Deep cycle batteries for under bonnet use

[ShortyNavros]

Hey Guys,

I am going round and round in circles trying to work out which type of battery to buy when mounting it under the bonnet and using for deep cycling ie. fridge/lights/camping.

So far I know this:
1. AGM batteries are probably the best choice however they arent the most heat resilient and are prone to failure in the engine bay due to temps. Can handle DOD's (Depth of Discharge) of up to 80% (more usable power than a regular flooded lead acid). The local battery shop I went to said to avoid the shiny case AGMs as they offer no protection against heat and would be no good under the bonnet of a car.

2. People recommend marine deep cycle batteries which are essentially like a regular flooded lead acid battery just with thicker plates for better deep cycle capacity, they deal with heat better, so better for under bonnet? These also dont like any more than 50% DOD or you start to severely impact on the battery's life.

So the choice is between and AGM or a marine flooded lead acid, AGM are superior with relation to accepting higher charge rates, can be used to a greater capacity, have a higher CCA than marine batteries, but are susceptible to heat.

I want to mount the battery in the passenger side back corner of the engine bay, this is relatively close to the turbo and exhaust so heat is an issue. My plan is to buy a temp gauge and read what sort of temps I can expect the battery to be exposed to in this position. I have been looking at SSB AGM dry cell (they arent dry cell as AGMs still have lead acid) which have a 3 year warranty and are warranted for under bonnet use. http://www.superstart.com.au/tabid/108/bid/7/Products/DeepcycleBattery/SSBDryCell.aspx

Can anyone offer anymore guidance on this topic? What level of heat will kill and AGM?

Cheers,
Alex

 

[d22dave]

Im running a supercharge battery on my d22 in the same spot your talking about. Wanted a flash battery but the autoelec we deal with who I trust said just this in. Anyway 4 years later its still running. Only ever have the 40l engel running off it and maybe 2 days between starting the ute and driving it. But for a $120 and still running after 4 years thats good value imo

 

[ShortyNavros]

what do you have charging dave? isolator or 12v dc to dc charger?

 

[d22dave]

Just redarc isolator. $130 worth nothing flash. But it seems to work for me

 

[Old.Tony]

I'd just use the SSB AGM one you chose. It's warranted to do it, underbonnet temps are going to be similar in every car because they all run coolant levels around 90C and exhaust temps will always be under 800C unless you're racing or hillclimbing or just live to see if you can dent the carpet with the accelerator.

 

[Bad Juju]

Whatever you look at getting, check its charging requirements. Alternator charging of some deep cycle batteries buggers them. Just somthing to factor in.

 

[ShortyNavros]

Okay so if I go with the SSB Dry cell AGM above I will pair it with a dc to dc smart charger. I have been looking at the 20A matson dc to dc smart chargers. They look similar to the redarc unit (comparable size) and are relatively small which is good in the engine bay with little room, which is where the ctek is a nuisance.

This is the one I am looking at http://www.ebay.com.au/itm/Dual-Bat...=AU_Car_Parts_Accessories&hash=item27e1ecec82

Good price and size are my drivers here. Now I have read on other various forums that above 50 degrees ambient that these charger de-rate their output, so I will try and source a suitable cool location. My ideal spot is up in the back corner of the engine bay on the drivers side just on the side of the engine wall near the brake booster. Does anyone know of any other good locations to mount these? I have thought of mounting it in the cab which would be good but I can't really find any space suitable.

Cheers,
Shorty

 

[Old.Tony]

That's the best side of the engine bay - as far from the turbo/exhaust as possible!

No room there in the D40. The brake booster is fairly close to the side wall and the ECU is tucked in there - it's quite difficult for me to get my hands down there to organise cabling that I'm running from the battery/relays to the rear of the car. The picture in my garage does show a lot of stuff in that area - I supposed I could take another from that side to show just how jam-packed things are in there!

If you've got space there, that's definitely the place for it.

 

[ShortyNavros]

Yeah Tony, thats what I was thinking, just had a feel there today after a drive home from work and it was very cool, so ideal for charger placement. Matson also do just a dc to dc charger without the solar input for $50 less, so I may consider this as I cant see myself using solar anywhere in the near future, however for only $50 extra it seems like I should get it just in case I ever feel the need for solar.

