Engine Cranking Battery

Electrical and electronic topics for small boats
jimh
Posts: 2312
Joined: Fri Oct 09, 2015 12:25 pm
Location: Michigan, Lower Peninsula
Contact:

Engine Cranking Battery

Postby jimh » Tue Jan 10, 2017 1:50 pm

WHAT TO BUY

I am in the market for a new cranking battery to start my 225-HP outboard engine. The engine specifications call for a battery with a rating of 1,000-MCA. For several years the engine cranking battery on my boat was an INTERSTATE BATTERY model 24M-XHD. See the specifications at

http://www.interstatebatteries.com/p/interstate-batteries/interstate-batteries-24m-xhd-24m-xhd

The INTERSTATE 24M-XHD can deliver 1,000-Amperes of cranking at the usual marine rating of 32-degrees-F (the "marine cranking Ampere or MCA rating.) That is a very substantial amount of cranking Amperes, and just about any outboard engine should be able to be cranked over and started with this battery. The 24M-XHD is a BCI case size Group 24, so it fits in practically any battery box, including the classic Desert Tan Boston Whaler OEM battery boxes. One of the more outstanding features of the INTERSTATE 24M-XHD is the price: only $118 at retail from an Interstate store or dealer. In these days of 12-Volt batteries that cost $250 to $400, the 24M-XHD looks like a bargain.

The 24M-XHD is a classic lead-acid, vented, flooded-cell battery. There should not be any problems charging this battery from an outboard engine with the usual simple charging output with only voltage regulation. The only disadvantage of vented batteries is the electrolyte level may become low, either due to evaporation or perhaps from over-charging, but cells can be easily refilled with distilled water to replace any lost electrolyte.

If you want to avoid having to worry about checking the electrolyte level, a sealed battery will eliminate that chore. In the INTERSTATE line there are sealed batteries with absorbed glass mat (AGM) construction that have a rating of 1,000-Amperes of cranking. The model 34M-AGM battery is rated for 1,000-Amperes. See the specifications at

http://www.interstatebatteries.com/p/interstate-batteries/interstate-batteries-34m-agm-34m-agm?dsNav=N~4165663998-2147384903

The AGM construction comes at a price; this battery retails for $300. That is almost three times the price of the 24M-XHD.

For the last six years my outboard engine has been getting cranked over by a SEARS DIEHARD PREMIUM MARINE battery, a very nicely rated AGM battery that used to sell for about $220 and was often on-sale at a reduced price, sometimes as low as $180. This battery was widely believed to be a private-label version of the ODYSSEY AGM battery, which sold for a higher price. Unfortunately, it appears that the arrangement SEARS had with ODYSSEY to sell their AGM battery at a substantially lower price must have ended, and SEARS no longer offers that product.

I believe the equivalent product from ODYSSEY is labeled as their 34M-1500 battery. That battery is rated for 1,050-Amperes. The specification can be found at

http://www.odysseybattery.com/marine_battery_specs.aspx

The ODYSSEY 34M-1500 has a retail price of $302. (See http://shop.odysseybattery.com/p/34m-pc1500st) This model has dual terminals; it has the usual automotive posts, and it has 3/8-inch positive and 5/16-inch negative threaded SS stud terminals.

If you don't need the dual terminals, there is a less expensive version with only the automotive type posts, the 34-PC1500T that sells for $276. If your boat is rigged with conductors for terminal posts--as mine is--the extra $26 for the marine version will be a good investment.

Both the ODYSSEY batteries are BCI Group 34, which will fit in a standard battery box, but the battery is not as tall. To compensate you can buy a plastic riser plate for $4. See http://shop.odysseybattery.com/p/spacer-for-group-34-batteries?referring_products=%7Cdfaf9aed24f729642a834e76f380e305

WHERE TO BUY

Distribution of INTERSTATE flooded cell batteries is a bit of a problem because they cannot be shipped. You have to go to a dealer and buy the battery. Presumably INTERSTATE delivers the batteries to their dealers on their own trucks, as I doubt you can ship a flooded cell battery with electrolyte in the cells by any common carrier. Finding a dealer can be a problem, particularly for a marine battery. Generally the INTERSTATE marine batteries are sold at marine stores--that's where I first found out about the 24M-XHD, at my own marine dealer. They are also sold through many automotive shops, but I suspect it might be hard to get a marine battery from a place like Midas Muffler, an INTERSTATE dealer.

