Starter battery voltage whilst cranking

[nicknorman]

Beta 43 2010 vintage with about 4500hrs. It has always started nearly instantly without using the heaters even in cold weather. Beginning of last year it was getting a bit more sluggish - still started after 2 or 3 compressions but it felt like the starter was struggling a bit. So I got a new starter battery, it’s a bog standard 110Ah wet lead acid. Didn’t really make much difference.

 

Fast forward to now, it seems more sluggish and takes perhaps 4 or 5 compressions to start from cold even having used the heaters. Still, that’s not too bad. Except that now it is upsetting the Travelpower. The TP rocker switch on the box is permanently on, we switch it on and off via the remote panel. The 12v supply to the TP is via the ignition switch so it comes on with the engine. But now after starting, the remote panel is dead and there is a flashing light on the box. Cycling the on-off rocker switch on the box restores normal operation. I presume this is due to the 12v power dipping too low during start and browning-out the TP box. Again, not a massive deal but it hasn’t been like this for the past 12 years so something is sub-optimal!

 

With the engine and fully charged battery at around 15C, cranking with the stop button pressed gives an initial dip to 8.something volts then 9.something whilst cranking. This is at the battery posts. The voltage at the studs on the side of the engine are perhaps 1/4v less.

 

So my question is, are these sorts of voltages at the battery terminals to be expected, or are they on the low side? Unfortunately I don’t have any clip leads with me so it’s difficult to check the voltage further along (eg at the ignition switch), and access to starter terminals is difficult. I’ll bring some next time.

 

[Tony Brooks]

12 minutes ago, nicknorman said:

Beta 43 2010 vintage with about 4500hrs. It has always started nearly instantly without using the heaters even in cold weather. Beginning of last year it was getting a bit more sluggish - still started after 2 or 3 compressions but it felt like the starter was struggling a bit. So I got a new starter battery, it’s a bog standard 110Ah wet lead acid. Didn’t really make much difference.

 

Fast forward to now, it seems more sluggish and takes perhaps 4 or 5 compressions to start from cold even having used the heaters. Still, that’s not too bad. Except that now it is upsetting the Travelpower. The TP rocker switch on the box is permanently on, we switch it on and off via the remote panel. The 12v supply to the TP is via the ignition switch so it comes on with the engine. But now after starting, the remote panel is dead and there is a flashing light on the box. Cycling the on-off rocker switch on the box restores normal operation. I presume this is due to the 12v power dipping too low during start and browning-out the TP box. Again, not a massive deal but it hasn’t been like this for the past 12 years so something is sub-optimal!

 

With the engine and fully charged battery at around 15C, cranking with the stop button pressed gives an initial dip to 8.something volts then 9.something whilst cranking. This is at the battery posts. The voltage at the studs on the side of the engine are perhaps 1/4v less.

 

So my question is, are these sorts of voltages at the battery terminals to be expected, or are they on the low side? Unfortunately I don’t have any clip leads with me so it’s difficult to check the voltage further along (eg at the ignition switch), and access to starter terminals is difficult. I’ll bring some next time.

 

 

The Lucas test card for starters said 10V minimum, but I found a bit less would usually be OK. No idea what the beta maker's figures are. However, unless you measure at the battery terminals, it is more likely to volt drop somewhere in the circuit.

 

I have had low voltage under cranking caused by bad lead burning on a cell interlink, but that would not be likely to be true for the old and new battery.

 

It might be a problem in the motor. I think it is a geared motor, so if the gearbox has lost lubrication, then it may well draw more current and cause a volt drop across the battery.

 

Not much help, I am afraid.

 

 

 

 

 

 

[Tracy D'arth]

Cranking voltage drops too much.

If you are really happy with the battery, ( suggest you try jumping onto the cabin battery as well to confirm )  then either its the starter motor of more likely a cable/crimp/connection fault.  Beta do not use over thick cable and I have seen metal fatigue adjacent to a crimp before. 

Edited December 26, 2023 by Tracy D'arth

[Journeyman36]

You say it's a standard 110Ah battery - as in leisure battery?
I'm no battery expert but I believe for a starter battery you need higher CCA numbers, Ah are not so important.
Do you have a CCA figure for the battery?

[nicknorman]

7 minutes ago, Journeyman36 said:

You say it's a standard 110Ah battery - as in leisure battery?
I'm no battery expert but I believe for a starter battery you need higher CCA numbers, Ah are not so important.
Do you have a CCA figure for the battery?

I think it’s one of those “dual purpose” batteries that are basically a starter battery. The label on top says S664 (which is the size I think) and 650A (EN) which I presume is the CCA.

21 minutes ago, Tony Brooks said:

 

The Lucas test card for starters said 10V minimum, but I found a bit less would usually be OK. No idea what the beta maker's figures are. However, unless you measure at the battery terminals, it is more likely to volt drop somewhere in the circuit.