I had a feel of my battery tray and it is going to get ripper hot haha. I have used a 1mm sheet of aluminium joined to the battery tray to try and shield off the tray from the exhaust a bit. But it is still going to be ripper hot there I think, will be interesting what temp readings I get, does anyone have any ideas how I could insulate it better? I have seen things like this http://www.aussiebatteries.com.au/batteries/boxes/battery-heat-shield ? Or I could try and get another plastic cover thingo, like the stock battery has on? Or even just move the stock battery cover onto by aux as the stock battery cover is relatively cool where it is. But if I buy a battery with underbonnent warranty then I dont have a lot to worry about, if it dies prematurely due to heat it will be replaced and I can move it to tub is need be, Id really like to conserve space and keep it in the engine bay though.

 

[Old.Tony]

I thought you had room to put the battery there - my bad!

You should try to get the charger as close to the battery as possible. This minimises losses in the cable, giving the charger a better look at the battery.

To go solar or not ... looking back, I should have gone DC-DC with a solar input. Would have saved me a bit of bother - my system is unnecessarily complex now, although components are readily replaceable it's not the sort of system I'd introduce to someone who just "wants something that works". The DC-DC+solar option does that. And there's nothing stopping you from getting a solar panel, attaching an anderson plug, then connecting that to the anderson plug you put on the solar input of the DC-DC charger.

If you stop somewhere for 2-3 days in summer you'll appreciate it when your food hasn't started growing extra bits!

 

[bods]

What model have you got again? Worst case it would be possible to swap the "main" battery to the passengers side, if you have a yd25 d22 with the factory dual batteries.

You could then have the "aux" on the driver's side and the charger where you want to put it. I guess that would be possible with a zd30 too, you'd just have to change the wiring around a bit...

 

[ShortyNavros]

I have a ZD30 mate so only one battery.

I have a 80 series air box installed and moved my fuel primer+filter to the other side of the engine bay. So I now have a battery tray mounted where my fuel filter was and attached to that is my provent 200.

I thought about doing swapping the battery positions, as it would be better to have an AGM in a cooler spot and a standard SLA flooded cranker in a hot spot. But I am assuming all my wiring would change and that would be a massive hassel.

 

[bods]

Yeah, would be. Oh well, just a thought lol. Good luck getting it sorted...

 

[ShortyNavros]

This is how my engine bay looks at the moment

 

[75 GRC]

This is how my engine bay looks at the moment

Shorty,

Have you thought about using aluminium
To make up your battery box - batt tray

It will get hot like steel,but aluminium dissipates heat very quickly.it might save your battery undue heat in the long run.


Just a thought.

Cheers Geoff Go the V-6's

 

[ozstickman]

Shorty,

Have you thought about using aluminium
To make up your battery box - batt tray

It will get hot like steel,but aluminium dissipates heat very quickly.it might save your battery undue heat in the long run.


Just a thought.

Cheers Geoff Go the V-6's

Put some cooling fins on it also will help keep it cool if it can catch a little breeze somewhere. Even if you have to make a duct too.

 

[ShortyNavros]

Hey Geoff,

I already have the battery tray in place, its just one of those supercheap large jobs so it is steel and does heat up, was thinking of just putting a piece of plastic underneath the battery and then trying to find one of those plastic battery cases like the one off the start, see if a wrecker has one.

Ozstickman, there is actually a large gap underneath the airbox as it doesnt sit flush the engine bay wall so cool air coming from behind the head light should flow through the battery at the back pretty well, dont think I really need any ducting.

 

[ShortyNavros]

Also another option I could look at, mounting the starter batter on the hot side and mounting my agm deep cycle on the cool side where the original starter position is.

I know this would be a mess around as I would have to redo all the factory wiring, but it may be worth it in the long run. What would I need to re-wire? Alternator, starter motor......? Anything else?

 

[Old.Tony]

You'd have to put lengthy cables in that could carry the 500+ amps needed to turn the engine over. I'd do what I could to minimise that. The feed from the battery to the fusible links and power distribution can be extended with some 2G cable. Use 0G for the starter (both positive and negative). Heavy welding cable would also do the trick but it's often aluminium cable which is a better conductor but is more brittle and susceptible to motion damage (only marginally - and maybe not enough to be of any concern at all).

 

[ShortyNavros]

Yeah I scrapped the agm idea with moving the battery positions. I ended up buying a marine pro 730 flooded lead acid type battery. Still can't decide between the red arc solenoid ($100) or a matson 12v solar charger ($233)