Is a Battery Equalizer recommended dual batt 24v system?

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NEWFISHER
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Is a Battery Equalizer recommended dual batt 24v system?

Post by NEWFISHER »

I am running 2 gel 12v Optima's and have done a small amount of reading up on the topic, but no definitive answer. I would love a 24v to 12v charger, but it seems only 1 available I can find out of Australia and I am thinking that a Battery Equalizer will help maintain and provide a longer life span of my batteries?

Thoughts?
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TechMOGogy
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Re: Is a Battery Equalizer recommended dual batt 24v system?

Post by TechMOGogy »

Search the forum for Equalizer - you will need a blocking diode or bad things will happen.
I purchased a Vanner Vann-Guard waterproof 60 amp equalizer from a bus - PM if have any interest as I then purchased a Victron Energy 70 amp DC-DC converter for my PS setup. The Vanner should fit in the top of the battery box.
http://www.vanner.com/manuals/70-60.pdf
Dan

rmel help me out a lot!
See this post: viewtopic.php?p=76790#p76790
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Garrycol
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Re: Is a Battery Equalizer recommended dual batt 24v system?

Post by Garrycol »

If you are going to tap one battery for 12v you will definitely need an equalizer particularly if higher loads are needed.

When researching this many years back I priced the costs of an equalizer vs that of a 24v -12v charger - when comparing like with like the equalizer was 1/3 more expensive than the battery charger. I use a 60amp 24v to 12v charger.

If you cannot find a 24v to 12v smart charger then as an alternative use a suitable 24v to 12v reducer to power a 12v to 12v Dc charger.

garry
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Re: Is a Battery Equalizer recommended dual batt 24v system?

Post by rmel »

It all depends upon what your application is.

For loads which have a HUGE instantaneous current demand let's say hypothetically 150A the Equalizer
approach may be better suited than an equivalently rated converter -- at 150A that converter would be
huge. The advantage of the Equalizer approach is the direct connection to the battery which then is charged
by the equalizer -- in parallel. But there are caveats! First if you want the Ground break switch to continue to
function you will need a Battery isolater Diode in series with the tap point of the battery or you will have
reverse currents potentially flowing in your system -- these are high current low voltage drop Schottky
diodes and ain't cheap. Second, the average current draw on the battery has to be LESS than the output
current of the Equalizer otherwise you will discharge the lower battery (not to mention you better add up the
totals that would be needed for your alternator). Basically the Equalizer approach is great for large peaks in
demand but moderate average current -- the Equalizers are designed to support that.

But in general the best solution is to get the problem you are trying to solve well stated; it may be that your
situation is better off with a simple 24V-12V converter, or a 24V-12V charger into an isolated 12V sub-system,
or an equalizer. I am running a REDARC 24V/MPPT) to 12V converter with 4 Yellow Tops for 12V (yes 4). I
imported this from REDARC through a distributor out of the land of OZ, if your interested PM me.

ron
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Re: Is a Battery Equalizer recommended dual batt 24v system?

Post by audiocontr »

I was never able to successfully install an isolator without eventually frying it. I gave up.
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Re: Is a Battery Equalizer recommended dual batt 24v system?

Post by rmel »

A battery isolater with proper rating is a very robust solid state device
which should never fail. Y'd need ~200A rated one for most equalizer applications.
If one is using the lower battery for a 12V winch for then I'd go 400A. Many of the
battery isolaters are dual diodes (3 terminals) so you could tie both in parallel to
get 2X the rating.
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Re: Is a Battery Equalizer recommended dual batt 24v system?

Post by rmel »

I should have added, I kinda take it for granted --but-- current sourcing/sinking nodes
should always be protected with an appropriate fuse. A decent choice are ANL fuses,
compact, and a wide current range e.g. 50A to 600A. Good for protecting the Equalizer
and the 12V output.
ANL-200A.JPG
ANL-200A.JPG (7.19 KiB) Viewed 6478 times
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Re: Is a Battery Equalizer recommended dual batt 24v system?

Post by Dreadnought »

Just my experience......I ran my Pinz with no problems for the first 5 years with the batteries that came when I bought it........then I changed one of the batteries due to it showing less voltage that the other consistently and starting became harder......I used any old big battery that I had laying around......but it wasn't exactly the same capacity as the original......problems with holding a charge in both of them ensued.......It wasn,t until I bought another pair of twin batteries of a good capacity that things went back to normal....indeed I can now leave the Pinz for a month or more and know that it will start immediately.....the batteries need to be the same. (appx 7 years now and still loving my 710K)
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Re: Is a Battery Equalizer recommended dual batt 24v system?

Post by 63rover »

I don't need the high loads others are referring to. I have 2 optima blue top batteries (came with my truck), a 24 volt battery tender with the quick connect wired through to the grill for charging and a 6A battery equalizer from a solar power set-up to keep the batteries level. For 3 year I've run 24v only and had no differing voltage issues. I'm adding some 12v accessories and have 2 small 24-12 converters and a single 30A one. Each will have a shut off switch for when they are not needed. My winch is mounted on quick release plate so that it can be used front or rear. It has a quick release that connects to the down-stream battery (negative side). My electronic engineer friend assures me it will cause no issues and that with patience the batteries will equalise just fine. I'm still waiting to get stuck to try it! :lol: No issues so far this season.

