Solar Question

You haven't stated how big the Engel is but this may be affecting the higher consumption of the van batteries, espesially if you have a longish lead back to the vehicle.

It is more likely however, that the van batteris are shot and not reaching their full charge capacity.
The only way to check this is to charge each battery with the 240v charger then take them to a battery shop or auto electrician where they can be load tested.

Hi Molly,

The straight answers are – Yes you have a problem, and No, you are not expecting too much from your system. It sounds a good setup to me with plenty of storage and good solar capacity. You don’t mention how (if?) you are charging from the vehicle when the engine is running, so I assume it’s a simple system with a controller in the engine bay and then a long run of wire from the engine to the van.

Assuming I’m right about charging from the engine, I’d be very suspicious that you are not getting a decent charge from that wiring. Perhaps you never have had a good charge, so the batteries were never fully charged, but without the fridge making demands this didn’t show up as a problem until now.

Suggest check, with no fridge or other load connected and no solar charging, the van battery voltage, then start the engine and measure that voltage again. 1) If it doesn’t rise at all you have a break somewhere between engine and van batteries, possibly at the connection at the towbar. 2) The initial voltage should be around 12.6 to 12.8 volts and this should rise when charging. Ideally the charging voltage should be at least 14.4, though if the battery is much discharged it won’t be this high. If it’s less than about 13.4V I’d check the voltage at the vehicle’s own battery (that’s what’s feeding the charge line to the van batteries.). For most vehicles the battery voltage should be around 14.4V while charging, dropping a bit as the engine warms up. If there is much voltage drop (say more than about 0.75V) between the vehicle battery and the van battery, you have found your problem – could be the wire between them is too small, could be a dirty connector or a bad connection somewhere. (Note that this all assumes that I’ve assumed rightly about your setup!!) There are two wires involved here, one positive and one negative, and each contributes its own losses. Ideally both should run all the way from engine to van batteries, though often the negative one will simply be connected to the vehicle body – check that connection! This wire should be heavy, 6 B&S size is good (that’s about 6mm diameter).

One final point – Measurements and units of measure are confusing. Your 2 batteries have a total (nominal) capacity of about 200 amphours, i.e. you could expect to draw say 10 amps from them for 20 hours, or 20 amps for 10 hours, or 1 amp for 200 hours. It isn’t quite that simple, but close enough for present purposes. Assuming the motor in your Engel actually runs for about 1/3 of the time, and that it draws about (say) 3 amps when running, it will draw an average of about 1 amp, so in 24 hours will require 24 amphours. In our experience, the fridge accounts for most of the daily drain, lights etc are relatively minor. On this basis, your daily drain isn’t likely to exceed 50 amphours, so your batteries should be ok for up to 4 days without any charging. (Actually it’s best never to fully discharge them, so say 3 days.)

A final thought – is there a 3 way fridge in the van that’s also connected to these batteries? If so, it is quite capable of flattening the batteries overnight. These fridges draw 12-15 amps continuously and cannot be run satisfactorily from batteries. Because of their high demand, they shouldn’t share the same wiring from the engine bay that’s used to charge the batteries either.

You might find Electricity for Camping a useful read.

Cheers

John

Hi Mrs Molly,

You seem to have a good setup and it should easily handle your load. The Engel will typically use 40-50 A/hrs over a 24 hour period, though this will vary with size and temp (I run 2 x 40L engels, one as a fridge and the other as a freezer). Your total load would likley be less than 100 a/hrs over 24 hours but even if 114 a/hrs, your batteries should easily supply this overnight. Throw in 270W solar and it should last indefinetly in sunny conditions.

As said above, I too would suspect one or both of your batteries are shot. While they may apear to be fully charged, they have likley sulphated and no longer capable of holding their 97 a/hr capacity. I too would suggest you have your batteries load checked. Also, perhaps add a battery monitor in the van, its is a good way to measure your battery usage (I have a Nasa BM1 and it is very useful) and will highlight a problem like this before it occurs.

Cheers

Captain

An important consideration is what model Engel do you have, and are you using it on freeze at all?

Hi Mrs Molly,
If you place each of your batteries, one at a time, on the CTEK and put them on recondition mode it should solve any sulphation problems. Check the voltage of each before and after charging and a couple of hours after that to give you a pretty good idea of what is going on.

Your solar panels should be able to do all you require given normal sunny weather, that is a typical day, part cloudy but mainly sunshine, even in the middle of winter.

As the others have said you have a very good setup so I would also think your problem lies in the batteries.

At quiescent state (resting) your batteries should have about 12.9 volts a couple of hours after being charged up, as they get older this level drops but unless there is something wrong with your battery/batteries they should read somewhere around 12.7 volts.

Cheers, Bruce.