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AGM killer

pyemaster

Member
Joined
May 22, 2014
Messages
139
Garage
Hi all

Currently have a 110aH flooded Numax leisure battery connected to my starter with a Durite split charge relay.

Installed it 3 years ago and it's been okay, but not great. Within a couple of years the battery couldn't power the fridge through the second day, and now only reads 12.3v resting voltage. Clearly sulfated and on its way out.

My alternator charges fairly consistently at 13.9v, so I'm looking at upgrading to an AGM, charged through one of the new Adventure Kings 25a DCDC chargers to get its bulk charge up to 14.5-14.7v, and then maintain the float at the correct reduced level. I'm hoping a few hours driving each day will get more juice into an AGM with a DCDC than I was getting into my flooded battery with a simple voltage sensitive relay.

My issue is the only place I can fit an AGM is under the bonnet. I know heat kills all batteries, but apparently AGMs are more susceptible. The space for it is behind a headlight, on the opposite side from the turbo, so one of the cooler areas, but still, I'm concerned I'll kill it fairly quickly in the engine bay.

Can anyone here who's fitted an AGM in the engine bay share their experience? Not sure if I'm just concerned for no reason.

Thanks
Owen
 
Cant help you Owen, I know nothing of fridges and split chargers... But was nice to read something other than the Corona Virus... Someone on here will know.. Good luck:thumbup:
 
I run AGM behind the headlight charged with a DCDC - absolutely no issues and nor should there be. It is a common set up. AGM perfectly okay under a bonnet and DCDC offers a much better charging profile than an alternator.
 
Thanks Lorin, that's great to know. My fear was AGM don't like over 40C and some people have measured engine bay temps more than 70C+ in the summer from what I've heard.

Good to know yours works fine. What brand do you use out of interest? Do you use an insulating guard or anything?

Best
Owen
 
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Have you got space to build some kingspan round the battery to insulate it from the engine heat?
 
There's not a huge amount of space, though I was considering a thermal battery wrap of some sort, just to try and keep the heat out. Not sure how effective they are though.

Owen
 
while some folks might be happy with the life of an AGM under the bonnet, if you open a manufacturer sheet of any AGM, over 40 celsius the life drops from 7-10 years to 4.. maybe less, depending of the severity of the temp..

You might save you current battery by connecting it to a smart 4 stage charger.. they have a de-sulfation cycle.
 
Had to chuckle, when reading this thread on my iPad, I got a low battery warning...







I’ll see my own way out :lol:
 
while some folks might be happy with the life of an AGM under the bonnet, if you open a manufacturer sheet of any AGM, over 40 celsius the life drops from 7-10 years to 4.. maybe less, depending of the severity of the temp..

You might save you current battery by connecting it to a smart 4 stage charger.. they have a de-sulfation cycle.

Thanks yeah, I've actually tried to desulfate it several times on my 8-stage smart wall charger, but no luck.

I'm hoping with a thermal wrap the AGM might go a little longer. Is that info sheet manufacturers covering their arses, or based on your experience chap?

Thanks
Owen
 
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