I recently discovered that INTERSTATE has their own retail store in my area, just a short distance away, and I can walk in and buy the 24M-XHD battery from them at the retail price and during some promotion periods, like during parts of Spring when boaters are fitting out, at an even lower price.

ODYSSEY sells their batteries on their shopping website. The prices include free shipping in most instances. This is one of the great advantages of the AGM construction: the vendor can ship the battery to you. The shopping site includes a possibility to enter promotion codes, so there might be a promotion or discount available at some times. ODYSSEY batteries are also sold by dealers with retail stores, like BATTERIES+BULBS.

Curiously, I just tried to find the ODYSSEY 34M-1500 at BATTERIES+BULBS. In that search I came across their house-branded X2 battery, model SLI34AGMDPM. The specifications and appearance are quite similar to the ODYSSEY or SEARS batteries, and the price is more attractive, about $235, or around the price that the SEARS version was selling at when not on promotion. Compare at

https://www.batteriesplus.com/battery/marine-and-boat/starting/bci-group-34m/sli34agmdpm

The specifications only give cold-cranking Amperes (at 0-degree-F or CCA rating), but with 880-CCA that is generally the equivalent of 1,000-MCA.

BATTERIES+BULBS does sell the OYDESSY 34M-1500ST battery, but their price is a bit higher, $346 retail. See

https://www.batteriesplus.com/battery/marine-and-boat/starting/bci-group-34m/heppc1500mst

MY NEXT BATTERY

This spring on my boat the SEARS-ODYSSEY battery will on its eight season of use, and I will probably demote it to the house battery, and look for a new battery for engine starting. Right now the first-place candidate is the INTERSTATE 24M-XHD. I like the price. Because of its location in my boat, to check electrolyte level and add distilled water is not very difficult, so I don't see a problem with the flooded-cell vented design. Now that I have found a dealer just a few miles away, I can easily get this battery. (My marine dealer that sold me the original one about ten years ago no longer carries INTERSTATE.)

Next in line would be that house-brand X2 version of the ODYSSEY. It is about double the price of the flooded-cell battery, but I may talk myself into spending more to stay with the sealed AGM construction.

If readers have any alternative suggestions for a good quality, good price cranking battery rated at 1,000-MCA, please mention your choice in a reply to this thread.

Tom Hemphill
Posts: 10
Joined: Fri Oct 16, 2015 5:04 pm

Re: Engine Cranking Battery

Postby Tom Hemphill » Tue Jan 10, 2017 6:06 pm

If you can't easily get the Interstate battery you describe, based on personal experience I recommend NAPA Auto Parts 8304 Marine Starting Battery -- Group 24M 800 CCA (1000 MCA), currently offered for $108.

RichS
Posts: 1
Joined: Wed Oct 21, 2015 11:33 pm

Re: Engine Cranking Battery

Postby RichS » Tue Jan 10, 2017 7:32 pm

I purchased two Exide Edge FP-AGM24DP AGM batteries for my 1988 Outrage 18 with a new Suzuki 140 and paid $150 each (free shipping) from LM Fleet Supply. I see they are out of stock now, but they are available from others for a little more. Rural King has what I believe is the same battery with their own label for $130 in store only. They are dual purpose, so they can be deep-cycled. The trade-off is that they have a little lower MCA rating of 930-Amperes.

I haven't installed them yet so can't comment on performance, but they do get good reviews. They'll be installed with a Blue Sea Add-A-Battery kit.

porthole
Posts: 448
Joined: Tue Oct 27, 2015 9:57 pm
Location: Jersey Shore

Re: Engine Cranking Battery

Postby porthole » Tue Jan 10, 2017 9:10 pm

My local Costco carries Interstate. My curiosity will have me check to see what they have in marine battery choices.

So Jim, are you to run a new battery along with an 8 year old battery on the same charging system?
Thanks,
Duane
1999 Outrage 21
1999 Yamaha SW Series II 200

jimh
Posts: 2312
Joined: Fri Oct 09, 2015 12:25 pm
Location: Michigan, Lower Peninsula
Contact:

Re: Engine Cranking Battery

Postby jimh » Wed Jan 11, 2017 7:18 am

ASIDE to PORT' on the sidebar topic of having batteries of different types or ages in the primary power system of a boat:

I don't worry about mixing two batteries of different age. The boat's outboard engine (2010 E-TEC 225) has two charging outputs, main and auxiliary, and the boat's two batteries are not wired in parallel, except in an emergency to start the engine. (I gave more details on the primary power distribution wiring, battery charger wiring, and fuse and circuit breakers in an earlier article.)

