Charging Issue - Completely Fuggled (1 Viewer)

[SwissBob]

Cristec CPS120-1A charger with two LED one green for ehu connected one amber (float mode) or amber flashing ( boost mode).

Fuses all good from the internal charger 15A through the 30A on the dist board and near the battery.

LEDs show functioning as expected but it appears the 2 X 80AH (18 months old) batteries are not being charged.

Into the mix = 300W solar panels which charge the leisure batteries during the day without issue.

Fridge works on ehu as do the 230v sockets.

Overnight and on ehu the battery voltage reduces slowly depending what we're up to (ooer missus).

Can the charger be dead even though the led says it's charging?

Haven't poked around too much as electrickery scares me.

Any thoughts? - a quick search didn't find the cristec in the forum so not holding out any great hopes but you never know ....

 

[gus-lopez]

I'd be looking at the charger even though it is saying it is charging. Can you check it with a meter disconnected & then when connected, & showing as charging ,the volts should rise?

 

[Jaws]

Overnight and on ehu the battery voltage reduces slowly depending what we're up to (ooer missus).

What are they dropping to ?
Most van chargers I have come across recently seem to let the batteries drop to 13.2v ( and in two case, both Sargent units, the dropped to12.7 before doing anything

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[Reusables]

Yep you definitely need a multimeter to establish if the charger is putting enough out..

 

[SwissBob]

What are they dropping to ?
Most van chargers I have come across recently seem to let the batteries drop to 13.2v ( and in two case, both Sargent units, the dropped to12.7 before doing anything

Thanks, it was down to 13.5 last night so that could be a thing. We'll add some load tonight and see if it makes a difference.

 

[mitzimad]

is the charger just 1 amp are you drawing more than its putting in?

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[autorouter]

The Cristec charger looks like a good quality 3-stage intelligent charger. The voltage varies up and down as a normal part of this procedure,which goes like this.
Stage 1 is bulk charging, where the charger puts out its full amps output, and the voltage gradually rises from whatever it starts at to about 14.5V. This can take several hours, but if the battery is already nearly full it will be completed in a few seconds.
Stage 2 is absorption charging, where the voltage is held constant at about 14.5V, and the amps gradually falls as the battery fills up. When the amps has fallen to a predetermined level, the charger decides the battery is 100% full, so it switches to Stage 3.
Stage 3 is float charging, where the voltage is reduced to about 13.5V, which is chosen because it keeps the battery topped up but does not overcharge it. It can stay in this state indefinitely.
The exact value of the absorption voltage and float voltage depends on the details of the battery type (flooded, gel, AGM etc). On some chargers these values can be set by switches.

It sounds to me like you are seeing the normal variation of a battery while it is charging. If you think there's a problem, you'd need to get some voltage readings using a meter on the battery terminals.

A battery that is not being charged will have a voltage of between about 12.8V (full) to 12.0V (about as low as you'd usually let it go).

 

[Jaws]

Stage 3 is float charging, where the voltage is reduced to about 13.5V, which is chosen because it keeps the battery topped up but does not overcharge it. It can stay in this state indefinitely.

Totally agree.. Just wish someone would tell Sargent !!

 

[SwissBob]

The Cristec charger looks like a good quality 3-stage intelligent charger. The voltage varies up and down as a normal part of this procedure,which goes like this.
Stage 1 is bulk charging, where the charger puts out its full amps output, and the voltage gradually rises from whatever it starts at to about 14.5V. This can take several hours, but if the battery is already nearly full it will be completed in a few seconds.
Stage 2 is absorption charging, where the voltage is held constant at about 14.5V, and the amps gradually falls as the battery fills up. When the amps has fallen to a predetermined level, the charger decides the battery is 100% full, so it switches to Stage 3.
Stage 3 is float charging, where the voltage is reduced to about 13.5V, which is chosen because it keeps the battery topped up but does not overcharge it. It can stay in this state indefinitely.
The exact value of the absorption voltage and float voltage depends on the details of the battery type (flooded, gel, AGM etc). On some chargers these values can be set by switches.

It sounds to me like you are seeing the normal variation of a battery while it is charging. If you think there's a problem, you'd need to get some voltage readings using a meter on the battery terminals.

A battery that is not being charged will have a voltage of between about 12.8V (full) to 12.0V (about as low as you'd usually let it go).

I had the charger out and it looks like new, no obvious marks that may suggest something had failed so I suspect you're correct, it's just that I haven't seen this behavior before. Cristec superceded this particular charger in 2000 so assuming it's 20 years old it's in great condition.

So, allowing that the charger is working ok, I still have some issues to fix or explain.

The van has been standing for a few days, nothing is turned on on the 12v system - I know there are a couple of things that draw a little bit like the boiler sensor and the solar controller but nothing significant. It is getting up to 13.5v in daylight but the moment the solar goes to 0 input it starts to drop, 12.2v last night. I have an Inovtech coupler between the leisure and starter batteries. The leisure batteries are practically new, the starter battery is a few years old, about 6 I think.

So my thought now is that starter battery is on the way out and it draws power from the leisure batteries via the coupler. Possible or bonkers?

I have a CT (same as MOT) this week so don't want to cause any issues but after I will disconnect the coupler and see what happens.

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[autorouter]

If you still think you have issues, it's time to do some trouble-shooting. Measuring a current flow (amps) through a wire is not as simple as measuring a voltage. To use a standard multimeter you need to disconnect the wire and put the meter to link the two disconnected wires. Apart from the faff of doing that, there's the issue that disconnecting and reconnecting can disturb the circuit, so if it's an electronic unit that's drawing too much power in one of its modes, you've just reset it back to its original state.

Because of that it's best to use a clamp meter, which simply clips round a wire and measures the amps by sensing the magnetic field it generates. No need to disconnect or disturb anything.

Many clamp meters you see in DIY stores, for house electrics, only measure AC amps, not DC. They say AC/DC but that's often just the volts. Also the ones that can measure DC amps often have a good high range but struggle to measure small amps values like the ones you are interested in. I use this meter (Uni-T UT210E) which has a 2A low range. It can also be used with probes to measure voltage and resistance, and it's the one I keep handy in the MH.

Pince ampérométrique et multimètre UNI-T UT210E

Pince ampérométrique et multimètre UNI-T UT210E avec valeur efficace vraie, 600 V, 100A, CA, CC

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[SwissBob]

Update.

Replaced engine battery which turned out be faulty. Everything now working as expected .