Upgraded? To Walmart Value Power Battery...

[DriveHard]

The original OEM battery on my truck was starting to get tired. Slow cranks in the cooling fall weather and the low battery alarm would go off if I listened to the radio for anything more than a minute or two. The Wallyworld Everstart Maxx direct drop in was about $125 (size H8). So instead I decided to "upgrade" to two batteries. Since the Silverado already has two battery trays I picked up two 24F Value Power batteries for $49 each and dropped them into the truck. My thought is stressing two cheaper batteries half as much should make them last twice as long...right ;-) If I get 5 years out of the pair I will be more than satisfied. For now the crank speed is dramatically increased and I have not heard a peep about low battery and I listened to my radio for a good 10 minutes yesterday without it running. We will see I guess.

 

[skyactiv]

How did you isolate the two batteries?

 

[HerrStig]

Car radios don't draw much unless there are some large amps drawing high idle current. You ought to check your charging system.

 

[DriveHard]

I didn't isolate the batteries. They are just wired in parallel. I have one 4 gauge wire connecting the two + terminals of the batteries, and I ran an additional 4 gauge wire from the + of the new battery to the alternator. The new battery is grounded to the body. The original battery is grounded directly to the engine block.

Charging system is fine. The old battery was clearly starting to die.

 

[Klutch9]

Originally Posted By: DriveHard
I didn't isolate the batteries. They are just wired in parallel. I have one 4 gauge wire connecting the two + terminals of the batteries, and I ran an additional 4 gauge wire from the + of the new battery to the alternator. The new battery is grounded to the body. The original battery is grounded directly to the engine block.

Charging system is fine. The old battery was clearly starting to die.


Yep. I had a battery go within a very short amount of time, and at the very end even a few minutes of the radio being on would kill the thing.

 

[crazyoildude]

They are not bad batteries i see the used car dealers buying them and i have one in use for 1 year on a car that sometimes sits for 2 weeks

 

[crazyoildude]

The $49.00 value battery at wal mart is a good buy. They are an ok battery...

 

[bubbatime]

That's a pretty cool idea, I like it.

The charging system might not ever put a really good charge on both batteries, so might not be a bad idea to put the batteries on a charger once a month.

 

[Doog]

I always buy the gold top 700CCA battery. If you get it from AAP and use the discount codes it comes to about $94 out the door. Just bought one for the wife's Lexus. They will always get me to the 200k trade in mark. Every Spring I check the water level and top off with distilled water. Never a problem. I always charge the new battery on a 2Amp trickle charger for 4-5 hours prior to installation.

 

[Rand]

Originally Posted By: Doog
I always buy the gold top 700CCA battery. If you get it from AAP and use the discount codes it comes to about $94 out the door. Just bought one for the wife's Lexus. They will always get me to the 200k trade in mark. Every Spring I check the water level and top off with distilled water. Never a problem. I always charge the new battery on a 2Amp trickle charger for 4-5 hours prior to installation.


Those are my goto battery.. price varies from 70 to about 125$ after coupon depending on fitment.

Right now many kmarts have some of their diehard batteries 50% off as well.

The 8 year old battery in the deere 850 is on its way out.. they had Group size M-4 on sale for 64$

 

[kc8adu]

you greatly increased the reserve capacity.so if the alternator dies you can go a lot further to get help or even get home to deal with it on your terms.
and your radio playing will have less impact on life as you wont cycle them as deeply.
i do this myself because of radio equipment loads.a 1 kw hf amp can be rough on the system!
but i use true deep cycles in mine.

 

[Johnny2Bad]

Ideally with a 2-battery system you have one battery for "start" and one battery for "accessory", managed by a dual battery "black box". When set up this way, your start battery will never fall below a certain voltage and always be available to start the vehicle, while the the accessory battery will be allowed to run down to the minimal voltage level (around 10VDC) to keep powering offroad lights, radios, etc as long as possible. An engine start condition could also employ both batteries in parallel, either manually or automatically, depending on the battery management "Black Box" you choose.

Because such a setup is specifically designed to handle batteries of different charge levels, there won't be any issues with battery life.

When you have a simply wired system with two batteries in parallel (2x 12V parallel = 12V total at twice the current) it's critical that they both have identical states of charge. If one battery is lower charge than the other, it will drain the other battery. If one battery has a bad cell it will permanently cause the other battery to drain down regardless of the charge rate or health of the alternator / voltage regulator. So, you should always replace both batteries at the same time and be careful that one does not have a failure of some type (sulfation, for example).

