Running amp off of old car battery

Discussion in 'Amps and Cabs [BG]' started by basslust, Jul 16, 2013.

  1. basslust


    Apr 18, 2011
    I've got a nice outdoor spot where I want to play music and I'd like to power two amps (one guitar, one bass). The bass amp I would like to use is a TC Electronic BG250 combo amp. I've read that I can use an old car battery and a power inverter to do the trick but am not sure exactly how to do it. Any help as far as power inverter specs, setup, etc would be appreciated.

    Edit-- I'm not opposed to the idea of using a portable power supply either... It just seems like I might need a few of them as they drain quickly, and that would be more pricey.
  2. joelb79


    Mar 22, 2006
    Lansing, Michigan
    would be easiest to find a large computer backup UPS and bring that out. However, with 250w going hard, I would expect battery life to be short. But yes you can do that. There are ways to figure out your battery life given the draw of current based on the milli-amp-hours (mAh) of the battery in a UPS. Car batteries are spec'd out different but one can do some math and get similar figures. The problem is the inverter also uses current while converting so there is some efficiency lost to the inverter.
  3. basslust


    Apr 18, 2011
    ^Yes, I've read that there is some loss, but that I could still expect to get a few hours out of an old car battery (for one midsize combo amp). I think this is the route I have to go because there is no way I'm going to get hours out of a single battery pack.

    What I need to know is what kind of inverter are we talking about? Something like this:

    Just this hooked up to a car battery?
  4. two fingers

    two fingers Opinionated blowhard. But not mad about it. Inactive

    Feb 7, 2005
    Eastern NC USA
  5. An old thread was resurrected not long ago about this subject: link
  6. 1958Bassman


    Oct 20, 2007
    You may want to buy a new battery- one that would work could be bought for less than $50. The reason I recommend this is that an old one may show 12V, but it might not have much reserve capacity.
  7. One of the members on the Bill Fitzmaurice board had a mobile bass cart he used with a high school marching band.
    This was powered by a battery system of some sort.
    Combined with an efficient cab, it worked well for him.

    I have plans to join the Shrine Marching Band, and do something similar on a small cart.
    If anybody has a recommendation for a 12v, efficient bass amp, I'd like to hear about it.
  8. Agosix

    Agosix Supporting Member

    May 7, 2013
    Woodhaven NY
    You need a deep cycle battery such as a golf cart or a marine battery in addition to an inverter/charger which will allow you to charge the deep cycle battery by house current, gas generator, car, solar panel. The big perk behind this method is will serve as a small electric backup generator during a power outage. Car batteries are not made for long periods of usage whereas deep cycles are meant for long usage. The other perk is that you can as time goes on add the amount of deep cycle batteries as your funds allow thus taking you of the grid partially. Start small and there is lots of info on the Internet. I am looking into doing this myself.
  9. GirouxJB


    Jun 18, 2013
    Manager - Warwick USA
    I agree with Agosix. I used to play bass in my high school marching band and have someone pull a cart with with a regular car battery and power inverter. I would have the battery charging until our parades and during the parade only had a small amp(can't remember anymore what it was) and a wireless system. Every time, without a doubt, it would die well before the end of our parade which couldn't have been more than an hour long. I decided to learn the tri-tom parts and switch with one of the percussionists after it died :D
  10. nukes_da_bass

    nukes_da_bass Inactive

    Feb 19, 2006
    west suburban boston
    If i were gonna try playjng while marching, id try and rig a Phil Jones Briefcase into a hikers backpack, and have a professional seamstress cut holes for where the speakers are going to point out of the bag.
    The briefcase is already pre- wired for some kind of lithium battery config. They do not include the battery however!
  11. The "Deep Cycle" label on batteries identifies their ability to be discharged very low and charge back. It doesn't really indicate that they can supply power for longer however, typically most Deep Cycle batteries are sized larger for marine applications so in effect your right. There are dry cell batteries (Odyssey) that are deep cycle that carry no more capacity than regular $50 car starter batteries.

    Rule of thumb with this is, the larger the battery the more capacity. There are different constructions that lend themselves better to this application such as Gel Cell or Dry Cell, or even a Spiral Cel technology. Most of them are expensive so a regular Car battery can be used. If you link two up in parallel, "ding!" twice as much time pumping out bass.

    I've used a similar Pulse Width Modulation inverter to the one linked above for years and it works perfect for me with a variety of different amps. TB user "Agedhose" is a brilliant engineer for Genz Benz who doesn't recommend those types of inverters but rather one that can supply a perfect sinewave. Again, cost can be a limitation with high end inverters like that.

    Do check the old battery for it's capacity. 1958Bassman is bang on about that.
  12. 1958Bassman


    Oct 20, 2007
    The reserve capacity is important and is shown on the battery and literature. If a deep cycle battery is used and it has great reserve, it will be the best. Honestly, if a small-ish amp is used with an inverter on a regular car battery and a voltmeter is connected, making sure to charge it when it gets to about 11VDC should make it last a long time. Going below that means it will die early, so a deep cycle is recommended.

    Here's a site that was recommended to me by an Electrical/Computer Engineer who happens to be a great bass player-
  13. wcoffey81


    Feb 3, 2012
    S/E Michigan
    an optima yellow top is one of the better options for deep cycle batteries.
  14. Exploiter8

    Exploiter8 Demons run when a good man goes to war

    Jan 18, 2010
    Commercial FREE!
    Just because a battery is labeled RV/Marine doesn't automatically mean it's a true DEEP CYCLE. Many are combo Starting/Deep Cycle.

  15. gericinla


    Oct 2, 2016
    since i don't want to compete with other buyers, no gonna say which brand name of SS practice amp has a dc source connector on it. But physically adjacent to the ac to dc tranformer, it se3med like heck, why think it would work? But I hooked a 12 v battery to it, and it runs off dc. So an inverter is stupid inefficient and theres a fairly recent sealed lead acid battery, 5 to 10 amp hrs in different sizes, safe gell electrolyte in fabric layers internally, recargable (smart charger and battery together under $30) and guess what--the first thing done to the ac power is it's transformed to dc. Thes don't run off all that much current yeah, dont try it on a 200 watt amp, and I am trying to find what other ss combo amps will work fine just applying 12v in place of the ac transformer. The rechargeable powered c9mbo amps on the market, the hog30 from 40 years ago? New designs are screaming to come out utilzing the new sealed lead acids, and I bet theres a number of ss combo amps, probably the cheapest oldest ones, where a quick and dirty mod will work right off. Stick you inverters where the sun don't shine....