 

I have had low voltage under cranking caused by bad lead burning on a cell interlink, but that would not be likely to be true for the old and new battery.

 

It might be a problem in the motor. I think it is a geared motor, so if the gearbox has lost lubrication, then it may well draw more current and cause a volt drop across the battery.

 

Not much help, I am afraid.

 

Yes I was wondering if the starter motor could be tired. Look quite difficult to get to in our installation though!

[Journeyman36]

4 minutes ago, nicknorman said:

I think it’s one of those “dual purpose” batteries that are basically a starter battery. The label on top says S664 (which is the size I think) and 650A (EN) which I presume is the CCA.

The 650 (EN) is the EU version of our CCA I believe.
I'm not sure of the CCA requirement for the Beta engine, should be easy enough to find I would think. Given that it's not that cold at the moment I'd think 650 would be enough to start most engines. I have an 850 on mine and it's probably way more than I need.

[nicknorman]

44 minutes ago, Tracy D'arth said:

Cranking voltage dopos too much.

If you are really happy with the battery, ( suggest you try jumping onto the cabin battery as well to confirm )  then either its the starter motor of more likely a cable/crimp/connection fault.  Beta do not use over thick cable and I have seen metal fatigue adjacent to a crimp before. 

with the voltage at the battery posts already dropping to 8.something I’m thinking it’s probably not a cabling issue, but I will try to get a connection directly onto the starter motor to check that.

 

The other thing I’ve noticed is that the engine battery voltage drops from 12.7v to 11.8v at the battery terminals when I operate the heaters. Again, seems on the low side although I don’t know how much current the heaters take.

16 minutes ago, Journeyman36 said:

The 650 (EN) is the EU version of our CCA I believe.
I'm not sure of the CCA requirement for the Beta engine, should be easy enough to find I would think. Given that it's not that cold at the moment I'd think 650 would be enough to start most engines. I have an 850 on mine and it's probably way more than I need.

650 EN is about 710 SAE it seems. The engine manual specifies 580-670 without specifying which standard.

Edited December 26, 2023 by nicknorman

[GUMPY]

My manual says 120Ah 600cca minimum so battery is close to minimum required.

I used a 130aH 950cca EN with no problems on  mine.

[jonathanA]

I'm sure you will have checked this but are your battery terminals clean and the connectors nice and tight. 

 

Not meaning to teach you to suck eggs but had a problem with my old shogun re ently and was convinced it was time for a new battery went to take it off and realised the crappy top hat type terminal connector was not on properly although it appeared to be on well it  wasn't actually....

 

I don't know the rating of beta glow plugs but most seem to have a 70A relay/controller so guess in thst sort of region ..

Edited December 26, 2023 by jonathanA
Add heater comment

[nicknorman]

Just now, jonathanA said:

I'm sure you will have checked this but are your battery terminals clean and the connectors nice and tight. 

 

Not meaning to teach you to suck eggs but had a problem with my old shogun re ently and was convinced it was time for a new battery went to take it off and realised the crappy top hat type terminal connector was not on properly although it appeared to be on well it  wasn't actually....

I’ve been measuring the voltages actually on the posts, not on the terminal clamps. I’ll check again for no volt drop in the post/clamp interface but I cleaned it all up when I replaced the battery less than 2 years ago so I doubt it.

[MtB]

18 minutes ago, nicknorman said:

Again, seems on the low side although I don’t know how much current the heaters take.

 

A lot. Mine take about 40A for the pair initially stone cold, but this falls to about 20A as the glow worms inside warm up and their resistance rises. IIRC. 

 

But surely you must have a clamp meter lying about somewhere! What current is the starter motor drawing? 

[nicknorman]

4 minutes ago, MtB said:

 

A lot. Mine take about 40A for the pair initially stone cold, but this falls to about 20A as the glow worms inside warm up and their resistance rises. IIRC. 

 

But surely you must have a clamp meter lying about somewhere! What current is the starter motor drawing? 

I found in the manual the glow plugs are 1ohm each, so that would be around 45A but as you say, the resistance changes with temperature.

 

I could measure the starter current (assuming less than 400A) but since I don’t know what it should be, I don’t see how that will help me.

Edited December 26, 2023 by nicknorman

[MtB]

4 minutes ago, nicknorman said:

I could measure the starter current (assuming less than 400A) but since I don’t know what it should be, I don’t see how that will help me.

 

I was thinking it would allow calculation of what the internal voltage drop ought to be inside the battery.

 

I have a Mercedes glow plug here on my desk. It measures 1.8 Ohms at room temp, about 20c. 

Edited December 26, 2023 by MtB

[nicknorman]

4 minutes ago, MtB said:

 

I was thinking it would allow calculation of what the internal voltage drop ought to be inside the battery.

 

I have a Mercedes glow plug here on my desk. It measures 1.8 Ohms at room temp, about 20c. 

Good point, I’ll try it.