The 2 in parallel system can work, but it is not as reliable as the system with a battery management box, where you would instead be free to replace just one battery or to use two batteries of different health.

Care should be taken so that the wiring can accommodate the higher current capacity. For example, if the wiring to the starter solenoid and starter itself is only sized for a single battery, you will not be able to avail yourself of the starting power of the two batteries completely, plus it is a fire hazard. If the dual battery setup was OEM it is probably OK, but if you are retrofitting a system yourself, a wiring upgrade is in order. OEMs do not normally build in extra capacity when it comes to wire size, because for one thing, copper is expensive and OEMs are cheap, and for another, copper is heavy and OEMs are all about minimal weight. You might think a little wiring is no big deal, but the modern vehicle has miles of wire, and it truly adds up.

Note that if you are replacing wire, the correct SAE grade wire has the proper insulation for automotive use. If you choose instead to use AWG grade wiring, know that AWG 20 (for example) is heavier and larger in cross section area than SAE 20, but it may not have the proper insulation suitable for automotive use. Avoid trailer wire (which is often the only kind an automotive store sells), which is not rated for under-hood or automotive interior use.

 

[DriveHard]

Originally Posted By: Johnny2Bad
Ideally with a 2-battery system you have one battery for "start" and one battery for "accessory", managed by a dual battery "black box". When set up this way, your start battery will never fall below a certain voltage and always be available to start the vehicle, while the the accessory battery will be allowed to run down to the minimal voltage level (around 10VDC) to keep powering offroad lights, radios, etc as long as possible. An engine start condition could also employ both batteries in parallel, either manually or automatically, depending on the battery management "Black Box" you choose.

Because such a setup is specifically designed to handle batteries of different charge levels, there won't be any issues with battery life.

When you have a simply wired system with two batteries in parallel (2x 12V parallel = 12V total at twice the current) it's critical that they both have identical states of charge. If one battery is lower charge than the other, it will drain the other battery. If one battery has a bad cell it will permanently cause the other battery to drain down regardless of the charge rate or health of the alternator / voltage regulator. So, you should always replace both batteries at the same time and be careful that one does not have a failure of some type (sulfation, for example).

The 2 in parallel system can work, but it is not as reliable as the system with a battery management box, where you would instead be free to replace just one battery or to use two batteries of different health.


Yes, I understand how folks who have high load items running without the engine running would have this arrangement. I rarely do anything except listen to the radio for a few minutes while waiting to pick up a kid from somewhere, so really the isolator box was not really needed for my setup. I was just looking for a cheap battery replacement and realized I could get two of the "value" batteries for less than one good one. I did know about one battery draining the other, bad cells, etc. That is why I got two identical batteries with the same date stamp at the same time. This is the arrangement many diesel trucks and off highway equipment use, so I think I am good to go.

 

[Johnny2Bad]

Originally Posted By: DriveHard
Originally Posted By: Johnny2Bad
I
...


Yes, I understand how folks who have high load items running without the engine running would have this arrangement. I rarely do anything except listen to the radio for a few minutes while waiting to pick up a kid from somewhere, so really the isolator box was not really needed for my setup. I was just looking for a cheap battery replacement and realized I could get two of the "value" batteries for less than one good one. I did know about one battery draining the other, bad cells, etc. That is why I got two identical batteries with the same date stamp at the same time. This is the arrangement many diesel trucks and off highway equipment use, so I think I am good to go.


I would point you to the notes about charging and health of a non-regulated dual battery setup. That is where you are going to find issues, if there are any. The parts about a regulated dual battery system having (for example) reserve capacity to run a radio is simply a feature that is part of the implementation at no additional cost to build in. It is not the main reason; the ability to use and charge two batteries of a different state of charge or age is.

You are correct in that if there are no issues and the batteries age identically, it's a reasonable setup. But once you get past a certain age in a lead-acid battery, any two batteries, even those made on the same day in the same factory, generally do not have the same charge and discharge characteristics. The problem comes when one needs to be replaced, because you are now required to replace both, regardless of how healthy the second battery is. This may involve replacing the batteries earlier than necessary with a regulated system.

You could always go back to a one battery system with the known good battery, though, and wear that down to it's natural life, before replacing both again.

I appreciate how it's done in industry with 12, 24V and 36V systems (eg forklifts) but commercial parts management tends to pay close attention to parts life and to replace on a schedule, which is not quite the same as an individual owner trying to eke the longest possible life out of a part.

In any case, as long as you embark with eyes wide open, feel free to do as you see fit.