The outboard engine on my boat is typical of outboard engines: its battery charging output is just regulated to a particular voltage, and the engine tries to maintain that voltage at the charging output. The amount of current that will flow is determined by the load on the charging output, that is, by the battery, its state of charge, and its ability to accept charging current. Each output has roughly 25-Amperes of current available.

The HOUSE battery on my boat for the last four years has been a big 78-Ampere-hour AGM battery. That battery was probably four-years-old when I put it on the boat. It came out of a big uninterruptible power supply (UPS) that had 40 batteries (in series). When we are on a cruise we might be seven to ten days without shore power. I want to be sure the engine can start in the morning.

jimh
Posts: 2312
Joined: Fri Oct 09, 2015 12:25 pm
Location: Michigan, Lower Peninsula
Contact:

Re: Engine Cranking Battery

Postby jimh » Wed Jan 11, 2017 7:28 am

RichS wrote:I purchased two Exide Edge FP-AGM24DP AGM batteries for...$150 each (free shipping) from LM Fleet Supply.


I see the Exide Edge FP-AGM24DP Flat Plate AGM Sealed Marine Battery on Amazon at $205

https://www.amazon.com/Exide-FP-AGM24DP-Sealed-Marine-Battery/dp/B00HAIGJF0

At $150 they'd be quite attractively priced.

jimh
Posts: 2312
Joined: Fri Oct 09, 2015 12:25 pm
Location: Michigan, Lower Peninsula
Contact:

Re: Engine Cranking Battery

Postby jimh » Wed Jan 11, 2017 7:31 am

Tom Hemphill wrote:...based on personal experience I recommend NAPA Auto Parts 8304 Marine Starting Battery -- Group 24M 800 CCA (1000 MCA), currently offered for $108.


That looks like a nice option. Here is the link to the on-line store:

https://www.napaonline.com/p/NBD8304

jimh
Posts: 2312
Joined: Fri Oct 09, 2015 12:25 pm
Location: Michigan, Lower Peninsula
Contact:

Re: Engine Cranking Battery

Postby jimh » Wed Jan 11, 2017 7:38 am

Generally the price of the battery is quoted without the "core charge" or the deposit you pay for the lead in the battery to encourage you to recycle it. Some retailers have a core charge of $18. I usually keep at least one extra lead-acid battery around so I can use it as the "core charge" exchange core. I remember when the core charge was $4.

If you buy a battery on-line and have it shipped to you, I don't think you can avoid the core charge; it must be built into the battery price. You really can't exchange an old core for a new one if buying on-line and receiving the new battery by direct shipment. That extra cost--perhaps $18 now--is a consideration for buying the battery at an actual brick-and-mortar store, or at least to pick-up the battery at a real store and exchange the core with them.

alloyboy
Posts: 23
Joined: Thu Dec 24, 2015 8:15 pm

Re: Engine Cranking Battery

Postby alloyboy » Wed Jan 11, 2017 1:37 pm

Any opinions as to why the MCA rating is as high as it is?

A starter motor normally draws about 200 peak amperes or less. The Etec apparently needs about 1000 watts (83 amps at 12 volts or 18 amps at 55 volts) to operate itself on so why the battery requirement being what it is?

Anyone care to speculate?

jimh
Posts: 2312
Joined: Fri Oct 09, 2015 12:25 pm
Location: Michigan, Lower Peninsula
Contact:

Re: Engine Cranking Battery

Postby jimh » Wed Jan 11, 2017 6:24 pm

alloyboy wrote:A starter motor normally draws about 200 peak amperes or less.


That is a very interesting value for the "normal" "peak" draw of a starter motor. Where did you come up with it?

Did you measure it?

If so, can you explain the instrumentation you used and the technique? I would be interested in knowing where your data comes from.

I have measured the peak DC Amperes of the starter motor of a four-cylinder 2.5-liter automobile engine. About 350-Amperes peak current during cranking was typical. I measured with a FLUKE clamp-on DC Ammeter. This engine has a larger diameter flywheel than the typical outboard engine, so I suspect the gearing of the starter may make it easier to turn the flywheel.

jimh
Posts: 2312
Joined: Fri Oct 09, 2015 12:25 pm
Location: Michigan, Lower Peninsula
Contact:

Re: Engine Cranking Battery

Postby jimh » Wed Jan 11, 2017 6:40 pm

alloyboy wrote:Any opinions as to why the MCA rating is as high as it is?


