Battery cable splice


#1

Long story short: I want to lengthen the battery cables to accommodate a battery that has the terminals reversed. The negative cable looks especially difficult to replace with a longer cable because it snakes around the back of the engine.

Yes, I know there are batteries with terminals in the correct positions. But I want this battery for a specific use, and the cables don’t reach.

Are those battery cable splice kits OK for long-term use (as in, are they reliable over the long-haul)? The splicing mechanism seems essentially the same as these underground waterproof splices.

I’ve searched extensively on the web and haven’t yet found anything conclusive to answer this question one way or the other.


#2

I’m really curious what your “specific use” is. Because this seems like an invitation to disaster.

Based on my own experience, I know wacky things can happen when your battery/electrical systems aren’t totally 100% in sync.

On the off chance that your van needs a jump start…are you going to be 100% vigilant that the “jumper” with the “donor” battery doesn’t reverse the polarity and fry your electronics?

I’d really think hard about doing this. Good luck.


#3

Yeah :slight_smile:

I’m really curious what your “specific use” is.

The specific use is that I’m installing a small solar system, and I need a battery with good reserve capacity.

I don’t want an extra battery inside the vehicle, and I don’t have anywhere else to put a second battery.

Thus, I want to replace the starter battery with a dual-purpose battery. I haven’t found one that has a good reserve capacity and reversed terminals, so I end up at a battery that has standard terminals.


#4

What was your experience?


#5

Good, long lasting splices can be done pretty easily, it just requires the right compression splice and tool. This is something you may want to have an electrical shop do for you. The proper crimp tool needed for the job can be fairly expensive to purchase. A proper tape job will protect the connections.


#6

Far better to remove both cables and make new ones of the proper length with no splices. Solder lugs can be used, and I prefer them to crimp style. You have to remove the cables to solder them without burning the car down so why not just donthe job correctly?


#7

A proper, longer cable is your best option and a mechanic may be able to put it in in reasonable time if you can’t. Splicing is possible, also bolting to a properly sized terminal block, rated for cranking current and under hood environment. You might consult a welding equipment shop and/or electric car gurus as they deal with cables and currents of this size.

Survey the physical environment of the new positive terminal position, whether the closed hood will touch or come close to it, what will happen if the battery shifts position, etc. - be sure the positive terminal is well insulated and clearly marked. Protect against over charging by the solar system.
If the vented type, ensure the battery is well ventilated during solar charging as when parked there won’t be the airflow to carry off hydrogen as when driving. Due to design differences between utility and starting batteries you may need to check the battery acid level and add water (distilled or deionized) more frequently.


#8

If the battery you’re trying to adapt into this solar system is a starting battery, that’s the wrong type of battery for this application.

Instead, you want to use a deep cycle battery.

A starting battery has thin plates, and loses its charge rapidly. Starting battery’s aren’t designed to be deeply discharged. Starting battery’s require a long period of charging time to bring them back up to full charge.

A deep cycle battery has thicker plates, This allows the battery to provide power over a longer period of time before requiring recharging. A deep cycle battery can be deeply discharged and recharged without doing damage to the battery. And a deep cycle battery takes a recharge very rapidly. That’s why they’re used in golf carts.

So. It sounds like the battery requires replacement due to the application.

Tester


#9

There’s also the marine starting deep cycle batteries AKA marine dual purpose.

Usually used to start the gas engine and get you to your fishing spot, then shut off the gas engine and use your electric trolling motor and other electronics all day long, and then start your gas engine and go home at the end day all with one battery.

Biggest problem I see with what the OP wants to do is will this battery even physically fit in the battery tray.


#10

Thanks for all the input.

I know that a true deep cycle is the best choice for a solar setup, but I definitely want a 1-battery system.

I have not found a true deep cycle battery that:

  • Fits.
  • Has terminals on the correct side.
  • Has enough CCA to start the car (3.3L engine, manufacturer recommends something like 620 CCA min).

So, I’m looking at dual-purpose batteries. I have not found a dual-purpose battery with a decent reserve capacity that is the correct size and has the correct terminals (24R/F).

The battery I like (which has the terminals on the wrong side) is a dual-purpose battery recommended for trolling / starting applications and has a large RC.

The biggest problem is that it has terminals on the wrong side.

The solar isn’t installed yet. The current battery requires replacing b/c 1) it’s worn out, and 2) it’s a standard starting battery that won’t work for my plans.

@Mustangman, @ken2116

To me, the negative battery cable looks like it’s more of a harness that goes to the back of the engine compartment with several leads going to different places in the engine compartment.