 

[DriveHard]

Originally Posted By: Johnny2Bad

Care should be taken so that the wiring can accommodate the higher current capacity. For example, if the wiring to the starter solenoid and starter itself is only sized for a single battery, you will not be able to avail yourself of the starting power of the two batteries completely, plus it is a fire hazard. If the dual battery setup was OEM it is probably OK, but if you are retrofitting a system yourself, a wiring upgrade is in order. OEMs do not normally build in extra capacity when it comes to wire size, because for one thing, copper is expensive and OEMs are cheap, and for another, copper is heavy and OEMs are all about minimal weight. You might think a little wiring is no big deal, but the modern vehicle has miles of wire, and it truly adds up.

Note that if you are replacing wire, the correct SAE grade wire has the proper insulation for automotive use. If you choose instead to use AWG grade wiring, know that AWG 20 (for example) is heavier and larger in cross section area than SAE 20, but it may not have the proper insulation suitable for automotive use. Avoid trailer wire (which is often the only kind an automotive store sells), which is not rated for under-hood or automotive interior use.


I used 4 gauge wire I had laying around from some old amplifier installs. So yes, it is automotive grade, and good to go.

I don't see your logic in upgrading the wire leading to the starter. I am still running a 12V system, and the current going to the starter during operation is a function of the voltage available and the resistance of the starter in operation. The voltage is still the same, and the starter is still the same. Yes, maybe the voltage will not drop quite as much as it did with one battery, but I am pretty sure it is close to what the drop would be with one properly sized and charged premium battery. I'll take my chances and leave the starter wire alone...I'm pretty confident there is no danger or need to change it.

 

[DriveHard]

Originally Posted By: Johnny2Bad
Originally Posted By: DriveHard
Originally Posted By: Johnny2Bad
I
...


Yes, I understand how folks who have high load items running without the engine running would have this arrangement. I rarely do anything except listen to the radio for a few minutes while waiting to pick up a kid from somewhere, so really the isolator box was not really needed for my setup. I was just looking for a cheap battery replacement and realized I could get two of the "value" batteries for less than one good one. I did know about one battery draining the other, bad cells, etc. That is why I got two identical batteries with the same date stamp at the same time. This is the arrangement many diesel trucks and off highway equipment use, so I think I am good to go.


I would point you to the notes about charging and health of a non-regulated dual battery setup. That is where you are going to find issues, if there are any. The parts about a regulated dual battery system having (for example) reserve capacity to run a radio is simply a feature that is part of the implementation at no additional cost to build in. It is not the main reason; the ability to use and charge two batteries of a different state of charge or age is.

You are correct in that if there are no issues and the batteries age identically, it's a reasonable setup. But once you get past a certain age in a lead-acid battery, any two batteries, even those made on the same day in the same factory, generally do not have the same charge and discharge characteristics. The problem comes when one needs to be replaced, because you are now required to replace both, regardless of how healthy the second battery is. This may involve replacing the batteries earlier than necessary with a regulated system.

You could always go back to a one battery system with the known good battery, though, and wear that down to it's natural life, before replacing both again.

I appreciate how it's done in industry with 12, 24V and 36V systems (eg forklifts) but commercial parts management tends to pay close attention to parts life and to replace on a schedule, which is not quite the same as an individual owner trying to eke the longest possible life out of a part.

In any case, as long as you embark with eyes wide open, feel free to do as you see fit.


Yes, I am well aware of this. Again, I can replace BOTH of these batteries for less than ONE of the Maxx batteries...I am saving $25!

There is additional cost in the form of a solenoid, or battery isolator for the setups you are talking about. I had the wire and connectors laying around...all I had to pay for was a $4 battery hold down block. Besides the maybe 45 minutes it took me to make up the wires and install them, this was a cheaper solution than just swapping out my battery for a Maxx battery.

As you can see from my first post I am pretty pro-active with parts replacement. My OEM battery is 5 years old, and just starting to show signs of dying. I am guessing I could limp it along for another year if I wanted...but not wise really, nobody likes being stranded. I will replace the two batteries I have now at first sign of failure or in 5 years in the future at the same time, or go back to one single premium battery if the economics play out.

 

[Johnny2Bad]

You have doubled the current available to the starter. Voltage is irrelevant to wire size, current is critical, however.

A single 12V battery in good charge and condition (13.2V) has about 400 Amps of current available. You have now built a system with 800 Amps available.

Electrical systems do no work the way you describe. All electrical systems will attempt to deliver any load that is asked for, up to it's limit.

