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Old 07-02-2014, 00:23   #76
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A wire has no smarts either. By that logic no batteries should ever be wired in parallel because the wires have no temp sensing or ability to limit current. Is that your point?

Fuses would likely not prevent this failure as the current needed to blow up a shorted cell battery is small (< 20A). It just takes time.

Having significantly different age and type of batteries in parallel isn't the best idea either.

There seem to be a bunch of things wrong with this installation but the ACR isn't the root cause of this failure based on what has been reported. A wire in place of the ACR would have had the same outcome. I would not blame the wire in that case either.
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Old 07-02-2014, 01:03   #77
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Re: Danger Warning ACR's

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A wire has no smarts either. By that logic no batteries should ever be wired in parallel because the wires have no temp sensing or ability to limit current. Is that your point?

Fuses would likely not prevent this failure as the current needed to blow up a shorted cell battery is small (< 20A). It just takes time.

Having significantly different age and type of batteries in parallel isn't the best idea either.

There seem to be a bunch of things wrong with this installation but the ACR isn't the root cause of this failure based on what has been reported. A wire in place of the ACR would have had the same outcome. I would not blame the wire in that case either.
I think we all agree that the ACR is not really material to this discussion, and I think we all interpret what Lloyd is saying as: Paralleling batteries in inherently dangerous. Solution: Unparallel them, with temperature sensing on each bank. I think that we can all agree with this formulation of Lloyd's point, although in practice, as you point out, it's hard to avoid.

I think another point Lloyd was making is that the remote bank connected via ACR may be at a different temperature. Maybe, but I don't think that improper temperature compensation -- which amounts to a few tents of a volt -- is going to cause this kind of failure, nor do I think that any temperature compensation the way it is implemented on our chargers will prevent such a problem unless you happen to be lucky enough to have the temperature sensor mounted on that one battery which fails.
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Old 07-02-2014, 07:33   #78
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Re: Danger Warning ACR's

Unless one uses unusually large batteries ($$$), most of us cannot reasonably avoid parallel connections in order to obtain desired bank capacity. For that reason, using a shore charging scheme that limits current once the bank reaches float conditions seems a more realistic way to avoid this scenario. This could be done cheaply by turning off the primary charger (perhaps with a timer) after float is reached and letting a small charger or solar maintainer float the batteries, or as one poster mentioned, using a shore charger that is programmed to stay in float mode unless it is disconnected from shore power (as would happen when leaving the dock, for example).

Downside is that the parallel batteries would still be able to pump current into a bad cell, but the available AH would at least be limited. This would also inhibit any special battery longevity routines that some shore chargers have.

No?
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Old 07-02-2014, 07:43   #79
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Re: Danger Warning ACR's

I don't see how a paralleled separate start battery is any different than a paralleled string of batteries in the same housing.

When we were hit by lightning, it shorted one of our batteries in our house bank of 6 6V series/parallel string. The charger temp sensor was not connected to the shorted battery.

The short caused that battery to get very hot and boil over, yet the charger did not know that.

Mark
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Old 07-02-2014, 07:53   #80
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Re: Danger Warning ACR's

Dumb question. What's the risk of fire in all of this as opposed to just getting acid everywhere? If there is no fire risk and it will just spew acid then wouldn't putting each battery in a battery container/holder be a low tech cheap solution to minimizing the damage? I am well aware that we would all rather prevent the issue then contain it but if I can't set up a temp sensor on each batt in my bank I would figure this would be the next best thing.

Now if there is a good chance for fire all the previously stated is moot.

Thoughts?
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Old 07-02-2014, 08:49   #81
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Re: Danger Warning ACR's

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I don't see how a paralleled separate start battery is any different than a paralleled string of batteries in the same housing.

When we were hit by lightning, it shorted one of our batteries in our house bank of 6 6V series/parallel string. The charger temp sensor was not connected to the shorted battery.

The short caused that battery to get very hot and boil over, yet the charger did not know that.

Mark
Mark,

As I mentioned earlier it is not any differnt. There are literally dozens of scenarios that can cause this exact type of situation.

The Duo Charger is a great device but it is not a panacea for all situations.

I would LOVE to use them to feed windlass banks in the bows of boats but unfortunately they are limited to 30A and when 30A or more is needed by the batts they lock out very quickly. The sample time is very short so they will simply sit there and go ON/OFF/ON/OFF etc. etc. and not effectively charge the bow bank.... For a start battery they are great but they could be better if simply limited to 28A continuous or so and the lockout/reset was re-engineered.

I have been going around on this with the guys at Balmar for many years but this is a low volume seller, and not on the re-engineering budget I guess.

The good news is that internal shorts in batteries, especially good quality deep cycle batteries, are very, very rare. With proper care, feeding and regular testing of your batteries these failures can be brought into the almost non-existent category, unless hit by lightning...
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Old 07-02-2014, 09:15   #82
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Quote:
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Mark,

As I mentioned earlier it is not any differnt. There are literally dozens of scenarios that can cause this exact type of situation.