[jonathanA]

9 minutes ago, nicknorman said:

I’ve been measuring the voltages actually on the posts, not on the terminal clamps. I’ll check again for no volt drop in the post/clamp interface but I cleaned it all up when I replaced the battery less than 2 years ago so I doubt it.

Yeah that's what I thought 😄. I found that if the mitzy didnt fire straight away then the battery seemed to go flst very quickly and in typical diesel fashion if it wasn't spinning fast enough it wouldn't go. 

 

I can't help think that 12.7v for a rested fully charged starter is a bit low ? 

[nicknorman]

Mid 300s just for a moment, then high 200s say 280A. It fluctuates a lot as the engine goes over compressions of course. The meter has a relatively slow sample rate so there could be (probably are) more extreme transients.

 

12 minutes ago, jonathanA said:

Yeah that's what I thought 😄. I found that if the mitzy didnt fire straight away then the battery seemed to go flst very quickly and in typical diesel fashion if it wasn't spinning fast enough it wouldn't go. 

 

I can't help think that 12.7v for a rested fully charged starter is a bit low ? 

It was 13.3v when I started the process, but after a short crank it was 12.7v. I think that is the normal fully rested 100% SoC voltage isn’t it? The 13.3v was the surface charge left over from when we cruised for a couple of hours this morning.

Edited December 26, 2023 by nicknorman

[jonathanA]

Fair enough thought starting at 12.7 seemed a bit suspicious. 

 

Tony's suggestion of jumping off the domestics seems worth a go (if you can from the lithium i think you have ? )

 

It's a good one ! 

[nicknorman]

2 minutes ago, jonathanA said:

Fair enough thought starting at 12.7 seemed a bit suspicious. 

 

Tony's suggestion of jumping off the domestics seems worth a go (if you can from the lithium i think you have ? )

 

It's a good one ! 

Jumping from 600Ah of lithium is certainly going to make the starter go a lot faster, but again not sure what it would prove. Even if everything is in perfect condition, jumping from the Li is always going to make the starter spin faster.

[alan_fincher]

I see you are measuring the voltage across the actual battery terminals when trying to start.  I may have missed whether you have also read the voltage across the starter motor terminals.

 

Any difference must be what is being lost in cables or connectors.

 

I have always understood that ideally one would be delivering at least 10 volts at the motor, (although many engines will of course start on far less).

 

It's interesting if you have bought a so called "multi purpose" battery and it actually has a cold cranking amps figure - I can't recall ever buying a "leisure" battery marked with a CCA figure - pretty certain I have only ever seen it on a straight "starter" battery

[MtB]

1 minute ago, nicknorman said:

Jumping from 600Ah of lithium is certainly going to make the starter go a lot faster, but again not sure what it would prove. Even if everything is in perfect condition, jumping from the Li is always going to make the starter spin faster.

 

It might also cause a really big current to flow initially as the lithiums drag the starter batt up to their voltage.

 

 

[nicknorman]

3 minutes ago, MtB said:

 

It might also cause a really big current to flow initially as the lithiums drag the starter batt up to their voltage.

 

 

No it shouldn’t do. If you raise well charged LA up to 13.3v you wouldn’t expect a big current to flow into the LA.

[Sailbadthesinner]

300A causing Voltage at battery posts to drop to 8 or 9V suggests to me that the battery (if fully charged) is on the way out. I would suggest buying or borrowing a proper car or van starter battery, not a dual purpose or leasure battery. Highest possible CCA. Ah rating much less important.

 

 

Edited December 26, 2023 by Sailbadthesinner

[nicknorman]

6 minutes ago, Sailbadthesinner said:

300A causing Voltage at battery posts to drop to 8 or 9V suggests to me that the battery (if fully charged) is on the way out. I would suggest buying or borrowing a proper car or van starter battery, not a dual purpose or leasure battery. Highest possible CCA. Ah rating much less important.

 

yes I’m inclined to agree. Annoyingly, the battery is less than 2 years old and as a leisure boat only gets infrequent use on an engine that starts easily - and when in the marina it is trickle charged via the Combi.

[Tony Brooks]

Now you have clarified that you were measuring the voltage at the Battery POST it has to be a battery fault or the starter drawing far too many amps. Once spinning I would expect sub 200 amps flow and possibly not much more than 100 amps. measuring at the posts and finding ~8V indicates it is nothing to do with wiring volt drop, UNLESS the wiring volt drop between battery and starter is so bad it limits the cranking speed. That would cause higher than normal starting currant flow, but with 8V at the battery terminals, I would expect something to be smoking. I know the motors are a sod to access on Betas, but try feeling the motor during cranking. It might be warm, but never hot.

 

[Quattrodave]

If you have a decent set of jump leads you could connect battery posts to starter to rule out bad / high resistance wiring.  If you are in the market for a new starter battery goto a decent motor factors and ask for a 'black cab' battery...

Edited December 26, 2023 by Quattrodave