No OEM starting circuit can handle the power available at the battery on a continuous basis. They are sized to allow a brief starting load, then to cool. In a v8 powered truck the starter and wiring to the solenoid / starter is designed to handle 200A, no more. They get away with this because of the brief duration of a start sequence.

If the wiring is inadequate for the load, the wiring will heat up faster than designed, and as wire heats up it's ability to deliver current to the load falls. At some point all the current is used to heat the wire and none is delivered to the load. It's important at this juncture to mention you have 800A available and so the system will not quit delivering power if asked. Yet if the starter circuit is still engaged, current will continue to flow into the wire, which is where the fire hazard comes into play. The electrical system does not know whether it is turning a starter motor or burning up a wire, it only knows there is a closed circuit and power is available.

If you increase the current capability of the wiring, the time before all current is no longer delivered to the load is increased significantly.

4GA is not particularly robust for a 12V car system; many OEMs use that gauge wire as standard for the charge / starter / battery wiring.

 

[bullwinkle]

That's just like the setup that my '93 6.2 has-one battery (Interstate MTP) is over 12 years old, the other one is 8 years old, one cheap solar maintainer keeps them both charged. Distilled water once a year & a shot of Permatex Battery Protector keeps the wonderful

GM stud mount clamps from corroding.

 

[DriveHard]

Originally Posted By: Johnny2Bad
You have doubled the current available to the starter. Voltage is irrelevant to wire size, current is critical, however.

A single 12V battery in good charge and condition (13.2V) has about 400 Amps of current available. You have now built a system with 800 Amps available.

Electrical systems do no work the way you describe. All electrical systems will attempt to deliver any load that is asked for, up to it's limit.

No OEM starting circuit can handle the power available at the battery on a continuous basis. They are sized to allow a brief starting load, then to cool. In a v8 powered truck the starter and wiring to the solenoid / starter is designed to handle 200A, no more. They get away with this because of the brief duration of a start sequence.

If the wiring is inadequate for the load, the wiring will heat up faster than designed, and as wire heats up it's ability to deliver current to the load falls. At some point all the current is used to heat the wire and none is delivered to the load. It's important at this juncture to mention you have 800A available and so the system will not quit delivering power if asked. Yet if the starter circuit is still engaged, current will continue to flow into the wire, which is where the fire hazard comes into play. The electrical system does not know whether it is turning a starter motor or burning up a wire, it only knows there is a closed circuit and power is available.

If you increase the current capability of the wiring, the time before all current is no longer delivered to the load is increased significantly.

4GA is not particularly robust for a 12V car system; many OEMs use that gauge wire as standard for the charge / starter / battery wiring.


Just because I have 800 amps available does not mean my starter will be drawing all 800 amps. By that logic just upgrading to the Maxx battery with ~730 CCamps available would have the same problem.

The starter on my truck is rated for 1.7 kW. Now I don't know if that is the output or the input rating. If it is the output rating, and it was horribly inefficient (say ~75%) then the average current draw would be about 177 amps (1700 watts * 1.25)/12V. If battery voltage drops to around 8 volts during cranking (which is VERY low as most only drop to around 10V) then I would be drawing an average of 265 amps (1700 watts * 1.25) / 8V. (Hey this lines up with your assumption my truck wiring is set up for 200 amps). I realize with voltage drops and power wasted in the cable, etc. that it is probably higher than that...but I can promise you I have nowhere near 800 amps going to my starter now.

Again, the voltage is staying the same...there is just more capacity available. If the starter is drawing any more current than it was before, it is only because of the slightly lower voltage drop the system is now experiencing.

Yes, I agree...if the starter got stuck on, or the truck would not start, and I kept cranking and cranking and cranking I do have a higher risk of melting my cable. But that is because of the increased reserve capacity I now have that would have killed a single battery setup in less time.

I essentially have two 4 gauge wires connecting the batteries. One directly connects the two + terminals. Then I have another wire running from the + of where the old battery was to the alternator. Then I have another 4 gauge running from the alternator to the new battery +.

If I added four of these batteries in parallel I would still not feel the need to upgrade the wire to the starter. Obviously I would have to be smart and not ever crank and crank and crank until I melted something, but if my truck doesn't pop right off in the first rotation or two, then something is wrong and I am starting to investigate what is up with my truck...not mindlessly cranking away.

 

[bullwinkle]

It's also possible to burn up a starter/battery cable with one strong battery-I've done it. In the early '00s we had several company vans with 2 batteries in parallel, gasoline engines-none of them burned up while we had them.