Battery Tenders

[GA1dad]

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.

[austingta]

My friend Dale went on a 3-month road trip and when he got back his new Cadillac started right up.

[Lynnmor]

Trackrig wrote:


My Ford truck will die if I leave it for about eight weeks, but what really gets me is the DWs Ford Escape that goes dead in about ten days. It's been two two dealers and both said that was the way Ford designed them, there's nothing they could do.

Bill

I very much doubt that the dealer is starting and letting run all the new and used vehicles on the lot every few days. Doubtful they could sell anything when most won't start for a demo ride.

[Bedlam]

beergardens wrote:

mkirsch wrote:
"Have truck checked..."

For what, exactly? Any good mechanic will tell you that minor electrical gremlins are extremely tough to track down, and to pay them to do it may well cost more than the vehicle is worth.

It's a routine matter for a technician to go over the charging system. Test the alternator output, load test AND cell test the batteries, and measure the ignition-off draw. If the draw is over 50mA after everything has timed out, then it's time for the OP to decide if he wants to hunt it down, which often isn't as horrifying as people make it out to be, as long as the tech is knowledgeable.

It's pretty easy to use an ammeter between the truck and battery and start pulling fuses until you find the biggest draws. This will isolate the problem down to one circuit. You may find it is as simple as a cigarette lighter adapter that is always running or a glove box light that never turns off.

[Trackrig]

mkirsch wrote:
"Have truck checked..."

For what, exactly? Any good mechanic will tell you that minor electrical gremlins are extremely tough to track down, and to pay them to do it may well cost more than the vehicle is worth.

My Ford truck will die if I leave it for about eight weeks, but what really gets me is the DWs Ford Escape that goes dead in about ten days. It's been two two dealers and both said that was the way Ford designed them, there's nothing they could do.

Bill

[theoldwizard1]

austingta wrote:

GA1dad wrote:

gbopp wrote:
How long does your truck sit between uses?

A couple of weeks and it goes down enough to keep it from starting. It'll roll over a few times, then click/click.

There is something wrong for sure. The ECM and other things that use current don't use very much at all.

2 weeks and you should be able to start it.

4 weeks, less than 50% chance.

[beergardens]

mkirsch wrote:
"Have truck checked..."

For what, exactly? Any good mechanic will tell you that minor electrical gremlins are extremely tough to track down, and to pay them to do it may well cost more than the vehicle is worth.

It's a routine matter for a technician to go over the charging system. Test the alternator output, load test AND cell test the batteries, and measure the ignition-off draw. If the draw is over 50mA after everything has timed out, then it's time for the OP to decide if he wants to hunt it down, which often isn't as horrifying as people make it out to be, as long as the tech is knowledgeable.

[mkirsch]

"Have truck checked..."

For what, exactly? Any good mechanic will tell you that minor electrical gremlins are extremely tough to track down, and to pay them to do it may well cost more than the vehicle is worth.

[boshog]

Chuck_thehammer wrote:
answer is not so easy..

the older the battery . the faster it discharges.
I avoid the cheaper tender types.. Deltron Battery Tender was top. others are catching up.

1.5 amp with 2 batteries.. adding a single 2 amp diode will stop back draw.

over 3 weeks I can see a slow start. but NOT a No start.. if it continues have truck checked..

do you have add-on electronic devices in truck, they may not be turning off.

Keep in mind diodes also have a voltage drop, enough drop and you may be doing a disservice to your batteries, particularly if their chemistry is AGM.

[Snowman9000]

Yeah the batteries could simply be old and feeble.

My 2004.5 Duramax has a parasitic draw of 21 mA. Which I think is not much?? I was chasing a battery problem recently. Starting was weak on a good day, and got worse as the truck sat. It turned out to be a corroded + terminal on one battery. Prior to that I had never seen corrosion in a GM style terminal. I cleaned it up and everything has been great since.

[Chuck_thehammer]

answer is not so easy..

the older the battery . the faster it discharges.
I avoid the cheaper tender types.. Deltron Battery Tender was top. others are catching up.

1.5 amp with 2 batteries.. adding a single 2 amp diode will stop back draw.

over 3 weeks I can see a slow start. but NOT a No start.. if it continues have truck checked..

do you have add-on electronic devices in truck, they may not be turning off.

[Strabo]

I use a solar maintainer for our toyhauler after I fully charge the battery bank. It's important to have a small constant charge on batterys that are not used regularly. Seems to work fine, 3 watt output.

[Turtle_n_Peeps]

austingta wrote:

GA1dad wrote:

gbopp wrote:
How long does your truck sit between uses?

A couple of weeks and it goes down enough to keep it from starting. It'll roll over a few times, then click/click. Seems like I recall the gauge showing around 10 volts when this happens. If I drive it every few days there is no issue. I should just break down and drive it daily, it gets better mileage than my s-10 4x4. But that little 4 door S-10 is a good commuter.

Thanks for the advise folks!!

There is something wrong for sure. The ECM and other things that use current don't use very much at all. You may have a battery or alternator problem.

Are there other uses that are left connected?

^^^^ This. Somethings up.

[rhagfo]

GA1dad wrote:

gbopp wrote:
How long does your truck sit between uses?

A couple of weeks and it goes down enough to keep it from starting. It'll roll over a few times, then click/click. Seems like I recall the gauge showing around 10 volts when this happens. If I drive it every few days there is no issue. I should just break down and drive it daily, it gets better mileage than my s-10 4x4. But that little 4 door S-10 is a good commuter.

Thanks for the advise folks!!

That is the best thing you can do for the truck, drive it.

[Isaac-1]

It all depends on how much you want to spend, I have one of the cheap $20 1.5 amp harbor freight battery tenders on my 30KW diesel home standby generator it has been hooked up for 6 or 7 years and is still working. I change the battery out every 5 years regardless if it needs it, just because I don't want to ever have to deal with a dead battery during a storm. By contrast I have an BatteryMinder model 2012 which sells for $90 on amazon on my old diesel 7.3 F250 pickup (2000 model) which only gets driven occasionally to haul stuff on the weekends, again it works, gives a few more bells and whistles than the $20 Harbor Freight model, I don't know if it really worth an extra $70 though. (I bought it on one of their lightning deal specials a year or two ago for about half off during the holiday season.

(my motorhome has 400 watts worth of solar panels on the roof which keep the batteries charged)