Mixing batteries

[halcyon]

Re: Barking, completely barking....

Think mixed up is more accurate.
It is continuous as in 24 / 7, and intermitant as in running engine.
Thus 13.8 volt is for 24 / 7 charging from the mains, and 14.7 ( I think ) volt was for intermitant charging as in engine.
Complicated answer to a simple question.


Brian

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[pvb]

No, that\'s not what Bedouin said...

Read his posts again.

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[halcyon]

Re: No, that\'s not what Bedouin said...

I have been reading this post for 6 days now, read every word, have you?, spent time researching Red flash web site, even tried helping a number of times, the problem is trying to get a dialogue going.

Brian

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[pvb]

Yes, Brian...

Yes, Brian, I've done all of that. And I find it mightily annoying when the sound, carefully researched advice I've given is rubbished by Bedouin when there's no basis for doing so, other than (it seems) personal animosity. Bedouin has misquoted me, used anonymous hearsay as "fact", and twisted the real facts. As you know only too well, there are lots of people out there in boatingland who don't know much about batteries/charging/etc, and we should try to help and educate them through this forum, not confuse them by making lunatic scaremongering assertions such as "a higher charging voltage than 13.8V...would fry his batteries". But then I've only been working with boat electrics for 30-odd years, so maybe I'm not the best qualified practical boat owner to offer advice here. Rant over.

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[halcyon]

Re: Yes, Brian...

Fully agree, I've only been designing them for the same length of time, gets one most frustrated. Though I do find it useful, as in researching Red flash, you learn that there is nothing to learn about them, but it's a bit more gen for the file.
Back to earning a crust.

Brian

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[bedouin]

Put up or shut up

But for all the abuse I've suffered - neither of you has pointed out any problem with the system I proposed or any simpler system that would achieve the same result (i.e. maximum usable capacity with minimum engine time).

Stop sniping and come up with a better proposal...

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[halcyon]

Re: Put up or shut up

Been trying to answer your statement

There are two things about recharging the Red Flash that concern me. Firstly my domestics are el-cheapo flooded lead acid - which means they can be charged at 14.8V and the electrolyte topped up as required. No sealed battery will take that voltage.

Secondly, starting the battery takes very few Ah out of the starter battery, and that charge is probably put back within 5-10 mins. Even if I were to reduce the charging voltage to 14.4V I am still not convinced that the Redflash would be happy having 14.4V applied in its fully charged state for hours on end.


But if you do not want to listen.

Brian


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[halcyon]

Re: Put up or shut up

Forgot to add I've shut up.

Brian

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[bedouin]

Re: Put up or shut up

No - you're EXACTLY right - and if you check back to the relevant posting you will see that that is the point I was making before pvb threw his toys out of the pram /forums/images/icons/smile.gif

I believe that in order to use Red Flash alongside El Cheapo Flooded batteries I need an independent charging control on the Red Flash in addition to the alternator controller. In an earlier posting I was suggesting the use of controllers aimed at high-powered solar banks as an appropriate "off the shelf" technology.

Yes I know it is a complicated solution, but it is the best I can come up with without taking out my soldering iron...

In contrast pvb seems to recommend a standard alternator and a VSR!

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[pvb]

One last time, very slowly...

Will (bbilly) has told us he has a Volvo inboard with a standard alternator. He doesn't have a smart regulator fitted, just the standard alternator regulator. His alternator voltage is unlikely therefore to exceed 14.4volts.

DMS Technologies (the European distributor for Redflash batteries) say that, during charging by the alternator, the voltage supplied to a Redflash battery should be between 13.9 and 14.7volts.

Will's charge voltage is therefore within the limits set by Redflash.

That's why I said there's no problem using a Redflash with Will's alternator.

If anyone still doesn't understand this, just email DMS at info@dmstech.co.uk and ask them. Remember that they are covering the battery with a warranty, so they won't condone anything which would damage the battery.


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[bedouin]

Re: One last time, very slowly...

I fully understand what you are saying , and wouldn't argue with the facts, but I emphatically do not agree that that is the best solution to his problem.

IMHO, the most important part of solving the battery capacity problem is to fit an advanced alternator controller.

I assert that my approach of fitting an external battery sensed alternator controller greatly increases (i.e. almost doubles) the usable capacity of the battery bank in practice as well as reducing the amount of time I have to run the engine to recharge.

Which bit of that do you disagree with?

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[halcyon]

Re: One last time, very slowly...

OK I'll bite, were is the evidence in your statement:-

I assert that my approach of fitting an external battery sensed alternator controller greatly increases (i.e. almost doubles) the usable capacity of the battery bank in practice as well as reducing the amount of time I have to run the engine to recharge.


Just trying to carry out a logical discussion

Brian

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[bedouin]

Re: One last time, very slowly...

My understanding is that charging at 13.7-13.8V will only charge a battery to about 80% of its capacity whereas at 14.4-14.8V will get it to 100%. Similarly it is recommended not to discharge a general purpose battery below 50% capacity otherwise the life of the battery will be reduced. Hence adding the fast charger will increase the usable from about 30% of rated capacity to 50% of rated capacity.

Also going to 14.8V means you can chuck the Ah in much faster than you can at 13.7V

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