24v Winch by adding another battery?

[NC_Mule]

Yes. The second battery will not "leak" back to the first. Both sides use common negative, but different positive.


What you would be doing is connecting two 12V batteries in SERIES to create 24V, no different than loading batteries end to end in a flashlight. The "house" battery remains at 12V since you aren't taking power from the downstream battery at all.
The main drawback to this, in my opinion, is that the second battery is not isolated from your start battery.
As the winch draws down both batteries, the charging system is putting voltage into the start battery. The voltage to charge the winch battery is "leaked" to it. I doesn't get a direct charge. The negative consequence of this is that you can quickly flatten both batteries. If you are without means to get restarted, you could get stuck.
For extended winching with 24V, you should really add a second 24V alternator and battery system that is completely separate from your 12V electrics. 24V has many advantages.

Nice man, thanks for a clear explanation. I think I understand what you are saying. I see what you mean about having a seperate
24v system and alternator as being the best option. I'll run the numbers and put a $$ on my options.
Can you explain some of the advantages of having 24V?

[o2batsea]

sure.
24V means you slice your current draw in half. So, a winch motor that would draw 100 amps on 12V draws 50 amps on 24V. In addition, voltage drop over a given wire length is also halved. 24V motors tend to last longer since they are loaded half as much, and so on and so on.
With batteries, you get a double bonus as doubling batteries lengthens their lives by more than 120%, as long as you discharge them and recharge them with enough "wiggle room" (generally not below 50 percent so that you aren't constantly recharging at high amps = cooking). Sizing batteries isn't rocket science. Basically you stuff in the largest, heaviest batteries you can.
Get a copy of "The 12 Volt Bible", an very reader friendly introduction to batteries, management and power usage. It's directed at boaters, but useful for anyone who has a 12V system.