Hello good people,
I have a Waeco CF50 in the rear of my car. It has low voltage protection which comes in at 10.5V.
The problem I have is that even with thick wire, I lose 1 to 1.5 volts in the wiring over the length of my car. This means my fridge will turn off when my batteries (I have dual batteries) are at between 11 and 11.5V.
Can I install a small capacity sealed lead acid battery near my fridge to compensate for the voltage drop? Will this then enable all batteries to be run down to 10.5V?
Before you ask, I have hard wired the Waeco plug to the battery so there are no dodgy connections other than a fuse.
The total length of the wires are about 4m (I have a fridge slide which makes the wiring even longer)
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Voltage drop affecting fridge. 3rd Battery?
Moderator: -Scott-
Posts: 3523
Joined: Sun May 18, 2003 8:42 pm
Joined: Sun May 18, 2003 8:42 pm
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Still sounds like a wiring/connection problem to me.
1. Fuse. Whats type of fuse holder are you using, glass or blade fuse holder? the generic glass fuse holders are renowned for poor contact pressure and current loss due to poor conduction.
2. Earthing. A poor/undersized earth will return correct voltage measurements but poor load consumption.
In my mav (wagon) I have a dual batt system, with a cable run to the rear of the cargo area to run the Engel, DC batt chargers, AC inverter for other chargers, prolly about 6 m of cable all up. total loading would be around 18amps, I built the system to run at 25A constant draw. I have a Digital multimeter built in to accurately monitor the voltages when under load, voltages are still within .5 of a volt measured at either end (battery or breakout box in cargo area)
You will spend more than you need to on a SLA batt. Not sure what the current drain on the Waeco is, but say it was 5amps. if you had a 24 Ahr SLA batt (which is only good for about 75% of it stated capacity at full current draw,before voltage drop occurs) , the SLA would be able to deliver slightly under 4 hours of run time (depending on ambient conditions and other factors) for the fridge load. So an SLA would not be the best way to go. Better to spend the money on getting your existing system running better.
How old is the battery dedicated to running the fridge? Buy a cheap hygrometer and check for cell imbalance and in the battery, the batt may be shagged.
1. Fuse. Whats type of fuse holder are you using, glass or blade fuse holder? the generic glass fuse holders are renowned for poor contact pressure and current loss due to poor conduction.
2. Earthing. A poor/undersized earth will return correct voltage measurements but poor load consumption.
In my mav (wagon) I have a dual batt system, with a cable run to the rear of the cargo area to run the Engel, DC batt chargers, AC inverter for other chargers, prolly about 6 m of cable all up. total loading would be around 18amps, I built the system to run at 25A constant draw. I have a Digital multimeter built in to accurately monitor the voltages when under load, voltages are still within .5 of a volt measured at either end (battery or breakout box in cargo area)
You will spend more than you need to on a SLA batt. Not sure what the current drain on the Waeco is, but say it was 5amps. if you had a 24 Ahr SLA batt (which is only good for about 75% of it stated capacity at full current draw,before voltage drop occurs) , the SLA would be able to deliver slightly under 4 hours of run time (depending on ambient conditions and other factors) for the fridge load. So an SLA would not be the best way to go. Better to spend the money on getting your existing system running better.
How old is the battery dedicated to running the fridge? Buy a cheap hygrometer and check for cell imbalance and in the battery, the batt may be shagged.
Built, not bought.
Thanks for the tips.
Both batteries are good. I have a spade style sealed fuses.
I have had someone look at the wiring and I have installed the incorrect wire. What Waeco suggest in their booklet is 6mm wire. I went to Bursons and they sold me 6mm diam (including insulation!) wire. What I need is 6mm square (cross section). This will solve my problems apparently.
I have a good earth and have earthed as close to the fridge as I can.
I will re-wire it on the weekend.
Cheers,
Glen.
Both batteries are good. I have a spade style sealed fuses.
I have had someone look at the wiring and I have installed the incorrect wire. What Waeco suggest in their booklet is 6mm wire. I went to Bursons and they sold me 6mm diam (including insulation!) wire. What I need is 6mm square (cross section). This will solve my problems apparently.
I have a good earth and have earthed as close to the fridge as I can.
I will re-wire it on the weekend.
Cheers,
Glen.
There's no way you should be losing that much voltage across that distance unless something's dodgy with the wiring.
I'd play with that more before forking on an additional battery - heck there must be squillions of people running a fridge the same as yours in a car the same as yours without a need for such measures.
Jason
I'd play with that more before forking on an additional battery - heck there must be squillions of people running a fridge the same as yours in a car the same as yours without a need for such measures.
Jason
This is not legal advice.
ive had 30mm squared flex running from my battery (when it was under the tray.) to my starter motor, then from there to my 120A alternator.
sometimes id go to start it up and find that my battery was flat. turns out was a bad earth.
2.5mm2 cable is good for 25A. and should be good for your application.
try running a wire from your fridge back to the negative battery terminal.
sometimes id go to start it up and find that my battery was flat. turns out was a bad earth.
2.5mm2 cable is good for 25A. and should be good for your application.
try running a wire from your fridge back to the negative battery terminal.
who measures wire by dia. anyway? 
insulation types are so varied, you could get a 8mm2 core with a small insulation or a 4mm2 with real thick.
a guy from tradeschool thought that cables were measured in dia. i asked him how big are 500mm2 mains. he got out his tape measure and realised they arent half a meter thick.
insulation types are so varied, you could get a 8mm2 core with a small insulation or a 4mm2 with real thick.
a guy from tradeschool thought that cables were measured in dia. i asked him how big are 500mm2 mains. he got out his tape measure and realised they arent half a meter thick.
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