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Aygo being towed gets flat battery
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userNikko
Posted: 21 October 2015 7:04 PM
Subject: Aygo being towed gets flat battery
 
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Had a Smart-Tow system fitted to our Aygo and 7-pin towbar electrics fitted to our Autotrail Apache about 18 months ago and all was well until we used the rig in the mountains with lights on and lots of braking - on arrival the car's battery was flat on 2 occasions. Can anyone advise how a 12v supply should be connected into the Aygo from the motorhome so the car's battery gets continuously topped up?
userRogerC
Posted: 21 October 2015 7:23 PM
Subject: RE: Aygo being towed gets flat battery
 
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Rather than try getting a charge system going my first thought would be that your Aygo battery is suspect, possibly knackered if it goes flat in that way.  My Smart is towed on an A frame and the only lights that come on are the running lights and brake lights so I don't honestly see, assuming your set up is the same/similar to ours, how those small consumers of elektrickery can flatten the vehicle battery......unless of course you travel with the Aygo headlights on?
userVandaemon
Posted: 21 October 2015 8:12 PM
Subject: RE: Aygo being towed gets flat battery
 
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When I towed with a Car a Tow I had initially this problem and found that it was caused by the brake lights being operated continuously. On the Aygo the brake lights come on if the pedal is lightly pressed even with the ignition off. The Car a Tow used a bungee between the pedal and the seat frame to ensure the pedal was pulled back but in my case it was not tight enough and the lights stayed on. You might find that you have a similar problem. Check that the lights are off before moving and after running for a while. The pedal is probably not returning fully after being operated by the Smart Tow mechanism.

Alan

Edited by Vandaemon 2015-10-21 8:16 PM
userNikko
Posted: 29 October 2015 9:13 PM
Subject: RE: Aygo being towed gets flat battery
 
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Thanks, Stalwart, but it seems the lights are powered from the motorhome but the Smart-Tow auxilliary vacuum pump for the brakes is powered by the Aygo. This operates the piston which works on the pedal and also the brake servo system. We will check that the brake pedal is fully retracting next time we tow. There's an indicator light on the car windscreen which illuminates when the brakes operate. It's difficult to see from the front of the motorhome when the sky reflects off the glass but we haven't noticed it's on when we've not been braking. We don't know how many amps the pump draws.
userthebishbus
Posted: 30 October 2015 8:24 AM
Subject: RE: Aygo being towed gets flat battery
 


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You could charge the car battery while on the move from the M/H via a relay as with the fridge circuit I would think.
Brian B.
userDerek Uzzell
Posted: 30 October 2015 8:35 AM
Subject: RE: Aygo being towed gets flat battery
 


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Nikko

It’s evident from the Smart-Tow website that the installation and operation of this USA-sourced A-frame-towing system is much more complex than the straightforward inertia-braked variety traditionally used by UK motorcaravanners.

http://www.smart-tow.com/

As discharging of the towed car’s battery seems to be an inevitable consequence of the power-braking system used, it’s likely that the Smartt-Tow company will be aware of this potential problem and should be able to advise.

Unless there is something actually wrong with your Smart-Tow system (I note that the system is warranted and that regular checking and maintenance is recommended) and as battery-flattening has only occurred twice when high demand on the Aygo’s battery might be anticipated, RogerC’s suggestion that the Aygo’s battery may be below par is definitely worth following up. Even if the Aygo’s present battery tests out OK, it might be preferable to replace it with a larger, heavier-duty battery (assuming this were practicable of course) to better cope with high battery-demand situations than to try to modify the system in the way you’ve envisaged.

If you have not already contacted Smart-Tow about this, that should be your first port of call: if you have contacted Smart-Tow, it might be useful to know what advice you were given.
userRayjsj
Posted: 31 October 2015 8:42 PM
Subject: RE: Aygo being towed gets flat battery
 


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I tow a Yaris behind my Autotrail Savannah, but I use the Car-a-tow overrun braking system, and the brake pedal 'bungeed' to the seat frame as mentioned, I have towed in nightime conditions for many hours, and never suffered a flat battery. I am not familiar with the power required to drive the 'Smart Tow', but I would have thought that a suitable 'spare' pin could be found within the 7 pin Plug, to power it, and save the towed vehicles battery. As I believe not ALL are used to power the lights ? On mine that would be PIN 6 Red, as my brake lights are activated by the car itself rather than a repeat of the Towing vehicle ( Don't know if caravans are the same ?) That could give you a Constant 12v Alternator backed supply if sourced correctly. (can bus ?). I would ask a Towbar fitter to do it for me. Ray

Edited by Rayjsj 2015-10-31 8:49 PM
userDerek Uzzell
Posted: 1 November 2015 8:17 AM
Subject: RE: Aygo being towed gets flat battery
 


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Installation instructions for the Smart-Tow braking system can be found here

http://www.smart-tow.com/docs/DUO%20Instructions.pdf

It should be plain that the system is quite different to a simple inertia-braked A-frame-towing arrangement and (apparently) it’s wiring assumes a 4-wire connection as used in the USA.

As Nikke has explained, the Smart-Tow system uses an electricallly-operated vacuum-pump to power the towed-car’s brakes. If the electrical demand for that pump is being met solely by the car’s battery and that battery’s charge-state is not being maintained, repeated and frequent braking will eventually flatten the battery. As car-battery flattening appears to be (potentially) unavoidable if the car-battery is not being recharged when the car is being towed, it needs to be asked whether the Smart-Tow system includes a battery-charging capability and, if so, whether this is failing to operate correctly in Nikko’s case.

