2007 XC70: think I need a new battery. How do you test/where do you buy replacements?

[Durenol]

Costco sells them, pretty reasonably priced, if they have your group #.

A dealer battery over $190 is probably too high, but make sure you get a price with the core (old battery) returned. That usually saves an additional $15 or so.

How do I tell what my group number is? There's nothing in the manual about the battery type.

... and those prices ARE with the returned battery, unfortunately.

[93SCMax]

Unfortunately, the wife is out with the car right now, or I'd go look at it, but I think the group # is on the battery.

If you are thinking of Interstate, You may be able to go to their website, put in your car specifics, and they will tell you what battery you need. Group code should be listed. Then you could check if your local Costco carries that group.

[Rattnalle]

I Europe we don't use group codes so a factory original made in Germany probably won't have one printed on it.

The battery compartment will fit several sizes since the diesels have larger batteries than the petrols. The largest is 300-something millimeters.

[Rattnalle]

The unit in question is an ancient Sears "4 amp" battery charger I inherited from my father, so old it has a 6v/12v switch. I have no idea if it's a fast charger or a trickle charger or what. It has a VU meter thing on the front labeled "DC amperes" with numbers 0,2,4,6 (the numbers aren't evenly spaced). I've had to take the battery out and connect it to this charger a couple times now, but IIRC only the first time did I leave it overnight because I wasn't sure how long it would take. The other times I only left it plugged in for an hour or two. It usually starts with the needle slightly above 2 and drops to 1 after around an hour, and 0.5 hours later. The needle needs to be at least at 1 before the battery can start the car (and even at that it's a very hard start).

All things considered, should I install a proper trickle charger first and try to eek more life out of the current battery before replacing it? The only time this car is parked overnight or longer is when it's back home.

Get a new smart charger. It will tell you when it's done and you can leave it hooked up if you like. They begin at $30 or so.

A standard size battery for these cars is something like 60 Ah. At 4 A that should take at least 15 hours to charge if empty. It takes longer since the battery doesn't charge as quickly as it fills up. This is ignoring the fact that actually emptying the battery will pretty much kill it. So overnight is most likely needed.

[abscate]

It's 11 years old and been heavily discharged? It's dead, Jim

You can get the silver Advance Auto battery for about $110 less coupon which I have been running in my P2 for 3 years now

Once that old charger tails off to 1Amp you should not leave it connected for more than a day

[Durenol]

OK, new battery it is then, just as soon as I can find one for a reasonable price. (There are few autozones near me and shipping on a battery is a killer).

Is there any easy way to test my voltage regulator?

[abscate]

Put your new battery in.

Charge it up,fully.

Turn on headlights for 30 seconds

Measure battery voltage with VOM

Start engine

Measure voltage at battery...a good alternator and regulator will measure> 13.8 volts

[Georgeandkira]

Durenal said, "There are few autozones near me and shipping on a battery is a killer."

Where do you live requiring shipment of a battery?

[Durenol]

> Turn on headlights for 30 seconds
> Start engine

Ahh... there's no way to turn the headlights on in this car without starting the engine first. I can turn on the running lights, but the state of the actual headlights is directly tied to the state of the ignition, on=on and off=off. (I've already had shops measure the electrical when the car is running and they say it looks good despite the flicker).

> Where do you live requiring shipment of a battery?

I don't require it be shipped, there are various shops and dealers that sell batteries, it's just a question of finding the correct type for my car for a reasonable price at a reasonable distance.

[jimmy57]

10 years is an eternity for a car battery actually. The only ones that go that long do not have the battery in the engine compartment and the nicer climate of the cargo area is the prime reason they last longer there. You have two major choices: AGM or FLA batteries. FLA is flooded lead-acid which is the conventional type available forever. The absorbed glass mat is effectively fiberglass mats holding a gel acid and having sealed cells with pressure relief vents in case it ever gets hot and must vent. Trunk mounted batteries have very little risk of outgassing so the benefits of extra cost are not likely to realized.
Three manufacturers have the US and Canadain market wrapped up pretty tight. Johnson Controls (which is maker of interstate batteries and most OEM new car dealer sourced), Exide, and DEKA/East Penn. Of these three there is no winner that I can tell. The parts stores and big box stores have one of those three making their batteries. The best advice is fill the battery space up with battery. If your car had one of the smaller batteries then put in the bigger ones that has an exisiting hold-down bolt hole available. In the newest battery nomenclature your car likely has an H7 but it might be an H6. (H6 is group 48, H7 is group 94, H8 is group 49. Group numbers are the older designations but some sellers may still use the group # and not the Euro "H" system) If the larger H8 will fit with existing hole for hold down then do that one. Battery life is ALWAYS improved with larger capacity battery. The longer warranty battery offered, if there are choices, is always the highest capacity in the group size. Starting the car produces X drain on battery with a resulting sulfation. The sulfation is not 100% reversed by alternator charging so the battery basically begins a stair step downward towards battery death. Charging the battery with a battery charger at a lower rate can reduce the sulfation more, so periodic but infrequent charging is a good maintenance practice. Larger higher capacity battery sees less sulfation so you add flights of stairs to that stair step to death. You make the decision. If ten years is the goal then go big. If you think the car is good for 3 more years then save the money and do cheaper and smaller.
That car has a voltage regulator that uses remote control from another control module, in this case the CEM. The voltage target is variable and hard to predict. It will go higher charge on coast and can reduce charge rate for hard acceleration. These alternate voltages are only going to happen if the system decides battery is near full charge. The initial charge voltage can be over 15V or as low as 14.2V you will only have full charge capability if the engine speed is raised to 1200RPM or more so idling will produce readings below those listed. Charging checks are not specified at idle speed by the manufacturer if max output is what you are checking.