The Duo Charger is a great device but it is not a panacea for all situations.

I would LOVE to use them to feed windlass banks in the bows of boats but unfortunately they are limited to 30A and when 30A or more is needed by the batts they lock out very quickly. The sample time is very short so they will simply sit there and go ON/OFF/ON/OFF etc. etc. and not effectively charge the bow bank.... For a start battery they are great but they could be better if simply limited to 28A continuous or so and the lockout/reset was re-engineered.

I have been going around on this with the guys at Balmar for many years but this is a low volume seller, and not on the re-engineering budget I guess.

The good news is that internal shorts in batteries, especially good quality deep cycle batteries, are very, very rare. With proper care, feeding and regular testing of your batteries these failures can be brought into the almost non-existent category, unless hit by lightning...
In my humble opinion, a better solution for windlasses (and bow thrusters) is 24 volts, and main battery bank near the center of the boat, in order to avoid a separate bank altogether. Windlasses and, especially, big bow thrusters want the full output of the alternator on top of battery power - and how you you get that if you're running the thruster off some echo-charged separate, and inevitably smaller bank? I'd much rather put up with 7 or 8 meters of cabling, than give up the full force of the whole battery bank, plus full output of the alternator.
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Old 07-02-2014, 10:04   #83
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Re: Danger Warning ACR's

LMAO.

If the batteries had been in parallel for charging with a BOTH switch would this topic have been titled "WARNING, NEVER USE A BOTH SWITCH"?

Or if in parallel, "WARNING, NEVER USE A BATTERY CABLE?
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Old 07-02-2014, 10:19   #84
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Re: Danger Warning ACR's

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LMAO.

If the batteries had been in parallel for charging with a BOTH switch would this topic have been titled "WARNING, NEVER USE A BOTH SWITCH"?

Or if in parallel, "WARNING, NEVER USE A BATTERY CABLE?

Absolutely... A misleading post that misses the point entirely. It has nothing to to with ACRs specifically.

The point is, not to leave your batteries paralleled while off the boat or you run this risk. That fact that an ACR connected them or a both switch is irrelevant.

And when you read what I just wrote, the whole post seems even more silly.

People do leave their batteries paralleled and occasionally this will happen.

Run 2 volt fork truck cells in series if you don't want to have this risk.
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Old 07-02-2014, 10:24   #85
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Re: Danger Warning ACR's

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In my humble opinion, a better solution for windlasses (and bow thrusters) is 24 volts, and main battery bank near the center of the boat, in order to avoid a separate bank altogether. Windlasses and, especially, big bow thrusters want the full output of the alternator on top of battery power - and how you you get that if you're running the thruster off some echo-charged separate, and inevitably smaller bank? I'd much rather put up with 7 or 8 meters of cabling, than give up the full force of the whole battery bank, plus full output of the alternator.
I would tend to agree! Sadly this is NOT how builders ship these boats and I only have to make them work correctly and safely. Owners don't want to reconfigure the entire boat because the builder did things with little fore thought they just want it to work........


Dealing with one right now where the builder installed a 12V Vetus Thruster, 12V windlass and two G-24 batteries then fed them through a diode isolator with 8GA wire from the stern to the bow... Batteries were lasting about 12 months and thruster and windlass performance sucked...... Go figure when the alt was set at 14.1V and the actual voltage at the batteries was barely breaking 13.0V......
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Old 07-02-2014, 13:25   #86
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Re: Danger Warning ACR's

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I would tend to agree! Sadly this is NOT how builders ship these boats and I only have to make them work correctly and safely. Owners don't want to reconfigure the entire boat because the builder did things with little fore thought they just want it to work........


Dealing with one right now where the builder installed a 12V Vetus Thruster, 12V windlass and two G-24 batteries then fed them through a diode isolator with 8GA wire from the stern to the bow... Batteries were lasting about 12 months and thruster and windlass performance sucked...... Go figure when the alt was set at 14.1V and the actual voltage at the batteries was barely breaking 13.0V......

I also agree, there is only one way to do this right and that is to have 24v house battery bank in the center of the boat and to have 24v bow thruster and anchor winch.
You can then concentrate on charging it all properly with a decent large frame industrial alternator.

Otherwise it's..........
Batteries in the bow, echo chargers, batteries a bit flat, what's this wire do, what's this strange box for, 13.9v going in , circuit breakers tripping, alternator overheating, regulator cutting back the volts to keep it cool, long battery cable runs with too small a cable, wire showing between insulation and lug, what's this relay do.
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Old 11-02-2014, 08:16   #87
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Re: Danger Warning ACR's

In 5/6 cases of shorted cells, the temperature sensing will do nothing to prevent the overheating since the sensor only monitors the terminal of one cell. In my only shorted cell experience in 15 years, there was no trouble identifying which cell was shorting, it was quite hot and boiling however the temperature of the adjacent cells was not even painful to the touch. Without a temperature sensor on EACH cell a SINGLE battery will risk boiling and exploding.

It sounds possible that the pressure relief valve failed causing the stress for breaking apart??
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