battery charger wiring

[Bob Gil]

OK now that I have a battery charger (Iota dsl-75) I am wondering if the wiring done as showen in the dirgram below will charger both batteries.

The charger is attached to 1 battery and the cables on the other battery conect to the starter in the exact same places for both batteries. 

Will that charge both of them or just the one the charger is attached to?

[JohnEd]

Me thinks that if you leave that hooked up for weeks you will hurt a battery.  The start should NOT be in parallel with the house.  Install a solinoid BETWEEN the house and start so if you need to you can call the house into play to assist the start......momentarily.  Ideally you should only strap batteries in parallel that were bought at the same time and are from the same manufactures lot number.  Tehy tend to discharge into each other when not connected to a charger.  You can use your charger to charge either bats but not at the same time.  Keep the charger hooked up all the time if it has a float voltage and sw off the converter and having different bats in parallel in the House circuit won't matter so much if at all.

HTH and others will comment...I hope,

John

[fe2_o3]

For what it's worth, I have a similar charger and I wired it to the house batts. I also have a rotary switch that connects the coach to start batt, house batts. or both.  When in the both position it charges both start and house batts. Hope this helps...Cable

[Bob Gil]

at the time they are both starting batteries I donot have any house batteries.

The charger soes have a float charger in it I am hopeing it will keep them both up while i am working with the system so I don't have to charger them aonther way.

Thanks

Bob

[luvrbus]

Bob your batteries are in parallel but in a strange way for most attach the + to one and the - to the other and both will charge with the float working also

[buswarrior]

Looks good from here, Bob!

You can attach the battery charger anywhere that is convenient. At the batteries, at the starter, at the alternator, anywhere you can get the positive and negative easy, the charger will do the job.

happy coaching!
buswarrior

[makemineatwostroke]

Your float option will not work hooking to one battery it will float one battery I have a Iota dsl-75-IQ4 so hook the positive to 1 and the negative to the other or it will boil the water in the first battery   great chargers   have a great day

[JohnEd]

I think Busswarrior is right.  If you hook the charger to one battery and one of the two bats in parallel starts to boil you have problems.  Maybe the bats being way different in age would cause that but it shouldn't happen if all connections are good and the bats are matched even close.  Then on the other hand, Luvr and 2Stroke are not rookies or stupid either one.  I'm confused now.

John

[Sojourner]

Being they are starter battery as a unit...you can charge both batteries at the same time and read on....

However, you must hook positive charger to #1 battery + post and hook the negative charger to #2 battery - post. The reason is to equally spread the resistance load of the starter's cables while being charging.

Other wise you will under charge one of two batteries according to your wiring schematic. Or charge one battery at a time if you don't follow the above direction.

All parallel batteries hook up to starter and charger as per attach picture of parallel batteries connection.

FWIW

Sojourn for Christ, Gerald

[JohnEd]

Gerald I have no doubt of your positive intention or sincerity.  My understanding of "tricity" leads me to doubt your procedure.  My experience says you may be compensating for anticipated deterioration in t5he quality of the connections in the bat circuits.  I don't know.  If that is in fact the case this some sweet piece of news cause the "need" to hook up that way is not intuitive to me at all.  On the other hand I am sure that connecting as you have suggested will have no harmful affect.  Does anybody have a technical explanation for the need for this procedure?

Thanks,

John

[gumpy]

Yeah, what Sojourner said.

I tried to write a technical explaination, but realized I don't know the technical terms, but basically it has to do with the charger making a circuit between it's positive and negative leads. If you hook it to a single battery, that circuit only includes that one battery. The remaining batteries only get charged by way of the little lectrons flowing from the high state battery to the low state battery through the interconnecting cables, whcih results in lower voltage and current.

If you hook it up the way Jerry says, the circuit includes all the batteries and they all become a single battery at the same voltage and current. Note that the interconnecting cables could restrict the charge current if they are too small.

