Charging batteries in series with 20 amps

spec said:

You have also just made the case for individual chargers.

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Hardly.

Batteries are not built to serve the purpose of making a perfect battery charger. They are built to serve the purpose of powering a load. The recharging is just an unavoidable secondary effect to powering said loads for the least cost and physical work as possible.

Regardless of what some think, batteries are a consumable. They wear out no matter how well you take car of them and at some point cost of maintenance Vs operating cost comes into play.

Di-ionized water is better for batteries than distilled.

tcmtech said:

Hardly.

Batteries are not built to serve the purpose of making a perfect battery charger. They are built to serve the purpose of powering a load. The recharging is just an unavoidable secondary effect to powering said loads for the least cost and physical work as possible.

Regardless of what some think, batteries are a consumable. They wear out no matter how well you take car of them and at some point cost of maintenance Vs operating cost comes into play.

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That's a good speech tcm.

spec

KeepItSimpleStupid said:

Di-ionized water is better for batteries than distilled.

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It is very rare to have batteries that can be filled in the UK; most are now the sealed type. The battery on my automobile is now 13 years old and still going strong. I hope that saying this is not the kiss of death.

This is a genuine question though: what exactly is deionised water as opposed to distilled water?

The wife's delux iron got badly furred up, so after cleaning it out with citric acid- you should have seen the cludge that came out- she now uses deionised water and it is a different iron with no further problems.

spec

spec said:

This is a genuine question though: what exactly is deionised water as opposed to distilled water?

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They are the same, except that one is made by distillation and the other by deionization and might have slightly more dissolved ions than distilled. Same water obtained through reverse osmosis would probably be called deionized as well since there is no distillation in the process.

spec said:

That's a good speech tcm.

spec

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It had to be said. There seems to bee too many people in this world who have their priorities out of order or just plain backwards when it comes to what should be obvious concepts to understand.

The guy had a 36 volt 200 Ah system with a charger that could more than likely bring them from deeply discharged to full charge in ~10 - 12 hours ( standard overnight charger) but decided to replace it with six smaller smart chargers that will now take some 60 - 80 hours ( full three day weekend chargers) to do the same job.

Seems like a pretty obvious step backwards in the overall usability of the machine they power.

But hey, At least now that the machine can only be used for one day out of every four to four so yea the batteries should last much much longer time wise.

Hy SimomTHK,

Your old arrangement was charging each battery at 24A and your new charger will be charging each battery at 4A, which means that the batteries will take six times longer to charge. But having a charger for each battery is a much better arrangement because the voltage across each battery is controlled independently according to the needs of each battery.

If you are not worried about the long charging time that is fine. The batteries would be very happy about such a light charge. If you want a fast charge, six 20 Amp chargers would be ideal.

spec

Just in case you haven't read this thread the above is what I said in post #4 of this thread.

You are making sweeping statements and circular arguments and talking about talking and not sticking to technical matters. Why I do not know.

spec

kubeek said:

They are the same, except that one is made by distillation and the other by deionization and might have slightly more dissolved ions than distilled. Same water obtained through reverse osmosis would probably be called deionized as well since there is no distillation in the process.

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Not exactly, DI water is reactive. Distilled or ultra-pure water is run through a an electrically charged resin to make DI water. A mixed ion exchange bed with both positive and negative charged resins ( H+ and OH-) is used convert cations and anions in the water to H2O.
Distilled water is not totally pure. It still contains lots of ions. If you let DI water sit exposed to air it will react to the carbon dioxide and drive the pH from 7 to below 6 quickly.

spec said:

I'm not sure what you are saying here. If you charge a battery at a constant current of say C/10 and pay no attention to the battery voltage you will either boil off all the electrolyte or the battery will explode....

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You made it sound like that the only important control parameter to be considered when charging LA batteries is voltage.

I am pointing out that controlling charging current is what is important during the initial step of the three-step LA charging process, during which the battery voltage is constantly increasing from 1.75V/Cell to 2.15V/cell. The current is the controlled parameter during this phase, either to prevent it overheating the battery, or blowing up the charger... Say it another way, the charger acts like a constant-current source during this step. Current is the independent variable; voltage is the dependent variable.

In the case of the Lester 18 cell golf-cart charger, it is current-limited to about 30A if connected to a badly discharged battery bank. This is due to the way the transformer is made (core saturation?). As the battery climbs toward ~39V during the charge cycle, because of the transformer turns ratio, and the resonant secondary winding which bucks the primary winding, the battery charge current drops to about 5A. The timer in the charger cuts off charger after about 4hours after the battery voltage reaches ~39V. The timer period controls how long the battery string is equalized by the 5A current. During this final timed period, the battery voltage climbs north of 42V.

The Trojan T105s used in the golf cart industry have a large electrolyte reservoir above the plates. They are made to evolve gas during the latter part of the charge cycle. They do need to have water added ever few weeks to months...

I think the TS's problem is that he is mixing old batteries with new batteries. In golf carts and other electrically powered vehicles, it is bad practice to replace individual batteries. You get much better results if you replace the entire string with new batteries at the same time...

What is with, 'you make it sound like'. Either I have said that the only thing important with charging lead acid batteries is voltage or not. If so please quote me in full context.

