New Batteries, SOC, squealing belts

arf145 · Nov 30, 2015

You don't say what kind of engine you've got. Single cylinder? So are you saying you hooked the two new batteries together in parallel (positive to positive, neg to neg) without any other batteries hooked up? Depending on the engine, I would have thought even at 12.5 a battery would start it. And BTW, batts don't come from the store fully charged. It depends on how long they were sitting around. I like to take a voltmeter with me.

Ron20324 · Nov 30, 2015

I bought three of those batteries from Sams. I made a point of looking at the sticker when they were made, so as to get the freshest ones all the same age (months).

Benny17441 · Nov 30, 2015

First of all a voltage reading taken immediately after a battery has been subject to a load will show a lower figure than actual. At 12.5V a battery is 90% charged and at 12.3V it is 70% charged thus allowing for these being lower readings than actual your batteries would still have more than adequate capacity to start a small diesel. Diesel engines burn fuel by compression and at startup they build up compression by repetitive cranking strokes. If the engine cranks too slow it does not build up adequate compression to heat the fuel to its combustion temperature and as a result fails to start. ( some engines have an electrical heating element to help them start) If your engine is turning too slow it is likely bad or dirty connection(s) or a bad starter with worn brushes or bushings. Since you report belt screeching it raise the possibility of a frozen alternator which does not allow the engine to turn freely. In extreme cold temperatures the thickness of the oil may also cause slow turning. To find out what is causing the slow cranking I would first remove the alternator belt and crank the engine. If it starts readily and runs well then replace the alternator. If it does not start and the alternator turns freely by hand then install the belt back and properly tighten it. You have not solved the problem but the belt should screech no more. Now check all the connections and cables of the high current circuit going to ground and the starter. If they are all clean and tight and still experiencing a problem then remove the starter and take it to an electrical shop to have it checked. It might not be a bad idea to have it cleaned and new brushes and bushings installed. Batteries do not come charged and should be charged prior to installation. good luck.

DougM · Nov 30, 2015

I would never count on a battery being fully charged at the time of purchase unless it had been slow charged by the seller.. That said, a new battery should be charged enough off the shelf to at least start the engine.

As for the squaling belts, it seems like they may be loose, or the alternator has seized up.

Benny17441 · Dec 1, 2015

cbourne200 said:
Westerners 10-2 diesel.

Squealing belts could be explained by one/other being seized. Starter problem would explain why new batteries only turned motor slowly. Turned water pump small amount, but didn't try alternator. Which way is rotation?.

Don't know your engine, it does not matter as all you be looking for is whether the alternator has seized or not. Take off the belt and with the key switch off just turn the pulley to the alternator back and forth by hand. If it is frozen or seized it will hardly move but if it turns freely it should not be the reason for the squealing. A wet cell battery is considered fully charged at 12.67 V and voltage readings are more accurate when taken with the battery at rest (no charge, no loads) for at least two hours. Fully discharged is considered at 10.5V. New batteries should be fully charged and then put through a couple of slow discharge cycles to help them attain maximum capacity.

Maine Sail · Dec 1, 2015

A Westerbeke 10-2 can be started off a lawn and garden battery quite easily. Two batteries wired in parallel are cake walk for a Westy 10-2. Something is wrong.

Be sure to clean ALL battery cable terminations including engine ground lug, starter positive lug, engine ground point, at busbars etc. etc... Test that the water pump and alternator spin easily. If they do and all connections are clean then the problem is likely the starter. Also be sure the engine turns over by hand and a breaker bar can be used for this. It is always possible it has become hydrolocked..

Benny17441 said:
A wet cell battery is considered fully charged at 12.67 V and voltage readings are more accurate when taken with the battery at rest (no charge, no loads) for at least two hours.

Resting voltages for accurate OCV readings can easily take 24 or more hours especially after a charging episode. After sufficient discharging it can still take multiple hours to reach a steady resting voltage. The colder the batteries the longer this an OCV reading takes..

As for an OCV (open circuit voltage), for a full battery, that depends upon the specific manufacturer. Trojan for example is 12.73V fully rested at 80F to = 100% SOC. Most others are right in the 12.72 -12.73 range these days. If you set the bar on Trojans at 12.67V you will be under charging them. When each 0.1V difference in OCV represents approx 10% of the batteries Ah capacity even 0.06V difference means the difference between approx 95% full and 100% full. AGM & GEL batteries will rest significantly higher than most flooded batteries. I have about 8 to 10 AGM's in my shop now all at well over 13V after many weeks off charge...

Benny17441 said:
Fully discharged is considered at 10.5V.

10.5V as dead is only during a 20 hour capacity test at the 20 hour rate or during a reserve minutes test at 25A. The resting rebound OCV, after a full 10.5V capacity test, will be around 11.4V +/-. If you discharge a battery to a resting voltage of 10.5V you will have gone well beyond 0% SOC to do so and can severely damage the battery. For Trojan batteries 11.51V rested at 80F is 10% of capacity and from experience on my test bench this can range anywhere from 11.36V to 11.44V as 0% SOC this after a 20 hour rate, 10.5V capacity test. AGM batteries will rest higher at about 11.66 to 11.72 after a 20 hour rate 10.5V discharge capacity test.

Benny17441 said:
New batteries should be fully charged and then put through a couple of slow discharge cycles to help them attain maximum capacity.

Absolutely flooded batteries take a long while to cycle up to full usable capacity. Many boaters will never even get to rated capacity before damaging them due to chronic undercharging and sulfation. For commissioning new flooded batteries, especially series batteries, I push the voltage to 15.5V (temp compensated) for about 2 hours before installation and then do a number of discharges to 12.1V, under load, and follow that with a full 100% recharge. Customers can do this on their own too but they rarely do...

mitiempo · Dec 1, 2015

cbourne200 said:
Ran below to find pump not turning.

Engine started so easily w/o pump/alternator being driven from engine makes an electric pump seem like a good idea. Has anyone done this and what problems/advantages can I expect?

I don't believe a diesel exists with an electric water pump. They are all either belt driven or gear driven. The faster the engine runs the more water the pump pumps.

If your pump is seized it can be rebuilt - probably needs a new bearing, and an impeller change is probably a good idea as well. Worth re-building as they can be expensive.

mitiempo · Dec 2, 2015

There are only 4 engine water pump manufacturers - Jabsco, Johnson, Sherwood, and Oberdorfer.

Here are some possibilities: https://www.marineparts.com/partspages/pumps/ENGINES/WESTERBEKE.HTM