rotary switch to off for the start battery, disconnecting it from the boat.

    This is the one I just bought for starting, can add water,
    Duralast 29DP-DL Group 29 Deep Cycle Marine and RV Battery (autozone.com)
     
  4. fallguy
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    fallguy Senior Member

    Just get a Victron smart charger like the one linked, except the 12-12 v version. It'll charge the start battery when it is low. It has engine on detection. Did you read the link I gave you?
     
  5. sdowney717
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    sdowney717 Senior Member

    Yes, but why not just replace the whole thing with this charger has 3 banks
    Amazon.com: Victron Energy Blue Smart IP22 12-Volt 15 amp 120V, 3 Output Battery Charger NEMA 5-15, Bluetooth: Automotive

    Might be the better thing to do versus spend some money and still have an old non smart charger.
     
  6. ondarvr
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    ondarvr Senior Member

    I'm a bit confused too.

    Smart chargers do exactly what you appear to desire.

    They monitor every aspect of the battery's condition and adjust output for maximum efficiency and battery life.

    They can extend the life of a battery by many years.

    Old school chargers can fry your batteries like you described, if you pick the correct new models they don't.

    And yes, my vehicles are plugged in to smart chargers anytime they'll be sitting unused for an extended period of time.

    Over the last year and half they haven't been driven much at all.

    My 2016 CRV only has 10,000 miles on it.
     
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  7. ondarvr
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    ondarvr Senior Member

    Also

    Many new vehicles have charging systems designed to float the charge at about 12.4 V unless it senses a load. This is done to get the last .002 better MPG for CAFE requirements.

    This leaves the battery perpetually under charged and can drastically shorten its useful lifespan.
     
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  8. Rumars
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    Rumars Senior Member

    Your batteries would be happiest if they would be forever charging on float.
    As I see it, your problem is that combining relay, wich parallels the house bank with the starting battery when charging. You actually have a good setup with different alternators charghing separately, you could adjust the regulators for the individual batteries needs. By combining them you overcharge the starting battery because the regulators see a bigger and more depleted bank. The only time that relay should be on is if you need to start the engines from the house bank.
    For AC charging get a smart charger that supports two separate banks with two different profiles, or two individual ones. The same applies if you have solar panels.
     
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  9. sdowney717
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    sdowney717 Senior Member

    It only does that when engines are running, and I can turn it off.
    I may get the Victron IP22 20 amp 3 bank charger, it is $176
    I dont get as much life out of batteries as I think I should, and I just bought 3 new ones and it cost me about $400. I bought 2 Deka golf cart for the house side.
    They are 230 amp hour batteries.
    Deka 6-Volt 448-Amp Golf Cart Battery in the Power Equipment Batteries department at Lowes.com
     
  10. Rumars
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    Rumars Senior Member

    If you want better life from your batteries you need to optimize the charging not only on the AC side, but also on the DC side. The starting battery has different needs from the house batteries, you need to cater to that. If you don't want to spend much money, don't use the combiner and keep the AC charger always on at the dock to keep the individual banks on float.
     
  11. sdowney717
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    sdowney717 Senior Member

    it has always been plugged in to the dock power on the Raritan charger , I think that is part of the overcharging issue, the charger charges at 13.8 v
    It is adjustable, but since I bought $400 of new batteries, I also decided to buy a new Victron IP22 3 bank 30 amp charger for $200
    Maybe it can do a better job, make the batteries last longer.
    Amazon.com: Victron Energy Blue Smart IP22 12-Volt 30 amp 120V, 3 Output Battery Charger NEMA 5-15, Bluetooth: Automotive
    it is a 4 stage charger, bulk, absorbtion, float, storage. 4th stage is at 13.2v
    It also can equalize at 16.2v
     
  12. missinginaction
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    missinginaction Senior Member

    I can't speak to the Raritan or Victron chargers as I use Xantrax equipment. I'm a single engine cruiser so my setup is a little different than if I had twins. Sdowney, didn't we have a conversation about charging your start battery off one engine and your house bank off the other? I seem to remember something about that some time ago.

    Even with only one alternator that I have connected to my house bank and then to my start battery via a Blue Sea Systems ACR, my batteries have been in my boat since 2013 and they are still fine. Based on my experience the house bank (a couple of 105 amp hour AGM's from East Penn) currently has about 75% of it's original capacity. I haven't measured the start battery but it starts the boat just fine.

    The vast majority of the time the batteries are maintained by a Xantrax True Charge 2, 40 amp charger. All the batteries are AGM's. The charger sends current to the batteries that need it.

    I just replaced that charger this past winter when it acted up. Except for a few times when we lost power at the docks or in the yard that charger kept my batteries charged 24/7/365. It ran for 8 years.

    Make sure all your batteries are of the same type.
    Be sure your charger is sufficiently large to handle your charging loads.
    Monitor your charging voltages from time to time to insure that your charger is functioning properly.
    Does your charger have settings for flooded, AGM or Gel? Are the settings correct?

    In my experience, once you have your system set up properly, using a "smart charger" and an ACR, all you should have to do when you leave the boat is to make sure the charger is on and the battery selector switch is off. It's about as close to set it and forget it as you can get.

    MIA
     
  13. sdowney717
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    sdowney717 Senior Member

    The Raritan charger is also a power supply. Whoever wired it decades ago, wired it to the buss bars for each bank, after the battery switches. I plan to leave that as is. Not sure why it would matter, this new charger can also act as a power supply, has to be selected as either a PS or a charger. AND, it has been a while since I looked into how it was done, so I could be totally wrong, it may be wired direct to batteries.

    I can see an advantage to having charger connected direct to batteries, as if battery switches are set to off, the charger can still charge. If it is not too much effort, I may mod the system. I suppose I could connect direct to the wires that come off the switch that are on all the time that power bilge pumps, it is a big 8 gauge wire that runs from switch to some breaker under the helm for both banks. Each bank has a bilge pump I think, boat has 5 bilge pumps.
     
    Last edited: Jul 13, 2021

  14. rangebowdrie
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    rangebowdrie Senior Member

    Automotive style starting batteries require a diff charging regimen than do deep-cycle types.
    An auto batt can typically float at a higher level due to its internal resistance being higher,, this is why you can drive coast to coast without shutting off the engine, (several days driving,) with the volt meter always showing 13.8>14 and still not overcharge,, (see note below).
    But for long term float an auto type starting batt should float in the 13.3>13.4 range,, a flooded deep cycle should float in the 13.17>13.2 range,, (both need to adjusted for batt temp),
    A charger, (smart or dumb,) works best when it is not connected up to mixed batt types.
    Note; IIRC, an "auto" battery is a "Lead-Calcium" style, whilst "Deep Cycle" batteries are of a "Lead-Antimony" plate construction.
    For every 1/10 volt over optimum float the currant doubles.
     
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