Installing a battery to battery Charger.
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| Nasa BM1 with Engine running showing charge going in |
Problem, our charge or battery discharge is to high. It
means that Nikki can never dry her hair, and it means that we are constantly
having to get the generator out. Also Harley is a gamer, using his laptop to
game on means that regualy he drains the batteries quick-
Things carried out- I have installed solar panels, result,
if lucky 4 amps in full hot sun, result no good.
Extra Batteries 2 good batteries brand new 120 amp
batteries, still no good.
Both the panel and extra batteries help, but do not give us
what we need.
Therefore after extensive research I opted to install a
battery to battery charger. Most use for this will come when Skiing. During the
morning the answer will be to run the battery for 1 hour allowing 50 amps to
fly in to the batteries and then have the solar panel kick in for a few hours
high in the mountain sun.
This is how I completed it, only how I did it, doesn’t mean
it’s right but I know it was the correct way based on the research that I
carried out.
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| switch to allow everything to work whilst engine runs |
First problem was that I wanted to move the batteries so
that I could keep everything in one place. The Bessie has a couple of batteries
in a special compartment underneath the twin floors. I also wanted to use this
space to store my generator should it be required. Moving batteries I thought
would be the simple job, wrong, I had to carry out some pretty extensive wiring
add on’s to move the batteries less than 12 inches to underneath the seats.
That carried out the next thing I concentrated on doing was
to install a Nasa BM1 this is a comprehensive very special bit of battery
monitoring commonly found on boats. It would be used to establish how many amps
were going in coming out, what my inverter would pull solar panels would put in
etc etc. The installation for this is really quite simple although I did have a
little trouble understanding what a shunt does and how it should be wired. A
quick call to the manufacturers helped me understand that one bit goes on the
neg post and everything you want measured goes on the other post hence
measuring the output. So with that carried out and wired in, I was ready and
able to carry on with the main job in hand.
So, Batteries installed to where I want them and safely
strapped in, battery monitor installed, oh and then a quick rewire of the solar
panels and I was finally ready for my parcel from Mr Charles Sterling.
The
Sterling Battery to Battery charger arrived in the post with some very simple
instructions. One wire to the starter battery, one wire to the Battery to
Battery charger then the wire on to the Leisure batteries and the negative to
the negative post. Simple right? Well yes and no, time consuming running cables
around the place for sure, fidely beyond belief. The starter battery is located
under the floor in front of the passenger seat which is difficult to route from
there to under my habitation seats.
Having done this part, I then made sure that
I had my Inverter installed before the job of positioning and installing the
Battery to Battery charger. With all this done I then came across a little
problem that some say is not there. This is the fact that the van already has a
split charge relay system in place. Therefore with this in place the likely
hood would be that in mine and others opinions you would be creating a circuit
within a circuit, coupled with the fridge drawing at least 15 amps I believe
the leisure batteries would not be able to be monitored correctly by the
battery to battery charger. Therefore I believe it would still work and throw a
lot of amps in to the leisure batteries but at risk of a power spike or a
continued charging even when the batteries are actually full. Others I know
have installed it without this worry but I just wanted to make sure and go on the advice of some people
that I have spoken to. For the sake of £7 for a relay I thought it worth doing.
Threrefore with some advice and help from an elecky techie motorhome friend he
set about installing the relay. Basically we located a live feed from the back
of the sergeant unit, connected this to the relay along with the Solar panel
input and positive from the battery cable. This would mean that when the engine
was running the split charge relay would not run and the battery to battery
charger would do the job of charging the batteries, then the fridge would run
from them ensuring that the Battery to Battery charger would be able to monitor
all that was happening efficiently. We even connected up the solar panel so
that any charge coming whilst driving down the road would not be misread by the
B2B charger.
So all done? No not quite, there was another thing that I
would need to do that owners of british vans may find useful. For some time I
have owned forighen vans. When in one, you start the engine and it makes no
difference to the electrics in the back, the lights work without a problem and
so should a passenger need a quick visit to the loo it could be done, or if the
kids wanted to read, the lights in the back could be used. On British vans
there is some caravan council building regs that mean that when you start the
engine, everything in the back goes out. So what I opted to do was override
this feature as when the B2B charger was running we could still sit in the van
and use everything in the back. I therefore had to locate the wire in to the back
of the sergeant unit, on mine it was the smaller brown and white wire. I found
this by turning the lights on and pulling plugs out one by one until when
starting the engine until the lights stayed on. That meant a block of 4 wires
and then I had to locate the correct one by using a volt meter and starting the
engine. Then with the wire found, I cut it, installed a switch under the seat
so that when Im on a site, or skiing and want to stay in the van and charge the
batteries via the B2B charger, I could just switch the switch.
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| solar regulator being rewired |
So all done, and bingo, with the batteries nearly drained I
started the engine, within a couple of minutes (the B2B ensures the starter
battery is full first) the Nasa BM 1 started to show the amount of charge
flowing in to those nearly flat leisure batteries. Within a couple of mins we were throwing in
50 amps and the B2B was kicking its fan on….
Result.
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| my little ultra reliable honda genny, will it ever get used again? |
So to get 100 amps in to my batteries via my little Honda
10i I would get about 16 amps, meaning a full 6 hours to recharge the batteries
against 2 hours of running the engine.
Solar panel? Wouldn’t even guess it as there are too many
variables.
Only thing I would do is get my self some traction batteries
next time round.
Happy touring.