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ESM2000 Caravan Mains / Battery charger repair

This information is supplied in good faith and you use it entirely at your own risk. Probably if you need this, your alternative is to scrap the unit so you have little to loose by trying. This information was worked out while (successfully) repairing the unit from my own caravan and the unit is now reinstalled, so is no longer available for inspection. Therefore I cannot guarantee to help with further queries, but by all means ask! Let me know if you have found this page useful!

Lots of Photographs of the ESM2000
Diagram of connectors to the ESM2000

The ESM2000 as used in Swift Caravans was manufactured by CEC/Plug-in-Systems. Part number CTTH/12A. There is what can only be considered a design fault - there is a very heavy component soldered into the charger circuit board which can (and likely will) shake loose from its soldered joints over time and will then stop the charger working. Resoldering it in place will restore operation. Since the unit was not designed to be easily serviced, repairing this is appears to be a daunting task for most, but here's how. It's simpler than it first appears!

1: Remove the distribution unit from its housing: top and bottom of the plastic panel are plastic strips which conceal the fixing screws. Lever the plastic covers up and down respectively, with a small flat screwdriver, to unclip them.

Connectors at rear of ESM2000
Connectors at rear of ESM2000

2: Unscrew the four fixing screws. The unit can now be pulled out. Contrary to the www page on the Swift Owners Club page, there is plenty of lead length to pull it out completely but there is a screw head protruding at bottom left which fouls on the wood, so some manipulation is required. The photo was taken with leads still attached. The window in the woodwork is only just large enough for the ESM2000 and can use some enlargement!

3: Unplug all the leads. There are only two plugs which can be re-assembled in the wrong place but these are colour coded. Fitting them wrongly would (probably) cause no damage but trips would not operate as labelled! Also unscrew the earth (green and yellow) lead.

4: Drill out the 11 pop-rivets that retain the charger's cover. Rivets are 3.5 mm and drilling with a 3mm or 1/8" drill will remove them. 11 rivets total: top, 2 each in side. The cover is now loose: remove it and shake out any loose rivet heads.

inside of ESM2000 showing charger
inside of ESM2000 showing charger
At this stage you may feel a large object moving about: this will be the loose toroidal inductor on the circuit board. This component is marked with a green dot in the photo where it looks a bit crooked. It was loose!

5: Unplug the leads to the circuit board. There are 5. Note what colours connect where, but lead length is such that reconnecting properly is not difficult. The leads are:

6: Unscrew the screw on the underside of the main chassis. This retains the chassis of the charger.

7: Now release the three pegs which lock the charger sub-chassis in place: each peg has a tongue which must be compressed to pull the chassis off the peg. If you have a suitable tube (4mm i/d - I used a section from a telescopic radio aerial) this can be used to release the peg. Once these 3 pegs are all free and the chassis lifted off them, the charger chassis can be pulled out from below all the wires.

ESM2000 Charger chassis.
ESM2000 Charger chassis.
8: Unscrew the fixings of the 3 power devices clamped to the upright of the L shaped chassis. These are indicated by red arrows in the photo. These devices are in insulating silicone sleeves which, over time, will have pressure-stuck to the aluminium. They can be unstuck with a sharp blade but be very careful not to cut or damage the silicone insulating tube.

ESM2000 Charger circuit board
ESM2000 Charger circuit board

9: The circuit board is held to the chassis by 4 screws near the corners. Remove them. The board is now free for inspection. The most likely problem is that the main inductor has worked loose. It is only held in place by two solder joints which, with time and vibration, will break. Reposition it and resolder the joints. I also milled two small slots in the board (between the copper tracks) and used a small plastic tie to retain the inductor. However the 'knot' of the tie must be on the component side so fitting is not easy. You could use something else but do not use anything metallic or a transformer effect will occur. The caravan was made in 2002 and the charger did last 17 years before the charger failed!
Diagram of solder side of ESM2000 board showing the joints, circled in red

10: Reassemble the board to its chassis and refit the power-device clamps.

11: If you are competent to do so, now is a good time to apply mains to the charger and to check that it is giving the correct output - mine, off load, gave about 13.8 volts. I suspect most will have to skip this test! If the problem was a loose inductor, no other damage should have been done.

side view of ESM2000<br>showing 12v + and -
side view of ESM2000
showing 12v + and -

12: Refit the charger chassis into the main chassis and reconnect the 5 wires you removed in step 5. The photo shows the 12v +ve (red and black wires) and -ve (white wire). The red goes to the fuse fitted in the wiring, the black through the rear panel grommet to the relay on the back of the ESM2000.

13: The unit should now be ready to re-fit the cover. It was originally fitted using 3.5mm break-head pop rivets. Break-head pop rivets should be safe as the head of the rivet is designed to stay captive - and usually does, but this cannot be guaranteed. You could drill the holes in the cover 4mm and use suitable sheet metal screws. I used 3.5mm plastic push-rivets, since I had a ready source! However these push-rivets have heads a little larger than the original pop-rivets. I had to slightly enlarge the hole in the woodwork.

14: The ESM2000 is now ready to be refitted into your caravan.

Happy caravanning!

Please let me know how useful you found this page.

We have now to moved to Dorset (our new house) and have sold our caravan.

About the charger

The battery charger in the ESM2000 appears to be a switch-mode float charger. It has switch mode mains converter - which saves on a large transformer - but there is feedback to regulate the output voltage to a nominal 13.8. There is a lot of extra circuitry which I did not analyse.

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Page first published: 8th of March, 2020
Last modified: July 01 2021 16:06:05.
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