Dual battery help please

[Tailortaker]

Hi all, I'm currently running a 50hp electric start and sounder ect off one battery. I don't venture far ATM but intend to. My main problem is that we do alot of camping and use the boat to get there so i will need to run an led anchor light all night. My old boat was a pull start 25hp and i ran the lights off a small deep cycle batteries and had spares so no issue but now with new boat I'm relying on my cranking battery. what do i need to hook up the second battery so i can run the anchor light off it instead off my cranking battery and how do i do it ? I was going to install a second anchor light wired to the second battery but think a dual set up would be a better option all-round.

p.s I know dual battery threads have been flogged to death but after sitting here for hours searching through them I'm still confused

Cheers, TT

[Chimo]

PM sent

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[Tailortaker]

Ok, I've got a 4 way switch, I've done the obvious( i think ), i hooked battery 1 to post1 and 2 to 2. I've got the cable to the motor and accessories coming out from the common post. they are atm both earthed to battery one so batt 1 works but not 2. So is it now a simple case of running a cable from negative to negative on the batteries or not ? please help.
Cheers, TT

[Angla]

Yes. The negatives should not be switched, just all connected together.
This translates to running one heavy wire from batt2 neg post to batt1 neg post.

Cheers
Chris

[Fed]

With a 50HP I'd definitely learn how to pull start it TT, a never ending supply of cranking power depending on your deckies arms.
Mate of mine has done a V4 115 with success and he weighs about 60Kgs, desperate times you know.
It's on my to do list but my 90 has got me a bit scared. LOL

[Tailortaker]

Thanks fed, I can pull start if need be but I figured why do that if I can just turn a key. It's lease effort installing dual batteries than pull starting a cold motor every morning for a week but it is comforting knowing that I can pull start it in an emergency situation.
Cheers, TT

[deckie]

often doing a 2 batt sysytem connected together is just unnecessary , overkill and actually introduces saftey issues by increasing things that can go wrong. If all u want to do is run an anchor light, make sure its a good LED and it should only draw maybe 0.5A...u could run it for 12 hrs tonight and all it would soak is maybe 6A. Whynot just carry say a 50A agm deep cycle type batt as 2nd and wire the anch light to it ? Just check the cranking amps rating is also enough to start for your 50hp and buy that one as spare. You can drain them down to maybe 25-30% and recharge a thousand times at home. i.e on a 50A deep cycle you'd have 30-40A workable reserve equating to at least 3-4 nights continuous operation (if the anch light is all u ever draw on it). Dont see the point in connecting batts up together if all u need is to run an anch light. Good to carry the second but realistically unless wanting to charge it up whilst out there there's little point getting fancy...especially when the charging output of the 50hp isnt that much anyway.
Best dual batt system isnt complciated, its simple and cant go wrong with few connections to vibrate/get wet or corrode over time. Stuff like batt switches/vsr's etc etc can be just an added slowly corroding eventual problem u dont need. You can always alternate days using one batt then the other for charging off the donk for long trips away.. Carry a set of jumper leads or make them up the right length as an emergency with some 2 AWG cable. Definitely practice the pull start. A good home multistage charger keeps them tip top and ready.
Steve

[battler1]

Simple Call BLA get yotself a BEP Battery switch with a VSR as this will solve your dramas there the best on the market.

Joe

[deckie]

see thats what i dont understand...how is that simple ? just a total bloody waste of money. Calling bla and getting a batt switch and vsr is only likely to hand him an expensive problem if his 50hp doesnt put out much charging current....and why would u bother ?

Why is there such an assumed rush to install these things these days ?...especially where they're unlikely to provide any advantage. Larger capacity donks sure..or when a def need to charge two batts whilst out there. But if its of no use (in this case its almost worthless), then its presence is just introducing a safety risk itself Less electrical crap the better.

[battler1]

Its simple as when you put a BEP VSR Battery switch on you have a dedicated house bank which is isolated for the main circuit but shares the same common earth & when one battery is weaker than the other the VSR kicks in and charges the weakest battery and for less than $200 bucks its worth it & you will get trouble free batteries for a shit load longer than running a battery switch that only isolates the earths .

Commons earths are the main cause of problems on vessels as if all your earths go to a number of earths you will create earth loops which will send your electronics ape shit make sure all you earth go to the commen link ie negitive to the same battery and i promise this will stop all your battery problems.

Also make sure all your batteries are the same amps as this also cause a nightmare so if you have 120amp hour battery you need to have the same for your house bank i can go deeper but im stuff & a 50 Hp would have a 20 amp charging circuit which is ample.

Cheers Joe.

Ps Im just not a painter

[Grand_Marlin]

Ok, I've got a 4 way switch, I've done the obvious( i think ), i hooked battery 1 to post1 and 2 to 2. I've got the cable to the motor and accessories coming out from the common post. they are atm both earthed to battery one so batt 1 works but not 2. So is it now a simple case of running a cable from negative to negative on the batteries or not ? please help.
Cheers, TT

Yes, as Angla stated, run a 2 or 3 B&S size cable to link the battery negatives together.

