I wonder if I can safely add an AGM battery to my 2007 HHR along with my current OEM battery so I can get a longer Parking Mode video time on my dash cam? Anyone added an AGM with an isolator? Or even 2 OEM batteries with an isolator?

I have a Power Magic Pro connected to my BlackVue dash cam that shuts the cam off when the battery drops to 12.5V so I get about 5 hours video when parked…maybe less if more camera activity. I’d really like 12-16 hrs video time in Parking Mode (or more).

Some info I read says the second battery will never be charged to the full because of the isolator or the HHR Battery Saver Function…is this true?

Thanx, squibt

 

Cheap isolators are just a big diode. Going through a diode you will get a voltage drop of about 0.7V.

This means that the battery that is being isolated will always be charged with a voltage that is 0.7V lower than the other battery. So if your main battery is charging with say 14.5V, the battery after the isolator will only see 13.8V. Would this be a problem? Maybe. The charging systems on modern cars are controlled by the computer, so the voltage is varying instead of a fixed charging voltage.

I installed a dual battery setup in our Suburban, and used the following isolator, which is a solid state isolator using MOSFETs instead of a diode. This reduces the voltage drop across the isolator to almost zero instead of 0.7V:

Solid State Battery Isolator

Steve

 

Why an isolator? Just wire them in parallel, that would give 12 volts at double the amp hours. An isolator would just give you 12v and 1 battery worth of ah. The only problem with that is you need 2 matched batteries.

 

Thanx Steve good info.
Thanx also donbrew, guess that’s the info I needed…makes sense.

Squibt

 

There is a lot of room for a battery, but it can be problematic to put in a second battery.
In addition, the second battery will have to be secured, otherwise it will dangle during turns and hard braking. In this case, the clamps will simply loosen and fall off, and will not be charged. And maybe even worse - a heavy battery in a jerk will crush something useful.
I do not see an elegant alternative solution. Unless you replace the standard battery with a large battery of increased capacity, for example, from a heavy truck + put a pulley of a slightly smaller diameter on the generator so that the generator can pump this bruiser.

 

Second battery installed today. Ordered the same battery because it is the perfect size for the space….and parallel wired. Needed to cut away the trunk floor insulation on the far left side where there is a hump that goes up out of the battery “well”. The new battery sits perfectly right next to the original battery without moving it or unbolting it…and at the same level. New battery covers the vent thru the floor but I ordered 2 new vent hose kits from Amazon…drilled 2 new holes and installed the grommets, hose and plastic elbow tap for each battery. The fit could not be better or tighter. The spare tire butts right up to the new battery, and it’s wedged tight between the battery “well” and the old battery. I used plastic terminal covers for all terminals and covered the top of both batteries with a plastic fibre fish filter type stuff for some cushioning. Slapped the trunk tray down and it covers nicely….no bulging or deformation when tightening it down. No worries about it moving around at all. I think the car goes faster with 2 batteries….gonna add a racing stripe on the front hood for some extra horse power too. 😎 Have to wait and see how long my dash cam records now in parking mode before the Power Magic Pro shuts it down.

 

Maybe post a photo or two of your install!

 

Will do…need a nap first.

 

K , we’ll wait patiently.

 

Here are pics…

2007 HHR Sunburst Orange 119,440 km

Shows new vents

Side by side R side battery shows cut sound proofing and battery’s sitting at same height.

Not shown are battery covers to protect terminals…just flat cardboard with a fish tank filter type plastic mesh on top that fits across both battery tops

Clean and neat….no bulging