Hey folks, first post on the forums. I've taken a look at the battery thread at https://www.fitfreak.net/forums/1st-...two-years.html but my questions are a little different.

I got a 2008 Fit Sport with the 5 speed automatic, and the battery on it died when the dealer kid (!) ran out of gas (!!) on the way to get a cosmetic issue taken care of before handing me the keys. It tested good twice but died several times in the next few days after keeping the radio on for as little as 5 minutes, so eventually the dealer replaced it free of charge.

It's working fine now, but I notice this is a very small battery without much reserve capacity. Because the Fit is such a roomy little car, we're planning to go camping much more now that we can stuff ourselves and our gear into the little car. We're gonna be out in the woods. I am getting a LiPo emergency jump kit, but my main concern is actually getting more reserve capacity for electronics and such.

Has anybody had experiences with hybrid batteries like the Odyssey AGM batteries that deliver cranking power AND deep cycle capacity? Or, would I be better off leaving the stock battery in and getting a $20 battery isolator and a generic deep cycle battery to mount in the trunk?

The use case is charging phones, computers, etc; rare use of headlights (setting up tents, whatever, for car camping); sometimes running the fan or stereo a little. I just would prefer not to run down a starting battery that isn't really designed for it and has very little spare capacity.

Edit: am I correct in assuming that sealed lead-acid is still the best choice if I go with a second deep-cycle battery, or would some other battery tech + a voltage regulator to step up/down to 12V be better for powering electronics and mayyybe the headlights or fan for short duration? Lithium tech batteries are obviously way more power to weight, NiMH is also pretty good, but I've only used those in the context of electronics and electric bikes.

 

I've used some of the AGM batteries for some time, but I will say this, certain batteries are not designed to be cycled. Like you stated a deep cycle may be the best bet, and an isolator will help keep you getting on the ride home after the rear battery is dead. As a long time competitor in the stereo lanes that key on (non motor running) listening or usage in your case may lead to other problems. Most charging circuits are designed to keep the battery charged, not re-charge a dead battery. I've had two batteries in my Accord since 2000 with no issues because I keep the battery charged with a separate charger when the car sits for a few days. My Accord has 217,XXX miles with the original OEM alternator because it's there to keep the charge up.

Like I said earlier if you use an isolator to keep the two batteries separate may work but you may hurt the alternator when it tried to charge the dead battery.