Techincally, if you hook them up the way Bob shows in his diagram, it would charge, eventually. It might cause the battery you hook the charger to to boil, while the second battery might be undercharged. If you hook them up the way Jerry shows, it would be more efficient, and all batteries will get an equal charge if the interconnect cables are sized properly.

[Len Silva]

Gentlemen,

Gerald's solution is probably the best from a theoretical  standpoint, but practically it makes no MEASURABLE difference how the parallel battery/charger/load are connected as long as the interconnecting cables are of adequate size.

Actually, the connection shown below would be the best assuming that all the connections from the batteries to the junction were exactly the same length.  It really makes no real difference whatsoever if the cables are adequate and the connections well made.

If you have one battery in a parallel string that is boiling, it is a bad battery.

If in Bob's situation, that batteries are 20 feet apart, that's a whole different discussion.

[makemineatwostroke]

Well guys I can tell you one thing Lifeline replaced the first 8D in my battery bank 4 times because of over charging ( would swell and blow the valve) the Iota charger was hooked to the first battery in the string and the electronics in the charger would not read it properly.Iota and Lifeline hooked it + to the first battery and - to the last battery and no problems since.It was a blame game between the 2 for about 2 years.If it is not clear to Bob I suggest he call Iota the manufacture that made the charger this is not your Dads charger made in the 50s and 60s.Solar chargers will do a number on the first battery in a bank if hooked up to one everyone does it their way  have a great day

[Len Silva]

Well guys I can tell you one thing Lifeline replaced the first 8D in my battery bank 4 times because of over charging ( would swell and blow the valve) the Iota charger was hooked to the first battery in the string and the electronics in the charger would not read it properly.Iota and Lifeline hooked it + to the first battery and - to the last battery and no problems since.It was a blame game between the 2 for about 2 years.If it is not clear to Bob I suggest he call Iota the manufacture that made the charger this is not your Dads charger made in the 50s and 60s.Solar chargers will do a number on the first battery in a bank if hooked up to one everyone does it their way  have a great day

I am not doubting you, just trying to understand it. If the straps and connections between the batteries are the right size (I'm using 4/0) then they are essentially 0 ohms. When you were having that problem did you ever measure the voltage at each battery to see if there was a difference?

As a matter of fact, I did wire my batteries as you suggest because it assured the same load in each strap and it happened to be convenient at the time.  I still can't understand how it would affect charging.

Len

[JohnEd]

Len,

You ARE correct.  If all the wires are of adequate size they will not drop voltage and if all the connections are good they won't either.  What the others are trying to prove is that you have significant, and "different" voltage drops across a couple feet of WIRE.  You can prove the folly here by looking up the resistance of 0000 cable by the foot and assuming that the connectors are resistance free.  If they carry the chargers 25 amps their will be the same voltage in the entire + or - circuit within a hundredth or thousandth of a volt.  The other assumption is that the internal resistance of all the batteries in the parallel bank is equal and that they "all" charge at not only the same rate but to exactly the same voltage when full.

Gumpy,

I am certain without doubt that you corrected the problem by resolving the symptom.  You are one of the greatest guys for creating your site and sharing your experience and joys with the board.  I have spent many an hour learning from you and to my distinct advantage as I didn't need the harsh teachings of failure and experience to gain the knowledge.  You did resolve your problem but I think you now have a system that isn't working as well as it could.  The up side of that is that you may be missing only a small fraction of a volt or a few amps. without consequence.  What is probable to have been the problem, after you verified that ALL the connections were perfect, is that there was a difference between the battery that boiled and the rest of the bats in the bank.  Maybe the others were from the same mfr run and the "odd" bat took the hit and that position continued to get trashed until you got a bat in that position that  had a match to the others.  For me, the up side here is that you solved the problem.  Lets see now, you had the "elephants" involved....hmmmmm .....They were confused and finger pointing... hummmmm..you finally resolved a problem that was destroying batteries that confused every mothers son involved?....HUMMMM.  How did you do that again?   Thanks Gumpy.  I would have fought your solution cause it flies in the face of what I know about simple "DC Circuit Analysis" and I taught that subject.

John