Is a 2nd battery vital with a winch?

andrew just wondering what battery you have ur winch powering off, the main or 2nd battery.

thanks
lost

The winch is hard wired to the main battery, but my set up is a simple solenoid, so whin the engine is running both batteries are in parallell, so it runs off both.

It hasn't ben set up that long, but I haven't had a problem with starting. Initially I was a little concerned that if I drained the aux substantially, when I turned the ignition on (thus connecting the batteries together) the flat battery would suck the power from the starter during glow time, and then I'd be left with not enough power to start it. It hasn't happened yet.....I have a cheap isolator on the negative termanal of the aux so I can take it out of the system.

Cheers Andrew

thanks andrew

i had that same set up in my old hilux and it was good for a yr or so, then i started having the problems like you have spoke about, main battery dead so it started sucking the guts out off the 2nd battery, it got a pain in da butt having to try and start in the mornings, ended up having to push start( i had fridge and accesserys running off 2nd battery over night.

lost

I'm a little concerned this may happen, one good battery may hide the other one's deterioration, especially in the situation you stated above where the starter is stuffed, the aux does the starting, then when you run the aux down camping you end up stranded. I suppose keeping an eye on battery condition regularly will help. I like the simple set up though. Have heard of a similar setup where the relay is somehow wired into the oil pressure switch, so they are not in paralell until the engine starts, but that is getting a little bit more complex.....possibly should get a smart solenoid, but they may not allow winching from both batteries. A manual switch may be the go, but then human error may be the biggest problem.

Cheers Andrew

I may stand corrected here, but I have been told that the " flat battery would suck the power from the starter during glow time, and then I'd be left with not enough power to start it" thing is a myth. Apparently modern batteries don't do this (?).

I also run a solenoid and the only drama I have is failed solenoids! So the aux battery sometimes doesn't charge up.

Cheers

Brian

I have a smart solenoid on mine with the winch connected to the main/starter battery. However, if worse comes to worse I have button on the dash which I can press which connects the two batteries. (it is sprung so as soon as you take your finger off the button it goes back to the smart solenoid).
The idea is that for example think of the 2 batteries as glasses of water.. if one is empty, without the smart solenoid, the 2nd glass will fill the other until they are both at the same level (ie now both are only 1/2). and will always be trying to bring them both to the same level.. (bad news if one battery is stuffed) If you keep doing this you will eventuially stuff both batteries.. With the smart solenoid, the second battery (glass of water) stays isolated until the first one is full, then it will fill/charge the second.. if worse comes to worse and my 1st is empty becuase I left the lights on or winched myself out of the creek with the engine dead... then when I get to the other side and the battery is flat. I can press the button and this connects the 2 batteries hopefully giving me enough charge to crank the engine.. I wouldn't operate a winch without a dual battery or as you say at least a jump start kit etc.. All well and good to say you will winch with the engine running.. but what if you can't . I do a lot of travelling solo so I need the security..if you are with a club then all you need is some jumper leads.. in fact better still - a Snatch strap.

If you plan on winching with a setup like this use REALLY heavy cable. If I get time later I'll do the calculations but you aren't going to be anywhere near cheap in dollar terms.

A winch pulls over 400 amps near stall or pulling off a full drum on a short winch.

If you are bridging two batteries you are going to be trying to achieve 200+ amps from each. Any isolator switches or solenoids used need to be rated at well above this for continuous duty. Many are rated for this current for less than 30 seconds only.

If you go undersize on your cable for this purpose over a long cable run to the rear of the vehicle you won't get a very usefull voltage from your aux battery after the voltage drop and you could well end up with a fire.

Battery equalisation (ie. full to flat) in a short space of time is a bit of a furphy. I wouldn't worry too much about it, your batteries need to be isolated when the vehicle isn't running anyway with a bypass switch or solenoid for winching or self sufficient jump starting. If there's one thing on a 4wd setup you need to do properly it's a dual battery system. Cutting corners now will cost you in early replacement of expensive batteries, and upsizing cables to what they should have been in the first place later.

Dave