Battery Question

[rssnape]

So I installed two buss bars, a 200 amp fuse, and a battery disconnect. I installed 3 group 31 batteries to replace the 4 old batteries. Although I couldn't fit 4 of the 31's in I gained about 80 amp/hrs over the 27's.
Got the batteries wired correctly for even charge and discharge, as well as easy access to the caps for watering.

Pictures are before and after


1997 Tiffen Allegro Bus 37', Cat 3126

[Thor Man]

Where did you get your bus bars? They look like maybe Blue Sea.

[chboone]

Now all you need to keep the batteries full is a Flowrite Battery Watering System. I have it on my coach and chassis batteries, very simple to keep batteries topped off. The link is a double set for 12V, you will need a single set and the hand pump.

Flow-Rite MP-2000 12V Double Battery Watering System

[rssnape]

Originally Posted by Thor Man

Where did you get your bus bars? They look like maybe Blue Sea.

Buss bars are Marinco. As is fuse and disconnect.


1997 Tiffen Allegro Bus 37', Cat 3126

[garymunson]

Far better to have two 6V batteries connected in series. When you connect batteries in parallel, as they age, one begins to hold less charge than the other and you get a current flow between the two as the better battery discharges into the weaker one. This means the charger will be continually having to try to keep the two charged. This will boil water out much faster.

[twinboat]

Some information about parallel batteries, from Yandina.com


Q Can I parallel different size batteries within one bank? A Although the standard recommendations are not to mix old and new, good and bad, big and small, etc., you should understand the reasons and make up your own mind.


The truth is that you can parallel just about anything. The downside is, if they are not matched, one battery (the newer) will tend to carry most of the load and the total capacity will be slightly less than the sum of the individual capacities. The one with the lower internal impedance will tend to take more of the load. If your new battery has a capacity of 100AH and the old one still had 45AH, then in parallel you will get something less than 145AH, but it will help and it will work.

When the old one eventually DIES, it will drag the new one down but this happens whenever two batteries are in parallel and one dies, the only difference here is it is going to happen sooner than it would had they both been brand new. So big deal, you gained some residual use out of the old one and the new one will not be permanently damaged - just charge it up again.
The bottom line is the batteries in parallel provide more power - never less - than either one on its own - it just may not be the "ideal" way to do it.


Q Won't the smaller battery get overcharged if put in parallel with a large one?

A The whole process of charging batteries in parallel is naturally self regulating, naturally governed by terminal voltage and current flowing through the internal equivalent resistances. For simplification, each battery can be considered as a perfect battery that holds the charge combined with a series resistor representing the internal resistance, and a parallel resistance representing the self-discharge leakage current.

Lets say you have a charging source dumping out say 100 amps. If you have 4 batteries in parallel sharing this source the distribution of the charge current is governed by those internal voltages and internal resistances. From Ohm's law, the charging current that flows into each battery is the voltage divided by the resistance. In this case the voltage is the charging voltage arriving at the terminals minus the actual internal voltage divided by the series resistance of the battery. A discharged battery is going to put a larger voltage differential over the internal resistance so more current will flow to it. A charged battery is going to put less voltage drop across the internal resistance so it will take less or none of the available charging current. A large plate battery which has a correspondingly lower internal resistance will demand more current because of this lower resistance. A small motorbike battery in parallel will have a high internal resistance and demand very little current.
All these demands for current result in a common voltage on the parallel circuit which is what the alternator or charger sees.

None of the batteries will ever be "overcharged" as a result because the charging voltage is controlled. Even the smallest battery will only be seeing the same voltage so it is like the other batteries are not there. If you suddenly removed all the big ones and left just the tiny bike battery on the 100 amp alternator, the voltage would immediately rise because the amps trying to flow into the tiny battery have to pass through its internal resistance which is high. But instead of the voltage or current going to an excessively high value, the regulator in the alternator cuts the current back to a level that limits charging to a safe level.

Good infomation

[TQ60]

Yes you can mix battery types as long as tech is same as voltage.

It is best for matching units though.

12v floaded with (2x6 floaded) okay but 12v floaded with 12v agm no.

The charging system expects one good battery. (6 in parallel is one battery....look it up)

However if one cell SHORTS then it pulls all of them down and the charger gets a little funny too.

If doing series (2x6) then it takes out the other one.

So for repair for short term in a multiple battery plant remove the bad one until the rest can be evaluated and if they are all good replace bad one with exact same.

Best to replace all but may not be needed.

[rssnape]

Originally Posted by garymunson

Far better to have two 6V batteries connected in series. When you connect batteries in parallel, as they age, one begins to hold less charge than the other and you get a current flow between the two as the better battery discharges into the weaker one. This means the charger will be continually having to try to keep the two charged. This will boil water out much faster.

I wanted 6v batteries, but all of them that I looked at with a desirable capacity were taller than my in floor battery bay would allow. So I was stuck with the 12v.


1997 Tiffen Allegro Bus 37', Cat 3126

[cbilodeau]

Originally Posted by rssnape

I have a battery bank with 4 12v flooded batteries. They are charged with a 3 stage charger. I have already scolded myself for being in attentive. I checked one battery and there was adequate fluid. I was in a hurry and didn't check the others.
I finally checked all 4. 2 were severely low on water, the other 2 were fine. What causes this situation? Why are they not all low on water?
Thanks
Battery Killer ��


1997 Tiffen Allegro Bus 37', Cat 3126

I had the same problem on my Pace Arrow Vision 1999 F53. My 3 stage charger was not in fact a 3 stage charger. It is a Progressive Dynamics PD9100 charger (Inteli power PD9155). I had to purchase the PD9105 Charge Wizard (30$) to make it a 3 stage charger. It connects above the fuses.

Now my batteries never needs water.

[rssnape]

Well the engine batteries were 7 yrs old and giving a few headaches so I replaced them as well along with 4 new terminals to insure excellent connections.



1997 Tiffen Allegro Bus 37', Cat 3126