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Today I installed a on board battery tender.
The reason for the install was to top the batteries off each night. Do to my very short commute to work my batteries are not getting topped off each day. I believe this lead to a premature failure on my batteries after only 2 years. I recently installed 2 new Napa sealed batteries and built my own new battery cables using military style battery terminals. I have a on board Engal fridge that is plugged in each night to house AC. I already had a 3 foot extension cable with 3 outlets install in the engine compartment near the driver side battery.
I wanted to get the NOCO Genius GENM1 4 Amp 1-Bank On-Board Battery Charger. But after several attempts to order through amazon I could not seem to get one delivered. I settled on a less expensive
Schumacher SC1300 1.5A 6/12V Fully Automatic Battery Maintainer. I set it up last last night temporally and hooked it to the driver side battery. I had not driven the truck for about a week and the charge went into charge mode right away. I checked it 2 hours later and it was still charging. When I checked this morning it was in float mode.
This after noon I went about mounting and wiring in the charger permanently. I install the charge near the driver side battery. I then hook the Red(positive) wire from the charger to the driver side battery, I then used some 12 gauge black wire to lengthen the Black(negative) to reach the Negative post on the passenger side battery. I ran this along the battery cable running along the top of the radiator core support. This is the recommend way to hook up a charge for a dual battery system when the batteries are not isolated, like what we have in our diesel powered trucks.
Nice install, I did the exact same install about 7 years ago using the Deltran 1.5 amp Battery Tender and I connected it to a Marinco power inlet that I installed in my bumper so I can plug in without raising the hood. The parasitic loads on these trucks is quite noticeable and just sitting a week draws the batteries down more than I like but the 1.5A Tender keeps them topped off at all times. The Deltran actually fits nicely on the fender alongside the pass side battery
The older DelTran Tenders had protection circuitry that automagically switched to float after about 8 hours. The idea is to prevent excessive outgassing. If you want to keep two large automotive start batteries wired in parallel charged and equalized it's important that the charger is "sized" to the battery Ah rating. About 15 amps is what you're looking for. In this situation a "dumb" charger is kind of what you want. A float charger is just that, they are way too small for what you're trying to do.
The older DelTran Tenders had protection circuitry that automagically switched to float after about 8 hours. The idea is to prevent excessive outgassing. If you want to keep two large automotive start batteries wired in parallel charged and equalized it's important that the charger is "sized" to the battery Ah rating. About 15 amps is what you're looking for. In this situation a "dumb" charger is kind of what you want. A float charger is just that, they are way too small for what you're trying to do.
My truck has always lost voltage fairly quickly so I must keep something on it or in a week it will be showing about 12.3 volts. I tried Harbor Freight (free or almost free) and they didn't have the amps to hold a charge plus they wires are so small, they break off the alligator clips. But I bought one of these LST float chargers and it keeps it about 13.5v. As I understand it 13.2v to 13.5v are a good float voltages but as you approach 14v, you start to gas the battery. It came with a quick disconnect plug and 2 types of connectors. One is eye connectors which i used to permenantly attach to the batteries, the other is alligator clamps which I suppose I can use on another battery if I need to. Now when I know the truck is going to set for a few days, I pop the hood, plug in the charger to the extension cord and quick connect it to the installed eye connector. Quick and easy. I got it at Amazon.com for $16.99 with free "Prime" delivery. I've had it for a couple months now and no problems.
Every month or so I connect my Shumaker 10 amp charger which runs them up to almost 15v for a while (a couple hours) before going back to float voltage, which would seem to equalize them.
Dumb question, but don’t both batteries get charged when you hook up to the charger to just one battery?
It would but the charge would be evenly applied across both batteries if connected like shown in the diagram, which is the recommended way to charge a battery bank
There is no automatic correct answer to the correct charge or float voltage. Both vary by battery condition, battery type, and temperature. Temp is probably the most important for the float, if the temp/voltage are too high you will damage the battery. This is especially important with a sealed battery because it'll loose electrolyte that can't be replaced. If the voltage is too low you loose some of the benefits but won't cook the battery. Right now 13.5 might be fine, in the summer it could cook the batteries.
Dumb question, but don’t both batteries get charged when you hook up to the charger to just one battery?
They do. Technically the one connected to the charger will see higher voltage, but with something as low powered as this charger it probably won't be more than .01volts. Wiring it the way he did helps prevent any imbalance. It's a cure to a non existent problem, but it's only being installed once so why not go all out.
A purist in the battery world would evaluate wire gauge, wire condition, wire length, battery age, battery condition, battery type (LA, AGM), battery temperature, battery load, battery Ah rating, battery maintenance, etc... Then the purist would purchase and utilize a charger/maintainer that fits their situation PERFECTLY and walk away knowing they have done everything they possibly can in order to keep their batteries charged and securing their place at the "battery chargers table" for eternity in this life and the next.
Common people like me have used, do use (until today when I received a Noco 4A single bank charger as a gift) a much smaller battery maintainer. I have two 930CCA Northstar AGM batteries that have been kept up by a Battery Tender Jr. which is rated at 12v and 750mA. That is right, mA... It has two alligator clips that connect to either battery and provide enough of a maintenance charge to keep the batteries topped off. I did not and do not have the BT Jr. on the truck all the time, as a matter of fact the BT Jr. makes its rounds to all of our vehicles. The 2008 Subaru, the 2003 VW, the 2016 Ford, the 2000 Ford and the 2010 John Deere riding mower. This little guy keeps all the batteries topped off and has been doing so for nearly 10 years now.
I have used this same BT Jr. to maintain four 6v Trojan T-105 batteries tied together as one big *** battery. The small 750mA tender will not bring a dead battery back to life, but it will maintain the charge of a healthy battery which is what I believe 95% of the population is looking to do.
Why did I receive the Noco 4A Gen1Mini? Well, I am lazy and getting fat because I don't exercise like I used to when I was active duty. The truck sits in the corner of our property at the tree line and I don't feel like walking about there to plug up the BT Jr. anymore... That is all, otherwise the BT Jr. would continue to service the AGM batteries. I will install the Noco into the engine bay with an outlet mounted into the bumper and simply plug the truck in when it is parked out there, like it is most of the time. Again, this is because I am lazy and getting fatter as the days go on. The beer and hot chocolate consumption don't help with that, but I don't give a ****...
As for which battery to connect the single bank charger, well connect it to either one you want. Really the negative should be on one battery and the positive should be on the other, but they are wired up together anyway and the voltage drop between the two is minimal and nothing anyone other than a purist should worry about. The alternator designed from the factory is only hooked up to one battery. Yes, I upgraded my wiring and have dual positive and negative cables running to each battery, but that is because the alternator is 160A, not a 4A charger and maintainer...
You can discuss battery tenders, maintainers, chargers and how they are supposed to be used all day long until you are blue in the face. What it comes down to is what you are happy with for your budget, install time and use.
Is that battery tender okay to be in that environment all the time? Just asking.
The Battery Tender Jr. I have been using is NOT waterproof. When I use the BT Jr. I am using it in the garage or shed except for the truck. The truck sits under and RV cover, then I put the BT Jr. under the hood for a bit more protection from the weather.
The bilge/engine room of a boat doesn't get as hot as a truck's engine compartment so being marine rated doesn't guarantee it'll survive, but probably.
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