1gm10 Charging problem

[david100952]

My batteries (60 amp start +60 amp house) have gradually discharged through normal usage last year and did not seem to recharge from the motor despite regular 2 hr sessions while motoring down the Exe, necessitating regular intervention with a battery charger from shore power. I have had the batteries tested and they are ok but the reoccurrence this year leads me to suspect there is a problem with the charging system (standard Hitachi 35amp alternator).
I have consulted my Clymer "official manual" which is next to useless in that it outlines several tests but does not suggest any remedy other than replacement of the alternator.
The confusing thing for me is that the "charging warning light" on the engine control panel goes out on the engine control panel as soon as the motor starts which seems to indicate that a charge is being produced. Anyone had any experiences that suggest an alternative to chuck it and buy a new unit?

 

[KenMcCulloch]

Have you measured the voltage at the battery terminals when the engine is running? 2 hours motoring is not a very long time to be recharging a battery that has been discharging for several hours running instruments VHF etc.

 

[halcyon]

My batteries (60 amp start +60 amp house) have gradually discharged through normal usage last year and did not seem to recharge from the motor despite regular 2 hr sessions while motoring down the Exe, necessitating regular intervention with a battery charger from shore power. I have had the batteries tested and they are ok but the reoccurrence this year leads me to suspect there is a problem with the charging system (standard Hitachi 35amp alternator).
I have consulted my Clymer "official manual" which is next to useless in that it outlines several tests but does not suggest any remedy other than replacement of the alternator.
The confusing thing for me is that the "charging warning light" on the engine control panel goes out on the engine control panel as soon as the motor starts which seems to indicate that a charge is being produced. Anyone had any experiences that suggest an alternative to chuck it and buy a new unit?

Typical signs of under charging.

What do you use to charge the second battery bank ? if blocking diodes this is your problem.

If not blocking diodes you need to check voltages at alternator and each battery.

Without voltages you are just guessing.

Brian

 

[Tim Good]

Had a similar issue but it just turned out to be not enough time motoring to accommodate the equipment and it slowly adding up over time. We tightened the belt which have about 0.3v more and have since instated a solar panel.

I was also told that the 1gm10 is so small that is needs to be run are pretty hi revs to get any reasonable charge to the batteries... So if you are like me an
D you like to sail a lot, plus just potter at 3 kts with the engine then likely you're never getting a good charge, 2 hours or not.

 

[Pye_End]

Can you take a voltage reading of the battery before you switch anything on and do anything, and another after you have started the engine (with revs a bit over tickover) and post the results.

How were the batteries tested?

Can you also say what electrics you tend to run - 2 hours charging could be plenty, unless your sailing to motoring ratio is particularly high, or your demand for power is high.

 

[Burnham Bob]

my standard procedure is to spend a night in a marina connected to shore power and make sure the batteries get at least 12 hours charge from the onboard charger. i was always taught that you will never charge a battery fully through the alternator and that a battery charge was the best way to get them up as far as they would go and then the alternator would keep them topped up.

i had a 1GM10 in the old boat but only one battery and expecting it to charge two might be a bit optimistic. take SWMBO somewhere nice where you can enjoy a meal ashore and leave the boat hooked up - she'll never know there's an ulterior motive...........

 

[Pye_End]

i had a 1GM10 in the old boat but only one battery and expecting it to charge two might be a bit optimistic.

Surely it depends rather on how flat the batteries are and how long they need to be charged to replace the lost amp hours rather than how big the battery bank is?

I ran a 1GM10 with 2 * 85 amp hour batteries for 10 years+ with no issues with a 20 minute charge at each end of a sail (in and out marina), plus whatever was needed on passage.

To make the judgement over if there is a fault or whether the mathematics of in/out need to be looked at we need rather more information.

 

[Appledore]

I ran a 1GM10 with 2 * 85 amp hour batteries for 10 years+ with no issues with a 20 minute charge at each end of a sail (in and out marina), plus whatever was needed on passage.
.

Same as me. I have one of those plug-in battery voltage meter monitors which shows about 14.2 volts on engine start-up, and then settles at 13 something whilst motoring. When crossing the Channel -, especially at night, I usually run the engine at quite high revs (as you should!) to re-charge both batteries, and after about 45 minutes they both are fully charged.

 

[rob2]

It is possible that your alternator has a fault, but as others have implied, fixing it will help but your batteries will still slowly discharge without a bit more help. The charge light really only tells you that there is an output from the diode pack, and it is across one pair of diodes, so shold the other pair fail you lose half your output whilst the indicator continues to function. Checking the charging voltages at the battery should show up such a shortfall, though.

Replacement isn't the only option - it's not difficult to unbolt the alternator and take it to an automotive repairer (not "marine" unless your particularly keen on throwing money away..) they're usually a one-man concern working from their garden shed and servicing any garage that hasn't managed to sell you a new unit. They can test and rebuild anything using spare parts - giving you as new performance level at minimal cost.

Rob.

 

[Stemar]

I'd be inclined to measure the voltage at the batteries. If it's less than about 13.2v at the start with the engine running at cruising revs, you've probably got a problem with the alternator. If it's less than 13.2v just after you've turned the engine off after a couple of hours, the batteries aren't getting enough charge, either because the alternator is weak or it just isn't long enough to put everything back. Either run the engine more or get some solar panels. I just fitted a couple of 20w jobs and a dual controller (splits the charge to two batteries) to Jissel and I've spent a couple of weekends with no other input and the batteries have been fully charged when I've come down to the boat. Prices seem to have gone up significantly since I did it, but you should still have change from about £200.

 

[Eygthene]

After similar problems maintaining charge in two batteries with only the 1GM10 and its standard Hitachi alternator and using the engine for quite short periods at the start and end of a passage, I fitted a Sterling Alternator Regulator to the Hitachi and it completely overcame the problems. It was about £100 and I have used it for 10 years with never a problem since.

The Sterling unit increases the charge from the Alternator to charge up the batteries more quickly during the rather short times when the engine is running. If the engine runs for longer the charge reduces once the batteries are charged up.

 

[William_H]

I disagree with much that has been said in that regular 2 hour motoring sessions should keep a battery well charged. Not so l0ong ago most people relied on just engine generator to keep a battery charged both in boat and car without problems. needs to be more than 13.75v
As has been said OP needs to get and use a digital volt meter (multimeter) . The voltage across the battery with engine running will quickly prove if there is a problem. The charge light lighting then going out with engine running might indicate either dead diodes or a wiring problem between alternator and batter. OP could try an extra wire direct alternator big terminal to battery positive. If this improves battery charge voltage then there is a wiring problem. good luck olewill

 

[david100952]

Many thanks to all -
I used a multi-meter and tested the batteries with the switched off and then with the motor running and barely noticed the difference. I am taking the alternator in to an automotive diesel/electrical repairer(not Marine - thanks to fellow frugal sailor!) to bench test, at least if I know the unit is functioning properly I can look at other causes as suggested. If I can get a solution at a reasonable cost I might even take SWMBO to a marina and a meal anyway!

 

[Appledore]

Hi David,

This is what I use (as mentioned previously) :

http://www.ebay.co.uk/itm/Durite-Ba...arts_Vehicles_CarParts_SM&hash=item53f1ca1a06

Plug it into your cigarette lighter socket, and just leave it there. It will show voltage when engine isn't running, and the output when it is running. If the alternator isn't doing its job, you will see the problem immediately. Saves checking the actual batteries with a multimeter all the time. You will also see when it's time to start the engine to re-charge batteries! Much cheaper than one of those posh NASA ones too