Tractor Electrical System

[Walkin Horse]

In light of the recent posting about winches here's a question. I have a 850 cca battery in my tractor. It has a 55 amp alternator. What does that mean? That it would take about 16 hrs to recharge the battery.

I have found a truck recovery winch sold by Motoalliance a TBN sponsor. It has a 390 amp draw and requires a 650 cca battery. How do you figure all this. What do they mean exactly.

Does any body have any experience with viper winches.

 

[SPIKER]

No experience with those winches, but the 55 amp alt is how much current it will put out, same with the CCA (Cold Cranking Amps) when battery is Cold it will put out 850 Cranking Amps (available power to the starter motor.) The starter will only use as much power as it needs based on what it's needs to turn. Most starters are rated in Watts (or KW-kilowatts) similar to a light bulb.

Mark

 

[robstaples]

850 cold cranking amps means with a low impedence load like a starter motor or winch, it should put out 850 amps . Like you alternater will put out 55 amps. both of these are rates of current flow. Your battery may be a 100 ampere hour battery. Theoritcally, 100 amps for one hour or 200 amps for 30 minutes. Car batteries are designed for short bursts of power , like 850 for 3 seconds... as the motor spins up the current tends to lower until the engine starts. Your winch can draw 390 amps at full load rating.. pulling 4 tons or whatvever the max pull is. At lower pulling force the current draw (amps) will be less. Depending on how long you pull at max force, or duration of the pull, your battery should work fine.

 

[DuckSlayer1017]

Check out this online amp hour calculator. I think it will tell you what you need.
BatteryStuff Tools | Sizing a 12 Volt Battery to a Load Calculator

 

[Walkin Horse]

The calculator says 1100 ah at 20 hrs. What exactly does that mean.

 

[robstaples]

Lead acid batteries in general, lose life and capacity if they are discharged at a high rate. So the industry uses a 20 hour rate of discharge as a repeatable long life discharge rate. I did a dis service, by using the 200 amps in 30 minutes. A 100 ah battery would produce less than 200 in 30 minutes. A more relavent example for a 100 amp hour battery is 5 amps for 20 hours. So that web page is saying you need 11 batteries if they are 100 ah each in parallel for your solution. High discharge rates cause battery failures like heat induced warpped plates that then short out cells. IE less life.

More info at Battery Basics: A Layman's Guide to Batte | BatteryStuff Articles

 

[Walkin Horse]

That is a great explanation. I think that should explain better than anything that's been said on TBN about putting a winch on a tractor. I understand that every pull won't be a full 390 amp draw. Can you say by your example,a 200 amp draw, would still take 5 or 6 batteries? And how does all this affect the alternates. Assuming it has a 55 amp out put.

 

[robstaples]

The 5 or 6 battery suggestion is for a 20 hour current of 200 amps. That's a lot of winching. I would need to know more about your winch and its application. Your alternator would defer or replace 55 amps of the winch's current requirement and recharge anyrtime there was a winch "pause".
If you going to use it like a tow truck winch, your battery would work. Depending on how long a cable ( converts into time pulling) you'll shorten the battery's life. You'd want heavy cables to connect to the battery ,like welding cable.

 

[quicksandfarmer]

Here's an analogy that I think will be easier to understand because it uses familiar objects and units.

Imagine you have a pressure washer that needs 10 gallons of water per minute. You have a well with a pump that produces 2 gallons a minute. To run that pressure washer off of that well, you're going to need a storage tank and to store up some water. That storage tank needs two things: first, it has to be big enough to hold enough water for the amount of pressure washing you intend to do. Second, the pipe coming out of that storage tank has to be able to provide 10 gallons of water per minute. Let's say you get a 100 gallon tank, you could pressure wash for ten minutes and then you'd have to wait 50 minutes while the tank refills. If you put a one-inch pipe on the outlet of that tank it could provide 10 gallons per minute until it's empty.

In this analogy:
The well is the alternator
The pressure washer is the winch
The storage tank is the battery and the outlet pipe is the cca rating of the battery

Amps are a measure of flow, it's analogous to gallons per minute. Amp-hours are a measure of capacity, analogous to gallons. Multiplying flow (amps or gallons/minute) by time gives capacity (gallons or amp-hours).

So let's go over the numbers:

The winch has a maximum draw of 390 amps. This is analogous to the pressure washer needing 10 gallons per minute.

The battery is rated 850 cca (cold cranking amps). This is the battery's ability to provide flow, analogous to the 1-inch pipe. This battery has the ability to power this winch at maximum draw.

The battery has a capacity of 1100 amp-hours. This is analogous to the capacity of the tank. Theoretically, it should be able to power the winch for over two hours (but see below).

The alternator is capable of producing 55 amps. This is analogous to the capacity of the well. This means you can operate the winch 8 1/2 minutes out of every hour without draining the battery. Alternately, if you operate continuously and drain the battery it will take 20 hours to recharge it.

Finally, there is an important difference between batteries and water tanks. If you put 100 gallons into a water tank you can take 100 gallons out, and it doesn't matter how fast or slow you take that water out. Batteries don't return all of the energy put into them, and the faster you take it out the less you get. The 20-hour rating for amp-hours is the amount of energy you get by evenly draining a battery over 20 hours, which is much slower than most real-world applications. A rule of thumb for estimating capacity for higher-flow applications is to take the 20-hour rating and cut it in half. So in this application I would say one hour of continuous use (followed by 20 hours of charging) is your outer limit.

 

[Walkin Horse]

Robstaples and Quicksand you sirs are the hydraulic JJ of the battery world. I wish others could have explained it that well on previous threads about electric winches instead of it won't work and your wasting time. Now we have something to base it on. I think this info will make us wiser battery users and shoppers.

I'm assuming that the more you deplete a battery and the more often it's done, that is one thing that can ruin a battery. So let me throw this at you. Not knowing the specs of a deep cycle battery, does using one of these change run times or do they just have a longer life span when constantly depleting them.