I'm uncertain were to place this one.

This is a hypothetical question:

I have 4 car batteries (12 vt dc) and one charger. is it possible for me to hook up all four car batteries to the charger at the same time to were all 4 batteries will be charged simultaneously?

I would assume it is possible, but would take a longer time to charge all the batteries as compared to one.

If it is possible, could your briefly describe how I would hook them all up?

Thanks

David

Dave:
While what you discribe is certainly doable (And in fact done in numerous industrial & other applications) this isn't something I'ed try with regular components.

Below is a diagram of how this would be connected.


Only drew three batts. but the idea stays the same for additional.
(PLUS to PLUS & MINUS to MINUS)

Again I wouldn't try this, you could have one nasty explosion if anything went wrong.

Regards Mike b. (AKA Byter)

I agree with my learned friend, Byter. I would not do it.

Beside the potential for explosion, let's consider the following.

1) Let's assume that these batteries need some charging. If each battery pulled 5 amps, the total of the 3 picture would be 15 amps. you would need a 15-20 amps charger. The more batteries, the more draw.

2) If one of those batteries had a bad cell, or just wasn't up to par with the others, it would pull all the charge from the charger as well as pull the charge from the good batteriers. If I were going to try this, I would add a rectifier on the supply to each battery. This would stop the reverse flow from the good batteries.

All this is assuming that these are the same size batteries.

Industrial charges that are made to charge more then one battery have safeties built in.

I would buy several small charges, one for each battery. You will have less problems and you will charge faster,

And for safety sake, whether charging 1 battery or 10, there is always the possibility of explosion from the hydrogen gases and a spark. Remember the Hindenburg. Every year I hear of someone injured just jump starting a car.

Always charge in a well ventilated area. Turn power off before disconnecting charger leads from battery. Wear proper safety equipmemt like a full face shield.

In my experience most electric substations and power plants have station batteries to supply D.C for trip coils on circuit breakers. The purpose being to allow breakers to be tripped in the event of power failures so that they are open when poweer is resumed. In those cases 60 lead acid cells each capable of supplying 2 volts, are connected in series to furnish the 120 volts needed for the trip coils. A generator or rectifier source of power charges the batteries in series and the rate of charge is current controlled. I see no reason why if your charger is capable of supplying 55 or 60 volts, you coudn't charge them in series. As the batteries charge the current will decrease and the most fully charged battery will limit the current through all of them. Do any of you see a problem with that? I'm even older than Donald and out of the business for 15 years, so I'd welcome any comments.

To DvdGStart:

To your question, I concur with Byter & Walks-on-Water. Don't try to charge them up all at the same time.

However, you can charge one battery at a time. If the batteries are not too drawn down in charge it will probably take no more than an 60-to 90-minutes a piece to charge each of them.

To Frankvan:

Hi Frank. Long time no talk.

Like Byter said, the Series method is doable, & I must say, I have never done this myself. I'd leave this method to the professionals not to any amateur.

However, I would be concerned if there were one bad battery in the bunch that would draw a heavier current initially & possibly damage the other batteries until the current was limited by the other batteries.

Also, I believe the Charger that DvdGStart is probably talking about is only capable of providing 12-volts to the battery(s) & whatever nominal current is required to charge a car battery.

[This message was edited by donaldekliros on 02-05-03 at 07:42 PM.]

Hi Donald,
On second thought, I guess it assumed facts not in evidence on my part. For one thing the method I was talking about assumes a station control collection of identical cells, which would normally be kept on a floating charge of a few amps, and an occasional discharge and equalizing charge. I know David is a pretty bright guy, but I really don't know what kind of batteries he has or what kind of charging equipment; so it is probably wise to stick to less esoteric methods. There are too many horror stories involving automotive batteries. I'm just happy to find an actual electrical question now and then and compare notes with you occasionally.

Hi Frank; Also glad to see you around.
When I was with Lockheed our Main substation breakers were powered as you say. A bank of 10 12 volt batteries to provide ~120VDC to the trip coils and spring recharging motors of the 4160 VAC breakers. Both the batteries & charger were of special construction but they still gave me the willies.
I think I was more wary of that battery bank then being around the 4160 !

Mike b (AKA Byter)

Hmmm.

Alrighty then, lets change the idea and say I wanted to hook up the 4 12 volt batteries to charge of my alternator (in my truck) when I am driving around. Would this too include the possibility of explosions?

Thanx All for your input.

David

David,
Your alternator puts out a voltage around 13-15 volts or so so you would have to connect the 4 additional batteries in parallel with the existing truck battery. That would mean that the alternator would have a load of five batteries . You realize that the batteries are not always charging, when your headlights are on, the radio is playing and your idling at a stop light, the battery (batteries in this case) are carrying the load of any electrical equipment that is in use. Alternators come in different amperage ratings depending on the vehicle electrical load. I believe there are too many variables in this case to predict what kind of results you could expect; how much driving you do in the daytime vs night time, etc. I doubt that the danger of explosions would be any greater than under normal circumstances. They usually result from “hot shot” attempts and sparks around a gassing battery.
I would think the best thing to do would be to try it and see whether or not the results suit your need. Well see what the other guys have to add or disagree with. I know the alternators are equipped with voltage regulators and I would expect (?) current regulators as well. If not you would have to provide a fuse in line at the rating of the alternator. As Donald points out, the condition of the 4 batteries would enter into the equation. What do you use them for, is one more likely to be completely dead and the others fully charged, etc. Ideally they shoud be charged AND discharged together.

I realize this was posted about a month ago, but heres my 2 cents...

GOLF CARTS: They use many batteries and all are charged at once.... See how one is wired up and follow that....

donaldekliros used the term "in series" with the description at the top of this page. The diagram is shown "in parallel".

In series would produce a 36 volt current with the same reserve amp rating as one battery, assuming these were 12 volt batteries.

In parallel would produce 12 volts with roughly triple the reserve amperage/hour capacity.

I used to be a battery salesman for Interstate Batteries.

quote:

---

Originally posted by K.K.:
donaldekliros used the term "in series" with the description at the top of this page. The diagram is shown "in parallel".

_In series_ would produce a 36 volt current with the same reserve amp rating as one battery, assuming these were 12 volt batteries.

_In parallel_ would produce 12 volts with roughly triple the reserve amperage/hour capacity.

I used to be a battery salesman for Interstate Batteries.

---

No, Donald was referring to the fact that series charging was feasible, not to Byter's diagram. Trust me, Donald is well aware of the difference between series and parallel connections, etc.

Don't know if this will help, but here goes- I have three 12 vdc batteries, all three the same size, 600cca-750mca (don't think all three are the same condition). Wired in parallel on my boat. They are charged by the 12volt marine alternator(simalar to the truck alternator). It seems to work fine. Any one see anything wrong with this set-up??? Anyone see anything right with this set-up???

As long as there is some means of limiting the current drain or load on the alternator: a fuse, circuit breaker, or current regulator, I see nothing wrong with the set-up. If all three batteries are discharged there is the possibility of overloading the alternator, otherwise. Welcome to AP, neighbor!

Thanks for the advice and the welcome.

that setup above works very good regarless of what everybody says your ok with four or more batterys hooked up to charge. and if you all dont agree then you need to look at my desil truck and explain why there are four batterys hooked up and only one (note i said one ) alternator (hummmm )they charge up just fine and dandy. i worked at a shop and that was the means for keeping all the baterys charged up. just have to keep an eye on the ones that have dead cells and remove them

thanks for your replies!