"puffernutter" <peter@puffer-nutter.co.uk> wrote in message
news:1133169926.531274.213580@z14g2000cwz.googlegroups.com...
I have an interesting problem (all of my own making!)
To give a bit of background. In this weather my defender 110 CSW (19J
engine) struggles to heat the cabin. When travelling down a motorway
it just about keeps up, when down on the A and minor roads, you just
get colder and colder! In a few months time I will also be having dogs
sleeping in the back of the car through the night, so I wanted a way of
keeping the car warm separate (or additional to) the engine.
Prior to the recent thread I had been exploring diesel heaters and they
seemed an ideal solution. The problem was that at this time of year
the 12v versions were going for quite a premium. So I bought a 24v
version from eBay. (Just waiting for it to arrive).
This was bought deliberately (it was about £140 cheaper than the
equivalent 12v version!) and I now need to see how to provide the 24v
in the car for the diesel heater (in fact, providing it is easy, that's
just a second battery, keeping that second battery charged is the more
interesting problem!)
I think there are three options and there are pros and cons to all. I
would appreciate your views on the various options and whether any of
you have a similar problem and how you have solved it.
Firstly the battery drain is not huge. Start up is the worst at 11.25A
(due to heating the glowplug I suspect), the ongoing power for the fan
then drives the consumption which is quoted at 1.25A for boost and only
0.4A when running at low/medium power. This is of course at 24v.
So options:
Option 1 -
Weekly charge of second battery. Probably the simplest option and just
needs to be a good habit to get into. Remove the second battery once a
week and charge it overnight. With the drains quoted above, even
leaving the heater on all night shouldn't have a major drain on that
battery. The downside is the hassle of removing the battery once a
week. (This could be done through an isolation switch and an external
socket and may be the way that I go)
Option 2 -
Fit a 24v alternator (is one done for the 19J?) and charge both
batteries at once. Slightly more complicated and there will be a need
to uprate the charging light bulb to 24v. Also the batteries, even if
across the 24v will never charge equally. Remainder of car stays at
12v. Are there any issues I've missed?
Option 3 -
Fit a clever change over circuit that allows the 12v alternator to
alternately charge each battery. The lions share of the charge should
go on the "car" battery with occasional time for the supplementary
battery. For example I would expect that after initial starting there
is a minimum of 20 mins charging the main battery and then say and
uneven cycle of say 2 mins on the supplemantary batteyr and 6 minutes
on the main battery.
Possible problems as it is far more complicated and the risk of stray
(high current!) paths.
OK, I could have spent more and saved all this hassle, but what the
heck, this is an interesting challenge.
So any thoughts, comments, insults :-)
Cheers
Peter
Option 1. fit fork lift charging connector to second battery, isolated from
vehicle earth.
Option 2. fit small additional 24v alternator, make engine bracket for it
and leave it running all the time, no probs, just gove it a trigger feed to
the field terminal via a relay controlled by the ignition, so that the 12v
ignition switches the 24v field feed. Use 2 of the smallest 12v batteries
you can find, in series, and have it as a standalone system.
Option 3. too much hassle due to common grounding via the alternator body
Option 4. clever switchgear to put your second battery in parallel when the
engine is running, and series when stopped. 12v charging, 24v feed for your
heater.
Option 5. stop being a skinflint and get a 12v heater! ;-)
Badger.
Linear Mode
