I use my car on the road often with a small portable printer, to charge my laptop and some smaller devices like my phone and tablet. A person in my local Honda Dealer directed me to a local Auto AV installer for a solution, and that installer recommended and hard wired a 1500w power inverter into my vehicle, which is connected to the 12v battery. It has been working well for a year now, however, a month ago my 12v battery somehow drained overnight, and then more recently one day a warning light on my dash went off indicating that there was a 12v battery charging system problem.

I had my dealer check it out, and it seems that the warning was an anomaly, but the technician warned me that it is not a good idea to continue to use the 1500w power inverter. He indicated that there is a delicate balance between the 12v and electric batteries and that this hard wired third party device could throw off the balance, cause the system to short out, which would leave me with an expensive repair bill because it wouldn't be covered under warranty if the inverter blew my system.

Hearing this all it makes sense, but apparently the installer I used didn't use any when recommending the solution that he did.

Another installer suggested that I could put an independent AGM battery in the trunk that could probably power the devices that I need powered for the day as long as I charge each night. While this may work, it would require this huge 12v charger that I'd have to wheel out into my driveway nightly and then open up my trunk to charge the AGM battery, which seems not to be a practical solution.

Does anyone have any other ideas that has come across this type of issue?

 

1500 watts is 125 amps I doubt most car batteries can put that type of power out for an extended period of time. If you were drawing this current from your car battery, you significantly shortened the life of the battery. I agree you should be looking for a deep cycle marine batteries.

If you were drawing less than 40 amps of current, I would recommend a Battery Isolator that used for amateur radio applications http://www.westmountainradio.com/pro...cts_id=iso_pwr. The battery isolator allows for charging the battery while you are driving, you can draw power while driving or not.

Perhaps you could use a product like this to only charge your auxiliary battery? Disconnect the isolator before connecting the inverter.

Perhaps you can find a higher current battery isolator?

Please be careful of sparks in the trunk; there is 1.3 kWh lithium-ion battery and a full tank of fuel there.

 

thanks for the advice!

 

I have a hybrid, not the PHEV. I was wondering how you got the power to the trunk?

 

what do you mean how I got power to the trunk? I don't have power in trunk. I was thinking about putting a separate Battery in the trunk, but as of now my inverter is in the car and it draws power from the 12v battery under the hood b

 

I was planning to run a cable from the battery under the hood to the trunk to run amateur radio accessories. I have not figured out how I will route that cable. I had hoped you had ideas on that.

 

oh I see. I haven't done anything going into the truck as of yet. Sorry.

 

First, the power of the inverter only matters if you're using it at that level. Laptop, printer, etc. are all relatively low power consumption. I suspect your typical utilization is less than 500W peak and much lower when you're not printing.

I'm 99% sure you have a failing 12V. Honda manages their 12V charging pretty poorly in terms of maintaining sufficient charge and longevity. They deliberately lower the float voltage of the battery so it's typically not 100% charged and pulling a minimum drain on the system to maximize fuel efficiency. They have always done this.

Heavier 12V utilization like you're doing is likely contributing to it being maintained at an even lower state of charge, especially if you EVER use the inverter-powered items in accessory mode.

Lead-acid batteries eat themselves when not at 100% SoC. Your heavy utilization has likely hastened its deterioration, and you're seeing the first signs of failure.

In my experience, dealers frequently misdiagnose 12V issues, especially if they have a warranty liability on the battery.

Regardless of the reason, every time you "flatten" a 12V (run it down to low voltage), you cause substantial damage.

I recommend you remove the 12V, put it on a charger until it's full, let it rest overnight, take it to an auto parts store that can do a full load test, and have them do it 3 times. Even marginal batteries can pass a single load test once. 3 tests and they start to show their issues.

You should investigate installing a higher capacity battery. With your high utilization of the 12V system, you should expect 12V issues far more often than average (every 1-2 years).

Good luck,

Steve

 

Thanks Steve. Is there a specific, higher capacity 12V battery that you have in mind that might work with the Accord?

I'm honestly thinking of trading my Accord in and getting a Chevy Volt. It seems Honda's electric/hybrid offerings are not their best vehicles. I've not been happy with the car since day 1, and I am increasingly getting all kinds of anomalous warning notifications from the system computer that come and go and drive me nuts. Between the 12v charging error warnings, and emissions system warnings, and frequent tire pressure warnings, all of which seem to come and go by the time I get the car to a service center to diagnose, I've just about had it.

 

I do not have any recommendations.

The fact that you're getting multiple intermittent issues supports that you may have a failing 12V.

Note that any car you choose is at risk for odd behavior with heavy utilization of the 12V systems. Hondas are just a little more susceptible because of the way they manage their 12V charging.