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GA1dad's avatar
GA1dad
Explorer
Dec 11, 2016

Battery Tenders

Keep in mind I'm a noob to the diesel world,,,,,

So twice now the batteries have run down on my Duramax from lack of use. I'm starting to look for an inexpensive tender that I can mount to the vehicle. I'm kinda looking at the Tender Jr. 800. I know the 800 milliamps is not much for actual charging,, but I suppose it could maintain an already fully charged system. I want to mount the unit in the engine compartment somewhere, then hard wire at the battery terminals and have a 120 volt pigtail coming out of the grill.

My question is if I hardwire it to the terminals, would it be harmful to the tender if I drove the vehicle with it still hooked up ( not powered up,, but still hooked to the battery )., While running, will the current from the alternator reverse into the tender and burn it up?

Thanks in advance folks.

27 Replies

  • I have had a bunch of different tenders over the years. I have a little 40 acre hobby farm with a couple farm tractors, an old snow plow truck (Bronco) and a couple zero turn mowers and a side by side ATV and as the wife say way to much ****. I am finding out way more toys then an old dog in his 60's needs to maintain with a body falling apart.

    I also have Dodge truck with a 6.7L Cummins parked in the barn and we only use it to pull the 5th wheel, or a tandem axle utility trailer when we haul something. The latest tenders I have been using is a Black and Decker 2 amp and works great. It comes with 3 different plug setups (hard wire, cigarette plug, and alligator clamps). In the truck I plug it right into the 12 volt accessory (cigarette plug) on the dash and back feed to the batteries through that plug. I toss it on the floor and close door on the power cord. You need to make certain the accessory plug is hot all the time especially with the ignitions turn off.

    Black and Decker

    I pulled both 12v batteries from my 5th wheel when I winterized it. I have them in my garage on the workbench and have one on each battery with the alligator clips maintaining them for the winter. I like these the best of all the ones I have used so far over the last 30 years. I think they come in a lower amperage too if that's what you want. The 2 amp seems to work nice for me.

    Mi Bob
  • Since you are charging two batteries, I would use the 1.25 amp model. Battery Tender has an extension cord that would be a better solution. Just connect when you plug in and the a Battery Tender will be out of harms way and available for other uses when not connected.

    If you have had severly discharged batteries, they may well be on their legs.
  • It will work fine. I would suggest looking at the Noco brand instead of the Tender brand. I have switched over. They do more then the Tender brand. I picked up a 7amp version for just over $100 Canadian.
  • My 2005 Ford diesel goes dead in about 8 weeks so I use a battery minder on it also. I always leave it connected under the hood without any problems.

    Bill
  • Harbor Freight has several cheap ones. I use a multistage marine one myself.
    bumpy