Tuesday 1 October 2019

Charging Genny from 12 volt DC

If you travel with your Genny Mobility chair you have the issue of potentially different mains voltages or even no mains at all. Genny has the capacity to charge with between 100 - 240 V Ac 50 or 60hz, so as long as you have the appropriate adaptor to cope with differing sockets, it should charge. This post is about my experiences with charging from a vehicle battery

Charging with DC to AC inverter plugged into 12 cigarette lighter socket

I have a VW van with a rear hoist that can carry my wheels. Although not kitted out as a camper van it is big enough to take a small mattress and other bits to travel as I wish. Having my wheels with me enables me to do much more active holidays

My wheels have above 4,500 miles on the clock and I notice I am not getting the range I got when it was new. I am more conscious of how much life I have in the batteries and I would hate to run flat

In considering power options for my camper van I was not sure where to go with charging my wheels. Most camper vans would have an additional dedicated leisure battery that would power your fridge, TV etc. usually mounted under one of the front seats. It would be setup to charge from the vehicles alternator with maybe the addition of a solar panel. People use various charge splitting systems that ensure the main vehicle battery is always fully charged to avoid flat batteries when starting the vehicle

To turn 12vdc into something that will charge a Genny you need a DC to AC inverter which come in different sizes and qualities. I purchased the following inverter which I think is beyond the requirments but it was small and quoted to be about 90% efficient (LINK)

Genny is powered by 2 main batteries of 5.8Ah at 73.6vdc and a small 5Ah at 12vdc. I have read a number of forum posts on the charge consumption and I understand that a Segway requires about 180w to charge. I have assumed that Genny will require a maximum of 200w to charge for about 6 hours for a substantial charge

There are equations to work out the theoretical requirement for a vehicle battery that will deliver this level of charge rate. Unfortunately I don't know how to come up with the answer but I have some experience of getting it wrong

I did 2 charge sessions on my wheels, each of about 2 1/2 hours over 2 days with a run of about 10 miles to recharge the vehicle. This was done just using my main and only 95Ahr vehicle battery. When I came to start the van later it didn't have the power to start

I have not made up my mind what to do about an additional leisure battery for my van. There are various considerations like where it will live in the van as I have swivelling front seats that mean I can only use a short battery. Do I go for a standard or deep-cycle battery, how about lithium etc.

How I am coping is I only charge Genny when the van motor and therefore alternator, is running. I have also discovered you can get a very small but high capacity lithium jump start power pack something like the following (Link) I was rescued by a fellow camper with one of these packs and I couldn't believe that it worked. His pack was half the capacity of the one I have linked too
Lithium jump start power pack

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