Battery brands in dual set up

[mikeaus]

Is it really necessary for your deep cell aux battery to be the same brand as the starter battery in a dual VSR setup?

Also, is is really necessary for the battery to be a MARINE one. Seem these days adding the words marine to a product is like a license to double the price.

Its not like the battery is going to be placed in the water. I can see how how this would differ from driving your car down a road near the ocean with a the same battery on board. It would be in similar conditions, its still exposed to salty air.

Any thoughts?

[stue2]

Well they say you should have the same size battery.

I've been using the All rounder type as they handle the charging over the winter better or so I'm told.

marine batteries are supposed to be stronger inside to cope with the vibration and pounding that can happen on a boat. There will be a better answer here soon.

Cheers, Stu

[mikeaus]

marine batteries are supposed to be stronger inside to cope with the vibration and pounding that can happen on a boat.

Cheers, Stu

This was what I was told too, however would the ride on a boat be any rougher on a battery than sitting inside a hot engine bay of a 4WD traveling down a corrugated road in the NT.

[Floating Rib]

Mike, i heard the same as Stu in regards to vibration etc but agree with you with the 4x4 analogy, my boat came with marine start batt but i fitted an aux heavy duty deep cycle of larger size and different make(non marine), i dont think the Regulator i run cares whats hooked up it will just work on what voltage its seeing.
Cheers
Mick.

[BM]

Best practice in a dual battery setup is 2 identical batteries. This means they will charge equally as the internal resistances will be more or less the same.

A deep cycle battery and a starting battery are going to present different loads as seen by the alternator/stator which can result in undercharging and overcharging.

If you want to run a deep cycle and a cranking then you'd be better off keeping them independent. House battery runs everything but the engine and the crank battery only runs the engine. An emergency bridging switch can be employed for the obscure case of a flat cranking battery.

Or just leave it as is and be aware that they won't charge correctly together.

The info I have regarding marine or 4wd batteries is they are generally the same battery with a different label stuck on them as they are both built for a high vibration environment. In reality the engine bay of a 4wd is in probably just about all cases a far harsher environment than a marine application.

Cheers

[Chimo]

7425074251

Hi BM

I am led to believe that using an Auto Battery Coupler overcomes the issue. I have the setup you advise and have different batteries ie starting for just that and house for all else.

They are linked by the ABC and there is also a manually switchable link from one motor battery to the other in case one dies. Only had to use this once, ie start the failed battery motor, get it running and then disconnect and start and run the other. Proceed as normal.

Cheers
Chimo

[albey]

Batteries aint batteries even though they look the same,they definately aint.
A marine battery is designed to stand for lengthy periods without charge then perform at almost maximum-do the same with an auto battery and you will end up with sulfation problems which very quickly will write off the battery.
A marine battery therefore is made with thicker plates which are further apart,they also sit up further from the bottom of the case,these things help avoid sulfation but also go to assisting with the mechanical rigours of a boating battery.Those who say there is no difference between 4WD driving and boating ,then they just havnt been out in a consistantly rough sea.
Smaller boats and in particular planing hulls in a rough sea will come off a wave maybe every 10 secs or so and be called on to do this for lengthy periods,and EACH time that boat hits the bottom of the trough it is subjected to in excess of 5g's,so the battery internals have to be more ruggedly built,the case is also of heavier construction, than even say a battery for a 4WD,which doesnt even come near to the same sort of punishment.
So marine batteries heavier construction inside and out,they stand for long periods,then they are charged with low currents.
Horses for courses,auto for automobiles,marine for boats-there is just NO comparison between the two.
Use reliable brands of marine batteries and sleep well when your 60nm at sea.
Ive said it before,but because I do this for a living there is just no way I would NOT fit a marine battery into a boat-no matter what the saving,and that can be the only argument anyone would raise to avoid fitting the correct one.

[BM]

5G seems a little excessive to me unless perhaps jumping large waves and bottoming out big time. But maybe not even then. The 4G or do experienced on several theme park rides is more force than I have ever felt in a boat. I have no data though so it could certainly be true I guess.

I know of several brands of batteries that the marine or 4wd label goes onto the same battery. It's apparently quite standard practice. I deal with batteries in one business capacity but I am not involved in retailing new batteries.

Chimo, the ABC or VSR to my knowledge is simply electronically connecting/disconnecting twin batteries based upon predetermined threshold voltages and nothing more. I am unaware of any further function than that. I could be wrong but can't see how the VsR could achieve such a feat given 2 very different battery compositions in the cranking and deep cycle example.