Cheers, CLive
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Re: Is a Battery Equalizer recommended dual batt 24v system?

Post by undysworld »

63rover wrote:My winch is mounted on quick release plate so that it can be used front or rear. It has a quick release that connects to the down-stream battery (negative side). My electronic engineer friend assures me it will cause no issues and that with patience the batteries will equalise just fine. I'm still waiting to get stuck to try it! :lol: No issues so far this season.
Clive,

With no offense meant to your EE friend, I wish you good luck.

The link below is to a thread which discusses the need for periodic recharging of each battery independently. In it, I quoted Jim M. (whom I consider to be one of the most electrically knowledgable fellows here), and he discusses how draining one battery causes the truck to sense low 24v and thus begins charging of both batteries. The drained battery needs the charge, while the non-drained battery does not, but regardless they both are getting charged. I don't think most battery equalizers are capable of resolving this discrepancy, at least in the short term. I've lost batteries even when I ran an equalizer, but of course not all equalizers are "equal".

If/when you start using your winch and drawing one battery down, you may find that you begin to have problems. Monitoring the voltage of each battery independently would let you see a discrepancy and act to resolve it, if needed.


viewtopic.php?f=14&t=8245
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Re: Is a Battery Equalizer recommended dual batt 24v system?

Post by rmel »

Actually, Clive might be just fine -- depending upon the spec. of his 6A equalizer.

Ironically, I've been thinking about a "modest" Winch setup as well. These are typically
beefy ATV winches but 12V not 24V. Clive, I'd be very curious about who the manufacturer
is for your equalizer -- I'd be happy to crawl over the spec. I can tell you Vanner does it
right Victron would be a bit of a problem due to where they trigger equalization -- but their
converters are top draw.

cheers
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Re: Is a Battery Equalizer recommended dual batt 24v system?

Post by TechMOGogy »

I have always wondered about a 4k or 4.5k ATV winch with some pulleys.
I am not going through the Amazon rain forest - just need help the odd time up a smooth rock face or a slick hill
It's easier to carry 200ft+ of synth line and some pulleys
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Re: Is a Battery Equalizer recommended dual batt 24v system?

Post by Jimm391730 »

Charging an unbalanced pair of batteries (one discharged, one charged) is problematic. The charged one gets overcharged and the discharged one does not get enough charge. A battery equalizer typically takes equal power from both batteries but only returns this power to the more deeply discharged battery; essentially removing energy from the charged battery and giving it to the discharged battery. This is how the equalizer works.

Now let us do a rough thought experiment: If you use a 12V winch for one minute, and it draws 400 amps during that time (not unrealistic!) then that battery is being drained at 400A times 1 minute equals 400 amp minutes. The 6A equalizer will take over an hour (400 divided by 6 = 66.7 minutes) to theoretically bring things back into equalization. Until this time, the alternator is overcharging the upper battery - this creates heat (or at least more heat than "normal"). Heat is almost never your friend; the more heat, the shorter life most things will have. It is possible that a sealed battery might vent during this overcharge and venting is not normal for a sealed battery.

The above thought experiment shows that there is the possibility of damage/degradation even with an equalizer. However, if this only happens a few times per year and not an everyday occurrence, the likelihood of long term problems is probably almost zero - yes, the batteries are unbalanced, but in an hour (or two or three) things get back to an equalized normal. So it becomes a weighted decision to accept some slight possibility of creating a problem with the convenience of a 12V winch. The more you know and understand the better you can deal with the issues: what if you get REALLY stuck, and end up winching for a LONG time? After a bit, swap batteries! Balance their charge that way!

Everyone's "best" solution will be different. I elected to get a 24V winch and not worry about it. YMMV, but be sure to enjoy your choice and your truck!
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Re: Is a Battery Equalizer recommended dual batt 24v system?

Post by rmel »

Off topic somewhat but... If your looking for a moderately powered winch
e.g. ~6,000 lbs it's going to be 12V. So you got the lower battery as your
source unless you have aux 12V batteries (which I do). Ramsey's makes a
nice one at 5,000 lbs -- which with a snatch block you can "get otta there"
at 10,000 lbs pull. T-Max has a 6,000 lbs winch which seems to be a
Down'unda option only :(

I too would go with a higher capacity equalizer. But if Clive has this installed
already, and winch use is rare should be OK. The hope is a Winch is just ornamental :D
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Re: Is a Battery Equalizer recommended dual batt 24v system?

Post by 63rover »

I usually off-road with the local Land Rover club in either my 63 2a diesel or the Pinz. Either way I like to bring up the rear and see where others get stuck, avoid the problem or pull them out. I also carry 2-12v jump starter packs so if I really unbalance something I can make tea, wait for the equalizer to do its thing and then jump start of necessary. I'm in no rush. It's one of the advantages of being retired.
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