Overheating Engel Batt Box Charger

Submitted: Friday, Jan 10, 2014 at 21:15
ThreadID: 105765 Views:7754 Replies:3 FollowUps:6
This Thread has been Archived
I have the new Engel Batt Box with a 130 A/H AGM battery inside.
This is the same as the ARK Batt Box with the 150W Inverter etc.

When I charge it via the 12v plug in my 2013 BT50 the charging plug gets really hot. I have already blown one of the ceramic fuses and also the 20A fuse on the ute twice.

I then tried using the 240V charger plugged into my 12V to 240V 300Watt Inverter and I have the same problem. The plug gets really hot where I plug into the 12V outlet. It has also blown a fuse.

Next i am going to try to bypass the inbuilt charger and use my Ctek charger to charge the battery.

Is anyone else having this problem with the Batt Box??

Also the 12V Charger Box says something about not being suitable for Variable Voltage Alternators??

Can anyone shed any light on this issue.

Thanks in Advance!
Back Expand Un-Read 0 Moderator

Reply By: Member - Frank P (NSW) - Friday, Jan 10, 2014 at 22:03

Friday, Jan 10, 2014 at 22:03

Ciggy lighters are hopeless with high-current devices such as the charging system in your batt box. Typically, the spring in the ciggy plug pushes the plug away from firm contact with the socket creating a poor connection which then heats up.

I believe the only way to fix it is to upgrade the wiring to your accessory outlet and replace the ciggy lighter style plug and socket with a Merrit style plug and socket which positively click into place. Or wire in a completely separate one.

You might have a variable voltage alternator (temp regulated or ECU-controlled) on your BT50, which may be bad news. Someone here can probably advise on that, otherwise your dealer.

The Ctek sould work provided you're not using the same ciggy socket as a supply. If you use the ciggy socket you will likely have the same problems.

Sounds like the current draw is in excess of 20 amps. Off the top of my head I'd recommend 8 gauge cabling for that to avoid voltage drop.


Lifetime Member
My Profile  My Blog  My Position  Send Message

AnswerID: 524245

Follow Up By: Scott Bundy - Friday, Jan 10, 2014 at 22:14

Friday, Jan 10, 2014 at 22:14
Thanks for your advice Frank.

I will look into the Merrit style plug next week.

I'm not 100% sure on how the Variable Voltage Alternator works.
From what I have heard they are a fuel saving feature??

I will run 8 gauge direct from the battery to the Batt Box through an isolator. It must draw massive power. It does draw 12v, boosts it to 24v which runs into the internal charger to charge a 12v Battery. Sounds like hard work....

This one even has Engel Stumped.

FollowupID: 805828

Follow Up By: Member - Frank P (NSW) - Friday, Jan 10, 2014 at 22:52

Friday, Jan 10, 2014 at 22:52
Thinking further about it Scott, 20 amps is right on the limit of a Merrit plug and socket. I'm thinking of the Narva 82108BL found here. They are rated at 20 amps. Don't even consider the 82106BL with its single earth terminal. Maybe go for a 50 amp Anderson. Not pretty, but bullet proof.

Somebody else may have a better suggestion, but at those current levels Andersons are a practical solution.


Lifetime Member
My Profile  My Blog  My Position  Send Message

FollowupID: 805831

Follow Up By: The Bantam - Saturday, Jan 11, 2014 at 11:49

Saturday, Jan 11, 2014 at 11:49
Um yeh cigarett lighters where never designed as a power supply connector...they just got adapted.

The best ciggy socket I can fing is only rated at 15 amps..and that is generous.
The contact resiatance of ciggy plugs is very poor and unreliable.
I would not expact a ciggy plug to deliver more than about 5 to 7 amps on a continuous basis...even a good one.

Then there are the lower rated ones.
Look in your fuse box or woners manual.....lots of the "accessory sockets" that look like ciggy plugs in modern cars have 10 amp fuses on them..and that may service other things like the radio too.

As for the merit plugs...yeh well nice try but no cigar.....that are a better thing than a ciggy plug, but 20 amps on a merit plug.....not continuous no way.

The merit sockets I have here are all rated at 1amps max, the plugs well hell....one version I have come fitted with an 8 amp fuse.

If you are hooking a large 130 amp battery with a fairly low charging resistance to the main battery and charging system, what will limit the initial current flow will be the resistnace of the wires...and that current could be in the hundreds of amps if the wire is heavy, the main battery is fully charged and the aux battery is flat.

I mabe My visew on these battery boxes clear in the past.
They are a great marketing product, but they fall short in so many ways...ya far better off custom building.

FollowupID: 805849

Follow Up By: The Bantam - Saturday, Jan 11, 2014 at 11:52

Saturday, Jan 11, 2014 at 11:52
sorry typo..merrit sockets rated at 15 amps max.

and version of plug comes with 8 amp fuse fitted.

FollowupID: 805850

Reply By: blue one - Saturday, Jan 11, 2014 at 09:08

Saturday, Jan 11, 2014 at 09:08
Hey Scott,
I had a similar problem with the Engel plug where after years of use started getting hot to the extent the plug melted. I replaced the socket and plug with a marine similar to a RWB563 from JPW Marine. (first web site I found with one as I write). I had two Engels in the back of the Patrol and neither had a problem after the change. The marine type has a screw collar which holds the plug firm in rough conditions.


AnswerID: 524255

Reply By: Member - John and Val - Saturday, Jan 11, 2014 at 09:39

Saturday, Jan 11, 2014 at 09:39
Hi Scott,

As others have said, a better plug arrangement would be good, and heavier wiring. I'd use a 50A Anderson connector, certainly not a cigarette style.

But you clearly have another problem if you repeatedly blow 20A fuses. Suggest it's worth spending $10-20 on a multimeter to help track this one down. You may have a bad battery, maybe a fault in the battery box wiring, maybe heat has damaged the insulation in the present plug, the fault could even be in the vehicle wiring - lots of possibilities. A meter will help you identify just where the problem lies. One word of warning - most cheap meters won't handle over 10 amps, so recommend stick to voltage readings initially. I think though that voltage readings should be sufficient to locate your problem.

I'd certainly use your Ctek mains charger, connected directly to the battery, to charge the battery - not good for them to spend too much time discharged.


J and V
"Not everything that can be counted counts, and not everything that counts can be counted."
- Albert Einstein

Lifetime Member
My Profile  My Blog  Send Message

AnswerID: 524260

Follow Up By: blue one - Saturday, Jan 11, 2014 at 19:53

Saturday, Jan 11, 2014 at 19:53
Hot joint maybe?
FollowupID: 805888

Follow Up By: Malcolm 02 - Sunday, Jan 12, 2014 at 09:41

Sunday, Jan 12, 2014 at 09:41
Had a look at the Engel battery box and the DC - DC charger in it is meant to be only 6 amp output. Taking into account the voltage drop that occurs on the undersized wire of the average cig' lighter socket it still shouldn't have drawn more than 10 amps. If though there is a poor connection at the cig' lighter socket this will draw more current (amps) and cause heat, (blown fuse).
I would recommend that the cig' lighter socket be removed and replaced (ideally with a Merritt socket) and check that the wiring is OK. If it has been damaged the wire may create a fire hazard in the future and therefor need to be replaced.

Hope this advice helps.
FollowupID: 805931

Sponsored Links

Popular Products (11)