Deep Cycle Batteries and Inverters? I'm not clever

[Big J]

I would not cross-connect a deep-cycle with a normal starting battery
they charge/discharge at different rates and its not likely to end well for one of the battery's
and no I would not recommend bypassing the charging brick and running 12v thats idiotic to say the least
what you can do is get a decent dc-dc boost converter and set it to the needed voltage (just make sure its a quality one and not some cheap garbage )
finally if you wanna charge via SOLAR a MPPT is the way to go

RVs and campervans all connect starter batteries with deep cycle batteries though? I know most of them make use of Inverters and Voltage sensitive split relays, which is practically what I'm looking to install in my van.

 

[flmatter]

http://www.xantrex.com/documents/Po..._3000_Install_Guide(975-0556-01-01_Rev-A).pdf

scroll down to page 1-2 shows a typical install ou can go to xantrex.com find a model similair to yours and download install sheet for it. IT IS THE PROPER WAY to install these. Yes there are short cuts and redneck ways to do it and they will work but it is not proper and you are pushing your luck. Fuses are mandatory and you want them as close to the power as possible. I have seen too many fires because of half assed installs.

 

[Caring1]

RVs and campervans all connect starter batteries with deep cycle batteries though? I know most of them make use of Inverters and Voltage sensitive split relays, which is practically what I'm looking to install in my van.

The dual battery charging switch allows a deep cycle battery to be connected alongside a vehicles normal starting battery, it is a one way switch generally that prevents damage to the vehicle's battery.

 

[trog100]

normal starter batteries are not designed to be deep cycled.. they are lightly built designed to provide a high starting current for a very short time.. then it all gets put back by the alternator.. in essence a very shallow cycle..

connecting the two up together and deep cycling both will shorten the life of the lighter built starter battery.. by how much its hard to say..

trog

 

[Big J]

But I won't be deep cycling both, that's the reason for the switch..? It allows both batteries to be charged (first the starter), once the first one is fully charged, it switches over to the second one, but only allows the deep cycle battery to be used by external power drain

 

[Caring1]

But I won't be deep cycling both, that's the reason for the switch..? It allows both batteries to be charged (first the starter), once the first one is fully charged, it switches over to the second one, but only allows the deep cycle battery to be used by external power drain

Exactly what I said.

 

[trog100]

But I won't be deep cycling both, that's the reason for the switch..? It allows both batteries to be charged (first the starter), once the first one is fully charged, it switches over to the second one, but only allows the deep cycle battery to be used by external power drain

i just chucked my comment in to point out the general difference between the two types of battery.. i use a trailer/caravan off grid and have two 90 ah starter batteries in the tow truck giving 180 ah.. one 120 ah battery in the trailer mine are all linked up giving me 300 ah in all.. not the right way to do it but i never run them down too much..

i also carry a 1000 watt generator most of the time as a back up.. the generator would power the lot but fuel costs and noise limit its use.. i have a small 12 volt to 240 inverter for laptop use off the 12 volt system..

cooking heating and fridge are propane gas powered.. apart from water i am pretty well self sufficient for a fair while away from civilization.. he he

trog

 

[rruff]

normal starter batteries are not designed to be deep cycled..

Based on the OP's stated use, he won't be doing deep cycling. He likely won't need to add anything. I'd hook up a voltage gauge (required in any case) to what he has and run with it. If the battery deteriorates due to being cycled too deeply, then he has some options to consider. The simplest and cheapest is probably to buy two new (identical) starting batteries and hook them in parallel. The alternator will charge both when the engine runs. Or get one or two batteries that will both deep cycle and start. They make tweener lead-acid batteries that will do this, or you can go fancy and buy LiFePo (my choice actually for my next camper).

The absolute last thing I would do is add a separate deep cycle circuit because you need to charge it using a different system. You can't charge that with your alternator. Or at least it would require some sophisticated electronics. So that means you *need* to plug in the deep cycling battery regularly for charging, or use a solar panel which is unreliable. Since it sounds like he is going to be doing a fair amount of regular driving, it is silly not to use the alternator, and just let it charge everything.

