Speakerplans.com Homepage
Forum Home Forum Home > General > 12v Powered Systems
  New Posts New Posts RSS Feed - Best choice of battery type for cost/weight/power
  FAQ FAQ  Forum Search   Events   Register Register  Login Login

Best choice of battery type for cost/weight/power

 Post Reply Post Reply
Author
Message
Jack1991 View Drop Down
Registered User
Registered User


Joined: 05 February 2020
Location: Bristol
Status: Offline
Points: 491
Post Options Post Options   Thanks (0) Thanks(0)   Quote Jack1991 Quote  Post ReplyReply Direct Link To This Post Topic: Best choice of battery type for cost/weight/power
    Posted: 19 February 2020 at 9:43pm
Just wondered what choice of battery people are using or reccomend?

Im building a 12v off grid rig, consisting of car amplifier & car head unit, speakers/subs.

Im not clued up on the battery front. I only really understand that the higher the AH the better for lasting longer. Car batteries are heavy though! Wondered what other options i got?

-Ideally id like lightweight as i want to tow my rig on my bike (not all the time but sometimes) to get from A to B so weight is an issue. 

- Amplifier is Pioneer Class D and will be putting out 2x 300w rms.

- Would running multiple batteries in parrallel or series be better than 1?


Edited by Jack1991 - 19 February 2020 at 10:27pm
Back to Top
imageoven View Drop Down
Old Croc
Old Croc


Joined: 28 March 2007
Location: Scotland
Status: Offline
Points: 2186
Post Options Post Options   Thanks (0) Thanks(0)   Quote imageoven Quote  Post ReplyReply Direct Link To This Post Posted: 19 February 2020 at 11:17pm
Cost / weight / power is horses for courses - it entirely depends on application.

From your other thread it looks like weight is a major issue for you, so you need to do some research into the various lithium technology batteries, these offer a far greater power density (they are lighter) than lead acid. They are more expensive and 'complicated' - 12v lead acid batteries are what much kit is designed to work with, so are much more plug and play.

in terms of Lead acid batteries, car starter batteries are not ideal. They are designed to give lots of energy quickly. 'Leisure' batteries are better (for this application) as they are designed to give out energy for extended periods and survive greater discharge.

Remember you don't need all you energy in one place all the time. You can use multiple smaller batteries and transport them separately and change when necessary. A big lead acid battery is fairly easy even off road with a decent sack truck. 7Ah lead acid batteries weigh about the same as 4 cans of beer so are easy to carry in a rucksack (give one to all your mates to carry).


Keep pushing on, things are gonna get better.
Back to Top
imageoven View Drop Down
Old Croc
Old Croc


Joined: 28 March 2007
Location: Scotland
Status: Offline
Points: 2186
Post Options Post Options   Thanks (0) Thanks(0)   Quote imageoven Quote  Post ReplyReply Direct Link To This Post Posted: 19 February 2020 at 11:25pm
If you are running standard car amp (s) then you need to give them a nominal 12v so any multiple batteries used should be in parallel (assuming 12v batteries). it is a good idea to only parallel 'matching' batteries ie those of the same capacity and state of charge. This is to prevent one battery charging the other.

Many of the amplifier boards available from suppliers like Sure need higher voltages to get full power, so you may want to use batteries in series for these, or voltage boosters such as buck converters.
Keep pushing on, things are gonna get better.
Back to Top
Jack1991 View Drop Down
Registered User
Registered User


Joined: 05 February 2020
Location: Bristol
Status: Offline
Points: 491
Post Options Post Options   Thanks (0) Thanks(0)   Quote Jack1991 Quote  Post ReplyReply Direct Link To This Post Posted: 20 February 2020 at 10:54am
Thank you imageoven for both of your in depth replies ๐Ÿ™‚๐Ÿ‘๐Ÿผ

I will take a look at 12v lithium batterys, im new to anything like this so easier would be better if they are complicated to do, but as long as i got good instructions i should be alrite. 12v Deep cycle batteries is what i have been mainly looking at as the vast majority seem to use these and good that they are  "plug & play" but yeh as weight is an issue the lithium route might be better (if i can get my head around it). If not last resort is like you said get mates to bring batteries down to save the weight rather than all in one go.