Cheers

[Floating Rib]

Mike, want to clarify my statement, i run 2 diff types of battery but through a VSR and manual 3 pos switch, as BM has mentioned
its best done with the Marine start battery for all the starting jobs and house(deep cycle) for running electronics, The VSR (or ASR) will isolate a battery if its voltage drops below a certain level to prevent it being depleted. One position on the manual selector allows both batts to be combined to allow combined starting if required.So as mentioned by the guys above above it would be better for both batts to be the same if not running this type of dual battery system. Below is a description from the Blue Seas Dual system i use, also there website has fantastic diagrams and info. www.bluesea.com

From Blue Seas webpages:
A common way to handle additional loads beyond starting requirements is with a second battery and a 4-position selector switch. This enables the addition of more loads than a single battery system would tolerate. Either battery can be used to power the starting and house loads, and the switch will also combine batteries for charging or emergency starting. There is a problem with this arrangement, however. The switching sequence must be remembered and followed, every time. When charging of both batteries is desired, it is necessary to move the switch to the 1+2 position. If the switch is not moved back to the 1 or 2 position, and house
loads are being used heavily, both batteries can be drained. Since there is only a 1-volt difference between a fully charged battery and
a depleted one, it doesn’t take much to drain both batteries to a point where they will no longer start the engine.

TWO BATTERY BANKS, WITH THE ADD A BATTERY Dual Circuit System

An ideal way to switch and manage charge of the batteries while underway is with the ADD A BATTERY from Blue Sea Systems. This includes the Dual Circuit Plus™ battery switch and the 120 Ampere SI-Series Automatic Charging Relay (ACR). Together, these components simplify switching and automate charge sharing. In addition, the start isolation feature of the ACR protects sensitive electronics from potentially damaging voltage fluctuations during engine cranking. The SI ACR fully automates charging of two batteries from a single charge source, eliminating the complication of “sharing the charge” manually with the selector switch. If the SI ACR senses that a charge is present on either battery (indicated by a high enough voltage) it will offer the charge to both batteries. If the battery voltage subsequently drops to a preset threshold, the ACR will isolate the batteries. Even if the house battery becomes fully discharged, the starting battery will remain charged.

Ps. I have a spare Blue Seas dual battery system in the classifieds if anyone is interested.

[mikeaus]

I just purchase the ACR/Switch pack off you. However I clicked buy and it just disappeared?

[BM]

I note that the blue seas info talks mainly about the automation of the system and doesn't specifically talk about correctly charging different batteries in the two battery system.

Cranking batteries are designed for massive discharge over very short periods with very rapid recovery. Deep cycle batteries are designed for continuous discharge at low current levels. The longer the discharge period the more actual amperage that can be drawn from the same battery.

Deep cycle batteries have different ratings to cranking batteries. Whilst crankers are rating in cranking Amps deepies are rated often in a "C" rating. So a deep cycle battery rated at 10Amps C10 can provide 10Amps per hour for 10hrs before recharging, so 100Amps total. That same battery on a C20 rating may be rated at 7Amps per hour, giving 140Amps total draw.

Point here is that these are both lead acid batteries but internally are very different in their composition and intended application and require different charging techniques and voltages.

I am a keen advocate of using VSR's instead of battery switches. It's far more modern and technologically advanced to do so. Battery switches are a bit primitive these days IMO.

Sure, mismatched batteries in a twin battery system will still work but it's not ideal and in the long term, the batteries will suffer.

Best practice IMO would be to have your house battery separate from your cranker. You could have an emergency bridging switch in the event that your cranker went flat but that is remote, given that properly set up the cranker only runs the engine and engine instruments. The house runs everything else. Engine alternator chargers cranking battery and house battery recharged when you are home via an intelligent deep cycle charger.

But the simplest solution I suppose is a battery switch or a VSR and 2 crankers matched or not and leave it like that. Not really right but that's how 95%+ are set up. Crankers will handle the typical, relatively light electrical load on a trailer boat so it could be argued that in many cases a deep cycle battery is not required.

Edit: just had a thought. If the blue seas unit actually switches one battery out of circuit and commences charging the other then that would seem to be able to correctly charge the different battery types in a system. Although VSR's usually charge one battery and when it reaches it's threshold voltage they switch in the second battery and charge the 2 together.

Cheers

[Floating Rib]

Mikeaus, your message box is full need you to clear it so that i can send you details of batt system.
Mick.

[nautimax]

Mike,
I have two different battery brands hooked up to a BEP-716-100A-VSR cluster with no issues so far. The cranking batt came with the boat and is ok but I will be replacing both with a marine one soon. Reason for this replacement is that if something happens on-board and the cause is traced back to a non marine battery, I would be in the hoopla as far as insurance goes...