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Hi guys,

I posted this in the e-NV200 forum too, as that's the vehicle I have, but it's quite a general point so might be of interest to everyone...

So I'm just planning the electrics system for my e-NV200 camper conversion and had a thought...

In the past (in ICE campers) I've always used leisure batteries for the camper electrics, charged from the alternator via a battery-to-battery charge system (as well as solar and a 230v mains charger). But, in an electric vehicle, is there any reason I can't use the 12v under the bonnet?

Conventionally, the starter battery in an ICE vehicle will deliver a high surge current to start the engine, but won't like being deep discharged. Your leisure battery is the opposite and won't deliver a huge surge current, but will be more tolerant to bring deep discharged. So as far as I can see, the main reason for using a specific leisure battery as opposed as a starter battery, for your camper electrics (other than the obvious reason of not draining your starter battery whilst camping) is because the two batteries are actually different technologies (one for high surge low discharge, and the other for low surge but high discharge)

So it got me thinking... why can't I replace the 12v battery under the bonnet of my e-NV200 with a high capacity battery (maybe AGM or lithium) of 200Ah, and use that to provide 12v power to both the vehicle, and the camper 'leisure' electrics?

Our EVs don't pull a surge current from the battery when they start - they just use the 12v to keep systems running and boot up the vehicles drive systems etc. So if there's no surge current required, a 'leisure' type battery should be able to replace the factory 12v, no?

The benefits that I can see are:
*Only one 12v needed in the vehicle rather than 2, saving weight and space.
*No battery-to-battery charger or split charge relay required.
*No additional 230v mains charger required for the leisure battery, as the 12v charges when we plug the vehicle in (I assume?)
*There's plenty of space under the bonnet to fit the inverter and solar charge controller.

The only negative I can see is that you'd need to ensure that you don't drain the battery (rendering you unable to start the vehicle). Or does the vehicle sense when the 12v is low, and charge it via the DC-to-DC, automatically? Either way, you can fit a voltage sensitive relay, that cuts power to the 'leisure' system when the battery gets to a certain percentage state of charge, to ensure that there's always power available to start the vehicle.

Any thoughts on this? I'm sure many of you guys are far more clued up than me

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There are reports on the Leaf 24/30kWh forum of the Leaf electronics (and presumably the env200 electronics) being very sensitive to lower than expected 12v voltages.

I would go for split batteries as per ICE campervans, especially if you have a fridge, so that you can be sure of having sufficient 12v to get the vehicle electronics to power up correctly.
 

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Discussion Starter #3
There are reports on the Leaf 24/30kWh forum of the Leaf electronics (and presumably the env200 electronics) being very sensitive to lower than expected 12v voltages.

I would go for split batteries as per ICE campervans, especially if you have a fridge, so that you can be sure of having sufficient 12v to get the vehicle electronics to power up correctly.
Ah yes, that makes sense. But I wonder does the eNV200 have any kind of auto switch-on of the DC to DC converter, so that it will keep the 12v topped up, even if the vehicle isn't 'started'?

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No, it does not defend the 12V battery in that way. The early models were worse than the later ones, but they all require the car to be powered on to run the DC-DC charger for the 12V battery, and you cannot power the car on unless the 12V battery has a healthy charge. Running anything significant off of it for any length of time without the car powered on risks not being able to start, and the vehicle powers down after less than an hour unless being driven so leaving it on is not an option. The only sense is to fit a second battery with split charge as previously suggested. There is plenty of room to do so under the bonnet.
 

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Discussion Starter #5
No, it does not defend the 12V battery in that way. The early models were worse than the later ones, but they all require the car to be powered on to run the DC-DC charger for the 12V battery, and you cannot power the car on unless the 12V battery has a healthy charge. Running anything significant off of it for any length of time without the car powered on risks not being able to start, and the vehicle powers down after less than an hour unless being driven so leaving it on is not an option. The only sense is to fit a second battery with split charge as previously suggested. There is plenty of room to do so under the bonnet.
Thank you for clarifying. I guess the main objective was saving money (not needing to have the split charge relay and a separate mains 12v charger, but what you've said makes sense.

Many thanks

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Thank you for clarifying. I guess the main objective was saving money (not needing to have the split charge relay and a separate mains 12v charger, but what you've said makes sense.
Does the Leaf / env200 DC-DC converter operate while the vehicle traction battery is being charged? 12v will be required to operate the HV contactor and the BMS electronics (to control the traction battery charging current); would it be possible for a separate 12v leisure battery to be charged at this time from the main 12v battery via the split charge relay? [One problem may be that after a period, the DC-DC converter drops its 12v output from a charging voltage to a floating voltage].
 

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Yes. The voltage only drops to a float once the battery is charged. The only question in my mind is whether you want to have to charge at a minimum of 6A mains AC to get the car to charge, or do you want the option of charging just the 12V? If you were say at a campsite the latter may be the most cost effective solution and an alternative to carrying the granny lead.
 

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You can just leave the van on all the time, it will continually power the 12V circuit from the HV battery via the DC-DC converter.
 

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You can just leave the van on all the time, it will continually power the 12V circuit from the HV battery via the DC-DC converter.
Im planning to do just that, but does anyone her know how many Watts the dc-dc converter can put out. I've read different things but only reffering to different models of the leaf. I have a 2014 env200 myself
 

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For guidance, BEV DC-DC converters are usually in the 1 to 2kW range. Not sure of the Nissan specifics.
 
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