Dual Battery System with CTEK D250 not charging battery over 12 volts.

coolfeet

Mark Keeler
I have what I think is an awesome combined solar and vehicle alternator charging system. However, it failed me miserable.

I have a Lifeline AGM 80 ah battery connected to the CTEK D250s battery isolater and charger. I connected the Ford auxiliary 12 volt charging circuit directly to the CTEK D250. Additionally, I have a 160 W solar panel connected to the D250s.

The system worked fine for 3 days while parked. The house battery, according to the meter connected to the system never displayed less than 12.6 volts while running an ARB 60 liter fridge/freezer.

While driving through northern California in 90 degree weather, the house battery voltage dropped to 12 volts. The following day, I charged the house battery over night to full. The following day, after driving 2 hours, the house battery was at 12. something volts.

After putting on 1000 miles the van had starting issues. Turns out the main grounding cable for battery was loose. I drive a 6.0 PSD with 2 batteries mounted on the van frame rail. No doubt the 2 starting batteries were depleted. I was not in a place with shore power as I was on my way to Hyder, Alaska.

After being on the road for 2.5 weeks, I replaced the house battery with a new Canadian Tire 80 ah AGM battery. I connected the battery to solar panel and got it over 13 volts in less than 4 hours. I connected the ARB fridge/freezer to the cigarette lighter plug for another 8 hours.

The same charging problem occurred again.

Long story short, the house battery charged up to 12.4 volts and usually went down below 12 volts.

I charged both starting batteries and the 2 AGM house batteries. Not sure what to do next.

I emailed and called CTEK 2 days and have not received a response.

Any ideas where I should start testing? Maybe disconnect the alternator charging circuit and charge only with the solar while the vehicle is parked. I can do this with the fridge connected and disconnected.
 
Last edited:

rayra

Expedition Leader
so you have a solution, but what was it? You don't actually say. Maybe relate the info so someone later on can find the answer.
 

john61ct

Adventurer
Yes, you need to do some detailed measuring at the various points around your system

Take the fridge out of the equation completely until the charging issue's solved.

Also the solar to start, get the alt charging fixed first.

You should be charging 14.4+V at high amps while driving with depleted batts.

Maybe get an auto electrician, or alternative energy DC guy. Check your wiring gauge specs, connection terminations, fusing, busses, distribution panels etc.
 

dwh

Tail-End Charlie
CTEK 250 maxes out at 20a. Besides, "charging at 14.4v+" and " high amps" are mutually exclusive. By the time the battery reaches 14.4v+, it won't be accepting high amps.



OP,

What is this aux charging circuit you are using to feed the CTEK? Normally that unit gets fed directly from the engine battery.
 

coolfeet

Mark Keeler
The alternator according both my Scan Gauge and volt meter puts out 13.5-14.0 volts while driving. It's usually at 13.7 volts. I checked this without the fridge. The alternator puts out less than 13.5 vdc with the fridge connected. It's 115 amp alternator.

I think the CTEK unit has cut off points.
 

dwh

Tail-End Charlie
The CTEK is designed to pull the supply voltage down and then buck the voltage up to charge the battery. Feeding it 13.5v should be fine.
 

coolfeet

Mark Keeler
DWH, the Ford manual lists a trailer battery charging circuit. I have 2 Econoline vans and both have the same circuit. It's made for charging a trailer battery. I had an electrical engineer who owns an E350 diesel locate and wire the circuit for me. It's 12 volts and is isolated from the starting battery. When the ignition is off, the circuit is at 0 volts.
 

coolfeet

Mark Keeler
The CTEK is designed to pull the supply voltage down and then buck the voltage up to charge the battery. Feeding it 13.5v should be fine.
DWH, since I depleted my starting batteries (6.0 PSD), will that effect the charging of the house battery? I have all batteries charged again. I might stick the fridge back into the van and leave it in the parking lot with full sun and see how she does.
 

dwh

Tail-End Charlie
What is the voltage measured at the input terminals of the CTEK with the engine running?
 

dwh

Tail-End Charlie
DWH, since I depleted my starting batteries (6.0 PSD), will that effect the charging of the house battery? I have all batteries charged again. I might stick the fridge back into the van and leave it in the parking lot with full sun and see how she does.

Pretty sure the CTEK won't start charging the house battery until the engine battery voltage gets to some point...probably 13v or some such. So yes, dead engine battery could prevent house battery charging...until the engine battery got above 13v anyway.
 

DiploStrat

Expedition Leader
Read the Manual

The CTEK is designed to pull the supply voltage down and then buck the voltage up to charge the battery. Feeding it 13.5v should be fine.

The CTEK is designed to boost the voltage of your alternator up to the voltage that it already produces. There is a very legitimate question as to why you paid for the CTEK vs. a simple relay. But, we digress ...

Some comments:

-- As noted by dwh, above, the CTEK works its "magic" by dropping the voltage at the starter battery to about 13v. The forces the alternator to ramp up to its maximum amperage. Thus, when everything is running properly you should read a reduced voltage at the starter battery (perhaps as low as 13v) and a normal, lead acid charge voltage of around 14.4v at the second/camper/house battery. That is the way it works.

-- The maximum charge amperage to the camper battery should be around 20A when it is fully discharged, less as it recharges.

-- Your refrigerator and other loads should only cause a voltage drop when the engine is off. And perhaps not even then, if you have solar panels attached to the CTEK.

All of this is, of course, dependent on:

-- Proper wiring of the CTEK, and,

-- Proper wiring of everything else, wire gauges, grounds, etc.

My bet would be that the CTEK is working properly and that you have a flaw in your wiring.

READ THIS:
http://smartercharger.com/wp-content/uploads/2010/11/D250S-DUAL_EN.pdf
 

coolfeet

Mark Keeler
Pretty sure the CTEK won't start charging the house battery until the engine battery voltage gets to some point...probably 13v or some such. So yes, dead engine battery could prevent house battery charging...until the engine battery got above 13v anyway.

Your reply answered the cut off question. Thanks!

Will the CTEK charge my house battery if I disconnect the starting battery?

The loose ground cable probably started the problem. My starting batteries may be 3 years or older. May have to replace them soon.


Sent from my iPhone using Tapatalk
 

dwh

Tail-End Charlie
Or...you mean will it charge from the alternator with the engine battery unhooked? That would probably work fine but shouldn't be necessary.
 

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