Batteries

This page originally had batteries and fuses, moved the fuses to their own page Fuses-Wiring, also see AUX Power and Solar PV Panels and Systems 

Suspect a problem with your starting battery?

• Check the voltage with a meter, not the semi-accurate guesstimate gauge on the dash.  Harbor Freight used to have a coupon for a free digital volt meter w/ any purchase, even if you don't get one for free they can be had cheap.  You do not need to spend a lot of money for a digital multimeter for general automotive use.

• Remove/check/clean the main battery terminals/cables connections and the main cable that runs to the convenience center or firewall.  Always remove the negative terminal first and install last, that way your wrench can't short to the vehicle/brake lines.  Side terminals get tightened to 15Nm/133inlbs/11ftlbs.  Battery cable to starter solenoid and to power center 8Nm or ~80inlbs.

• Perform a load test on the battery - Most auto parts stores and service centers will load test your battery for free, these include the likes of O'reilly/Autozone/Advance/PepBoys/Walmart/etc.

• Make sure the alternator is working properly and that the connections are clean/tight.  Alternators 

• Check for Parasitic Battery Drain

Should I wait to replace my battery?

If you buy a $75 battery that lasts you 5years, that is $15 per year which every properly maintained/used SLI battery should last at least that long.  At 6 years it's $12.50 per year which is not a huge amount saved.  Is it worth being stranded, wasting time/money while you wait to get jumped or get a replacement battery?  How does that compare to carrying around a $100 jump starter, just in case your weak battery needs a jump start?

Jump starting an automotive battery

• There are a few ways to get your engine running again with a weak battery.  The best option is to put the battery on a charger until it's completely charged.  Charging a weak/dead/dying battery with your vehicle alternator is quite hard on it.

• Always, always follow the directions, it is important to connect the leads to the proper place and in the proper order.

• There are some 'smart' jumper cables/jumpers that will prevent operation when connected wrong, but you should understand how to look for the positive and negative of the battery or access points.

• ALWAYS READ AND UNDERSTAND WARNINGS AND CAUTIONS.  Connecting wrong can lead to a battery explosion or damage to vehicle electronics.

• Steps: 

  • Park the vehicles close but not touching, so the batteries can easily be reached with the cables.  Make sure both vehicles ignition switches are turned off.  Locate +positive and -negative terminals for both batteries and a clean metal ground on the vehicle with the dead battery.

  • While making sure that the clamps on the jumper cables don't touch anything else and are routed safely away from moving/hot parts, attach the red cable to the dead battery +positive post but do not attach the black negative clamp to anything.

  • On the healthy vehicle battery, connect the red end of the cable to +positive post, then attach the black clamp to the -negative battery post.

  • Move back to the vehicle with the dead battery and attach the black -negative cable to a bare metal spot on the vehicle, NOT TO THE BATTERY.  Make sure all connections are clean and secure.

  • Start the vehicle with the charged battery and let it run for a few minutes then try to start the vehicle with the dead battery.

  • Once started, leave both vehicles running and disconnect the cables in this order making sure to never let the ends touch anything else or each other:

    1. Starting with the dead battery vehicle, remove the -negative clamp then positive cable.

    2. Do the same on the vehicle with the good battery.

What starting battery should I get?

BCI Group78 is hands down the most versatile sized battery used in the Astro/Safari vans, it fits in all models.   Like the AC Delco 78AGM

Look for CCA rating of 700 and up, the higher the better, the only limit being your budget.

I like to have top terminals in addition to the required side terminals, so I usually buy group 34/78 like http://amzn.to/2C45kxD. It makes charging/jumping/adding accessories much easier and in most cases doesn't cost any more(shop around and use LAPS discounts).

Battery Sizes:

Gen1.5(95), Gen2(96-02) and Gen3(03-05) - Group78

Gen1(-94) Some called for Group 75 but Group78 is always an option.