I recommend you contact Evinrude to discover why they have established the ratings they have.

You can find the recommendation for Evinrude in their rigging guide. For the larger engines, 115 to 300-HP, it specifies a battery rated at 845-MCA for normal service and 1,000-MCA for service in weather below 32-degrees. In my case, I chose to conform to the higher recommendation.

Have you made a survey of other outboard engine brands to compare with Evinrude to see if there is much difference in the ratings of the battery? I know that the Brunswick outboard model called Mercury VERADO has quite specific requirements for its battery, including that it must be of a certain type (an AGM lead-acid). I don't recall the required MCA rating, but I am sure it is substantial since the VERADO cannot operate at all without a battery and is somewhat notorious for having problems running at low speeds if the attached battery is not up to proper voltage.

The Evinrude outboard engine is unique among all the larger horsepower outboard engines of any brand in that it can be started with a pull rope and can run without a battery. It does not need a battery at all, other than to crank it over for electric starting. Evinrude engines have had, for many years, a minimum engine cranking speed, I think 300-RPM, before the engine will create spark and try to start.

jimh
Posts: 2312
Joined: Fri Oct 09, 2015 12:25 pm
Location: Michigan, Lower Peninsula
Contact:

Re: Engine Cranking Battery

Postby jimh » Wed Jan 11, 2017 7:32 pm

alloyboy wrote:The [E-TEC] apparently needs about 1000 watts...to operate itself...


Have you measured the power consumption of the E-TEC? I would like to know the way you measured that power.

I think you are making an inference based on the notion the alternator can produce 1,700-Watts and dedicates about 725-Watts (or more) for battery charging. But you must take into account that the electrical load of the engine depends on the engine speed, and higher engine speeds will require higher electrical power, principally to run the injectors and fuel pumps at higher duty cycles. But all of that power is generated in the E-TEC itself, and has no influence on the Ampere rating of the battery. Once the E-TEC is started, it can run without a battery; this is evidence that the battery is not necessary to power the engine. I seriously doubt an E-TEC running at idle is consuming a kilowatt to operate its electrical system.

jimh
Posts: 2312
Joined: Fri Oct 09, 2015 12:25 pm
Location: Michigan, Lower Peninsula
Contact:

Re: Engine Cranking Battery

Postby jimh » Wed Jan 11, 2017 7:54 pm

ASIDE: a practical method to measure the DC current flow in a circuit, particularly when the DC current will be the range of hundreds of Amperes, is to use a Voltmeter to measure the voltage drop in a segment of the circuit whose resistance is know with fair accuracy. The method is simple; let's use a circuit with high current flowing through 10-feet of 4-AWG carrying power from the positive terminal of the battery to the starter solenoid of an engine:

--measure the voltage drop (E) in the wire segment during engine cranking;

--find the resistance-per-100-feet of 4-AWG from a table; (a good table is found at http://www.powerstream.com/Wire_Size.htm

--multiply the resistance value by the length divided by 1000 to find resistance (R) ;

--deduce the cranking current (I) from Ohm's Law: I = E/R

Here is the example problem worked out to find current:

--4-AWG has a resistance of 0.2485/1000-feet

--a 10-foot length of 4-AWG will have a resistance of 0.2485 x 10/1000 = 0.002485-Ohms

If we attach a Voltmeter between the two ends of the 4-AWG conductor with a peak-hold function, and crank over the engine, we might see a peak voltage drop across the conductor of, say, 0.666-Volts.

Now we compute the current from the two values:

E = 0.66-Volt
R = 0.002485-Ohms
I = E/R = .66/0.002485-Ohms = 266-Amperes

An alternative method is to measure with a clamp-on DC Ammeter. A FLUKE 374 is a typical choice; it sells for about $300.

Note that in the above example, there would also be another 10-feet of 4-AWG carrying the negative circuit back to the battery. There would also be the same voltage drop in that conductor, giving a total voltage drop of 1.33-Volts. That is more than ten-percent of the typical full-charge battery voltage of 12.7-Volts, so this sort of rigging results in quite a bit of power lost in the resistance of the conductors.


Return to “SMALL BOAT ELECTRICAL”

Who is online

Users browsing this forum: No registered users and 1 guest