Thread: AGM Battery

Given that they are actually slightly lighter than my 100Ah Full River AGM's (32Kg), I'd personally be a bit suspicious of their rating to be honest, but I'm not putting any more science into that assumption that 'More lead will give off more electrons each charge cycle' but not sure if I'm wrong or not there's always a first time for everything... 😉

Hi Pat and while I know nothing about that brand, but the initial recharge current limit of 30 amps, which is just 20% of it's capacity, is not that good for a new battery.

Most AGMs these days have an initial recharge current limit 30 to 35%, which would put the charge current at around 45 to 50 amps.

It just does not sound right.

keep away.

OK that's a shame then, if it's to good to be true then ...

Thanks for the advice guys, appreciated as always.
Pat

Ask rangieman about to good to be to true

Originally Posted by patclan

I am looking at getting another battery, my little 55 Ah yellow top won't run a fridge over night anymore, had it tested and it is supposed to be fine, it could be the fridge though.
Anyway an email from Dick Smiths (kogan) arrived and they are selling car stuff now. They have a 155Ah AGM for $289, they also have a 245Ah for $259.

These days I stick all the camping gear in the box trailer, including the fridge and run an extension from the car to it while driving, if I leave camp I plug the fridge in to a booster battery pack, but I would consider sticking one of these in the trailer with the fridge if it was any good, I could then leave it on site and charge from my solar panel.

What is the concensous? I dont want to sepend heaps of money on a battery for camping as eventualy we are getting a camper trailer or caravan, but this seems a good solution at a decent price (if they are any good).

cheers
Pat

Dick Smith | 12V 145ah AGM Deep Cycle Battery - AGM 145-12 | Power Tools & AccessoriesDick Smith | 12V 155Ah AGM Deep Cycle Battery - ZLR155 | Power Tools & Accessories

What fridge are you running? I had issues with my Waeco, I too suspected my 55amp yellow top. Turned out to be the fridge power cable and socket. It builds up oxidation and therefore resistance, triggering the Waeco's protection. I fixed it by turfing the socket and plug and hard wiring it. No more issues, battery runs it all night and the next day.

I am running a 38l engle off a 80ah AGM battery in my boat, It is powered by a 120w Primus fold up solar panel and it works flawlessly.
I am not sure of the battery brand but it wasn't an el cheapo.
In your truck or for any other use pay the extra for a quality battery otherwise you are wasting your hard earned quids.

................................... "my little 55 Ah yellow top won't run a fridge over night anymore, had it tested and it is supposed to be fine, it could be the fridge though"

From this I assume the fridge used to work OK on the battery but doesn't any more and that the battery is OK. So what's changed ?

There's a number of variables here, firstly what sort of fridge is it. If it's one of the older type absorption fridges then you've got a problem as these things burn power like there's no tomorrow and the only fix is to either replace it with a compressor type fridge ie. typical Engel, Waeco etc. or carry a trailer load of batteries to feed its appetite

Assuming you've got a half way decent compressor type fridge of average size eg. 39/40 litre Engel or Waeco then typical maximum current consumption would be in the order of 2.5 to 4.5 amps depending on the model. Also assuming its thermostat is operating correctly and it isn't set run as a freezer or at some ridiculously low temperature, I find around +2 to +4 degrees C to be pretty right to keep the beer drinkable and to keep the lettuce unfrozen . Also as Strangerover says check your leads/sockets/connections etc. When I was running my Engels I hard wired them to the battery with no plugs/sockets etc in between and found it to be a much more reliable system.

Is your 55ah battery starting off fully charged ? It should be reading a good 12.6v plus fully charged. If not your 55ah battery charging system leads might be too light or have crook connections etc or the wiring back to the car battery might be inadequate.

Assuming all is good, in the above example I'd expect the 55ah battery to be up to the job of keeping your fridge going overnight. Assuming a 50% duty cycle (fridge on half the time) and drawing say 3.5 amps max. (for example) and overnight being 12 hours this gives a theoretical consumption of 1/2 X 3.5 X 12 = 21 ah or around 40% of battery capacity measuring around 12.2v in the morning. In practice I'd expect a slightly higher end voltage/battery capacity as Optima battery's are IMO conservatively rated and with a low current drain setup like this will give more than their nominal rated capacity.

Deano