Get the Cole Hersee switch they last forever, that being said if you get a different one make sure you can switch between the batteries without going to both. Some of the cheaper switches make you pass thru both when going between 1 or 2 this sucks if one of the batteries is dead.
Never ceases to amaze me the wrong info from people that don't have the foggiest !
Batteries in parallel do NOT have to be the same capacity, not even close !
They do have to be the same voltage,....DUH,..and when you series a pair of 6v batts, it becomes a large 12 v battery, and can be paralleld w/ any other 12v battery of the same chemistry.
And yeah, I'm a RV battery expert !
So, believe whoever you want.
Rich
'98 Flair, 454, Onan Microlite 4k, Intel PD 9155 w/ wizard, Sta-power 1500 watt Inv, 2 6v batts, ammeters, KingDome/sat, Oly Catalytic Heat, hauling 2 Bent Bikes and sometimes towing a Tracker F&S boat.
I certainly appreciate the advise from the Battery Experts on this forum (like Rich) and would take their word over many other less knowledgable posters.
Myself, I would still install the A /B / Both switch. Not because it is necessary, but because I would prefer doing it that way. For me it is like having 2 LP tanks, with a switchover device. As a bonus, it makes it easy to isolate either component if there is a problem.
Since there is a "both" position, it is possible to use it that way if desired.
Well, it seems that the majority vote for the idea is positive, I will go ahead and do it - with the "300A Compact Battery Switch - Off/1/Both/2". (I mainly need it to disconnect the battery bank when I store it - if I can do it with this switch, I still have to look at the specs).
Thank you all for your advices and the useful info.
Isaac
Ford PSD, F350 Manual 4x4 CC SB, Firestone Ride-Rite, Rancho 9000, AIS air filter, ARE shell, Hensley hitch, Prodigy BC.
Old rig- 1999 SunnyBrook 30FK TT.
New rig- 2007 New Horizon 33f TT.
Mont G&J wrote: Batteries connected in parallel should always be of the same type, rating, manufacture, and approximately the same age. Connecting dissimilar batteries may produce undesirable or even dangerous results. Jack
Explain just how that can happen please.
Then I'll gladly tear your explanation apart for you.
Another good thing about a battery switch is you can use it as a disconnect like you want. Also if you run on battery bank 1 and kill it you can just switch over to 2 and you are good to go while charging the others. This setup has got me home on the boat more than once. Definition of and expert is a guy from out of town with a briefcase, at least on boats it is.
It has been my experience of 70 plus years, that when someone proclaims himself to be an expert on a subject you can disregard everything else he says.
For those of you that think you already know everything about batteries and don't want to bother clicking on the link, I've added some quotes from the information below.
"If more ampere-hours are required, you can connect two (or more) new and identical 12-volt batteries in parallel. You can also connect two larger new and identical six-volt batteries in series by attaching the negative terminal of the first battery to the positive terminal of the second battery. If you connect two 12-volt batteries in parallel that are identical in type, age and capacity, you can potentially double the total capacity. If you connect two that are not the same type, you will either overcharge the smaller of the two, or you will undercharge the larger of the two.
The recommended parallel and series connections are as follows:
When connected this way, the batteries will discharge and recharge equally. When connecting in series or parallel and to prevent recharging problems, do not mix old and new batteries or ones of different types. Cable lengths should be kept short and cable must be sized large enough to prevent significant voltage drop; there should be a maximum of 0.2 volts (200 millivolts) or less drop between batteries."
Mont G&J wrote: Batteries connected in parallel should always be of the same type, rating, manufacture, and approximately the same age. Connecting dissimilar batteries may produce undesirable or even dangerous results. Jack
Explain just how that can happen please.
Then I'll gladly tear your explanation apart for you.
Please read my above post, and then give it your best shot. Jack
Mont G&J wrote: If you connect two that are not the same type, you will either overcharge the smaller of the two, or you will undercharge the larger of the two.
First you said "When someone proclaims themselves to be an expert you can disregard everything they say.. And then you quote an self proclaimed expert.
This is, in fact, the standard claim I hear about non equal size batteries in parallel.. I want you to tell me how this happens
I often tell people that electricity and water are a lot alike And they are. Electricity, like water, "Seeks its own level"
Imagine two water tanks, one holds 100 gallons and one holds 50, You have a 4 inch pipe connecting the two, at the bottom, both tanks are the same height and are sitting on the same level This is just like having a gorup 31 battery next to a pair of U-220's or T-105's by the way
Now you start filling the tanks using a 1" water line
(Recall the connecting pipe is 4")
Which tank is going to fill first?,, Are you going to over fill one and under fill the other?
Answers: Both tanks will fill together as the cross over pipe only has sixteen times the capacity of the fill pipe. And both tanks will be exactly the same level of "Fullness" as water seeks its own level
now with batteries.. I'm going to use a #10 fill wire and a 4ga (many times bigger) jumper to parallel them (or perhaps a 4/0 in my case, bigger still) that is like using a 1' pipe to balance the tanks.
The level of charge is represented by the voltage SHOULD one battery charge faster.. The voltage will be higher, Since electricity (And water) tend to follow the path of least resistance.. The lower battery will thus take more charge.... Till they are in balance
NEITHER battery will over charge, or under charge, relative to the other
Likewise When you drain water out of the water tanks.. Via that same one inch line, they will constantly balance out
And so will the batteries when you drain power out of them via that #10 wire
IT very simply can not happen that way your ex-spurt says it will
(I did promise to happily tear apart the explanation didn't I)
now.. there is one slight danger
SHOULD the smaller battery short a cell.. The larger battery WILL try to charge the smaller one and it can deliver current fast enough to make a major mess of it.
This however is rare and can be protected against by use of a fuse
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