"Both batteries must be the same type"?

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popotla

Active Member
Posts
198
Location
Berlin, Germany
In my Defender Td5 110 (2005) I use a Delphi Freedom YOD 100860 (LR original part) as the starter battery. It’s connected to a second battery of the same make and specification via a simple connect/disconnect switch. From #2, I run a fridge, a light and sometimes an inverter.
I want to buy a new starter battery while keeping one Delphi Freedom, at least for the time being, since only one needs replacing. I could get an Enduroline 19001340 (120Ah / 1,000 CCA). This is marketed by Tayna as an equivalent replacement for the Delphi YOD 100860 but is imported from China. I have read of problems with Enduroline and in any case cannot trust it.
I’ve been told that if I’m replacing only one battery, I cannot use, for example, the 610 200 Varta Silver Dynamic. “Both batteries must be the same type, otherwise both will be damaged.” Is this correct? Can I not run, say, this Varta battery or an Excide Excel EB 1100 (110 Ah /850 CCA) (if either of these fit) with an existing Delphi YOD 100860?
Also, I don’t know how “both batteries must be the same type” would fit with the possibility of having, at some future point, a deep-cycle battery for accessories. That would mean they wouldn’t be the same type.
Please advise. Thank you.
 
I think he has what you might call a "manual split charge system" - there is a switch to disconnect the second battery from the first, so that it can be used for suply when the engine is off without flattening both.

I note that if you are towing a caravan and charging the caravan battery via a split charge relay, there is absolutely no requirement for both car and van battery to be the same - in fact they are almost certain not to be, as the van will probably have a deep cycle leisure battery.

I don't know who told you this, but perhaps they just want to sell you 2 batteries?
 
fit a split charger to it.

also if you flatten the second battery then manually connect it, it's going to drain the crap out of the first battery and possible damage it.
 
trax said:
fit a split charger to it.

also if you flatten the second battery then manually connect it, it's going to drain the crap out of the first battery and possible damage it.
Click to expand...

+1, also the same if the split charge relay is connected to the alternator light.
 
I think he has what you might call a "manual split charge system" - there is a switch to disconnect the second battery from the first, so that it can be used for supply when the engine is off without flattening both.

That is correct. The fridge is permanently connected to the second battery, which I disconnect from the first when parked (even for a short time). When driving I always have the two connected.

The system has worked for me and I'm reluctant to change it to split-charging. (When I had this work done, about six years ago, I thought I was getting a split charging system but didn't properly understand the matter and nor, I think, did the people who did the work.)

also if you flatten the second battery then manually connect it, it's going to drain the crap out of the first battery and possible damage it.

trax, I don't understand this (probably me that's thick). If the second battery is flattened, it is in any case (unless I forget) disconnected from the first, so wouldn't be draining the first. But then when I reconnect them, the second will recharge OK. Won't it?

Tayna batteries told me the following (quote):

Thank you for your response. You can only use the Varta I1 battery if you are replacing both, if you are replacing one battery then you will have to use the YGD100860 Enduroline. Failing to do so will damage both batteries.
 
when 2 batteries are connected together they try and equalise any current drain, so if either one is in a worse state than the other, then it will try and draw power from the stronger one. That will load the stronger one weakening it.

always fit two batteries of the same type, CCA and age.
 
popotla said:
I think he has what you might call a "manual split charge system" - there is a switch to disconnect the second battery from the first, so that it can be used for supply when the engine is off without flattening both.

That is correct. The fridge is permanently connected to the second battery, which I disconnect from the first when parked (even for a short time). When driving I always have the two connected.

The system has worked for me and I'm reluctant to change it to split-charging. (When I had this work done, about six years ago, I thought I was getting a split charging system but didn't properly understand the matter and nor, I think, did the people who did the work.)

also if you flatten the second battery then manually connect it, it's going to drain the crap out of the first battery and possible damage it.

trax, I don't understand this (probably me that's thick). If the second battery is flattened, it is in any case (unless I forget) disconnected from the first, so wouldn't be draining the first. But then when I reconnect them, the second will recharge OK. Won't it?

Tayna batteries told me the following (quote):

Thank you for your response. You can only use the Varta I1 battery if you are replacing both, if you are replacing one battery then you will have to use the YGD100860 Enduroline. Failing to do so will damage both batteries.
Click to expand...

The Mad Hat Man said:
when 2 batteries are connected together they try and equalise any current drain, so if either one is in a worse state than the other, then it will try and draw power from the stronger one. That will load the stronger one weakening it.

always fit two batteries of the same type, CCA and age.
Click to expand...

yup, the battery holds current. when you drain it by running your fridge and then reconnect it it tries to pull in current from anywhere it can.

not quite, but think of having two buckets of water connected at the bottom by a pipe with a valve and a slow trickle flow of water filling one bucket from a hosepipe.

as some water is used from a bucket, the level over both drop and slowly rises as the slow trickle fills it back up.

you decide to have a shower, so turn the valve connecting the buckets off, stopping the flow of water. you use all the water in the second bucket and then open the valve to refill it.

the slow hosepipe trickle can't fill it fast enough, so the water from the first bucket flows into the second until they are now both level and half full.

wow, that seems a lengthy analogy.. but that's kinda how it works. your alt is the slow trickle..
 