I did not state or imply that the only thing with charging lead acid batteries is voltage.

But you said that the only thing that is important in lead acid charging with on particular approach is current and you have now changed that to include voltage which is my very point.

The OP's question and problem is quite clearly stated ie serial charging does not work with his batteries.

You have once again described why charging batteries in series is unwise.

Basically serial charging wrecks the batteries and as I have said many times now is only used for cheapness.

An "equalizing phase" sounds very technical but it hides what is really going on, ie forcing current into the batteries that they do not necessarily need and hence stressing the batteries and causing gassing, both of which shorten battery life, although according to some parties that does not matter.

In conclusion, how anybody can claim any merit for serial battery charging, apart from low cost and convenience, is beyond me. Technically it is an abortion.

spec

spec said:

...
You have once again described why charging batteries in series is unwise....
...how anybody can claim any merit for serial battery charging, apart from low cost and convenience, is beyond me. Technically it is an abortion.

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Funny, since about 60,000,000 automobiles built in the last decade charge six cells in-series using a single charger (the alternator).

MikeMl said:

Funny, since about 60,000,000 automobiles built in the last decade charge six cells in-series using a single charger (the alternator).

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Hardly the 'last decade' - in the last century or so, and a much greater number

MikeMl said:

Funny, since about 60,000,000 automobiles built in the last decade charge six cells in-series using a single charger (the alternator).

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As I have said already the fact that standard batteries comprise N cells in series is unfortunate but at least the cells are more likely to be matched to a degree. And the batteries in automobiles are charged with a voltage source anyway.

I cant see anything funny neither can I see what you are trying to say. Are you suggesting that because batteries are constructed of multiple cells that it would thus be a good approach to further compound the problems by connecting more cells in series, especially as the OP has already had problems with charging his batteries in series.

spec

What I am getting out of this is the big picture of what the batteries are used for (never had been said has it? Current draw, run times, typical depth of discharges, that sort of stuff either.) is being ignored and the TS is focusing on the individual charging characteristics of each battery instead.

In an ideal condition every cell would have its own dedicated charging and data logging system but in reality, unless they are some huge highly specific application batteries, it's not warranted let alone a rational or financially valid concept to be concerned with.

The problem is even if every cell is ideally optimized being they come in groups of three, which when one battery goes bad and is replaced its set of three cells now no longer matches the other 15 in the group it screws up the stability, performance and overall working characteristics of the system, which again regardless of whether everything is charged one cell at a time or all 18 in series, there is an unavoidable and unfixable mismatch in the overall sets individual Ah capacities between cells that can not be fixed with any type of fancy charging system hence the rule of when one battery goes bad in a set all batteries get replaced even if 5 out the 6 are still testing as acceptable.

Given that the only way to optimize things with used and newer batteries is to thoroughly test each one to find its exact present Ah capacity and match it to other batteries with near identical Ah characteristics to work as a properly matched group and if there are no other spare batteries to use that test with matching capacity characteristics you're SOL!

BTW, presently there are about 80 million vehicles being built per year now not 60 million per decade. https://www.worldometers.info/cars/ was someone pulling numbers out of their butt again?

If your flooded Pb-acid batteries are not of the sealed type, but the ones which you replenish the water, get yourself a battery specific gravity meter, like this one:

https://www.delcity.net/store/Batte...p_kw=&mp_mt=&gclid=CPPkjsech84CFc1Zhgod2AIIpA

Some theory behind specific gravity measurement:

https://engineersedge.com/battery/specific_gravity_battery.htm

A note about safety: when working on flooded cells, always carry with you some household sodium bicarbonate to neutralize acid spills.

schmitt trigger said:

A note about safety: when working on flooded cells, always carry with you some household sodium bicarbonate to neutralize acid spills

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You can also mix a teaspoon of it with your distilled water and drink it if you ever get into a pedantic debate over how to charge your batteries, whilst totally ignoring the discharge and general working cycles (IE, primary battery damaging actions) and their effects on said batteries, that end up giving you heartburn.

tcmtech said:

You can also mix a teaspoon of it with your distilled water and drink it if you ever get into a pedantic debate over how to charge your batteries, whilst totally ignoring the discharge and general working cycles (IE, primary battery damaging actions) and their effects on said batteries, that end up giving you heartburn.

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You are being reactionary TCM.

This is a technical site not a site for unwarranted snipes.

spec

spec said:

You are being a bit childish TCM?

This is a technical site not a site for unwarranted snipes. Leave that to the ladies.

spec

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So you disagree that a bit of baking soda in water is not good for heartburn?

tcmtech said:

So you disagree that a bit of baking soda in water is not good for heartburn?

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TCM don't get me wrong. You are very knowledgeable person with a load of practical experience and some great ideas and I often learn a lot from your posts. But you do seem to get a bee in your bonnet about certain things and I can't see why.

spec

Best chargers will be 3 stage with temperature compensation.
1.CC mode fast or normal
2.CV mode temp compensated with decaying current.
3.CV float mode end of charge
premium chargers will have desulphation pulsers across the string
We used ti make similar to these and I tested how motive power cbatteries for plane tractors improved in a week from mismatched S.G. with this applied to charger. https://www.batterystuff.com/battery-restoration/36-volt/OBD-36.html