Engel Smart Battery Box 2 - Batteries

I have a couple of old 100Ah computer UPS batteries - these are normal lead acid batteries not deep cycle and fitted one to the battery box and charged the battery up via the inbuild Dc Dc charger (is actually 7 amp).

I connected up my Everkool RV 25 litre fridge (empty) to the battery with a Dr Watt meter on the outlet side. I set the temp at -2 and the fridge pulls 3.8 amps when running and with 25c days, 15c nights, nothing in the fridge and not opening it it averages 1 amp overall (1ah).

The display on the battery box (is in % battery capacity and watts in and out rather than voltage and amps) tied in with the Dr Watt meter so overall usage was 1 Ah.

I guess exactly as expected. i guess that with a normal lead acid battery you would not want to take it below about 60 -70% so without charging I would reasonably get close to 2 days out of the starter battery.

I have this chart which given where the yellow and red areas are is for a normal deep cycle lead acid battery (but it does seem a bit low to let a normal deep cycle go.
Attachment 149511

So where could I find similar charts for AGMs, Gel and Calcium batteries.

Thanks

Garry

Hi Garry and that chart is good for any lead acid battery that has a small load applied to it.

By small current load, it is any load up tp 5% of the battery’s marked Ah.

So with a 100Ah Battery, the chart will be fairly accurate.

Also note, all modern deep cycle batteries can be continually cycle down to 20% SoC or 11.56v and still get a reasonable life span from that battery.

This info is based on typical RV use where you might go camping about once a month and need to discharge the battery down to 20% SoC to meet your needs before you drive and charge the battery again.

If you were living in say a caravan, full time but off grid, then you should not discharge a deep cycle battery below 60% SoC.

The ratio of depth of cycles verses life span is based on a battery’s THROUGH PUT.

Through Put can be measure in the total amount of Ah ( Ampere Hours ) or total Watts that a battery will carry over it’s life span, provided the battery is properly charged and maintained.

The total Through Put is vary similar regardless of whether you carry out deep discharging a lot, or if you keep to a shallow discharge use.

Quote:

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Originally Posted by 101RRS

I connected up my Everkool RV 25 litre fridge (empty) to the battery with a Dr Watt meter on the outlet side. I set the temp at -2 and the fridge pulls 3.8 amps when running and with 25c days, 15c nights, nothing in the fridge and not opening it it averages 1 amp overall (1ah).

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Drivesafe - thanks for the information - very helpful.

I have had a 55l Ebay fridge for 10 years now and I have been very happy with it, being 1/3 the cost of the of the equivalent Engel and what I can see when away certainly matches Engel performance. Despite what the Engel naysayers said, it is quiet, has thicker insulation and does not seem to use the heavy amount of power the naysayers said it would.

The ebay fridge is my main fridge but is large so I bought the Everkool 25l for use on shorter trips. Cost more than the big fridge but straight away it was obvious it did not have the insulation and seemed to run more.

So the 25l uses 3.8 amps when running and averages about 1Ah in a 24 hour period so used 24 amps per day. I connected up the 55l ebay fridge up yesterday - running uses 3.2 amps so less than the 25l fridge but in a 24 hour period only used 13Ah so overall is only using just over .5Ah where the 25l manages to use nearly double - shows how important insulation is.

So even on a non Deep Cycle I can run my big fridge for a few days without a recharge.

Garry