Wiring Diagram for CTEK DC/DC Charger and BM1 battery monitor. Am I going to set my rig on fire?

Joined
Sep 5, 2018
Messages
7
Location
Ulaanbaatar, Mongolia
Hi all, I'm new to the forum but have been reading avidly for years. I'm putting an upgraded electrical system in my rig and I would love some feedback on my wiring diagram. I'm no pro at this--and was very confused with the BM-1 battery monitor that comes with the CTEK 20A kit.

A few specific questions:

1) Should I ground the aux batteries to the chassis from the BM1 shunt? Or somewhere else?
2) If I put in a battery isolator straight from the rear battery bank to the starter battery would I still need to put the negative through the shunt so that it doesn't mess up the calibration of the unit?
3) How do you all draw such clean wiring diagrams?!

Thanks for your advice.

 
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RFB

97 FZJ80 LIFTED SC DUAL BATTERIES,37s
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Hi all, I'm new to the forum but have been reading avidly for years. I'm putting an upgraded electrical system in my rig and I would love some feedback on my wiring diagram. I'm no pro at this--and was very confused with the BM-1 battery monitor that comes with the CTEK 20A kit.

A few specific questions:

1) Should I ground the aux batteries to the chassis from the BM1 shunt? Or somewhere else?
2) If I put in a battery isolator straight from the rear battery bank to the starter battery would I still need to put the negative through the shunt so that it doesn't mess up the calibration of the unit?
3) How do you all draw such clean wiring diagrams?!

Thanks for your advice.

so your running 3 batteries, whats the total AH/ and did this schematic work well?
 
Joined
Sep 5, 2018
Messages
7
Location
Ulaanbaatar, Mongolia
so your running 3 batteries, whats the total AH/ and did this schematic work well?
Hi unfortunately I haven't installed it yet. I've made some amendments to the wiring diagram based on some feedback on another forum. The main problem with the installation as shown is that it wasn't pulling amps evenly from both batteries. I'll update this thread with the new diagram when I'm on my computer.

I still haven't bought the batteries. I was looking for a total of about 200AH. But I found some long narrow batteries that would be a perfect fit--but 150AH each. Overkill for my needs, but maybe good for battery health if I'm only drawing the down 20% or so most nights.
 
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Joined
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Hi, I finally got the system all installed. Sorry my drawing got a bit messy, but here's what the actual wiring ended up looking like. I'm still doing a bit of troubleshooting. It currently works with no error lights--but I'm getting less charge from the alternator than I expected.
 
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After installed it seems like almost everything is working. The 250SA and Smartpass are lighting up showing normal operation.

The problem is that I'm only getting about 2-3A charging from the alternator. I can't figure out why. Here are some things I've done to troubleshoot:

  • I'm running 50mm2 cable from the starter battery to the CTEK units, both positive and ground wire.

  • I've upgraded the ground cable from the start battery to frame.

  • This afternoon I started the car and the BM-1 showed 2.1A charging. I used a clamp multimeter and confirmed that it was 2.1A both on the cable going from the start battery to the 250A breaker in the engine bay. Same from the breaker going to the back. During this time the voltage coming from the alternator was 14.2-14.3V.
*I turned the car off and put a load on the battery. The BM-1 correctly showed the Amp discharge.

*I put a 10A load on for about an hour and a half to discharge the battery. During this time the BM-1 showed capacity drop from 65% to 60%. After starting the car again the charging current was the same.

*The vehicle is a 2000 100 series. I don't think it has a smart alternator. But the CTEK 250SA comes with a lead that you're supposed to connect if you need to trick a smart alternator into providing more power. I held this lead to the positive busbar for about a minute (maybe less) while watching the BM-1 and the charging current didn't change.

*I turned on all the lights, seat heaters, radio, etc--the voltage coming from the alt dropped a bit, but the charge stayed at about 2.1A. I turned off all lights, heaters, etc and the current stayed at about 2.1A.

*I revved up the engine for a few minutes and charging current stayed the same.

*Voltage at the service batteries (being charged from the CTEK) was about 15.2V. It was about -15F this afternoon, so I think that's the temperature compensated charging kicking in.

*The batteries are new--I purchased them about a month ago and they were checked at the shop to be in good condition. I didn't install them until yesterday though.

Anything else I should look at for troubleshooting? Thanks!
 
Joined
Oct 9, 2019
Messages
2
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Gold coast
After installed it seems like almost everything is working. The 250SA and Smartpass are lighting up showing normal operation.

The problem is that I'm only getting about 2-3A charging from the alternator. I can't figure out why. Here are some things I've done to troubleshoot:

  • I'm running 50mm2 cable from the starter battery to the CTEK units, both positive and ground wire.

  • I've upgraded the ground cable from the start battery to frame.

  • This afternoon I started the car and the BM-1 showed 2.1A charging. I used a clamp multimeter and confirmed that it was 2.1A both on the cable going from the start battery to the 250A breaker in the engine bay. Same from the breaker going to the back. During this time the voltage coming from the alternator was 14.2-14.3V.
*I turned the car off and put a load on the battery. The BM-1 correctly showed the Amp discharge.

*I put a 10A load on for about an hour and a half to discharge the battery. During this time the BM-1 showed capacity drop from 65% to 60%. After starting the car again the charging current was the same.

*The vehicle is a 2000 100 series. I don't think it has a smart alternator. But the CTEK 250SA comes with a lead that you're supposed to connect if you need to trick a smart alternator into providing more power. I held this lead to the positive busbar for about a minute (maybe less) while watching the BM-1 and the charging current didn't change.

*I turned on all the lights, seat heaters, radio, etc--the voltage coming from the alt dropped a bit, but the charge stayed at about 2.1A. I turned off all lights, heaters, etc and the current stayed at about 2.1A.

*I revved up the engine for a few minutes and charging current stayed the same.

*Voltage at the service batteries (being charged from the CTEK) was about 15.2V. It was about -15F this afternoon, so I think that's the temperature compensated charging kicking in.

*The batteries are new--I purchased them about a month ago and they were checked at the shop to be in good condition. I didn't install them until yesterday though.

Anything else I should look at for troubleshooting? Thanks!
Late thread I know but have you checked all earthing points?
I had the same issue,I did have my aux battery grounded at my chassis but still wasn't working properly so just ran an earth cable from main battery to ctek
 
Joined
Oct 9, 2019
Messages
2
Location
Gold coast
Late thread reply but on the ctek there Is a red wire which needs to be connected to a 12v ignition feed like a cig lighter point or even stereo wiring.
The ctek needs to differentiate between when the alternator is charging and when it isn't.
 
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