85-90  2.5l 4cyl engines - Some called for Group70 or Group75, Group78 is always an option.

For more detailed look-ups: https://www.batteriesplus.com/battery/car-and-truck/chevrolet/astro

Checking Battery Voltage:

• Start with the engine off

• If you have been recently running the engine or charging the battery, turn on the headlights for ~1 minute to remove the surface charge

• Test across the battery terminals with your meter set to DC, usually 20vdc on manual ranging multimeters.

What is the difference between the starting battery and the house(deep cycle) battery?

Some of our vans have been modified to be used as conversion, RV, camper vans and they tend to have higher battery storage needs.  In a lot of these you have both a starter battery and 1 or more deep cycle house batteries.  There is a difference in the way that starting batteries and deep cycle batteries are made as to serve different purposes.  The following refers to lead acid batteries, that come stock in our vans and are generally used for house batteries with most conversions/RVs.  Though the use of lead acid batteries is declining as better battery technology emerges.

• • Starting battery(SLI): The starter battery is what comes stock with the vehicle and is used for starting the vehicle.  These are made with more and thinner plates designed to give short bursts of energy and should not be deeply discharged.  Repeatedly discharging this type of battery will quickly shorten it's lifespan.  Less than 20 cycles at 100% discharge, ~100 at 50% made even worse if charged by an alternator and not a battery charger.

  • House battery(Deep-Cycle): The deep cycle house battery/batteries are added to supply extended power to fans/furnace/house water pump/lights/inverter/etc.  These have thicker plates and a slightly different composition that resist the warping and pitting that happens with a deeper discharge, however, they usually can't supply the huge burst of energy like an SLI battery can.  The shallower the discharge, the longer they last, for lead acid batteries 50% is the absolute max discharge percentage you want to use and should plan for less(see DoD notes below).

  • Pseudo Deep Cycle Battery: True deep cycle batteries are "industrial" or "golf cart" batteries.  You really have to watch as there aren't standards for calling something deep cycle, some call a 350cycle battery at 50% DoD a deep cycle, and some are rated at 1300 cycles at 50%DoD.  You really have to look at the cycle/DoD charts that the manufacture provides as the rest is just marketing.

  • Example: One G27 sized deep cycle battery that was measured was found to have:

    • 1 fewer plate per cell than the same sized G27 Starting battery.

    • Positive plates were 0.002" thicker per positive plate than the same sized G27 Starting battery.

    • Plates were 15% taller than the same sized G27 Starting battery.

Can I use a deep cycle battery in place of my starting battery?

You sure can as long as you ensure that it has enough cranking amperage to start your engine.  You will, however, get a fewer number of starts per charge when compared to a starting battery.  This could be an issue if you have any hard start issues.  In addition, the no-start condition tends to come on much faster.  Not something I would recommend in really cold climates.

How much battery do I need for my RV/Camping conversion?

This is an extremely variable answer.  The best is to actually calculate how much battery you really need based on YOUR specific usage.  This will vary depending on what devices/appliances you are using, how long you use them for, how often you want to use them.  Even the method of charging, timing, how often, and your planned depth of discharge(DoD, see note farther down the page) make a difference.

Being a landlord has shown me that two single people living in the exact same unit(at different times), exact same appliances(except personal devices), can use extremely different amounts of energy.  Sometimes that usage can be more than double, so these calculations are really personal, and you might require half of the storage that the next guy might.

But there are ways that you can figure it out. Remember that Power x Time = Energy.  Make a list of your appliances and how much power they use, multiply that by the amount of time they run per day = energy needed.  Then add all of them up.

