OT trailer break away voltage

flembo · Jul 22, 2013

Can someone tell me what voltage a trailer breakaway battery should be. I expected to see 12volt but the meter shpws only 9.3 v. It has a small charger inside about .1/4 in x 1 x 1 no where does it say what voltage, on the outside it says to be sure it is charged each use.It has sat all winter so I pulled the plunger out and was still able to rock the trailer back and forth.

SDE · Jul 22, 2013

You should have a wire that you can connect to a hot wire from the vehicle, that will charge the battery. For example, if you wire it to your common taillight wire and you have your lights on as you drive, it should be charging as you drive. 12 volts, but low amps.
SDE

old · Jul 22, 2013

All the ones I ever saw had 12 volt batteries on them. As for rocking it well the brakes are electric so the magnets need time to move a short ways to push/pull the brake shoes out so yep you can rock one.

flembo · Jul 22, 2013

Thanks for the quick reply Old and SDE I have had this unit for 4 or 5 yrs with no problem I used it last wk for the first time after the winter but didn't have lights on. I supose I could charge it on 2amp for a few hours, my wife needs to use it thursday, piece of mind if I knew it was ok.
This is the load I had on it last wk.

Mike (WA) · Jul 22, 2013

Can't be anything but 12 volt- it has to operate the 12 volt brakes in event of a kerfluffel, and has to be charged by a 12 volt wire from the truck.

Dave Sherburne NY · Jul 22, 2013

I just put a new one on my trailer last month it's 12 volt. Same as the one that came on it.
Trailer Battery

flembo · Jul 22, 2013

Thanks don't want no Kerfluffles.

jon f mn · Jul 22, 2013

It should be 12v as the others have said. Yours is wired correct with the charger, if you hook it direct to the clearance light wire and you plug it in with a low bat. like you have, it can blow the fuse. Some hook them to the "hot" wire from the truck battery that is for charging camper batteries. If you do that it can cook the battery by charging it to fast. Yours will charge to 12v by just running it with the lights on for a bit, but you should be able to put a trickle charger on it for a while too. Just watch it for heat build up.

John T · Jul 22, 2013

Ive never seen one that wasnt 12 volt. The brakes are designed for 12 and if the break away switch closes it throws the full 12 volts to the magnets for max braking. Until such time the magnets are energized and pull over against the drum to enage and pull the lever arm, there shouldnt be any brake tension or dragging (subject to the adjustment). Id have a 20 amp circuit breaker at the battery and run a hot feed back to keep the trailer battery charged while driving IFFFFFFF its a chargeable battery that is.......

John T

jon f mn · Jul 22, 2013

His has a battery charger in the system and is the BEST way to do it. He just has to remember to run with the lights on. Lots of people do it the way you describe and it works ok, but it over heats the battery by charging it too fast and shortens the battery life significantly.

BhB · Jul 23, 2013

John T
Question about charging a second battery. I have a cargo trailer that I use to go to bike rallies and other things. It has brakes and lights in so I have a 12 volt battery. I don't have a diode in the charging system I just unplug the trailer when I park to keep from disgharging the truck battery. I checked the charging voltage, with the truck running the truck battery was 14 volt and the trailer battery was 12 volts. I then used another battery with jumper cables to another vehicle and had the same result. I asked a friend of mine who is an electrical engineer at NASA and he couldn't explain it. Do you have any thought about this? The trailer battery charges and I have no problems. I am just curious I would think that the voltage would be 14 volts unless the truck battery draws the voltage down.
Bill

John T · Jul 23, 2013

Not sure I can explain it either. Things that come to mind would be: 1) Voltage drop in the wire and/or any breakers or fuses and connections/splices in the line from truck battery back to trailer battery (but 2 seems a lot) 2) The trailer battery, for whatever reason, isnt achieving or maintainuing the state of charge as the truck battery. 3) A resisitve/burned/loose ground connection at the trailer.

If two batteries are in paralell one would think the voltages would be the same unless theres a voltage drop across a connection or splice or wiring or a ground I guess. If two batteries in paralell arent the same (should be matched in type size brand and age etc) one feeds off the other and thats not a good thing. Still if plugged in when driving the trailer battery should get some charge at least and as long as its unplugged when setting (or a diode) I dont see it as too serious unless excess current trying to charge a weak battery might overcurrent the charging system???

Just hard to say

John T

mkirsch · Jul 23, 2013

If the battery is only 9.3V, REPLACE IT.

Once a 12V lead acid battery goes down below 10V for any length of time, it's shot. It will never hold a charge again.

OT trailer break away voltage

flembo

Well-known Member

SDE

Well-known Member

old

Well-known Member

flembo

Well-known Member

Mike (WA)

Well-known Member

Dave Sherburne NY

Well-known Member

flembo

Well-known Member

jon f mn

Well-known Member

John T

Well-known Member

jon f mn

Well-known Member

BhB

Member

John T

Well-known Member

mkirsch

Well-known Member

Similar threads