 

[Big J]

Can I use circuit breakers instead of 60A fuses between my two batteries as recommended by the battery switch?

 

[Caring1]

The absolute last thing I would do is add a separate deep cycle circuit because you need to charge it using a different system. You can't charge that with your alternator. ..... Since it sounds like he is going to be doing a fair amount of regular driving, it is silly not to use the alternator, and just let it charge everything.

You just contradicted yourself like a boss, well done.
The solution has been given, he has the component required already, he doesn't need more confusing and stupid advice.

 

[rruff]

You just contradicted yourself like a boss, well done.
The solution has been given, he has the component required already, he doesn't need more confusing and stupid advice.

What did I contradict?

Typical of forum here I guess. Recommend the most elaborate, complicated, and expensive system possible to get the job done!

 

[Ahhzz]

You just contradicted yourself like a boss, well done.
The solution has been given, he has the component required already, he doesn't need more confusing and stupid advice.

Too many personal attacks here lately. There's no reason to take someone's opinion and honest offer of a solution to make degrading and offensive remarks....

 

[flmatter]

Something like this http://www.wiringproducts.com/80-amp-high-amperage-circuit-breaker.html yes

 

[trog100]

its standard practice to charge a caravan leisure battery from the tow vehicles alternator.. mine gets charged this way.. a caravan normally has a voltage sensitive relay switch (an occupation relay) which only connects the car alternator to the trailer leisure battery when the engine is running.. the idea behind this is simple.. its to stop the caravan from draining the car battery too much and the car starter trying to draw excessive current from the trailer battery via the connecting cables... the same circuit also connects the fridge up to the 12 volt system but only when the tow vehicles engine is running..

ether way the comment about not being able to charge a leisure battery from a car alternator is wrong.. you can and its commonly done this way..

my leisure batteries get charged three ways.. at home its all connected to the mains.. on the move from the tow trucks alternator and in an emergency from a portable generator.. this plugs in just like the at home mains does..

the isolation relay is simple.. it detects 13.5 volts from the running alternator and makes the connection.. but used with a bit of care (dont flatten the starter battery and get stuck) the whole lot can just be connected up together.. it will then all take a mains charge or an alternator charge.. the battery being charged gets 13.5 volts it dosnt care where its coming from..

trog

 

[Big J]

So a few things have changed since I last posted!

Just two quick simple questions, seeing as I am electrically challenged.

1. Blue batteries connected like this = 24V as needed by the inverter? Right?
2. Can I ground the two deep cycle batteries as indicated? (should I ground both deep cycle batteries or can I ground just the one? which one? does it matter? ie. can I connect a ground cable to a negative terminal which connects the positive and negative terminal of two separate batteries in series?)

Spoiler: What's happening

A quick explanation of what's happening up top, maybe I'm doing something wrong that you guys can help me with.

Yellow battery is the starter battery
The solid state switch connects my two deep cycle batteries to the starter battery, in order to charge once the starter battery voltage is larger than 12.8V
Switch also disconnects the starter battery from being drained below 12.8V at any given time
60A fuses near both the starter battery and connecting deep cycle battery as recommended by the switch instruction manual.
Deep cycle batteries connected in Series in order to get 24V output for the inverter to work

 

[rruff]

If you ground the 2nd deep cycle battery, very bad things will happen since it will short circuit your 1st battery.

Your switch sees 24v from deep cycle and 12v from starter. Why not a 12v inverter? Then you can charge everything on 12v also. Connect deep cycle batteries in parallel.

 

[Big J]

Can this work? Can I use two Battery Selector Switches in this fashion? (Green cable is combining two switches together at those points)
If this is 100% correct then I suppose:

1. I'd need to disable (OFF position) Switch Y before I can use switch X? otherwise I'd short out battery B?
2. Would I connect my starter battery positive to Battery A or Battery B positive?
3. Does anyone know of a better? maybe cheaper way of doing this?


If this is a plausible idea, my intention is to charge both batteries in Parallel 12V and use my two batteries in Series 24V as needed by my 1000W inverter.