Im led to believe this way of working out how much AH i need is correct?
Amplifier output wattage RMS, divided by volts 
So in my case 600w รท 12v =  50AH
I assume thats playing at full volume so if using a 50Ah battery it could last longer than 1 hour if played quieter? I will also have a bluetooth car head unit linked up for the input too though but id imagine they dont require much amps?

If thats not correct could you help me out please? As i need to make sure im in the right ballpark figure for AH.

Cheers ๐Ÿ™‚๐Ÿ‘๐Ÿผ


Edited by Jack1991 - 20 February 2020 at 11:40am
Back to Top
Monkeys View Drop Down
Registered User
Registered User


Joined: 30 August 2012
Location: Melbourne - Aus
Status: Offline
Points: 429
Post Options Post Options   Thanks (0) Thanks(0)   Quote Monkeys Quote  Post ReplyReply Direct Link To This Post Posted: 23 February 2020 at 11:11am
I've just done a decent amount of research on this recently, and in my opinion Lithium Iron Phosphate (LiFePO4) batteries are the way to go at the moment. From my view they offer the best balance between weight, capacity, reliability and affordability.

They are more expensive than Lead Acid batteries per watt hour, around $8-10 per amp hour (AUD, not sure about other currencies) vs about $2-3 per amp hour for lead acid. Seems like a big price difference initially, but the problem with lead batteries is that they can only be discharged to around 40% before they need to be recharged or they will get permanently damaged (or even no more than 50% in a lot of cases). If you ever fully discharge them it will really damage them badly, do that a few times and they are basically cactus. LiFePO4 batteries can be fully discharged without damaging the battery at all so they are much more durable in that sense. Even the cheap LiFePO4 batteries come with a 2+ year warranty (some have 5 year!) for that reason.

The "rated" capacity of lead batteries is fairly misleading, since you can't (or shouldn't if you want them to last at all) really deplete more than 50-60% of that capacity. With that taken into account LiFePO4 batteries are only slightly more expensive than lead per "usable" watt hour. Not to mention LiFePO4 are about 40% of the weight for the same rated capacity (about 20% of the weight for usable capacity).

Also, LifePO4 can be used in any orientation whereas most lead batteries need to be kept upright (except LGM, but even then they say you should keep them upright ideally).

Steer clear of Lithium Ion for anything other than small scale stuff at the moment I reckon. They are way too unreliable and there are heaps of dodgy cheap batteries on the market. The cheap 18650 lithium ion cell based batteries look tempting but look at a few reviews and see that they often don't last more than a few cycles before they fail. Hard to find warranties on any lithium ion batteries for this reason..

My $0.02, hope it's helpful =)


Edited by Monkeys - 23 February 2020 at 11:12am
Back to Top
carlosdelondres View Drop Down
Registered User
Registered User


Joined: 21 June 2012
Location: London
Status: Offline
Points: 243
Post Options Post Options   Thanks (0) Thanks(0)   Quote carlosdelondres Quote  Post ReplyReply Direct Link To This Post Posted: 25 February 2020 at 3:03pm
You can pick up used LiFePO4 cells on ebay or gumtree, need a bit of knowledge to use but nowhere near as dangerous as lithium ion. Still fairly easy to ruin them though! Building a 2P8S 25.6V/120Ah battery for mobile sound out of recycled cells at the moment. Here is a good bit of info on charging and setup (the other lithium battery posts on the site are well worth a read as well).

Back to Top
 Post Reply Post Reply

Forum Jump Forum Permissions View Drop Down

Forum Software by Web Wiz Forums® version 12.06
Copyright ©2001-2023 Web Wiz Ltd.

This page was generated in 0.090 seconds.