I had a thread on this subject at one time but it is so old now is been archived and it won't let me resurrect it. 

 

At the time i had some issues with the truck but they should be fixed now. I also had replaced my batteries as they were still giving me problems. It may be because of the issues i had. 

 

So i have new batteries, but it seems like they are still getting drained. I'm thinking the recent cold sub Zero weather has something to do with it. 

 

I was going to purchase a minder, tender but didn't know which one to get. Amperage wise i mean... i can get the Jr tender but it's .75a. So is that enough to maintain a float in two large batteries?

Whats the time frame?  How long is the truck sitting before the batteries are seemingly loosing voltage?  And have you done a parasitic drain test?

I'll check the batteries tomorrow before work again and see. It seems overnight but I'll check. 

 

I haven't but i guess i get to do it this weekend...

If the batteries have been drained of capacity low enough to not crank the engine then thats never good.  But if they're drained like that more than a few times and the odds are that the cells are toast and wont hold a decent charge.

 

If your batteries are draining as fast as you say then something is clearly draining them and needs to be found.  A tender wont help.

I totally agree... 

I just got the "Battery Tender Junior", and I love it so far. Didn't get it for the Cummins, as I can let that one sit for weeks without starting and it still never takes more than 2 cranks to fire up. So to that point - yes you should definitely figure out where your juice is going, because these trucks don't suck the batteries dry as normal behavior.

 

I rotate the tender between batteries in the cars that sit in the barn over winter, and it works great. I should really get more of these so I don't have to rotate it, but I switch it from one to the next about once a week or every other week, and it seems to work great so far. Spring will tell for sure, as I usually have to replace the battery in the Chevelle almost every year after I neglect to take care of it over winter.

My 1996 Dodge Ram 1500 sits for months and typical starts right up. I might remember to use the little truck for firewood and give it time to charge the battery. I agree it time to find the battery draw because these truck should only draw about 50mA typically with everything shut down. 

 Overnight i lost 10% charge. Had the battery charger on to top it up before heading to work. Over the weekend it was down to 70% after sitting 3 days. 

 

50ma? At least that gives me something to benchmark off of...

that's way to much drain, I would start looking for the circuit that is causing issues.

 

Any battery tender should be up to the task assuming there isn't an unnormal drain.

You may have a bad battery.  Disconnect you batteries and look to see if you have the same results.

4 hours ago, Hawkez said:

You may have a bad battery.  Disconnect you batteries and look to see if you have the same results.

Charge both batteries unhooked from the truck and then let stand for 24 hours. Check the voltage after 24 hours and see what your test voltage is.

Keep in mind too that voltage at the battery only drops about 1.5v from a fully charged to fully dead battery. You should only see this amount of fluctuation on a good battery. I don't remember the exact cut off number, but if you ever see voltages lower than 11 - there's a good chance your battery is toast.

 

Sorry, "fully dead" is probably the wrong way to describe it, but if a battery measures lower than that threshold it will be dead enough to appear to be dead to a vehicle anyway.

Edited January 10, 20178 yr by jokra

Just Google automotive battery state of charge chart and you'll better understand what the tester is telling you.  That said, 12.7 is 100% charge and 12.2 is around 60%.

10.5 is a dead battery and is taking on damage for sure.

Now what?

 

Still losing battery despite coming under 50ma...

Might have bad batteries with an internal short. So the batteries will be self-draining.

Edited January 23, 20178 yr by Mopar1973Man

Check see if the glove box switch is working sometimes those leave the light on and can't tell because it is shut..

 

How old are those batteries anyhow?

 

I know they loose voltage thru the dirt built up across the top of the battery so I keep mine clean around the posts too.

Edited January 23, 20178 yr by JAG1

Charge the batteries and then leave them disconnected and see if they hold their charge.  That would help you understand if the batteries are the problem or if there's something draining them.

18 minutes ago, KATOOM said:

Charge the batteries and then leave them disconnected and see if they hold their charge.  That would help you understand if the batteries are the problem or if there's something draining them.

 

 

That right there will test if there is a internal short of the batteries. If there is a internal short the battery with the problem will continue to go dead without being hooked up. So charge the batteries good for few hours. Then disconnect both batteries for the night and measure the voltage of both batteries while disconnected. 

 

Remember if one battery is bad you have to replace both anyways. 

I had a battery in a car that went bad and acted like this.  I could charge it up and then with a DVM I could watch the volts drop before my eyes--nothing hooked up to it.  Internally it was bad.  New battery and I was good to go.

My big solar system battery bank failed in the same manner. The batteries would get an internal short and the battery volts would bleed out over a 24 hour span to the point of being dead again without another hooked up to them. 

 

Just remember all batteries can get this issue including AGM batteries. The trick to preventing this issue...

• Never let a battery go dead. Dead in a manner of speak for 12V is anything under 11 volts (some state 10.5v but I like to error on the side caution).
• Never let the plate become exposed to the air. When the electrolyte get low enough that the plates are exposed to air that section of plates are now ruined. 
• Always recharge the batteries fully before leaving to rest. This mean don't go out start the truck on cold morning move 100 feet and shut down again the batteries cannot and will not recover their charge in that short time. Batteries require warmth to charge and time so if you start up make sure to fully charge before shutting down again. 
• When adding distilled water to the cells make sure to disconnect the batteries and do a equalize charge on the batteries to ensure that the distilled water and electrolyte is stirred back together again. If not this is what's called stratification and the acid become concentrated on the lower part of the plates. Also equalizing the batteries will also help repair sulphation of the plates. WARNING: Do not equalize an AGM battery you will most like do damage and dry out the cells.  

Edited January 23, 20178 yr by Mopar1973Man