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Battery Tender on 01 f350

3K views 12 replies 5 participants last post by  EOD Guy 
#1 ·
Went camping this weekend. Parked the truck at the campsite Friday night and went to start it this morning and it cranked pretty slow but it started. Hooked up the 5th and shut off the truck and continued to pack things up. About a hour later the truck wouldn't start. I removed the battery from the camper and installed it in the truck just to get home. I figured on reinstalling the battery in the truck when I got home and hooking up the battery tender to one of the batteries and letting it charge all week.

My question is since the truck has dual batteries if I hook the tender to just one battery will it charge both batteries? Will it damage the battery/batteries?

Or do I just need to remove both batteries and charge one at a time?
 
#3 ·
If the batteries are wired in parallel, it'll work just fine..... it's basically a 12v output. I have several batteries that I take in for the winter and use 8 gage jumper cables and a single tender to keep them topped off, takes a long time before the tender gets them to full charge, 2 weeks, but once they get there they stay topped off.
 
#6 ·
Depending on whether its a diesel vs. towing/camper special, the wiring for the batteries may be different. Diesels usually use both batteries to start and run, so the batteries are always connected to each other and one charger will work.

If its gas engine with a towing/camper special package it may be designed to separate the engine/starting battery from the camper battery by using a battery isolator. This allows you to get power from the camper battery while parked, and leave the other battery capable of starting the truck.

Bruce
 
#7 ·
7.3 psd, real trucks don't have spark plugs.

I'll put the battery tender on it tonight. I talked to the shop foreman in the truck garage today at work and he said, "the alternator keeps both batteries charged so why wouldn't the charger". He also told me if I brought the truck or just the batteries to him he could test them and tell me what condition they're in.
 
#8 ·
Your batteries are wired in parallel, one tender will keep both charged considering they are in good condition. If one battery starts to go south, my advice is to replace them both at the same time considering their age........ I have a F250 and one battery started to go south, I was advised to replace them both and decided not to...... end result I ended up buying 3 batteries. When I replaced the one bad battery, the older battery started to fail and caused the new battery to go south, I ended up replacing both. Shortly after this the alt started to fail (don't know if one caused the other). I replaced the alt with a reman from the dealer, it went south in a year..... ended up buying a "new" one from NAPA and all is good.
 
#9 ·
So........for the past couple years I've been switching my battery tender between different batteries over the winter. Boat, camper, quads, mud truck, etc. Your saying if I make jumper wires and hook all the positives together and all the negatives together the battery tender will float all the batteries, no matter the size of it? As long as they're all 12v of coarse.

I was going to buy 4 more tenders this year for winter storage but this sounds like a better setup.
 
#10 · (Edited)
I have 4 automotive batteries on one tender and three on another. I use the marine tender, 40-50 bucks on ebay. I took some 8g wire and made some 18" lengths, on one set I connected 4 jumpers to each leg of the quick connect bullet pig tails for the tender and a copper spring clamp on the other end...... the jumpers were really tight and needed to be longer.....but worked fine. On the 2nd set (3 batteries) I used 12" lengths but daisy chained them and connected the tenders spring clamp connecter to the center battery, this was much easier to connect as the batteries could sit side by side. the 4 battery setup took almost three weeks to get a green light (fully charged) and the 3 battery setup 2 weeks..... but I didn't have to buy new batteries this past spring!

I did put a full charge with a normal charger 1st and verified the batteries didn't have a bad cell. I use the CTEK 2500 multi charger, it has a reconditioning feature which blasts the poor preforming battery/cells with high voltage to blasts the build up from the plates etc....... It won't ever bring it to new status but I've saved several poor charge retaining batteries back to almost new charge retaining etc..... I don't know if I stated that correctly but you get the jist.

http://www.ebay.com/itm/CTEK-Multi-...es&hash=item589b901815&vxp=mtr#ht_3796wt_1106

http://www.ebay.com/itm/New-Battery...es&hash=item35da1a1b32&vxp=mtr#ht_3521wt_1132
 
#11 ·
Well to finally update. I ended up disconnecting one of the batteries to check the voltage output of each battery. The drivers side battery read 12.5 volts on the battery posts and also on the battery cable ends. The driver side battery read 12.5 volts at the battery posts and 8.xx on the battery cable ends. Cleaned all four cable ends and all four posts and everything is working as should now.
 
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