As I said above, the installer of the system (presumably the Smart-Tow company itself) is in the best position to offer expert advice on whether Nikko’s battery-flattening should be considered ’normal’ or whether there’s something wrong with Nikko’s system. There’s little point considering adding a charging capability if the Smart-Tow system should include that facility and, although - on the face of it - charging the car’s battery when it’s being towed seems straightforward enough to achieve, it’s surely commonsense to explore with Smart-Tow the possible consequences of doing this.


usergranddad
Posted: 1 November 2015 6:16 PM
Subject: RE: Aygo being towed gets flat battery
 


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right here we go had the same problem on my aygo so got a new batt but was not that what happens is that the brake lights on the car are being use by the m/h so it flattens the car batt //what you nead it a small dio put in the wiring which is down by drivers door takes 5mins at the most
userDerek Uzzell
Posted: 2 November 2015 7:56 AM
Subject: RE: Aygo being towed gets flat battery
 


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granddad

Is your Aygo towed via an A-frame using the Smart-Tow system, please, as I can’t see that merely inserting a diode in the car’s wiring is going to prevent the Aygo battery’s charge from being depleted by the braking system’s vacuum-pump if the car’s battery is not being recharged during towing?

Smart-Tow installation information for an Aygo is here

http://www.smart-tow.com/install/inaygo.htm

It will be seen that the standard installation includes powering the car’s rear-light clusters via the 7-pin connection cable, but ‘split-charging’ of the Aygo’s battery can be specified as a cost-option.

The latter capability is what Nikko was inquiring about originally and (as I was getting at in my last posting) if the split-charge option was included in Nikko’s installation, but is not working properly, that needs addressing (possibly under warranty).

If the split- charge ‘enhancement’ was not included in Nikko’s installation, there’s every reason to expect that it could be retrofitted and - as I’ve said repeatedly - Smart-Tow should be able to advise about this.



Edited by Derek Uzzell 2015-11-02 7:57 AM
usergranddad
Posted: 2 November 2015 7:50 PM
Subject: RE: Aygo being towed gets flat battery
 


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mine is on an a frame
the reason i said what i did was that my first aygo was ok as it was fitted by car a tow
but this one was fitted by a toyota garage that did not fit the dio well hope thats its ok for this winter

now got a jump pack just in case

what i should have said is that the m/h brake lights are drawn from the car so like in a jam at night
u are useing the car batt

Edited by granddad 2015-11-02 7:59 PM
userDerek Uzzell
Posted: 3 November 2015 7:31 AM
Subject: RE: Aygo being towed gets flat battery
 


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If a straightforward load-carrying trailer were being towed, or a caravan with no on-board battery, the lights at the rear of the trailer/caravan would need to be powered by the towing vehicle’s battery (as there would be no alternative) and I’d expect that to be true when a car is being A-frame towed. Consequently it seems a very peculiar situation to me - whatever A-frame system is involved - that (when towing) the towing vehicle’s brake-lights should take power from the towed car’s battery, but I readily admit to having no practical experience of A-frame towing electrics.

Nikko says earlier that”...it seems the lights are powered from the motorhome but the Smart-Tow auxilliary vacuum pump for the brakes is powered by the Aygo...” which is what I would anticipate happening. What you seem to be saying is that there is the potential when a motorhome is towing an Aygo on an A-frame for the car’s battery (rather than the motorhome’s battery) to power the outfit’s brake-lights and that a diode needs to be fitted to stop this and prevent the car’s battery being discharged. But even if that were happening in Nikko’s case, adding the diode would not prevent the Aygo’s battery being used to power the Smart-Tow vacuum-pump and it’s the pump that’s the prime suspect for flattening the car’s battery when towing in arduous conditions is being performed.

Although the opinion of a DVLA representative was that - under UK motoring law - a car being towed on an A-frame could be considered a ’trailer’, it’s apparent that the more sophisticated the car and the more sophisticated the explotation of the car’s own electrical and mechanical systems is while the car is being ‘trailed’, the more care needs to be taken regarding the system’s installation.
userNikko
Posted: 8 November 2015 7:02 PM
Subject: RE: Aygo being towed gets flat battery
 
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Regrettably Smart-Tow failed to answer the phone or respond to email and text messages, and I fear this is an issue where a three-way ping-pong match could start - Smart-Tow, fitter Essanjay and the car. Essanjay just say that there was no 12v MH-to-car supply incorporated in the Smart-Tow kit at the time it was fitted.

The Aygo battery is definitely still OK when tested by my friendly Bosch workshop despite the discharges. My feelings at present are to get a Clarke or Halfords Jumpstart kit with inverter as a standby for general 12v and 230v purposes. This will be cheaper than fitting a charging relay etc. or driving back to Essanjay for them to sort it out. When the car battery needs replacing I will definitely go for the biggest that fits. This is, I believe, a Varta D15 63 Ah. There's no Ah rating on the battery in the car but from the web I understand it may have only 30 Ah.

Clearly the lack of response from Smart-Tow doesn't go much towards recommending them. On the other hand the comparable Unibrake system involved controls being installed in the motorhome as well as the car. This adds to the complications when we move to a new motorhome. The Smart-Tow system does work well, and apart from the natural reduction in acceleration and fuel performance it is true that you don't notice you are towing

Many thanks for your suggestions.
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