Cheers

Pete

[MudRiverDan]

Connect battery in Parallel, double amp hours, same voltage.
Really with batteries you would not have any probs charging them at the same time.
Only issue is if you thought something on your boat was going to use all the power and they go flat leaving you with no back up, hence the amp hours would not be up to the job in the first place.


http://www.zbattery.com/Connecting-B...es-or-Parallel

[Grand_Marlin]

Deckie & Battler 1,

Sorry guys, but I have to straighten out a few things here.

Firstly, the BEP battery switches with VSR are without doubt the BEST way to install a dual battery system.
The switches are heavy duty and designed specifically for the marine environment.
If it is installed correctly with the right heatshrink covered heavy duty lugs, coated with vaseline or a spray protectant then corrosion is not an issue. Also, when people bring boats to us we check this as part of the ongoing maintenance program.

The electronic failure of these units is not an issue either. We have fitted hundreds of the Battery switches with VSR's and only ever had to return one. This switch had come apart on the inside ... it was nothing to do with electronic failure.

The safety issue raised in my opinion is not relevant. As stated, the switches are heavy duty and designed for the marine environment.
Also be aware that the switch is completely mechanical, the only electronic part is the VSR which is there solely for the automatic charging.
In a dual battery setup with separate start and house batteries, if the VSR were to fail it would mean the house battery would not get charged but the start battery still would.
The VSR always monitors and looks after the start battery first (priority battery) until it reaches 13.7 volts, then it switches and charges the house battery in parrallel to the start battery.
This connection via the VSR disconnects when the start battery drops down to 12.8 (this is generally when the motor is turned off)
It does not monitor and automatically charge the house battery if it is weaker ... it always takes care of the start battery first, house battery second, if it is set up correctly.

The output of the alternator has no relevance to a dual battery setup with separate house / start, unless there is a draw off the start battery that exceeds the capacity of the alternator. If the system is set up correctly, there should be nothing drawing off the start battery to cause this anyway.
The VSR monitors voltage and when the start battery is above 13.7 volts it connects the house battery ... the lower the amps from an alternator the longer this takes BUT the start battery should never be very far down on charge.
Set it up properly, or alternatively get someone who knows how to do it to set it up for you and it will be all but fool proof.

Price wise, the battery switch that we are talking about is around $260 (BLA part #113685). It has VSR, Start, House and Emergency Parallel Switches.
This is best suited to start / house systems that have both lead acid CCA rated start batteries and a bank of one or more deep cycle house batteries.

The other type has a rotary 1, 2, both, off selector switch and VSR (BLA Part #113651) is around $180. This switch is best suited to batteries of the same type - i.e. lead acid batteries and also where a spare fully charged battery, rather than a dedicated house battery is required.
There was some incorrect information I posted in a thread which is now long gone. It was stated by the manufacturer that this switch would allow the second battery to be used as a dedicated house battery, where in reality you were either using battery one to run everything (starting and accessories) or you used battery 2 to do the same.
I did find a way to work around this by always running your boat on battery one, and by running the accessories off battery 2 with the help of a BEP circuit breaker to not only protect but to isolate the accessories as well.
I bought this to the attention of BLA and BEP who have changed their literature to suit.

The amp size difference in the batteries does not matter in the slightest between start and house banks.
It is however advisable to have the same size batteries if linked together in a house bank.

The key with earthing is to have good sized cables (2 or 3 B&S) all coming back to a common point.
Usually this is the battery terminal of the start battery, but often we set up a heavy duty bus bar for this reason.

BLA is a wholesaler, not a retailer. They will probably appreciate it if they aren't bombarded with sales requests.
The BEP accessories are available through trade (such as us) or retailers like Bias Boating etc.

Cheers

Pete

[Scalem]

Deckie I agree. My all round light ( not the all round light required by law) for the cabin runs on a mid sized jump starter. The all round light is a 10 led bar and never has flattened the jump starter which is totally separate from the electrics of the boat. I leave the crank battery alone, charges fully when in use, not shared with another battery across a switch. I also have a spare battery on the other side of the boat which gets a charge externally and checked regularly. It's a little less convenient when the spare is not linked to the crank battery in any way, but my previous boat had a switch which failed to channel current to ANY battery because of corrosion, which is not a good thing. So I bought a new switch. Same thing happened within 2 years. I carry a good tool kit which enables a tranfer over to the spare battery in quick time. The chance of breaking down because of a failed battery has 3 other backup plans. A jump starter, and spare battery and a zip chord.....

Scalem

[deckie]

psst Grand Marlin..i know..i agree. Got things set that way myself.

BUT...all the guy wants is to run an anchor light.

There's a time to buy two new batts, having you do a great job on some cabling, vsr's, switches, clamps, boxes etc etc...and then there's the simple foolproof solution to just running a v low draw led anch light for 12hrs.

Especially on a 50hp...cmon. Surely he's better off practicing a pullstart than installing a $1000 worth of gizmo's he wont need. How much does his charge current put out and will thaty vsr chatter like a bitch all bloody day anyway ? Does he really need to charge a second battery out there with an anchor light only drawing 0.5A tops ?

If he said he wanted a fridge or to run everything else off a house..maybe. But the way i see things simplicity is the best and safest..he could just as easily stay with a single but bigger batt if thats all he wants...u dont camp 25nm out to see right ?

No disrespect coz your rep is first class...just prefer simplicity and all i reAd is he wanted to feel safe running an anchor light all night. That aint hard or difficult esp now with led's drawing 2/5ths of FA.