Daily usage in watt-hours by adding up all devices/appliances = 250 Wh per day

How many days before charging(running alternator/generator/cloudy days for solar/etc)= I plan for 3 days max so daily watt-hr(Wh) usage 250 x 3 = 750 Wh for 3 days

DoD(I will use 50% in this example) 3days watt-hr usage divided by 0.5(for 50%) =   1,500 Wh Total needed battery capacity(without temperature compensation) 

Temperature compensation is the total needed battery capacity multiplied by temp compensation number(60° 1.1, 50° 1.2, 40° 1.3, 30° 1.4, 20° 1.6), (I will use 40°) 1,500Wh*1.3= 1,950Wh

Then divide the real Wh needed by the voltage of the system 12 for common automotive systems equals the Ah capacity that you should have for your battery. 1,950Wh/12=163Ah battery bank.

How the heck do I know how much power my device/appliance uses?

For 120vac appliances that you use in your home, you can get/rent/borrow a meter or look at the information plate.  When powering through an inverter, you need to take into account the conversion efficiency of the inverter as well.  The kill-a-watt brand meters are quite easy to use though they are 4x more expensive than the watt meters I found in Europe.  For 12vdc devices/appliances you use in your vehicle, I have one of these: https://amzn.to/2GHjLqo  again quite easy to use, especially if you use inline connectors on it. 

AmpsXvolts=wattsXtime=Wh

You can also go by a chart of average usage, but it's best to know your actual usage.  Some common items used with RV/camping conversions:

• LED interior lights(if you are still using incandescent, don't)

• Water Pump

• Propane Furnace ignition/blower

• Fantastic Vent Fan

• 12 Compressor fridge

• Laptop(use a DC-DC power adapter, not an inverter)

• Phone/tablet chargers(use a DC-DC power adapter, not an inverter)

Then you also have to take into consideration https://en.wikipedia.org/wiki/Peukert%27s_law as the more you are using at once, the less overall capacity you have.

Depth of Discharge(DoD), a note: 

While the manufactures really say that you should keep your depth of discharge below 50% or less for your deep cycle batteries, there is in fact some wiggle room.  For example an RV that sees usage for less than 60 nights per year, you can probably go slightly deeper than 50% and have no real effect on the life of the battery as it's not going to see 300+ cycles per year.

Example(Using Trojan chart below): If your battery bank is rated at 3000 cycles at 20%DoD, 1200 cycles at 50%DoD, and 750 at 80%DoD, if you are a full time camper, you will see a difference, but if you camp for 60 nights per year you are probably going kill that battery from something else before you get to 12.5 years worth of cycles at 80%DoD.  However, if you are a full time camper at 350+ cycles per year, you are going to see a short 2yr battery life at 80%DoD.

https://en.wikipedia.org/wiki/Lead%E2%80%93acid_battery#Cycles

Is there a simple/cheap way to add a house battery that charges automatically when the engine is running?

Yes, the simplest way to add a house battery is using a constant duty solenoid/relay directly to a switched ignition wire.  This connects the house battery to the starting battery/charging system any time the ignition key is turned on.  Not as ideal as using a battery charger, but it's cheap and it works.

Some other options:

• The solenoid could be switched by an oil pressure switch, so it would only be connected while the engine is running.

• Automatic Charging Relay(ACR), these detect when the alternator is running and connect the vehicle charging system to the house battery.

• A DC-DC battery charger like this CTEK https://amzn.to/2ZNImUo that offer dual inputs and better charging/maintenance of your house battery, but at a cost.  Note that the temperature compensation probably won't work well with anything other than Lead-acid batteries.  There are some adjustable options out there that are usable with multiple inputs and you can change the settings depending on your battery bank.

I will give an example of how to do it on the cheap here:

1. A continuous duty solenoid/relay $22 https://amzn.to/2Jq0smb

2. A self resetting circuit breaker $7 https://amzn.to/2HYaDij

3. Some 6gauge(or thicker depending on the length of the run) wire with connectors. $30 https://amzn.to/2HsyiKX 

 Lead-acid Wet, AGM, Gel batteries.  What about Lithium?