That would mean, Mad Hat Man, that where two batteries are fitted, one of which needs replacement and one of which is still good, the good one would also have to be ditched.

Also, if two batteries of "the same type" must be fitted, that implies two starter batteries or two deep-cycle batteries, for example, rather than one of each.

When the two batteries (in my set-up) are connected, both are being charged, presumably. Under these circumstances, I don't know if "weaker drawing power from the stronger" is the case. When the two batteries are disconnected, neither can draw power from the other.

I suggest that the circumstance I'm seeking advice about depends on facts (what are the facts of the case?) rather than "maybe" // opinions. But there are wiser and more knowledgeable people than me out there on the forum. That's why I'm asking.
 
As long as both batteries are of the same sort of specification, you will not have a problem.
It's a nice idea to have them both the same, but in reality, there is no reason why you should change both batteries when one dies.

There is a caveat or two.
Both batteries must be of similar specifications and type.

For example, they should be similar capacities - having a 5ah and a 105ah could lead to charging the smaller battery too quickly ( too high a current) if it is completely discharged and then connected to a healthy big battery.

Quite obviously, they should be lead acid batteries with the same charging voltage ( pretty obvious really). Don't have one battery lead acid, and the other ni-cad, for example.

As they are both "car" batteries of similar capacities, and the same charging voltage, you will not have a problem.

If you have 2 batteries in series for 24 volts, then they really should be the same capacity, otherwise, in a discharge state, the lower capacity battery will be damaged by reverse charging by the larger battery... For the same reason the age should be the same. This is. Probably what the battery manufacturer was thinking.
 
captainbeaky said:
As long as both batteries are of the same sort of specification, you will not have a problem.
It's a nice idea to have them both the same, but in reality, there is no reason why you should change both batteries when one dies.

There is a caveat or two.
Both batteries must be of similar specifications and type.

For example, they should be similar capacities - having a 5ah and a 105ah could lead to charging the smaller battery too quickly ( too high a current) if it is completely discharged and then connected to a healthy big battery.

Quite obviously, they should be lead acid batteries with the same charging voltage ( pretty obvious really). Don't have one battery lead acid, and the other ni-cad, for example.

As they are both "car" batteries of similar capacities, and the same charging voltage, you will not have a problem.

If you have 2 batteries in series for 24 volts, then they really should be the same capacity, otherwise, in a discharge state, the lower capacity battery will be damaged by reverse charging by the larger battery... For the same reason the age should be the same. This is. Probably what the battery manufacturer was thinking.
Click to expand...

don't agree.

batteries don't maintain the same performance over their lifetime.

by sticking a new one with the old, then the old will drain the new and batter it, shortening its lifespan.
 
You are correct, older battery will have deteriorated more than the new one.
So it will give fewer amps at cranking - but at cranking, BOTH batteries are feeding the starter - so the imbalance has no ill effect.

While charging, the old battery might take a little longer to charge, as battery impedance increases with age, - so what?
The newer battery will charge quicker, and if they are left connected once the engine is switched off, the charge will rebalance over a period of time.

"The old one will drain the new one and shorten it's lifespan"

If the "old battery is discharging the new one" to the extent that it is shortening the life of the new one, then the old battery is a dead one and needs to be changed.

In reality, what is more likely is that the pair of batteries are both at the end of their lives ( if they were bought as a matched pair) and if one has failed, then the second will follow soon.
 
If you are talking about 24v twin batteries, then that is a different story - an older battery would not charge at the same rate ( in terms of actual energy stored for a given charge rate and time) and imbalances set in between the two batteries in the 24v stack.
That is why it's best to charge two 12v batteries separately in a 24v stack.

My old 101 had 5 batteries.
Two pairs of 12v batteries, providing main and standby 24v stacks, both charged by seperate outputs of the 2kva alternator, and could be switched in and out as needed, or paralleled to boost starting.
And a single 12 v battery for the cb standby.
I had 5 trickle chargers to keep them all charged up, and never had an " old battery pulling down a new one"
Batteries failed one at a time, usually the oldest first.
 
In the application that is discussed here, adding a split charge relay would ensure that the aux battery is always charged when the engine is running, is always disconnected when the engine is not running, and you maintain the ability to parallel the batteries together if your main battery dies.

It identical to the setup on my camper.
 
popotla said:
An odd reply. Is that your normal way of dealing with discussion?
Click to expand...

Discussion? You asked a question. I answered it. No discussion.

If you don't want to accept it, that's fine by me. I have no obligation to help you. You decide if you don't want to accept it. Unless you need to ask your mummies permission. :rolleyes:
 
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