Do you think a longer version of that cable can be manufactured easily? Or is it more a matter of adding an extension to a stock cable?

Thanks for the terminal block idea. I’ll look into that. I think the main issue is the negative cable. The positive cable looks pretty straightforward and easy to replace with a longer version.

@Mustangman

I’ve read soldered connections are more brittle in this type of environment b/c they’re rigid and can’t flex with vibrations. Does your experience indicate otherwise?


#11

@ledhed75 brought up a really good point, though.

While I would oversee any jumpstarting if I’m there, there may be times when I’m not there—such as if someone borrows the vehicle.

It also occurred to me that a mechanic who’s not really paying attention might accidentally reconnect the battery incorrectly when I get the vehicle serviced.

The consequences of this look pretty bad.


#12

Yes. This is a battery cable, not an ordinary wire. The solder lugs are heated and solder is melted into the recess and the cable is plunged in. The solder doesn’t wick up the wire and make it stiff.

As for making up a ground cable, it isn’t rocket science. The big wire gets lengthened as do the smaller ones. If those need to be spliced, OK, they aren’t carrying large amounts of current.


#13

After all this, someone pointed me to a great looking pure lead NorthStar AGM 24F dual-purpose that I had missed in previous searches. I searched a lot, but apparently not well enough.

That may solve the problem.

Thank you for all of your insights.


#14

It sounds like you may have found a battery of the same configuration, will assume the cable issue is moot for now. If you haven’t already done so check it for fit, both size and terminal style.

Check its chemistry and charging voltage requirements, all are some flavor of lead-acid but can vary a bit in maximum charging voltage spec. This one may be fine and at worst would need to adjust your voltage regulator or install a different one.

Don’t forget fusing.

If you’re going to be drawing on the battery with the car not running you’ll probably want an auto cut-off set for ~ 25% charge (so you can restart). Marine and RV vendors are sources.

Remove metal jewelry and wear eye protection when working around batteries. Disconnect the ground first, reconnect it last (so when you’re wrenching the positive terminal or any lead and the tool touches ground your life doesn’t get too interesting).

If you’re going to be drawing on the battery with the car not running you’ll probably want an auto cut-off set for ~ 25% charge (so you can restart). Marine and RV vendors are sources.

Make sure nothing about your set up can interrupt the connection between battery and alternator while the car is running, the battery must remain connected when the engine is running to snub high voltage spikes originating from the alternator, to protect electronics, control modules, etc. Sparking carries this risk, too.


#15

Thanks @ken2116.

If you haven’t already done so check it for fit, both size and terminal style.

Thx. I definitely will. It comes up as a “fit” for my vehicle in the product finder on various sites.

I’ll have 15A fuses on both the connection from the solar charge controller and the battery, and on my load connections from the controller.

I’m looking at battery monitors to protect against overcharging from the solar, and will have some sort of low voltage monitor and / or cutoff. My load is small; the battery is meant to be more of a fallback that I’ll use carefully. I read that these dual-purpose AGM batteries are drop-in replacements for flooded starter batteries and work with all modern alternators, but I’ll double-check.

Make sure nothing about your set up can interrupt the connection between battery and alternator while the car is running, the battery must remain connected when the engine is running to snub high voltage spikes originating from the alternator, to protect electronics, control modules, etc. Sparking carries this risk, too.

I didn’t know about the voltage spikes. That is good to know.


#16

If you haven’t done so it’s worth reviewing how RV’ers and cruising sailers manage this, both are good sources of information and equipment.


#17

I really don’t understand batteries I guess Boat battery after 15 years died, it was forgive my terminology a deep cycle battery, so costco had some other battery with the bolt on fittings I needed, but not a whatever I had, I am like it only has to start a 90 hp outboard, works great, still confused.


#18

Starting battery
Is designed to deliver a large burst of power for a short time as needed for normal engine starting and are not designed to withstand multiple discharge/recharge cycles, and draining it can significantly shorten its life.

Deep cycle battery
Is designed to provide a steady amount of current over a long period of time, like an electric trolling motor. Deep-cycle batteries can be repeatedly discharged and recharged without causing damage or shortening their life.

A dual purpose battery
Is designed to do both, they usually don’t deliver the same cranking amps as a starting battery or the reserve capacity of a deep cycle. They also cost more.


#19

Thanks. I’ve been looking into RV / marine systems… I believe what I’m setting up is functionally the same as a single-battery marine solar system.