Flooded lead-acid starting batteries have been installed by default in so many vehicles and RVs, they are definitely the standard.  However, there are some benefits from the other battery types out there as well.  I am currently moving to AGM in place of all of my standard starting batteries for the longevity and cleanliness benefits even if they do weight a little more.

Types of Lead-acid batteries:

• • Wet/flooded - this is your standard car battery where the lead plates are submerged in sulfuric acid, must be used upright, has caps for replenishing lost water

• • AGM -  Absorbed Glass Mat - Electrolyte suspended in glass mat, these are more expensive than a regular flooded lead acid battery, but have faster charging, higher output, more capacity in the same size, can be used in almost any position(not really upside down), better vibration/freeze resistance and are maintenance free.  The only real downside is the price.

  • Gel/VRLA/SLA - Electrolyte suspended in silica gel, you really don't use this for automotive purposes, they are more sensitive to charging, charge slower, less output, etc.  Often found in ATMs, electric wheelchairs, backup lighting, as well as alarm and UPS systems.

I also plan on replacing my house batteries with LiFePO4, these may work https://amzn.to/321JILN or https://amzn.to/2LYAV7U or similar in the near future.  The cost per cycle is now beating all others, up to 100% depth of discharge, won't need to trickle charge while in storage for my usage, significant weight savings, and the ability to take a charge faster will be worth it for me.

Thoughts about LiFePO4 batteries:

• • Upfront cost is quite a bit higher than with all lead acid type batteries but a lower TCO

  • Huge weight savings over lead-acid

  • Faster charging 0.5C(even up to 1C) vs 0.2C for lead-acid.  Ideally I want to be fully charged in 2.0-2.5hrs while driving  Charging is really fast to ~95% then slows down.

  • Larger usable capacity at usable DoD for the same physical size

  • Higher cycle lifetime.  2000+ vs ~500-1000 depending on battery chosen

  • Won't damage the battery if I don't consistently charge to 100%, unlike a lead-acid (HUGE benefit for me)  

  • It should be better to NOT charge to 100% SOC, should I shoot for charging to 90%?  What is the ideal and is it worth any added complexity?

How long should it take to charge my battery/battery bank?

This is a complicated one that will have many variables.  Here we will look at a single 100Ah AGM lead-acid deep cycle battery using a 10 or 20amp charger.  Always remember that rated capacity for lead-acid batteries is not the usable capacity, generally you want to stay at 50% or less DoD.  In other words a 100Ah rated lead-acid deep cycle has a 50Ah usable capacity.  If a lead-acid battery is not charged to 100% regularly it will slowly lose usable capacity over time.  Chronically undercharging your battery will lead to premature failure.

A lead-acid battery will accept a charge pretty fast during the bulk phase, but don't forget about the absorption phase.  This means that you can't just double your charger size and expect your battery to charge in half the time, it simply doesn't work like that.

• Total Charge Time = [Depth of Discharge(DOD/100)] x Rated Capacity (Ah) ÷ Charger output (Amps)] plus your absorption time.  =((A2/100)*B2/C2)+D2

• Absorption times DoD% = 51% or more = 4hrs, 30-50% = 3hrs, 29% or less =2hrs  =IF(A2>=51,"4",IF(A2<=29,"2","3"))

• Throw this in a spreadsheet: DOD%, Ah Cap, Charge Amps, Absorption Hours, Charge Hrs

• 100Ah battery 20amp charger at 40%DoD = ~5hrs Total Charge Time

• 100Ah battery 10amp charger at 40%DoD = ~7hrs Total Charge Time

• 100Ah battery 20amp charger at 30%DoD = ~4.5hrs Total Charge Time

• 100Ah battery 10amp charger at 30%DoD = ~6hrs Total Charge Time

• 100Ah battery 20amp charger at 20%DoD = ~3hrs Total Charge Time

• 100Ah battery 10amp charger at 20%DoD = ~4hrs Total Charge Time

Want to know even more, check out this great resource: http://jgdarden.com/batteryfaq/